Comparative Tooth Anatomy

description© of Jones each & Bartlett type ofLearning, tooth LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION in an adult and in a child.

9781284218251_CH01_001_048.indd 1 25/03/20 4:22 PM © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 2 25/03/20 4:22 PM © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Basic Terminology for © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 1 NOT FORUnderstanding SALE OR DISTRIBUTION ToothNOT FOR SALE OR DISTRIBUTION CHAPTER CHAPTER Morphology © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

The background terminology and tooth morphology concepts presented in this chapter are divided into 10 sections © Jones & asBartlett follows: Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION I. Naming teeth based on location within the F. Divisions (thirds) of the crown or root (for normal, complete human dentition purposes of description) A. Complete primary dentition G. Root-to-crown ratio B. Complete permanent dentition VI. Terminology used to describe the morphology II. Tooth identification© Jones systems: & Bartlett Universal, Learning, orldW LLCof a tooth © Jones & Bartlett Learning, LLC Dental FederationNOT (International), FOR SALE and OR Palmer DISTRIBUTION A. Morphology of an anatomicNOT crown FOR SALE OR DISTRIBUTION Numbering Systems B. External morphology of the anatomic root C. Cervical line (cementoenamel junction or CEJ) III. Terminology used to describe the tissues of a curvature tooth (and definition of anatomic crown and root) D. Relative size IV.© Introduction Jones & Bartlettto the periodontium Learning, (and LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION VII. TerminologyNOT FORrelated SALE to the idealOR DISTRIBUTION tooth definition of clinical crown and root) alignment of teeth in dental arches V. Terminology used to define tooth surfaces A. Midroot axis line and tooth alignment A. Terms that identify outer surfaces (toward the B. Crest of curvature (height of contour) on the facial cheeks or lips) of anterior versus posterior teeth and lingual surface © Jones & BartlettB. Terms Learning, that identify LLCinner surfaces (toward the © JonesC. & Contact Bartlett areas Learning, (or proximal crestsLLC of curvature) NOT FOR SALE tongue)OR DISTRIBUTION of maxillary versus mandibular teeth NOT FORD. EmbrasureSALE OR spaces DISTRIBUTION C. Terms that differentiate biting surfaces of anterior VIII. Ideal occlusion: inter (between) arch versus posterior teeth relationship of teeth D. Terms that differentiate approximating surfaces of teeth IX. Tooth development from lobes E. Terms to denote© Jonestooth surface & Bartlett junctions orLearning, LLC X. Interesting variations in© animal Jones teeth & Bartlett compared Learning, LLC dimensions NOT FOR SALE OR DISTRIBUTIONto human teeth using dentalNOT formulaeFOR SALE OR DISTRIBUTION

OBJECTIVES © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ThisNOT chapter FOR is designed SALE to OR prepare DISTRIBUTION the learner to perform the following: NOT FOR SALE OR DISTRIBUTION • Based on location in the normal, complete primary • Based on location in the normal, complete permanent dentition, name all 20 teeth by arch, quadrant, type dentition, name all 32 teeth by arch, quadrant, type (when applicable), and class. (when applicable), and class. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (Continued ) 3

9781284218251_CH01_001_048.indd 3 25/03/20 4:22 PM 4 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC • Use the Universal Numbering System to identify NOT• FORDescribe SALE and identifyOR DISTRIBUTION (by name) common tooth NOT FOR SALEpermanent OR DISTRIBUTION and primary teeth. rounded elevations, ridges, depressions, and grooves • Use the Palmer and International Tooth Numbering for each type of tooth. Systems to identify teeth, and “translate” them to the • Describe and recognize the parts of a root. Universal System. • Describe and identify the attributes of ideal tooth • Identify and describe© Jones the supportive & Bartlett structures Learning, of the LLCalignment and embrasure spaces© Jones relative & to Bartlett other Learning, LLC teeth (periodontium).NOT FOR SALE OR DISTRIBUTIONteeth within the arch, includingNOT the FOR cusp or SALE incisal OR DISTRIBUTION • Identify and describe the four tissues of a tooth and edge position relative to the tooth’s midroot axis line their location, mineral content, and function. (proximal views), location of crests of curvature and • Differentiate an anatomic crown and root from a proximal contacts (facial or lingual views), and relative clinical crown and root. sizes of embrasure spaces (facial, lingual, or occlusal/ © Jones & Bartlett Learning, LLC incisal views).© Jones & Bartlett Learning, LLC • Name each tooth surface on anterior and posterior NOTteeth. FOR SALE OR DISTRIBUTION • Describe NOTand identify FOR the SALE ideal interarch OR DISTRIBUTION relationship of teeth in class I occlusion, especially the relationship of • From all views, divide a tooth crown and root into first molars and canines. thirds and label each third. • Identify the number of developmental lobes that form • Define terms used to describe a specific dimension of each tooth, and recognize the anatomic landmarks of a a tooth. © Jones & Bartlett Learning, LLC © Jonestooth & thatBartlett form from Learning, these lobes. LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Just as you need to learn a new vocabulary before you can understood when discussing teeth. Do you comprehend speak a foreign language, you need to learn a new vocabulary what is meant when someone says “In ideal class I occlusion, before you can begin to understand the “foreign language” the mesiobuccal cusp of the maxillary first molar occludes of dental anatomy. Therefore,© Jones you &need Bartlett to understand Learning, each LLCwith the mesiobuccal groove of© the Jones mandibular & Bartlett first molar”? Learning, LLC new word defined in thisNOT introductory FOR SALE chapter OR (highlighted DISTRIBUTION If not, study each term in this chapter,NOT FOR carefully SALE analyze OR each DISTRIBUTION in bold) in order to be able to discuss and appreciate the figure when it is referenced, perform all of the learning exer- numerous traits that differentiate each type of tooth that are cises, and answer each study question. Then you should be presented in the next five chapters. Without this understand- able to comprehend and picture exactly what was said in that ing, you can neither understand others nor make yourself statement. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

NAMING TEETH BASED ON LOCATION WITHIN THE NORMAL, SECTION I COMPLETE HUMAN DENTITION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION This section is designed to introduce you to terms used when dentition has five teeth in each quadrant. The primary teeth naming teeth based on their normal location in the mouth. All in each quadrant are further divided into three classes based of the teeth in the mouth together are referred to as our denti- on their unique shape and function during chewing. Incisors tion [den TISH un]. Humans have two sets of teeth through- [in SI zerz] are shaped to incise and cut off pieces of food, out life: one during childhood,© Jones called & the Bartlett primary Learning,dentition, LLCcanines are shaped to pierce and© holdJones on to & food, Bartlett and molars Learning, LLC and one that will hopefullyNOT last FOR throughout SALE adulthood, OR DISTRIBUTION called are shaped to grind food. StartingNOT on FOR either SALEside of the OR arch DISTRIBUTION the permanent (also known as secondary) dentition. midline, that is, the demarcation between the right and left The teeth in the upper jawbones (called the maxillae [mak quadrants, the two front teeth in each quadrant of the pri- SIL ee]) collectively form an arch shape known as the maxillary mary dentition are incisors, followed by one canine, and [MACK si lair ee] arch, and those teeth in the lower jawbone then two molars. (called© theJones mandible) & Bartlett collectively Learning, form the mandibular LLC [man Two classes© Jones of primary & Bartlettteeth, incisors Learning, and molars, LLC con- DIB NOTyoo ler] FOR arch. Each SALE arch ORcan further DISTRIBUTION be divided into the left tain more thanNOT one FOR tooth SALEper quadrant OR DISTRIBUTIONand are subdivided and right halves, also known as left and right quadrants since into types within each class. Each type can be defined by its each quadrant contains one fourth of all teeth in that dentition. normal location within the complete quadrant. The type of primary incisor closest to the arch midline separating the A. COMPLETE PRIMARY DENTITION right and left quadrants is called a central incisor. The type © Jones & Bartlett Learning, LLC © Jonesof incisor & Bartlett next to, or Learning,lateral to, the centralLLC incisor is called a NOT FORThere SALE are OR 20 teeth DISTRIBUTION in the complete primary dentition (shownNOT lateral FOR incisor SALE. Next OR in DISTRIBUTION each quadrant is a canine, followed in Fig. 1-1). There are ten in the upper (maxillary) arch and by two types of molars: a first molar behind the canine and ten in the lower (mandibular) arch. The complete primary then a second molar (Fig. 1-1).

9781284218251_CH01_001_048.indd 4 25/03/20 4:22 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 5

© Jones & Bartlett Learning, LLC PRIMARY© Jones TEETH & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION MAXILLARYNOT FOR SALE OR DISTRIBUTION r te Anterio eth Incisors © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Canine NOT FOR SALE OR DISTRIBUTION C Canine NOT FOR SALE OR DISTRIBUTION e nt rs P h ral inciso o t s e t te e r r Lateral incisors io o i r r t e Molars e t Molars Canines e s

1st Molars

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 2nd Molars

RIGHT LEFT © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

2nd Molars

h o t

e t

e e

t 1st Molars

r i

r Molars

Molars t e Canines e

e s

t o

Lateral incisors NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Canine Canine C e nt rs ral inciso Incisors © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTION Anterior teeth NOT FOR SALE OR DISTRIBUTION MANDIBULAR

FIGURE 1-1. Maxillary and mandibular primary dentition. The midline of each arch is denoted by a line between the right and left central incisors. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEThe primaryOR DISTRIBUTION dentition is also called the deciduous [deNOT FOR SALE OR DISTRIBUTION SIDJ oo us] dentition, referring to the fact that all of these B. COMPLETE PERMANENT DENTITION teeth are eventually shed (like a deciduous tree loses its The complete permanent (or secondary) dentition is pres- leaves), being replaced by teeth of the permanent dentition. ent in the adult. It is composed of 32 teeth: 16 in the upper The mixed dentition is the term used to describe the denti- maxillary arch and 16 in the lower mandibular arch (shown tion where there is a mix© Jones of secondary & Bartlett and primary Learning, teeth LLCin Fig. 1-2). The permanent dentition© Jones has &eight Bartlett teeth in eachLearning, LLC visible in the mouth at NOTthe same FOR time, SALE during thatOR time DISTRIBUTION after quadrant, which are divided intoNOT four FOR classes SALE: incisors OR that DISTRIBUTION permanent teeth have begun to replace primary teeth, but incise food; canines that pierce and hold food; premolars, before all primary teeth have been lost. a new class for permanent teeth shaped to chew food; and molars, also shaped to chew food. Based on location, the two permanent front teeth in each quadrant are incisors, fol- LEARNING EXERCISE © Jones & Bartlett Learning, LLC lowed by one© canine,Jones then & Bartletttwo premolars, Learning, and finally LLC three NOT FOR SALE OR DISTRIBUTION molars. NOT FOR SALE OR DISTRIBUTION Using either models of the complete primary dentition or The classes of permanent teeth containing more than one Figure 1-1 while covering up the labels, identify each primary tooth per quadrant (namely, incisors, premolars, and molars) tooth based on its location in the arch. Include, in order, the dentition (primary), arch (maxillary or mandibular), are subdivided into types within each class. Each type can be quadrant (right or left), type (if applicable), and class. identified by its normal location within the quadrant. As in © Jones & ForBartlett example, Learning, the tooth next LLC to the midline in the lower left © Jonesthe primary & Bartlett dentition, Learning, the permanent LLC incisor closest to the NOT FOR SALEquadrant OR would DISTRIBUTION be identified as the primary mandibular left NOTmidline FOR SALEbetween ORthe right DISTRIBUTION and the left quadrants is called a central incisor. central incisor; the incisor next to, or lateral to, the central incisor is called a lateral incisor. Next in the arch is a canine,

9781284218251_CH01_001_048.indd 5 25/03/20 4:22 PM 6 PART 1 ■ Comparative Tooth Anatomy

Incisors

© Jones & BartlettCanine Learning, LLC Canine © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION C en s tra sor l inci Lateral incisors P Premolars Premolars o s h t t Canines e e r i e o t r r 1st Premolars t o e i e r

t © Jones & Bartlett Learning,e LLC © Jones & Bartlett Learning, LLC h t 2nd Premolars

s o

NOT FOR SALE ORP DISTRIBUTION 1st Molars NOT FOR SALE OR DISTRIBUTION

Molars Molars

2nd Molars

3rd Molars © Jones & Bartlett Learning,RIGHT LLC © Jones & Bartlett Learning,LEFT LLC NOT FOR SALE OR DISTRIBUTION NOT3rd MolarsFOR SALE OR DISTRIBUTION

2nd Molars Molars Molars

1st Molars

P o 2nd Premolars s © Jonest & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC e

r 1st Premolars h i t o NOT FORr SALE OR DISTRIBUTION NOTe FOR SALE OR DISTRIBUTION e t Canines t e e Lateral r t io h incisors r Premolars te Premolars s o P

Anterior teeth MANDIBULAR © Jones & FIGURE Bartlett 1-2. MaxillaryLearning, and mandibular LLC permanent dentition. The© midline Jones of each & Bartlettarch is denoted Learning, by a line between LLC the right and left NOT FORcentral SALE incisors. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION followed by a first premolar, and then a second premolar. teeth. Anterior teeth are those teeth in the front of the Continuing around toward the back in each quadrant are mouth, specifically, the incisors and the canines. Posterior three molars: a first molar, a second molar, and finally a third teeth are those in the back of the mouth, specifically, the premolar (sometimes referred© Jones to as a wisdom & Bartlett tooth ).Learning, LLCmolars and the molars. © Jones & Bartlett Learning, LLC In summary, whenNOT comparing FOR the SALE teeth in OR primary DISTRIBUTION and NOT FOR SALE OR DISTRIBUTION permanent dentitions, be sure to notice the differences. Although central incisors and lateral incisors and canines are similarly positioned in both dentitions, permanent LEARNING EXERCISE dentitions have a new class of teeth called premolars, which are ©located Jones between & Bartlett permanent Learning, canines and LLC per manent Using either© modelsJones of &the Bartlett complete permanentLearning, dentition LLC molars.NOT Premolars FOR SALE erupt intoOR theDISTRIBUTION spaces left where the or Figure NOT1-2 whileFOR covering SALE upOR the DISTRIBUTION labels, identify primary molars were located earlier in life. Also, there are each permanent tooth based on its location in the arch. To identify each tooth accurately, include, in order, the three permanent molars in each quadrant, whereas there dentition (permanent), arch (maxillary or mandibular), are only two primary molars in each quadrant. These three quadrant (right or left), type (if applicable), and the class. permanent molars erupt behind the premolars where no pri- For example, the last adult tooth in the lower right quadrant © Jones &mary Bartlett teeth were Learning, previously located.LLC © Jonesis correctly & Bartlett identified Learning, as the permanent LLC mandibular right NOT FOR SALEThere OR are twoDISTRIBUTION other terms used to categorize or distinNOT- FORthird molar. SALE OR DISTRIBUTION guish groups of teeth by their location: anterior and posterior

9781284218251_CH01_001_048.indd 6 25/03/20 4:23 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 7

These questions were designed to help you confirm that you 7. How many teeth are present in one arch of the primary understand the terms and concepts presented in this section. dentition? Select the one best answer. © Jones & Bartlett Learning, LLCa. 5 © Jones & Bartlett Learning, LLC b. 8 1. How many teeth NOTare present FOR inSALE one quadrantOR DISTRIBUTION of a NOT FOR SALE OR DISTRIBUTION complete adult (permanent) dentition? c. 10 d. 16 a. 5 e. 20 b. 8 c. 10 8. How many incisors are present in the complete adult d.© 20 Jones & Bartlett Learning, LLC dentition?© Jones & Bartlett Learning, LLC e.NOT 32 FOR SALE OR DISTRIBUTION a. 2 NOT FOR SALE OR DISTRIBUTION 2. What class of teeth is present in the permanent dentition b. 4 that is NOT present in the primary dentition? c. 6 d. 8 a. Incisors e. 12 © Jones & Bartlettb. Canines Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEc. Prem ORolars DISTRIBUTION NOT 9.FOR How SALE many molars OR DISTRIBUTIONare present in the primary dentition? d. Molars a. 2 3. In a permanent dentition, the fifth tooth from the midline b. 4 is a c. 8 d. 10 a. Canine © Jones & Bartlett Learning, LLCe. 1 © Jones & Bartlett Learning, LLC b. Premolar c. Molar NOT FOR SALE OR DISTRIBUTION10. How many molars are presentNOT in FOR each arch SALE of the OR adult DISTRIBUTION d. Incisor dentition? 4. The posterior teeth in the permanent dentition include a. 2 which of the following? b. 3 c. 6 a.© PremJonesolars & only Bartlett Learning, LLC © Jones & Bartlett Learning, LLC d. 8 b.NOT Mola FORrs only SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION e. 12 c. Premolars and molars only d. Canines, premolars, and molars 11. What is the fourth tooth from the midline in the primary dentition? 5. Which permanent tooth erupts into the space previously held by the primary second molar? a. Canine © Jones & Bartlett Learning, LLC © Jonesb. &First Bartlett premolar Learning, LLC a. First molar NOT FOR SALE OR DISTRIBUTION NOT FORc. Sec SALEond premolar OR DISTRIBUTION b. Second molar d. First molar c. First premolar e. Second molar d. Second premolar

6. How many teeth are© Jonespresent in& oneBartlett arch of Learning, the adult LLC © Jones & Bartlett Learning, LLC dentition? NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION a. 5 b. 8 c. 10 d. 12

e.© 16Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

1–b; 2–c; 3–b; 4–c; 5–d; 6–e; 7–c; 8–d; 9–c; 10–c; 11–d 10–c; 9–c; 8–d; 7–c; 6–e; 5–d; 4–c; 3–b; 2–c; 1–b; NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONANSWERS:

9781284218251_CH01_001_048.indd 7 25/03/20 4:23 PM 8 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION TOOTH IDENTIFICATIONNOT FOR SYSTEMS: SALE OR UNIVERSAL, DISTRIBUTION WORLD SECTION II DENTAL FEDERATION (INTERNATIONAL), AND PALMER NUMBERING SYSTEMS

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Documenting patient treatment with accurate dental records maxillary right third molar, going around the arch to the is an important task inNOT any dental FOR practice. SALE To OR do so DISTRIBUTION expedi- maxillary left third molar as 16;NOT dropping FOR down SALE on the OR same DISTRIBUTION tiously, it is necessary to adopt a code or numbering system side, the left mandibular third molar becomes 17, and then for teeth. Otherwise, for each tooth being charted, one must the numbers increase around the lower arch to 32, which is record the dentition, arch, side, type (if applicable), and class. the lower right third molar. This numbering system is used For example,© Jones describing & Bartlett a permanent Learning, maxillary LLC right second for each permanent© Jones tooth & in Bartlett the illustration Learning, in Figure 1-3LLC and molar requires five words, but it can be simplified by using seen in the mouth in Figure 1-4. the UniversalNOT FOR Numbering SALE ORSystem, DISTRIBUTION identifying this same For the NOT20 teeth FOR in the SALE primary OR dentition, DISTRIBUTION 20 letters of tooth with the number 2 (only one number). the alphabet are used from A through T. The letter A repre- The Universal Numbering System was first suggested sents the maxillary right second molar, sequentially around by Parreidt in 1882 and officially adopted by the American the arch and through the alphabet to J for the maxillary left © Jones &Dental Bartlett Association Learning, in 1975. ItLLC is accepted by third-party pro©- Jonessecond & molar, Bartlett then droppingLearning, down LLC on the same side to K viders in the United States and is endorsed by the American for the mandibular left second molar, and then clockwise NOT FORSociety SALE of OR Forensic DISTRIBUTION Odontology. Basically, the UniversalNOT around FOR theSALE lower OR arch DISTRIBUTIONto T for the mandibular right second Numbering System uses numbers 1 through 32 for the 32 molar. This system is used to identify each primary tooth in teeth in the permanent dentition, starting with 1 for the Figure 1-5 and in the mouth in Figure 1-6.

Anterior teeth

Incisors

© Jones & Bartlett Learning, LLCCanine Canine© Jones & Bartlett Learning, LLC 8 9 NOT FOR SALE OR DISTRIBUTION 7 10 NOT FOR SALE OR DISTRIBUTION C e rs 61ntr iso 1 al inc Lateral incisors P Premolars Premolars o 5 s h 12 t t Canines e e r e i t o

r 4 13 r 1st Premolars o t i e

r e

t t 3 2nd Premolars 14 h s

Molars Molars

NOT FOR SALE OR DISTRIBUTION 2 NOT FOR SALE15 OR DISTRIBUTION 2nd Molars 1 3rd Molars 16 RIGHT LEFT

3rd Molars © Jones & Bartlett Learning,32 LLC 17 © Jones & Bartlett Learning, LLC 2nd Molars NOT FOR SALEMolars OR 31DISTRIBUTION 18 Molars NOT FOR SALE OR DISTRIBUTION 1st Molars

P o 2nd Premolars s t 30 19 e 1st Premolars h r t i o e r e Canines t t 29 20 e r e Lateral io th incisors r Premolars 28 21 te © Jones & Bartlett Learning, LLC ©Premolars Joness & Bartlett Learning, LLC o 27 P 22 NOT FOR SALE OR DISTRIBUTION 26 25 24 23 NOT FOR SALE OR DISTRIBUTION Canine Central incisors Canine Incisors

Anterior teeth © Jones & Bartlett Learning, LLC MANDIBULAR© Jones & Bartlett Learning, LLC NOT FOR FIGURESALE 1-3. OR The DISTRIBUTION numbers 1 through 32 on the permanent teethNOT identify FOR each tooth SALE using OR the Universal DISTRIBUTION Numbering System, which is commonly used for record keeping in the United States and used in this book.

9781284218251_CH01_001_048.indd 8 25/03/20 4:23 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 9

© Jones & Bartlett Learning, LLC © JonesThere & Bartlett are also two Learning, other numbering LLC systems: the World NOT FOR SALE OR DISTRIBUTION NOTDental FOR FederationSALE OR (International) DISTRIBUTION System used in other countries and the Palmer Tooth Notation System. The World Dental Federation notation (also known as the Federation Dentaire Internationale or FDI System) uses two digits for 7 8 9 10 11 each permanent or primary tooth. The first digit denotes a 5 6 12 3 4 © Jones & Bartlett Learning,1314 LLCspecific quadrant (right or left),© Jonesarch (maxillary & Bartlett or mandibu Learning,- LLC lar), and dentition (permanent or primary) as follows: 27 26 25 24 23 22 30 29 28 NOT FOR SALE OR21 20 DISTRIBUTION19 NOT FOR SALE OR DISTRIBUTION

PERMANENT DENTITION 1 = Permanent dentition, maxillary, right quadrant © Jones & Bartlett Learning, LLC 2 = Permanent© Jonesdentition, & maxillary, Bartlett left Learning, quadrant LLC FIGURE 1-4. In the mouth of an adult, the permanent teeth that 3 = Permanent dentition, mandibular, left quadrant are visibleNOT are FORnumbered SALE using theOR Universal DISTRIBUTION Numbering System. 4 = PermanentNOT dentition, FOR mandibular,SALE OR right DISTRIBUTION quadrant

NOT FOR SALE OR DISTRIBUTION MAXILLARYNOT FOR SALE OR DISTRIBUTION

Anterior teeth

Incisors © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC E NOT FOR SALECanine OR DISTRIBUTIONF NOT FOR SALE OR DISTRIBUTION C Canine D e G nt rs P h ral inciso o t s e C t te H e r r Lateral incisors io o i r r t e Molars e t B Molars Canines e s I

1st Molars

NOT FOR SALE OR DISTRIBUTIONA NOTJ FOR SALE OR DISTRIBUTION 2nd Molars

RIGHT LEFT © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

2nd Molars

h o t

T K s

e t

e e

t 1st Molars

r Molars

e Molars Canines e t

e s

o S L t

Lateral incisors NOT FOR SALE OR DISTRIBUTIONR M NOT FOR SALE OR DISTRIBUTION Q N Canine P O Canine C e nt rs ral inciso Incisors © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION Anterior teeth NOT FOR SALE OR DISTRIBUTION MANDIBULAR FIGURE 1-5. The letters A to T on the primary teeth identify each tooth using the Universal System, which is commonly used for record keeping in the United States. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 9 25/03/20 4:23 PM 10 PART 1 ■ Comparative Tooth Anatomy

C D G H E F 3 2 112 3 S M R Q© JonesPO &N Bartlett Learning, LLC 4 © Jones & Bartlett Learning, LLC 3 2 11 2 3 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Lower right Lower left quadrant #8 quadrant #7

FIGURE© Jones1-6. In the & mouth Bartlett of a child, Learning, the primary teeth LLC that are © Jones & Bartlett Learning, LLC visibleNOT are identified FOR SALEusing letters OR as usedDISTRIBUTION in the Universal System. FIGURE 1-8. NOT When identifyingFOR SALE each primary OR DISTRIBUTIONtooth using the World Dental Federation or FDI International System, each quadrant is numbered 5 through 8 as indicated, and each tooth PRIMARY DENTITION within that quadrant is identified using numbers 1 though 5 with 5 = Primary dentition, maxillary, right quadrant number 1 for the central incisors, number 2 for lateral incisors, etc. © Jones &6 =Bartlett Primary dentition, Learning, maxillary, LLC left quadrant © Jones & Bartlett Learning, LLC NOT FOR7 SALE = Primary OR dentition, DISTRIBUTION mandibular, left quadrant NOTeach FOR primary SALE quadrant OR DISTRIBUTION is numbered 5 to 8 and each tooth 8 = Primary dentition, mandibular, right quadrant within that quadrant is numbered 1 to 5 (Fig. 1-8). (Using The second digit denotes the tooth position in each this system, tooth numbers within the range 11 through 48 quadrant relative to the midline, from closest to the mid- represent permanent teeth, whereas tooth numbers within the range 51 through 85 represent primary teeth.) To cite line to farthest away. Therefore,© Jones in &the Bartlett permanent Learning, dentition LLC © Jones & Bartlett Learning, LLC with 8 teeth in each quadrant, 1 is a central incisor clos- an example, 45 is a permanent mandibular right second est to the midline, 2 isNOT a lateral FOR incisor, SALE 3 is ORa canine, DISTRIBUTION and premolar since the first digit,NOT 4, indicates FOR SALEthe mandibular OR DISTRIBUTION so forth through 8, the permanent third molar, farthest right quadrant in the permanent dentition, and the second from the midline. In the primary dentition with only 5 digit, 5, indicates the fifth tooth from the midline in that teeth in each quadrant, the number 1 represents the tooth quadrant, namely, the second premolar. Using this numbering system for the primary dentition, tooth 63 is a primary closest© Jonesto the midline & Bartlett or the primaryLearning, central LLC incisor, and © Jones & Bartlett Learning, LLC the number 5 represents the tooth farthest from the mid- maxillary left canine since the first digit, 6, indicates maxil- line NOTor the primaryFOR SALE second OR molar. DISTRIBUTION In summary, each adult lary left quadrantNOT FORin the SALEprimary denORtition, DISTRIBUTION and the second quadrant is numbered 1 through 4 and each adult tooth digit, 3, indicates the third tooth from the midline, namely, within that quadrant is numbered 1 to 8 (Fig. 1-7), while the canine. To cite another example, 51 is a primary maxillary right central incisor since the first digit, 5, indicates the maxillary right quadrant for a primary tooth, and the © Jones & Bartlett Learning, LLC © Jonessecond & digit, Bartlett 1, indicates Learning, the first LLC tooth from themid line NOT FOR SALE OR DISTRIBUTION NOTin FOR that quadrant,SALE OR namely, DISTRIBUTION the central incisor. Finally, if the Upper right Upper left Universal number for a tooth was 32, the World Dental quadrant #1 quadrant #2 Federation number would be 48. If the Universal letter for a primary tooth was A, the World Dental Federation number would be 55. All tooth numbers and letters using both sys- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 1234 654321 tems are shown in Table 1-1. NOT FOR SALE OR DISTRIBUTIONThe Palmer Notation SystemNOT is FOR used bySALE many ORortho DISTRIBUTION- 5 4 6 dontists and other practitioners especially in the United 5 1123 234 Kingdom. It utilizes four different bracket shapes ( , , , and ) to denote each of the four quadrants. The specific Lower right Lower left quadrant #4 quadrant #3 bracket surrounds a number (or letter), which denotes the © Jones & Bartlett Learning, LLC specific tooth© Jones within that& Bartlett quadrant. Learning,The specific LLC brackets NOT FOR SALE OR DISTRIBUTION are designedNOT to represent FOR SALEeach of theOR four DISTRIBUTION quadrants of the FIGURE 1-7. Two methods are shown for denoting each quadrant dentition, as if you were facing the patient as seen in in the permanent dentition. The Palmer System uses a different Figure 1-7. “bracket” shape for each quadrant as you face the person, whereas the FDI International System uses the numbers 1 through 4 to denote is upper right quadrant. © Jones &each Bartlett adult quadrant. Learning, The numbers LLC on each tooth denote the method© Jones is& upper Bartlett left quadrant. Learning, LLC NOT FORfor SALE identifying OR teeth DISTRIBUTION within each quadrant beginning at the midline withNOT FOR is lowerSALE right OR quadrant. DISTRIBUTION number 1 for the central incisors, number 2 for lateral incisors, etc. is lower left quadrant.

9781284218251_CH01_001_048.indd 10 25/03/20 4:24 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 11

© Jones & BartlettTABLE 1-1 Learning, Major LLC Tooth Identification Systems © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION UNIVERSAL PALMER NOTATION INTERNATIONAL (FDI)

TOOTH RIGHT LEFT RIGHT LEFT RIGHT LEFT

Central incisor© Jones & BartlettE Learning,F LLC A A © Jones51 & Bartlett61 Learning, LLC Lateral incisorNOT FOR SALED OR DISTRIBUTIONG B B NOT FOR52 SALE OR62 DISTRIBUTION Canine C H C C 53 63 TEETH First molar B I D D 54 64 MAXILLARY Second molar A J E E 55 65 Central incisor P O A A 81 71 © JonesLateral & Bartlett incisor Learning,Q LLC N B © JonesB & Bartlett Learning,82 LLC72 Canine R M C C 83 73

NOTTEETH FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION PRIMARY DENTITION First molar S L D D 84 74

MANDIBULAR Second molar T K E E 85 75 Central incisor 8 9 1 1 11 21 Lateral incisor 7 10 2 2 12 22 © Jones & Bartlett Learning,Canine LLC 6 11© Jones &3 Bartlett Learning,3 LLC13 23 First premolar 5 12 4 4 14 24 NOT FOR SALE OR DISTRIBUTION NOT FOR5 SALE OR DISTRIBUTION5 TEETH Second premolar 4 13 15 25 First molar 3 14 6 6 16 26 MAXILLARY Second molar 2 15 7 7 17 27 Third molar 1 16 8 8 18 28 Central incisor© Jones & Bartlett25 Learning,24 LLC 1 1 © Jones41 & Bartlett31 Learning, LLC Lateral incisorNOT FOR SALE26 OR DISTRIBUTION23 2 2 NOT FOR42 SALE OR32 DISTRIBUTION Canine 27 22 3 3 43 33 First premolar 28 21 4 3 44 34 PERMANENT DENTITION

TEETH Second premolar 29 20 5 5 45 35 First molar 30 19 6 6 46 36

MANDIBULAR Second molar 31 18 7 7 47 37 © JonesThird & molarBartlett Learning,32 LLC 17 8 © Jones8 & Bartlett Learning,48 LLC38 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

The permanent tooth in each quadrant is numbered number or letters for key teeth, possibly the central incisors © Jones &from Bartlett 1 (nearest Learning, to the arch LLCmidline) to 8 (farthest from the© Jones(numbers & Bartlett 8, 9, 24, and Learning, 25) or the firstLLC molars (numbers 3, midline) as in the International System. To record a specific 14, 19, and 30). NOT FORtooth, SALE place OR the DISTRIBUTION correct number of the tooth in that quadrantNOT FOR SALE OR DISTRIBUTION within the bracket shape that identifies the correct quadrant (Fig. 1-7). For example, the lower left central incisor would Upper right Upper left 5 be 1 , the lower left second premolar would be , and the bracket shape bracket shape upper right canine would© Jonesbe 3. For & primary Bartlett teeth, Learning, the same LLC © Jones & Bartlett Learning, LLC four brackets are used to denote the quadrants, but five letters of the alphabet, A throughNOT FOR E, represent SALE the ORprimary DISTRIBUTION teeth C B AANOT FORB SALEC OR DISTRIBUTION in each quadrant (with A being a central incisor, B a lateral D C incisor, C a canine, etc.) (Fig. 1-9). For example, the primary C B AA B upper right first molar would be D. Comparing the Universal System© Joneswith the &Palmer Bartlett System, Learning, the permanent LLC maxillary © JonesLower right & BartlettLower Learning,left LLC right second molar would be tooth 2 using the Universal bracket shape bracket shape System,NOT but FOR would SALEbe 7 using OR the DISTRIBUTION Palmer System. If you are NOT FOR SALE OR DISTRIBUTION confused, study Table 1-1 and the figures that illustrate the quadrant brackets. FIGURE 1-9. When identifying each primary tooth using the Palmer Unless otherwise stated, the Universal System of System, each quadrant is denoted by bracket shapes as indicated, © Jones &tooth Bartlett numbering Learning, is used throughout LLC this text. To master© Jonesand each & tooth Bartlett within that Learning, quadrant is identified LLC using letters A though the Universal System, it may be helpful to memorize the B with letter A for the central incisors, letter B for lateral incisors, etc. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 11 25/03/20 4:29 PM 12 PART 1 ■ Comparative Tooth Anatomy

These questions were designed to help you confirm that you 4. If an orthodontist wrote about tooth 5, what would the understand the terms and concepts presented in this section. Universal number be? More than one answer may be correct. © Jones & Bartlett Learning, LLCa. 3 © Jones & Bartlett Learning, LLC b. 4 1. If you read an articleNOT in FORa British SALE dental OR journal DISTRIBUTION that NOT FOR SALE OR DISTRIBUTION refers to tooth number 48, you would suspect that c. 5 the authors were using the International Numbering d. 12 System. What Universal number (or letter) would they e. 13 be talking about? 5. What are the Universal numbers of the permanent a.© 25 Jones & Bartlett Learning, LLC mandibular© Jones first molars? & Bartlett Learning, LLC b.NOT J FOR SALE OR DISTRIBUTION a. 3 NOT FOR SALE OR DISTRIBUTION c. 30 b. 14 d. T c. 19 e. 32 d. 24 e. 30 © Jones &2. Bartlett Using the Learning, Universal Numbering LLC System, what numbers© Jones & Bartlett Learning, LLC are used to identify maxillary canines? NOT FOR SALE OR DISTRIBUTION NOT 6.FOR Fill inSALE the blanks: OR DISTRIBUTIONIf you are referring to the Universal a. 6 tooth 27, what is its position from the midline? b. 8 What is its arch? c. 10 In which quadrant is it located? d. 11 e. 27 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 3. If you read an articleNOT in a British FOR dental SALE journal OR that DISTRIBUTION refers NOT FOR SALE OR DISTRIBUTION to tooth number 55, you would suspect that the authors were using the International Numbering System. What Universal number (or letter) would they be talking about? a.© AJones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC b. 5 c.NOT E FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION d. T

e. 1 1–e; 2–a, d; 3–a; 4–e; 5–c, e; 6–3rd, mandibular, lower right lower mandibular, 6–3rd, e; 5–c, 4–e; 3–a; d; 2–a, 1–e;

TERMI NOLOGY USED TO DESCRIBE THE TISSUES OF SECTION III© JonesA TOOTH & Bartlett (AND Learning, DEFINITION LLC OF ANATOMICAL© Jones CROWN & Bartlett Learning, LLC NOT ANDFOR SALEROOT) OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Each tooth is made up of four tissues: enamel, dentin, cemen- Enamel [ee NAM el] is the relatively white, protective tum, and pulp. The first three of these (enamel, dentin, and external surface layer of the anatomic crown. It is highly cementum)© Jones are relatively& Bartlett hard Learning,since they contain LLC consider- calcified or© mineralizedJones & and Bartlett is the hardest Learning, substance LLC in the able NOTmineral FOR content, SALE especially OR calcium DISTRIBUTION (so these tissues can body. Its mineralNOT FORcontent SALE is 95% OR calcium DISTRIBUTION hydroxyapatite also be described as calcified). Only two of these tissues are (which is calcified). normally visible on an intact extracted tooth: enamel and Cementum [se MEN tum] is the dull yellow external cementum. Enamel covers the portion of the tooth known layer of the anatomic root. The cementum is very thin, espe- as the anatomic crown, and cementum covers the portion of cially next to the part of the root where the crown joins with © Jones &the Bartlett tooth known Learning, as the anatomic LLC root. The other two tissues© Jonesthe root. & ItsBartlett thickness Learning, can be compared LLC to the thickness of a NOT FOR(dentin SALE and OR pulp) DISTRIBUTION are usually not visible on an intact tooth.NOT human FOR hairSALE (only OR 50 to DISTRIBUTION 100 μm thick where 1 μm is one mil- Refer to Figure 1-10 while reading about each tissue. lionth of a meter). Cementum is 65% mineralized. (Another

9781284218251_CH01_001_048.indd 12 25/03/20 4:29 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 13

Cementum

© Jones & Bartlett Learning, LLC Dentin © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Anatomic Root Cementodentinal junction FIGURE 1-10. A maxillary anterior tooth Pulp chamber is sectioned faciolingually through the middle to show the distribution of the Cementoenamel junction tooth© tissues Jones and &the Bartlett shape of the Learning, pulp LLC © Jones & Bartlett Learning, LLC cavityNOT (made FORup of pulp SALE chamber OR and DISTRIBUTION NOT FOR SALE OR DISTRIBUTION root canal). On the right is a close-up of Enamel the root tip depicting the usual expected constriction of the root canal near the Dentinoenamel junction apical foramen. The layer of cementum covering the root of an actual tooth is Lingual surface of crown Anatomic Crown © Jones &proportionately Bartlett Learning,much thinner than LLC seen © Jones & Bartlett Learning, LLC NOT FORin SALE these drawings. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

author, Melfi, states that the mineral content of cementum is The dentinoenamel [DEN tin o ehn AM el] junction is about 50%.) Cementum is about as hard as bone but consid- the inner surface of the enamel where enamel joins dentin. erably less hard than enamel. This junction can be best seen on a radiograph (Fig. 1-11). The cementoenamel© [seJones MEN toe& Bartlettehn AM el] Learning, junction LLCThecementodentinal [se MEN© toe Jones DEN tin & al] Bartlett (or dentino Learning,- LLC (also called the CEJ or NOTcervical FOR line) isSALE the junction OR DISTRIBUTION between cemental) junction is the innerNOT surface FOR of cementum SALE OR where DISTRIBUTION the enamel covering the anatomic crown and the cementum cementum joins dentin. Cementum is so thin that it is dif- covering the anatomic root. This junction is also known as ficult to identify this junction on a radiograph. the cervical [SER vi kal] line, denoting that it surrounds the Pulp is soft, nonmineralized connective tissue contain- neck or cervix [SER viks] of the tooth. ing a rich supply of blood vessels and nerves located in the Dentin© Jones [DEN & tin] Bartlett is the hard Learning, yellowish tissue LLC underlying cavity or space© Jonesin the center & Bartlett of the crown Learning, and root called LLC the the enamelNOT andFOR cementum, SALE and OR makes DISTRIBUTION up the bulk of the inner pulp cavity.NOT The FORpulp cavity SALE has ORa coronal DISTRIBUTION portion toward portion of each tooth crown and root. It extends outward from the crown called a pulp chamber and a portion within the the pulp cavity (located in the center of the tooth) to the inner roots called a pulp canal or root canal. The pulp cavity is boundary of the enamel (covering the crown) or cementum surrounded by dentin, except at a hole (or holes) near the (covering the root). Dentin is not normally visible except on a root tip (apex) called an apical [APE i kal] foramen [fo RAY © Jones &dental Bartlett radiograph, Learning, or when the LLC enamel or cementum has been© Jonesmen] (plural& Bartlett foramina Learning, [fo RAM i LLCna]). Nerves and blood NOT FORworn SALE away, OR or cut DISTRIBUTION away when preparing a tooth with a bur, orNOT vessels FOR enter SALE the pulpOR canalsDISTRIBUTION through these apical foramina. destroyed by decay. Mature dentin is composed of about 70% Like dentin, the pulp is normally not visible, except on a den- mineralized calcium hydroxyapatite making it less hard (and tal radiograph (Fig. 1-11) or on a sectioned tooth. Functions less brittle) than enamel, but harder than cementum. of the dental pulp are as follows: © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Dentinoenamel junction FIGURE© Jones 1-11. A radiographs& Bartlett (x-ray) Learning, shows LLC © Jones & Bartlett Learning, LLC tooth crowns covered with enamel, and the toothNOT roots embedded FOR SALE within the OR alveolar DISTRIBUTION NOT FOR SALE OREnamel DISTRIBUTION bone. You can distinguish the whiter outer Dentin enamel shape from the darker inner dentin. The pulp chamber in the middle of the tooth is the darkest. The very thin, dark Pulp periodontal ligament can also be seen Periodontal ligament © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC(dark line) between the root and the bone, but the NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONAlveolar bone cementum is so thin it cannot be seen.

9781284218251_CH01_001_048.indd 13 25/03/20 4:29 PM 14 PART 1 ■ Comparative Tooth Anatomy

© Jones &• BartlettFormative :Learning, Dentin-producing LLC cells (odontoblasts©) Jonesdentin & Bartlett (odontoblasts Learning, ). Surprisingly, LLC blood being pumped NOT FOR SALEproduce OR dentin DISTRIBUTION throughout the life of a tooth. ThisNOT FORinto theSALE tooth OR pulp DISTRIBUTION had passed through the heart only normally maturing dentin is called secondary dentin. 6 seconds previously. • Sensory: Nerve endings in the pulp relay the sense of • Defensive or protective: Pulp responds to injury or decay pain caused from heat, cold, drilling, sweet foods, decay, by forming reparative dentin (by the odontoblasts). trauma, or infection to the brain, so we feel it. However, the nerve fibers in ©a dentalJones pulp & are Bartlett unable to Learning,distinguish LLCSome advanced information© onJones the embryology & Bartlett of tooth Learning, LLC the cause of the pain.NOT FOR SALE OR DISTRIBUTIONtissues that had been includedNOT in this FOR chapter SALE in previous OR DISTRIBUTION • Nutritive: Blood vessels transport nutrients from the editions is now presented at the end of the chapter in a sec- bloodstream to cells of the pulp and the cells that produce tion called “Advanced Topics.”

© JonesREVIEW & Bartlett Questions Learning, about LLC Tooth Tissues © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION These questions were designed to help you confirm that you 3. What tissue forms the outer boundary of almost all of a understand the terms and concepts presented in this section. pulp chamber? More than one answer may be correct. a. Enamel © Jones &1. Bartlett Which tooth Learning, junctions LLCare NOT normally visible on ©a Jonesb. &Dent Bartlettin Learning, LLC NOT FOR SALEhandheld OR intact DISTRIBUTION tooth? NOT FORc. Cemen SALEtum OR DISTRIBUTION d. Alveolar bone a. Cementoenamel junction e. Periodontal ligament b. Dentinoenamel junction c. Dentinocemental junction 4. Which of the following is (are) NOT functions of the d. Dentinopulpal junction pulp? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 2. Which mineralizedNOT tissue FORis the hardest? SALE OR DISTRIBUTIONa. Taste sweet and sour NOT FOR SALE OR DISTRIBUTION b. Sense pain a. Cementum c. Provide nutrition to dentin b. Pulp d. Produce new dentin c. Dentin e. Produce new enamel d. Enamel

e.© AlveJonesolar bone & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTION NOT FORe SALE4–a, 3–b; OR2–d; d; DISTRIBUTION c, 1–b, ANSWERS:

© Jones & Bartlett Learning, LLC INTRODUCTION TO© TH JonesE PERIODONTIUM & Bartlett Learning, (AND LLC DEFINITION SECTION IV NOT FOR SALE OR DISTRIBUTIONOF CLINICAL CROWNNOT AND FOR ROOT) SALE OR DISTRIBUTION

The periodontium [pair ee o DON she um] is defined as is the edge of the gingiva closest to the biting or chewing sur- the supporting tissues© of Jones the teeth & in Bartlett the mouth, Learning, includ- LLCfaces of the teeth (Fig. 1-13). © Jones & Bartlett Learning, LLC ing surrounding alveolarNOT bone, FOR the gingiva, SALE the OR periodontal DISTRIBUTION The gingival sulcus is not NOTseen visually FOR butSALE can be OR evalu DISTRIBUTION- ligament, and the outer, cementum layer of the tooth roots ated with a thin probe (periodontal probe), since it is actually (Fig. 1-12). Alveolar bone is the portion of the upper (maxil- a space (or potential space) between the tooth surface and the lary) or lower (mandibular) bones that surrounds the roots narrow unattached cervical collar of free gingiva. If you insert of the teeth. The gingiva is the part of the soft tissue in the a periodontal probe into this sulcus, it should extend only 1 mouth© Jonesthat covers & theBartlett alveolar Learning, bone of the jawsLLC and is the to 3 mm deep© inJones a healthy & person Bartlett (Fig. 1-14Learning,). The interdental LLC onlyNOT part of FOR the periodontium SALE OR thatDISTRIBUTION is visible in a healthy (interproximal)NOT papilla FOR [pah SALE PILL ORah] (plural DISTRIBUTION is papillae [pa mouth. Part of it is firmly bound to the underlying alveolar PILL ee]) is that part of the collar of free gingiva that extends bone and is called attached gingiva. The other part is free between the teeth. A healthy papilla conforms to the space gingiva (or marginal gingiva), which is a collar of thin gin- between two teeth (interproximal space), so it is very thin and giva that surrounds each tooth and, in health, adapts to the easy to damage near where the adjacent teeth contact. The © Jones &tooth Bartlett but provides Learning, access into LLC the potential space between© Jonespapilla & also Bartlett has a hidden Learning, sulcus where LLC dental floss can fit once NOT FORthe SALE free gingiva OR DISTRIBUTION and the tooth, which is called a gingival sulNOT- it FOR passes SALEbetween OR the teethDISTRIBUTION (Fig. 1-15). The floss must curve cus (crevice). The gingival margin (or free gingival margin) around the tooth to avoid cutting into the interdental papilla.

9781284218251_CH01_001_048.indd 14 25/03/20 4:29 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 15

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Gingival sulcus (a potential space) Free gingiva Gingival margin © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Cementum of root Attached gingiva

Periodontal ligament © Jones & Bartlett Learning, LLC © Jones(much & Bartlett smaller in the Learning, mouth) LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Alveolar bone

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-12. This diagram is a tooth supported within the periodontium. The periodontium is made up of alveolar bone, which surrounds the anatomic root; gingiva (gum tissue), which covers the bone; cementum, which covers the tooth root; and the periodontal ligament, which attaches the cementum of the tooth root to the bone. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC AlthoughNOT FOR the termSALE ligament OR DISTRIBUTION is most often defined as healthy periodontalNOT FOR ligament SALE is only OR about DISTRIBUTION one to four times a tough fibrous band of tissue that connects two bones, a thicker than the diameter of an average healthy human hair. periodontal ligament (abbreviated PDL) is a very thin CLINICAL CROWN AND ROOT: As mentioned pre- ligament that connects a tooth to its surrounding bone. It viously, the anatomic crown is that part of the tooth (in the is composed of many microscopic tissue fibers that attach mouth or handheld) normally covered by an enamel layer, © Jones &the Bartlett outer layer Learning, of the tooth LLCroot (covered with cementum©) Jonesand the & anatomicBartlett root Learning, is the part LLC of a tooth covered by to the thin layer of dense alveolar bone surrounding each cementum (recall Fig. 1-10). However, when the tooth is in NOT FORtooth. SALE The OR fibers DISTRIBUTION of the periodontal ligament representedNOT in the FOR mouth, SALE the amount OR DISTRIBUTION of the tooth that is visible in the oral Figure 1-12 are greatly enlarged. The averagethi ckness of a cavity (i.e., not covered with gingiva) is called the clinical

Attached © Jones & Bartlett Learning, LLCgingiva © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Free gingiva over the potential space: Interdental papilla gingival sulcus Gingival margin © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

FIGURE 1-13. Healthy gingiva surrounds each tooth forming a characteristic scallop-shaped gingival margin. Interproximal papillae fill © Jones &the Bartlett spaces between Learning, most teeth. LLC The attached © Jones & Bartlett Learning, LLC NOT FORgingiva SALE is theOR gingiva DISTRIBUTION that is firmly attached to NOT FOR SALE OR DISTRIBUTION the underlying bone.

9781284218251_CH01_001_048.indd 15 25/03/20 4:30 PM 16 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-15. Dental floss must adapt around the curved surface of each tooth when entering the gingival sulcus in order to clean FIGURE 1-14. A periodontal probe is carefully placed into the the proximal surface of the tooth and avoid damaging the free gingival sulcus. gingiva. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORcrown SALE, and OR the DISTRIBUTIONportion of the tooth that is not visible since NOTit disease FOR orSALE periodontal OR DISTRIBUTION therapy, exposing more of the ana- is covered with gingiva is called the clinical root. When the tomic root. In this case, the clinical crown is longer than the gingival margin in a 25-year-old patient with healthy gin- anatomic crown since the clinical crown in this mouth con- giva approximately follows the curvature of the cervical line, sists of the entire anatomic crown plus the part of the ana- the clinical crown is almost the same as the anatomic crown tomic root that is exposed (Fig. 1-16C). In this situation, the (Fig. 1-16A). However,© throughout Jones &life, Bartlett the gingival Learning, margin LLCclinical root is shorter than the© anatomic Jones root. & Bartlett Learning, LLC is not always at the levelNOT of the FOR cervical SALE line becauseOR DISTRIBUTION of the NOT FOR SALE OR DISTRIBUTION eruption process. For example, the gingiva on a partially LEARNING EXERCISE erupted tooth of a 10-year-old covers much of the enamel of the anatomic crown of the tooth, resulting in a clinical Examine the mouths of several persons of different ages crown (exposed in the mouth) that is much shorter than the © Jones & Bartlett Learning, LLC to see if the© cervicalJones line & of Bartlett each anatomic Learning, tooth is visible LLC anatomic crown (Fig. 1-16B). The clinical root (the part of or hidden. As the individual grows older, the location of the toothNOT not FOR visible SALE in the mouth)OR DISTRIBUTION would be longer than the the marginNOT of the FOR gingiva SALE may recedeOR DISTRIBUTION toward the root anatomic root, since it includes all of the anatomic root plus tip (apically) because of periodontal disease or injury. Of the part of the anatomic crown covered with gingiva. course, the location of the cervical line on the tooth remains In contrast, the gingival margin of an older person may the same. In other words, the distinction between the exhibit gingival recession, especially after havingper iodontal anatomic crown and root does not change over a lifetime. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Clinical crown (partially erupted) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© JonesA & Bartlett Learning, LLC B © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION FIGURE 1-16.NOT A. OnFOR a young SALE adult with OR healthy DISTRIBUTION gingiva, the entire anatomic crown is all that can be seen, so the clinical crown is approximately the same Clinical as the anatomic crown. B. Since this canine is partially crown Anatomic erupted, the anatomic crown is only partially exposed, so © Jones & Bartlett Learning, LLC crown © Jonesthere is& a Bartlettshort clinical Learning, crown. C. This LLC maxillary molar NOT FOR SALE OR DISTRIBUTION NOT FORhas a very SALE long clinical OR DISTRIBUTIONcrown since all of the anatomic crown and much of the anatomic root are exposed due C to recession of the gingiva and loss of bone.

9781284218251_CH01_001_048.indd 16 25/03/20 4:31 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 17

These questions were designed to help you confirm that you 3. Which of the following structures is (are) NOT part of understand the terms and concepts presented in this section. the periodontium? More than one answer may be correct. © Jones & Bartlett Learning, LLCa. Alveolar bone © Jones & Bartlett Learning, LLC b. Periodontal ligament 1. Which statement(s)NOT is (are) FOR likely SALE to be true OR on DISTRIBUTIONa person NOT FOR SALE OR DISTRIBUTION with a barely erupted tooth 9? c. Gingival margin d. Cementodentinal junction a. The clinical crown is larger than the anatomic crown. e. Attached gingiva b. The clinical crown is smaller than the anatomic crown. c. The clinical root is larger than the anatomic root. 4. The periodontal ligament attaches the alveolar bone to d.© The Jones clinical & root Bartlett is smaller Learning, than the anatomic LLC root. what tooth© Jonestissue? & Bartlett Learning, LLC 2. WhiNOTch statement(s)FOR SALE is (are)OR DISTRIBUTIONtrue regarding a tooth on a. DentinNOT FOR SALE OR DISTRIBUTION a person who has lost most of the bone and gingiva b. Enamel surrounding the tooth? c. Cementum d. Pulp a. The clinical crown is larger than the anatomic crown. © Jones & Bartlettb. The clin Learning,ical crown is smallerLLC than the anatomic crown.© Jones & Bartlett Learning, LLC NOT FOR SALEc. The OR clin icalDISTRIBUTION root is larger than the anatomic root. NOT FOR SALE OR DISTRIBUTION

d. The clinical root is smaller than the anatomic root.

1–b, c; 2–a, d; 3–d; 4–c 3–d; d; 2–a, c; 1–b, ANSWERS:

All teeth© Jones have surfaces & Bartlett that are Learning, named according LLC to their 5 in Fig. 1-17).© JonesIn the maxillary & Bartlett arch, this Learning, surface can LLCalso be normal, ideal alignment within the dental arch. Refer to called the palatal surface due to its proximity with the palate. Figure 1-17NOT whenFOR studying SALE the OR terms DISTRIBUTION to denote tooth surfaces. NOT FOR SALE OR DISTRIBUTION C. TERMS THAT DIFFERENTIATE BITING A. TERMS THAT IDENTIFY OUTER SURFACES SURFACES OF ANTERIOR VERSUS (TOWARD THE CHEEKS OR LIPS) OF POSTERIOR TEETH © Jones & BartlettANTERIOR Learning, VERSUS LLC POSTERIOR TEETH © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOTThe FOR occlusal SALE [ahk OR KLOO DISTRIBUTION zal] surface is the chewing sur- Thefacial surface of a tooth is the surface toward the face, that face of a posterior tooth (labeled on tooth 2 in Fig. 1-17). is, the surface of a tooth in the mouth resting against or next to Anterior teeth (incisors and canines) do not have an occlusal the cheeks or lips. Facial may be used to designate this surface of surface but do have a cutting incisal edge or ridge (labeled any tooth, anterior or posterior. Another name for the facial sur- on tooth 8 in Fig. 1-17). face of posterior teeth is ©buccal Jones [BUCK & k’l],Bartlett located nextLearning, to the LLC © Jones & Bartlett Learning, LLC cheek (labeled on tooth 3 in Fig. 1-17). Dental terms that begin D. TERMS THAT DIFFERENTIATE with “bucc” refer to a relationshipNOT FOR or proximity SALE to OR the cheek. DISTRIBUTION It is NOT FOR SALE OR DISTRIBUTION incorrect to use the term buccal when speaking about the inci- APPROXIMATING SURFACES OF TEETH sors or canines because the facial surface of these teeth does not Theproximal [PROCK se mal] surfaces are the sides of a tooth approximate the cheeks. The facial surface of anterior teeth is next to an adjacent tooth. Depending on whether the proxi- properly© Jones called a labial& Bartlett [LAY bee Learning, al] surface, located LLC next to the mal tooth surface© Jones faces toward& Bartlett the arch Learning, midline between LLC the lips (labeledNOT FORon tooth SALE 6 in Fig. OR 1-17). DISTRIBUTION The term labial should not central incisorsNOT or awayFOR from SALE the midline, OR DISTRIBUTION it is either a mesial be used when referring to the premolars or the molars. [MEE zi al] surface (closer to the midline) or a distal [DIS tal] surface (farther from the midline). Mesial and distal surfaces B. TERMS THAT IDENTIFY INNER SURFACES are labeled on tooth 1 in Figure 1-17. Note that the mesial sur- (TOWARD THE TONGUE) OF MAXILLARY face of a tooth touches, or is closest to, the distal surface of an © Jones & BartlettVERSUS Learning, MANDIBULAR LLC TEETH © Jonesadjacent & tooth Bartlett EXCEPT Learning, between the LLCcentral incisors where the NOT FOR SALE OR DISTRIBUTION NOTmesial FOR surface SALE of theOR right DISTRIBUTION central incisor faces the mesial sur- The lingual [LIN gwal] surface is the surface of a maxillary face of the left central incisor. Also, the distal surface of the last or mandibular tooth nearest to the tongue (labeled on tooth (third) molar in each arch does not approximate another tooth.

9781284218251_CH01_001_048.indd 17 25/03/20 4:31 PM 18 PART 1 ■ Comparative Tooth Anatomy

NOT FOR SALE OR DISTRIBUTIONeth NOT FOR SALE OR DISTRIBUTION te or eri Ant Midline of dental arch Central incisor Quadrant

Incisal edge Lateral incisor © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Canine NOT FORCingulum SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 1st Premolar Labial surface 8 7 6 2nd Premolar Lingual surface © Jones & Bartlett(palatal) Learning, LLC5 © Jones & Bartlett Learning, LLC 1st Molar NOT FOR SALE OR DISTRIBUTION4 NOT FOR SALE OR DISTRIBUTIONMaxillary Buccal alveolar surface process 3 th

Raphe 2nd Molar Median Occlusal © Jones & Bartlett iorLearning, tee surface LLC 2 © Jones & Bartlett Learning, LLC 3rd Molar

ster

NOT FOR SALE ORo DISTRIBUTIONMesial side NOT FOR SALE OR DISTRIBUTION

P 1 of 3rd molar

Distal side of 3rd molar © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-17. Maxillary dental arch of teeth with various tooth surfaces labeled. Remember that the labial surface of an anterior tooth and the buccal surface of a posterior tooth are both referred to as facial surfaces. Also, the mesial and distal sides or surfaces are both correctly called proximal surfaces.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Soft debris and food particles on proximal surfaces are not eas- is better to say distolingual than linguodistal.) Examples of ily cleanedNOT byFOR the action SALE of theOR cheeks, DISTRIBUTION lips, and tongue when external lineNOT angles FOR of a molar SALE crown OR include DISTRIBUTION mesio-occlusal, compared to most of the facial or lingual surfaces, which are mesiolingual, mesiofacial, disto-occlusal, distolingual, disto- considered more self-cleansing, that is, more easily able to be facial, bucco-occlusal, and linguo-occlusal. Point angles are cleaned by the rubbing action of the cheeks, lips, and tongue. the junctions of three tooth surfaces at a point, such as a mesiobucco-occlusal point angle. Examples of these external © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC E. TERMS TO DENOTE TOOTH SURFACE line angles and point angles are seen in Figure 1-18. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION JUNCTIONS OR DIMENSIONS To describe a dimension of a tooth, terms can be combined to denote the direction over which a dimension is taken. For The junction line where two tooth surfaces meet is called example, the length of an incisor crown from the incisal edge an external line angle. To name a line angle, combine the to the cervical line is called the incisocervical dimension or the names of the two surfaces, but change the “al” ending of the dimension incisocervically, and the width of the buccal surface first surface to an “o.” (A© guidelineJones &has Bartlettbeen suggested Learning, for the LLCof a molar crown from the mesial© Jonessurface to & the Bartlett distal surface Learning, LLC order used when combiningNOT terms. FOR Use SALE the following OR DISTRIBUTION order: is the mesiodistal dimension (Fig.NOT 1-18). FOR Other SALE examples OR ofDISTRIBUTION mesial is used first; then distal, facial, [buccal or labial] or terms used to describe a crown dimension include mesiodistal, lingual; and lastly occlusal or incisal. Using this guideline, faciolingual or buccolingual, and occlusocervical. The length of it is better to say mesio-occlusal than occlusomesial, and it a root could be described as its cervicoapical dimension. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION REVIEW Questions about Dimensions

1. What surface(s) of a tooth would you be looking at in 2. What surface(s) of a tooth would you be looking at when order to determine the mesiodistal dimension of a molar? measuring the buccolingual dimension of a molar?

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 1–Buccal, lingual, or occlusal surfaces; 2–Mesial, distal, or occlusal surfaces occlusal or distal, 2–Mesial, surfaces; occlusal or lingual, 1–Buccal,

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ANSWERS:

9781284218251_CH01_001_048.indd 18 25/03/20 4:31 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 19

Mesiodistal dimension © Jones & Bartlett Learning,Incisocervical LLC dimension ©Mesiobuccal- Jones & Bartlett Learning, LLC occlusal Buccolingual dimension NOT FOR SALE OR DISTRIBUTION NOTpoint angleFOR SALE OR DISTRIBUTIONLinguo-occlusal line angle Distolingual Mesiobuccal Distolingual line angle Mesiolabial line angle line angle Distobuccal line angle line angle Distolabial LINGUA line angle L L IAL© Jones & Bartlett Learning, LLC SIA ING© Jones & Bartlett Learning, LLC ES L ME UAL M NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

LAB BU L CC AL IAL AL T DISTA DIS

© Jones & BartlettANTERIOR Learning, TOOTH LLC POSTERIOR© Jones TOOT & BartlettH Learning, LLC FIGURENOT 1-18. FOR Diagrammatic SALE representationsOR DISTRIBUTION of an incisor and a molar crown have severalNOT examples FOR ofSALE line angles OR andDISTRIBUTION point angles labeled in red. Three examples describing dimensions are labeled in green.

F. mesial, middle, and distal thirds. When viewing proximal © Jones & Bartlett DIVISIONS Learning, (THIRDS) LLC OF THE CROWN © Jones(mesial & or Bartlett distal) surfaces, Learning, vertical lines LLC can be used to divide NOT FOR SALEOR ORROOT DISTRIBUTION (FOR PURPOSES OF NOTthe FOR crown SALE or root OR into DISTRIBUTION facial, middle, and lingual thirds. DESCRIPTION) When viewing a tooth from the occlusal (or incisal) surface, lines running mesiodistally can be used to divide the crown A tooth can be divided into thirds in order to define more into facial, middle, and lingual thirds, and lines running precisely the location of its specific landmarks such as proxi- faciolingually can be used to divide the tooth into mesial, mal contacts. When viewing© Jones a tooth & from Bartlett the facial, Learning, lingual, LLC © Jones & Bartlett Learning, LLC middle, and distal thirds. mesial, or distal surface,NOT horizontal FOR lines SALE can divide OR theDISTRIBUTION tooth NOT FOR SALE OR DISTRIBUTION crown into the following thirds: cervical, middle, and occlusal (or incisal) (Fig. 1-19). Similarly, horizontal lines can divide G. ROOT-TO-CROWN RATIO the root into thirds: cervical, middle, and apical (toward the If we know the length of a tooth root from the cervical line to root tip or apex). the tip of the root, and the length of the crown (as defined at When© Jones viewing & theBartlett facial or Learning, lingual surfaces LLC of a tooth, the end of this© chapterJones in &Dr. Bartlett Woelfel’s original Learning, research LLC data), verticalNOT lines FOR can beSALE used to OR divide DISTRIBUTION the crown or root into we can calculateNOT a FORroot-to-crown SALE ratio.OR DISTRIBUTIONTheroo t-to-crown

Division of teeth in thirds

© Jones & Bartlett Learning,Facial orLLC labial view Mesial view © Jones Fa&cial Bartlett or buccal Learning,view Distal LLC view NOT FOR SALE OR DISTRIBUTIONApical 3rd NOT FOR SALE OR DISTRIBUTION Middle 3rd Middle 3rd Mesial 3rd Distal 3rd Lingual 3rd Middle 3rd Buccal 3rd (facial) Occlusal 3rd Cervical 3rd Middle 3rd Cervical 3rd Cervical 3rd Middle 3rd Cervical 3rd © Jones Incisal& Bartlett 3rd Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONMiddle 3rd NOT FOR SALE OR DISTRIBUTION Apical 3rd Lingual 3rd (facial) Distal 3rd Labial 3rd Middle 3rd Mesial 3rd Middle 3rd

Occlusal views © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Facial 3rd NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Middle 3rd Lingual 3rd d d Distal 3rd Mesial 3r © Jones & Bartlett Learning, LLC Middle 3r © Jones & Bartlett Learning, LLC NOT FOR SALEFIGURE 1-19. OR DiagramsDISTRIBUTION of a maxillary canine and mandibular molarsNOT show FOR how aSALE crown or OR root canDISTRIBUTION be divided into thirds from each view.

9781284218251_CH01_001_048.indd 19 25/03/20 4:31 PM 20 PART 1 ■ Comparative Tooth Anatomy

© Jones &ratio Bartlett is the rootLearning, length divided LLC by crown length. Since© Jones & Bartlett Learning, LLC NOT FORalmost SALE all OR tooth DISTRIBUTION roots are longer than their crowns, theNOT FOR SALE OR DISTRIBUTION root-to-crown ratios for teeth are normally greater than 1.0. For example, the average root length of a maxillary central 16.5 incisor is only 13.0 mm and the crown length is 11.2 mm. The root-to-crown ratio is 13 divided by 11.2, which equals 13.0 1.16. When this numb©er Jonesis close to& 1,Bartlett it indicates Learning, that the LLC © Jones & Bartlett Learning, LLC root is not much longerNOT than FORthe crown. SALE Compare OR DISTRIBUTIONthis with NOT FOR SALE OR DISTRIBUTION a maxillary canine, where the average root is much longer, at 16.5 mm, but the crown is only 10.6 mm, for a much larger root-to-crown ratio of 1.56. This larger ratio indicates that the root is over one and a half times (1.56 times) longer 10.6 D M 11.2 D M than ©the Jones crown. &The Bartlett obvious Learning,difference between LLC the root- © Jones & Bartlett Learning, LLC to-crownNOT ratio FOR on theseSALE two OR teeth DISTRIBUTION is apparent in Figure 1-20. NOT FOR SALE OR DISTRIBUTION The ratio can be clinically significant, since a tooth with a FACIAL VIEWS small root-to-crown ratio (closer to 1) is not the best choice for attaching and supporting false teeth, because the addi- Right maxillary canine Right maxillary central incisor tional attached teeth would apply even more force on a tooth © Jones &that Bartlett already hasLearning, a short root LLC compared to its crown length.© Jones FIGURE & 1-20. Bartlett Compare Learning, the root-to-crown LLC ratio of a maxillary NOT FORTherefore, SALE OR the DISTRIBUTIONlong-term success of attaching false teeth NOTto central FOR incisor SALE where OR the rootDISTRIBUTION is not much longer than the crown a tooth like the maxillary canine with a large root-to-crown and the ratio is 13 mm of crown length divided by 11.2 mm of ratio of 1.56 would be better than attaching it to a tooth like root length, or only 1.16, with a maxillary canine where the root is considerably longer than the crown so the ratio is much larger: the maxillary central incisor with a small root-to-crown 16.5 mm crown length divided by 10.6 mm root length, or 1.56. ratio of 1.16. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION REVIEW Questions about Tooth Terminology

These questions were designed to help you confirm that you 4. The ermt labial refers to association with or proximity to understand© Jones the terms & Bartlett and concepts Learning, presented inLLC this section. the lips, ©and Jones the term & _____ Bartlett refers toLearning, association withLLC or MoreNOT than oneFOR answer SALE may ORbe correct. DISTRIBUTION proximityNOT to the FOR cheeks. SALE OR DISTRIBUTION 1. Which tooth surface(s) face(s) the lips or cheeks? a. Facial b. Buccal a. Facial c. Labial b. Distal d. Proximal c. Buccal © Jones & Bartlett Learning, LLC © Jonese. &Pala Bartletttal Learning, LLC NOT FOR SALEd. Occl ORusal DISTRIBUTION NOT FOR SALE OR DISTRIBUTION e. Labial 5. When viewing tooth 8 from the distal view, it can be divided into thirds from the incisal to the cervical and 2. Which pairs of teeth have a mesial surface touching a from the facial to the lingual. Which third is NOT mesial surface? possible to see from the distal view? a. 25 and 26 © Jones & Bartlett Learning, LLCa. Facial © Jones & Bartlett Learning, LLC b. 16 and 17 NOT FOR SALE OR DISTRIBUTIONb. Cervical NOT FOR SALE OR DISTRIBUTION c. 7 and 8 c. Middle d. 1 and 32 d. Mesial e. 8 and 9 e. Incisal 3. Which teeth have a distal surface that does not normally contact© Jones another & Bartletttooth? Learning, LLC © Jones & Bartlett Learning, LLC a.NOT 1 FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION b. 3 c. 8 d. 17 © Jones & Bartlette. 24 Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 20 25/03/20 4:31 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 21

© Jones &6. Bartlett When viewing Learning, tooth 19 LLC from this one view, it can be© Jones9. Whi &ch Bartlett of the following Learning, phrases LLCare correct? NOT FOR SALEdivided OR into DISTRIBUTION thirds from the buccal to lingual andNOT FORa. Buc SALEcal surface OR ofDISTRIBUTION tooth 10 from the mesial to the distal. From which view is this b. Labial surface of tooth 19 possible? c. Palatal surface of tooth 29 a. Buccal d. Occlusal surface of tooth 27 b. Lingual e. Facial surface of tooth 1 c. Mesial © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 10. Which term does NOT refer to a tooth crown line d. Distal NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION angle? e. Occlusal a. Mesio-occlusal 7. If you were observing the faciolingual dimension of a b. Mesiofacial tooth, what surface(s) could you be viewing? c. Mesiodistal a.© Mesia Jonesl & Bartlett Learning, LLC d. Distofacial© Jones & Bartlett Learning, LLC b.NOT Occl usalFOR SALE OR DISTRIBUTION e. Linguo-occlusalNOT FOR SALE OR DISTRIBUTION c. Proximal d. Labial e. Distal © Jones &8. Bartlett If the root-to-crown Learning, ratio LLC of a maxillary molar (tooth 14)© Jones & Bartlett Learning, LLC is 1.72 and that of a maxillary incisal (tooth 8) is 1.16, NOT FOR SALEwhich OR tooth DISTRIBUTION has the longest root relative to its shorterNOT FOR SALE OR DISTRIBUTION crown? a. Tooth 14. b. Tooth 8. c. More information© Jonesis required & in Bartlett order to answer Learning, this LLC © Jones & Bartlett Learning, LLC

question. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

1–a, c, e; 2–e; 3–a, d; 4–b; 5–d; 6–e; 7–a, b, c, e; 8–a; 9–e; 10–c 9–e; 8–a; e; c, b, 7–a, 6–e; 5–d; 4–b; d; 3–a, 2–e; e; c, 1–a, ANSWERS:

© Jones & Bartlett Learning, LLC © Jonescusp and & Bartletta lingual cusp. Learning, Three-cusped LLC premolars have one A. MORPHOLOGY OF AN ANATOMIC CROWN NOT FOR SALE OR DISTRIBUTION NOTbuccal FOR and SALE two lingual OR DISTRIBUTION cusps, and the two lingual cusps are Teeth are made up of many rounded elevations, ridges, depres- named after the adjacent line angles, that is, mesiolingual cusp sions, and grooves. Specific tooth structures that occur with and distolingual cusp. A four-cusped molar has four cusps some frequency on teeth within a class have been assigned named after the adjacent line angles: mesiobuccal, distobuc- specific names. To identify the following anatomic structures, cal, mesiolingual, and distolingual. A three-cusped maxillary reference will be made ©to Jonesrepresentative & Bartlett drawings Learning,of various LLCmolar has two buccal cusps (mesiobuccal© Jones &and Bartlett distobuccal) Learning, LLC teeth seen in figures throughoutNOT FOR this SALEbook. OR DISTRIBUTIONand one lingual cusp. On a five-cuspedNOT FOR molar, SALE the three OR buc DISTRIBUTION- cal cusps are called mesiobuccal, distobuccal, and the smallest distal cusp. Refer to Figure 1-21 for examples of cusp names 1. Elevations: Pointed Cusps and Linear Ridges on posterior teeth with two, three, four, and five cusps. a. Cusps: Cusp Names and Numbers © Jones & Bartlett Learning, LLC b. Cusp Ridges© Jones & Bartlett Learning, LLC A cuspNOT is a pyramidalFOR SALE elevation OR with DISTRIBUTION a peak called a cusp tip. NOT FOR SALE OR DISTRIBUTION Cusps are located on the occlusal surfaces of molars and pre- Many cusps can be thought of as having four cusp ridges molars and on the incisal surfaces of canines. Canines have (linear prominences of enamel) converging toward the one cusp, premolars normally have two or three cusps, and cusp tip. These four ridges form the shape of a four-sided most molars have from three to five cusps. On teeth with mul- pyramid with rounded surfaces. If you draw a line along © Jones &tiple Bartlett cusps, each Learning, cusp is named LLC according to its location on the© Jonesthe greatest & Bartlett linear bulge Learning, of each ofLLC these four ridges, the NOT FORtooth. SALE For OR example, DISTRIBUTION on a two-cusped premolar, the two cuspsNOT lines FOR would SALE intersect OR DISTRIBUTIONat the cusp tip indicated by the “X” are named after the surface adjacent to each cusp: abuc cal on Figure 1-22. On this example of a buccal cusp on a

9781284218251_CH01_001_048.indd 21 25/03/20 4:31 PM 22 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC VIEWED FROM© JonesOCCLUSAL & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Two-cusped Three-cusped Three-cusped Four-cusped Five-cusped premolar premolar molar molar molar

2-cusped 3-cusped mesiobuccal distobuccal mesiobuccal mesiobuccal buccal buccal B distobuccal B © JonesB & Bartlett Learning, LLC B distobu©ccal Jones &B Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALEdistal OR DISTRIBUTION

M D M D D M M D M D

L L L L lingual distolingual © Jones & Bartlett Learning,distolingual LLC L mesiolingual© Jones & Bartlett Learning,distolingual LLC mesiolingual mesiolingual NOT FOR SALE OR DISTRIBUTIONlingual NOT FOR SALE OR DISTRIBUTION

VIEWED FROM BUCCAL

© Jones & Bartlett Learning, LLCOne visible cusp © JonesFour & visible Bartlett cusps Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION mesiolingual distolingual mesiobuccal buccal

D M © Jones & Bartlett Learning, LLCD M © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

distobuccal

FIGURE© Jones1-21. Cusp & namesBartlett on teeth Learning, having two, LLCthree, four, and five cusps, viewed© from Jones the occlusal & Bartlett and buccal Learning,views. Notice that LLC the cuspsNOT are named FOR after SALE the adjacent OR sur DISTRIBUTIONface or line angle EXCEPT on five-cusped mandibularNOT firstFOR molars SALE with three OR buccal DISTRIBUTION cusps. On five- cusped molars, the two larger buccal cusps are named mesiobuccal and distobuccal cusps, as on the four-cusped molar, but the smallest cusp is called the distal cusp.

4 D 2 1 M © Jones & Bartlett Learning, LLC 6 © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION L Two-cusped One-cusped premolar canine FIGURE© Jones 1-22. The & four-cusped Bartlett ridgesLearning, of the buccal LLC cusp of a two-cusped premolar© have Jones a somewhat & Bartlett pyramidal Learning,design (actually, LLC a pyramidNOT with FOR rounded SALE sides called OR a gothicDISTRIBUTION pyramid). The cusp ridges are numbered 1NOT to 4 and FOR converge SALE at the ORcusp tipDISTRIBUTION (at the “X”). Ridge 1 is the mesial cusp ridge of the buccal cusp; ridge 2 is the distal cusp ridge of the buccal cusp; ridge 3 is the more subtle buccal ridge of the buccal cusp; and 4 is the triangular ridge of the buccal cusp. (Courtesy of Drs. Richard W. Huffman and Ruth Paulson.) Cusp ridges on the single cusp of a maxillary canine also have a mesial cusp ridge labeled 1 and distal cusp ridge labeled 2, the same as on the premolar, but 5 is the labial ridge of the canine cusp (similar to a buccal ridge on a premolar), and 6 is the lingual cusp ridge. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 22 25/03/20 4:31 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 23

© Jones & Bartlett Learning,Buccal LLC ridge © Jonesteeth from & Bartlett the occlusal, Learning, denoted in greenLLC on the two cusps of a premolar in Figure 1-25. NOT FOR SALE OR DISTRIBUTION NOT FORTriangular SALE ridges OR areDISTRIBUTION located on the major cusps of posterior teeth. Each triangular ridge extends from a cusp tip toward the depression (sulcus) near the middle of the occlusal surface faciolingually, most easily identified when viewing DM © Jones & Bartlett Learning, LLCa proximal surface as on Figure© 1-26Jones, but also& Bartlett evident when Learning, LLC NOT FOR SALE OR DISTRIBUTIONviewing the occlusal surface asNOT on Figure FOR 1-25. SALE When aOR trian DISTRIBUTION- gular ridge from a buccal cusp joins with a triangular ridge from a lingual cusp, these two ridges together form a longer ridge called a transverse ridge. A transverse ridge crosses the occlusal surface of posterior teeth in a more or less buc- © Jones & Bartlett Learning, LLC colingual direction,© Jones running & Bartlett between the Learning, buccal and lingualLLC NOT FOR SALE OR DISTRIBUTION cusps on a premolarNOT FOR (seen fromSALE an occlusalOR DISTRIBUTION view and a proximal view in Figs. 1-25 and 1-26) or connecting the buccal FIGURE 1-23. A rounded buccal ridge can be seen on the and lingual cusps that are lined up across from one another buccal surface of many premolars. on a molar (seen on a mandibular molar in Fig. 1-27 and on the two-cusped premolar). An oblique ridge is found only © Jones &premolar, Bartlett three Learning, of the ridges LLC are named after the circum©- Joneson maxillary & Bartlett molars. Learning,It crosses the occlusalLLC surface obliquely NOT FORferential SALE toothOR DISTRIBUTIONsurface they extend toward: the more subtleNOT (diagonally) FOR SALE and ORis made DISTRIBUTION up of one ridge on the mesiolin- buccal ridge extends onto the buccal surface, the mesial gual cusp joining with the triangular ridge of the distobuccal cusp ridge extends from the cusp tip toward the mesial sur- cusp (seen in Fig. 1-27 on the maxillary molar). According face, and the distal cusp ridge extends from the cusp tip to Ash,1 the ridge of the mesiolingual cusp that forms the toward the distal surface. The fourth ridge extends from the lingual half of the oblique ridge is the distal cusp ridge of the cusp tip toward the faciolingual© Jones middle & Bartlett of the tooth Learning, and is LLCmesiolingual cusp. © Jones & Bartlett Learning, LLC called a triangular ridgeNOT. FOR SALE OR DISTRIBUTIONThe single cusp of manyNOT canines FOR may SALE also have OR four DISTRIBUTION The buccal ridges that run cervico-occlusally on the ridges emanating from its cusp tip (Fig. 1-22): a mesial cusp buccal surfaces of premolars or molars are often the least ridge and a distal cusp ridge, a labial ridge similar to a buc- distinct of the four ridges that emanate from the cusp tip, cal ridge running cervicoincisally from the cusp tip, and although they may be more prominent on some types of sometimes a fourth ridge called a lingual ridge that extends teeth© (Fig. 1-23 Jones). &Lingual Bartlett cusps Learning,do not normally LLC have prom- lingually toward© Jones the cervical & Bartlett bulge (cingulum). Learning, These LLC ridges inentNOT lingual FOR ridges SALE running OR cervico-occlusally DISTRIBUTION from the can be prominentNOT on FOR maxillary SALE canines OR ( Fig.DISTRIBUTION 1-28A and B). cusp tips. The mesial and distal cusp ridges are also known as c. Marginal Ridges and Cingulum cusp slopes or cusp arms. They are most evident when viewing teeth from the facial or lingual aspect where they can be On the lingual of all anterior teeth, a cingulum [SING gyoo © Jones &seen Bartlett as inclined Learning, ridges that LLCconverge toward the cusp tip to© Joneslum] (plural & Bartlett cingula )Learning, is the prominence LLC or bulge in the cer- NOT FORform SALE an angle OR (seenDISTRIBUTION in green on a buccal cusp of a premolarNOT vical FOR third SALE of the ORlingual DISTRIBUTION surface of the crown (incisors and and on a buccal cusp of a molar in Fig. 1-24). For some teeth, canines) (seen on the lingual view in Fig. 1-29 and seen as a the sharpness or bluntness of a cusp angle can be an defining prominence in the cervical third of the crown on the proxi- trait. These ridges are more difficult to discern when viewing mal view in Fig. 1-30). On anterior teeth, mesial and distal

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC distal cusp NOTridge FORmesial SALE cusp OR ridge DISTRIBUTIONdistal cusp ridge of NOT FOR SALE OR DISTRIBUTION of buccal cusp of buccal cusp mesiobuccal cusp mesial cusp ridge of mesiobuccal cusp

D © Jones & BartlettD Learning,M LLC © JonesM & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Premolar Molar

FIGURE 1-24. Cusp ridges (cusp slopes) are labeled on the buccal cusp of a mandibular premolar and on © Jones & Bartlett theLearning, mesiobuccal LLCcusp of a four-cusped mandibular molar.© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 23 25/03/20 4:31 PM 24 PART 1 ■ Comparative Tooth Anatomy

© Jones & BartlettBuccal ridge Learning, LLC © Jones & Bartlett Learning, LLC Distal cusp ridge Buccal cuspNOT tip FOR SALE OR DISTRIBUTION NOT FOR SALEof buccal OR cusp DISTRIBUTION Mesial cusp ridge Distobuccal groove of buccal cusp Mesiobuccal groove Tr iangular ridge © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Transverse ridge NOT FOR SALE OR DISTRIBUTION FIGURE 1-25. NOTOn this FOR two-cusped SALE maxillary OR DISTRIBUTION Central developmental groove premolar, the mesial and distal cusp ridges Tr iangular ridge of the buccal and lingual cusps are shaded Mesial cusp ridge green. The triangular ridges of the buccal and of lingual cusp lingual cusps are shaded blue and together are Distal cusp ridge called a transverse ridge. The buccal ridge of of© lingual Jones cusp & Bartlett Learning, LLCLingual cusp tip © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOTthe FOR buccal cuspSALE is shaded OR greenDISTRIBUTION.

marginal ridges form the mesial and distal borders of the lin- d. Occlusal Table Outline versus Crown Outline gual surface, and these ridges converge toward a rounded ele- © Jones & Bartlett Learning, LLC © JonesWhen &viewing Bartlett posterior Learning, teeth from LLC the occlusal view, it is vation or bulge in the cervical third called a cingulum, as seen important to distinguish the entire crown outline of the tooth NOT FORon SALE an incisor OR in DISTRIBUTION Figures 1-29 and 1-30. When distinguishingNOT FOR SALE OR DISTRIBUTION from the occlusal table of that tooth. The occlusal crown a mesial from a distal marginal ridge on anterior teeth, it can outline is the outer outline of the entire tooth crown from be useful to remember that the mesial marginal ridge is nor- the occlusal view, whereas the occlusal table is the occlusal mally longer than the distal. When determining which mar- surface that is bounded by the continuous cusp ridges and ginal ridge is longer, think of the length of a marginal ridge as © Jones & Bartlett Learning, LLCmarginal ridges. On the premolar© Jonesin Figure &1-31, Bartlett the occ lusal Learning, LLC extending from the incisoproximal line angle to its junction table is bounded by a mesial marginal ridge joined with the with the cingulum (as onNOT Fig. 1-29FOR where SALE the mesial OR DISTRIBUTIONmarginal NOT FOR SALE OR DISTRIBUTION mesial and distal cusp ridges of the buccal cusp, then the dis- ridge appears slightly longer than the distal marginal ridge). tal marginal ridge, and the cusp ridges of the lingual cusp. On posterior teeth, marginal ridges form the mesial and This would be a good time to refer to Figure 1-32 and distal borders of the occlusal surface. The mesial marginal perform the learning exercise to test your knowledge of cusp ridge on a premolar is shaded red in Figure 1-31. © Jones & Bartlett Learning, LLC ridges. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Groove crossing mesial marginal FIGURE 1-26. When seen from the mesial view on Tip of buccal cusp ridge this maxillary two-cusped premolar, the outlines of two Sulcus © Jones & Bartlett Learning, LLC TipT of lingual© Jones cusp & triangularBartlett ridges Learning, form a “V” LLCshape and join at the NOT FOR SALE OR DISTRIBUTION NOT FOR SALEdepth of ORthe occlusal DISTRIBUTION sulcus to form one transverse Tr iangular ridges ridge.

9781284218251_CH01_001_048.indd 24 25/03/20 4:32 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 25

M distal D transverse marginal

triangular of MB triangular of DB © Jones & Bartlett Learning, LLCtransverse ©M Jones & Bartlett Learning,transverse LLC triangular of ML D triangular of DL NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION distal marginal ridge L

FIGURE 1-27. Three posterior teeth B Mandibular molar show transverse and oblique ridges. © Jones &A. BartlettTwo triangular Learning, ridges on a two- LLC © Jones & Bartlett Learning, LLC NOT FORcusped SALE premolar OR formDISTRIBUTION one transverse NOT FOR SALEB OR DISTRIBUTION ridge. B. Two pairs of triangular ridges triangular of MB on a mandibular molar join to form transverse two transverse ridges. C. One pair of triangular of DB M oblique D ridge of ML triangular ridges on a maxillary molar is triangular of ML aligned buccolingually and ©forms Jones one & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC transverse ridge in blue, andNOT another FOR pair SALE OR DISTRIBUTION L NOT FOR SALE OR DISTRIBUTION of ridges is aligned obliquely (diagonally) to form an oblique ridge in purple. C Maxillary molar

e. Other Bulges and Ridges © JonesLEARNING & Bartlett EXERCISELearning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION Other bulgesNOT or ridges FOR can SALE be seen OR on theDISTRIBUTION cervical third of certain teeth facially or lingually. On the facial surface of The diagram in this Figure 1-32 the ridges seen from the permanent molars, the ridge or bulge running mesiodistally occlusal view that bound the occlusal table of a two-cusped in the cervical one third of the facial surface of a crown is premolar. Name each ridge next to its corresponding number. (Note that ridges labeled 1, 3, 4, 5, 6, and 7 form a continuous called the cervical ridge. This ridge forms the greatest bulge © Jones & outlineBartlett on the Learning, occlusal surface. LLC The area inside of this line is © Joneson the & buccal Bartlett surface, Learning, which is known LLC as the crest of cur- called the occlusal table.) vature (or height of contour) (Fig. 1-33A and B). This ridge NOT FOR SALE OR DISTRIBUTION NOTis FOR most SALEevident ORon mandibular DISTRIBUTION second molars where the

distal marginal ridge

AB FIGURE 1-29. The mesial and distal marginal ridges are shaded red, and the cingulum is shaded green on the lingual surface of FIGURE 1-28. A. On this maxillary canine, a labial ridge can be a maxillary incisor. If you think of the length of a marginal ridge as © Jones &seen Bartlett running from Learning, the cusp tip LLCcervically along the labial surface. © Jonesrunning & from Bartlett the proximal Learning, incisal line angles LLC to the cingulum, you NOT FORB. SALE On this maxillaryOR DISTRIBUTION canine, a prominent lingual ridge is visible NOTcan FOR see that SALE this mesial OR marginal DISTRIBUTION ridge is slightly longer than the running from the cusp tip cervically to the cingulum. distal marginal ridge.

9781284218251_CH01_001_048.indd 25 25/03/20 4:32 PM 26 PART 1 ■ Comparative Tooth Anatomy

Root axis line © Jones & Bartlett Learning, LLC © JonesDistal cusp & rBartlettidge Learning, LLC Mesial cusp ridge of buccal cusp of buccal cusp NOT FOR SALEApex of rootOR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Distal marginal Mesial marginal ridge ridge © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Root axis line Mesial cusp ridge NOT FOR SALE OR DISTRIBUTION NOT FORof SALE lingual cusp OR DISTRIBUTION Distal cusp ridge of lingual cusp

Anatomic root FIGURE 1-31. Occlusal view of a two-cusped premolar shows the difference between the occlusal outline of the tooth (the black outline surrounding the entire tooth from this view) and the smaller © Jones & Bartlett Learning,Cementoenamel LLC © Jones & Bartlett Learning, LLC Cementum red occlusal table (or occlusal chewing surface) bounded by six NOT FOR SALE OR DISTRIBUTIONjunction NOT FOR SALE OR DISTRIBUTION ridges: the two cusp ridges of the buccal cusp (green), the two cusp Cervical line Cervical line ridges of the lingual cusp (green), and the two marginal ridges (red). Cingulum

© Jones & Bartlett Learning, LLC © Jonesworn off& Bartlettafter the toothLearning, comes into LLC functional contact with Enamel its opposing teeth. If you have the opportunity, observe a NOT FOR SALE OR DISTRIBUTION NOT7-year-old FOR SALE smile ORto see DISTRIBUTION these mamelons on newly erupted Lingual

concavity Anatomic crown permanent incisors. When mamelons remain on the incisors Tip of of an adult, it is because maxillary and mandibular anterior cusp teeth do not touch together to wear away the enamel. When a © Jones & Bartlett Learning, LLCpatient desires, the dentist can ©reduce Jones the mamelons & Bartlett to make Learning, LLC FIGURE 1-30. This maxillary canine demonstrates that the the incisal edge more uniformly curved. cingulum bulge in green is located in the cervical third of the NOT FOR SALE OR DISTRIBUTIONFinally, perikymata [pear NOTi KY mah FOR tah] SALE are the numerOR DISTRIBUTION- lingual surface. One visible marginal ridge is shaded red. ous, minute horizontal ridges on the enamel of newly erupted permanent teeth (Fig. 1-35). They form from the overlapping occlusal outline of the mesiobuccal cusp appears to bulge of layers of enamel laid down during tooth formation. These (Fig.© 1-33C Jones). & Bartlett Learning, LLC lines are closer© Jones together & in Bartlett the cervical Learning, third of the LLCcrown Mamelons are three small bulges or tubercles on the than in the incisal third. Perikymata are more prominent incisalNOT edges FOR of newly SALE erupted OR incisors DISTRIBUTION (Fig. 1-34). Usually, on the teethNOT of young FOR people SALE than onOR the DISTRIBUTION teeth of older per- mamelons are not evident on adult dentition since they are sons because perikymata, like mamelons, wear away from

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION2 1. ______1 3 2. ______8 3. ______Mesial 4. ______© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

Distal 7 4 5. ______ansverse NOT FOR SALE OR DISTRIBUTION Tr NOT10 FOR SALE OR DISTRIBUTION 6. ______9 7. ______6 5 8. ______© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 9. ______Lingual

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

10. Transverse

marginal ridge; 8—triangular ridge of buccal cusp; 9—triangular ridge of lingual cusp. lingual of ridge 9—triangular cusp; buccal of ridge 8—triangular ridge; marginal

4—mesial marginal ridge; 5—mesial cusp ridge of lingual cusp; 6—distal cusp ridge of lingual cusp; 7—distal 7—distal cusp; lingual of ridge cusp 6—distal cusp; lingual of ridge cusp 5—mesial ridge; marginal 4—mesial

cusp; buccal of ridge cusp 3—mesial ridge; (cusp) 2—buccal cusp; buccal of ridge cusp 1—distal ANSWERS: © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR FIGURESALE 1-32. OR IdentifyDISTRIBUTION the ridges numbered on this maxillary premolar.NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 26 25/03/20 4:32 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 27

B © Jones & Bartlett Learning, LLC © Jones & BartlettBuccal Learning, LLC NOT FOR SALE ORcervical DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ridge DL ML

DB MB Buccal D M height of D contour © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

A © JonesMandi &bu Bartlettlar first molar Learning, LLC BC© Jones & BartlettMandib Learning,ular second LLC molar NOT FOR SALE OR DISTRIBUTION NOT FOR SALEL OR DISTRIBUTION FIGURE 1-33. A. On this mandibular first molar from the buccal view, abuccal cervical ridge is the rounded prominence located in the cervical third of the crown. B. From the proximal view, the buccal cervical ridge forms the greatest bulge or crest of curvature in the cervical third of this molar. C. From the occlusal view on this four-cusped mandibular second molar, the buccal cervical ridge forms a prominent bulge on the mesiobuccal outline. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORongoing SALE abrasion OR DISTRIBUTION due to eating and even tooth brushing withNOT side FOR and SALE forward OR against DISTRIBUTION the upper teeth during chewing. abrasive toothpastes. Partially chewed food squirts out through grooves toward the tongue and cheeks. Each tooth has major developmen- 2. Depressions and Grooves of an Anatomic Crown tal grooves, which are often consistent in location for teeth © Jones & Bartlett Learning, LLCof the same type, and other ©minor, Jones supplemental & Bartlett grooves, Learning, LLC An occlusal sulcus [SUL kuss] (plural sulci [SUL sye]) of which can vary greatly from tooth to tooth. Developmental a tooth is the broad V-shapedNOT FOR depression SALE or ORvalley DISTRIBUTION on the grooves separate cusps and otherNOT major FOR portions SALE of aOR tooth DISTRIBUTION occlusal surface of each posterior teeth running mesiodistally formed from the developmental lobes (described later in between the buccal and lingual cusps. The sulcus is formed Section IX of this chapter). On most posterior teeth like by the sloping of the buccal and lingual triangular ridges the premolar in Figure 1-37A, a central groove is a devel- that ©converge Jones toward & Bartlett the developmental Learning, grooves LLC located in opmental groove© Jones that separates& Bartlett the buccalLearning, from the LLC lin- the depth of the sulcus on each posterior tooth (Fig. 1-36). gual cusps and is located near the buccolingual center of AlthoughNOT a FORsulcus isSALE a linear OR depression, DISTRIBUTION there is much varia- the tooth sulcus.NOT Other FOR dev SALEelopmental OR DISTRIBUTIONgrooves are named tion to the anatomy within the sulcus of each tooth. For according to their location. For example, on mandibular example, there are triangular and marginal ridges (discussed molars with two buccal cusps, a buccal groove separates previously) and grooves (channels) within the sulcus, as well the mesiobuccal and distobuccal cusps and is likely to as multiple depressions, each called a fossa [FAH sah] (plural, extend onto the buccal surface. On mandibular molars with © Jones &fossae Bartlett [FAH see]. Learning, LLC © Jonesthree buccal& Bartlett cusps, Learning,there are two LLC grooves separating the NOT FOR SALEGROOVES: OR DISTRIBUTION A groove is a linear channel often foundNOT three FOR buccal SALE cusps, OR so theyDISTRIBUTION are called a mesiobuccal groove between cusps in the depth of the sulcus and between that separates the mesiobuccal cusp from the distobuccal ridges. They serve as important escape ways for food mor- cusp, and a distobuccal groove that separates the distobuc- sels when the teeth of the lower jaw move from side to cal cusp from the smallest distal cusp (Fig. 1-37B). Both of these grooves are likely to extend onto the buccal surface. © Jones & Bartlett Learning, LLCMandibular molars also have ©a lingual Jones groove & Bartlett between theLearning, LLC NOT FOR SALE OR DISTRIBUTIONmesiolingual and distolingualNOT cusp, FORbut these SALE grooves OR are DISTRIBUTION not likely to extend onto the lingual surface. Most maxillary molars have a lingual groove that often extends onto the lingual surface between the mesiolingual and distolingual © Jones & Bartlett Learning, LLC cusps, and ©a buccal Jones groove & Bartlett between Learning,the mesiobuccal LLC and distobuccal cusps that does not normally extend onto the NOT FOR SALE OR DISTRIBUTION buccal surfaceNOT (Fig. FOR 1-37). SALE OR DISTRIBUTION Additional occlusal grooves that are not developmental grooves are called supplemental grooves. These small irreg- ular (extra) grooves do not occur at the junction of the lobes © Jones & Bartlett Learning, LLC © Jonesor major & portionsBartlett of Learning,the tooth and LLCdo not occur at the same FIGURE 1-34. Three distinct unworn mamelons are evident on location on teeth of the same type, so these extra grooves are NOT FORthe SALE incisal edgeOR ofDISTRIBUTION this mandibular incisor. NOTnormally FOR SALE not assigned OR DISTRIBUTIONa specific name.

9781284218251_CH01_001_048.indd 27 25/03/20 4:33 PM 28 PART 1 ■ Comparative Tooth Anatomy

ENAMEL © Jones & Bartlett Learning,SURF LLCACE © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

A © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett Learning, LLCC ENAMEL SURFACE ENLARGED© Jones & Bartlett Learning, LLC FIGURE 1-35. A. Perikymata are the small ridges visible on the labial surface of this incisor. B. Magnified cross section of enamel shows perikymata ridges on the toothNOT surface FOR (on SALE the right ORhalf). DISTRIBUTIONC. Higher magnification (220×) shows the enamelNOT rods FORthat make SALE up enamel OR DISTRIBUTION ending on the perikymata waves. (These scanning electron micrographs were provided by Dr. Ruth B. Paulson, Associate Professor Emeritus, Division of Oral Biology, the Ohio State University.)

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FOSSAE:NOT FOR Located SALE at the OR mesial DISTRIBUTION and distal ends of the which they aim,NOT for FOR example, SALE in Figure OR 1-38, DISTRIBUTION the distobuccal central groove on each posterior tooth within the occlu- developmental groove (more precisely called the distobuc- sal table and next to the mesial and distal marginal ridges, cal triangular or fossa groove) runs toward the distobuccal there are shallow depressions called a mesial fossa and dis- line angle of the tooth. A pit may form at the depth of a fossa tal fossa (sometimes called a mesial and distal triangular where central groove joins the fossa grooves. For example, © Jones &fossa Bartlett) (Fig. 1-38 Learning,). Fossa grooves LLC (also called fossa develop©- Joneswithin & the Bartlett distal fossa Learning, on a premolar, LLC there is a distal pit at NOT FORmental SALE grooves OR DISTRIBUTION or triangular fossa grooves) may be foundNOT the FOR junction SALE of the OR central DISTRIBUTION groove with the distobuccal and within these fossae splitting off of the ends of the central distolingual fossa grooves (Fig. 1-38). Most molars and groove directed toward the line angles of the tooth. These three-cusped premolars have an additional central fossa grooves can be named for the line angles of the tooth toward seen in Figure 1-39. Many anterior teeth have a shallow, broad lingual fossa © Jones & Bartlett Learning, LLCthat is located on the lingual surface© Jones between & theBartlett mesial andLearning, LLC NOT FOR SALE OR DISTRIBUTIONdistal marginal ridges and justNOT incisal FOR to the SALEcingulum OR (par DISTRIBUTION- ticularly on maxillary incisors, Fig. 1-40). The lingual ridge of some maxillary canines may divide the lingual surface into

Crest of curvature two fossae: a mesial fossa bounded by the mesial marginal ridge and the lingual ridge and a distal fossa bounded by the Crest of curvature © Jones & Bartlett Learning, LLC distal marginal© Jones ridge and & the Bartlett lingual ridge Learning, (Fig. 1-41). LLC Groove crossing Deep, defective pits and fissures may be found at the NOT FOR SALE OR DISTRIBUTIONmesial marginal NOT FOR SALE OR DISTRIBUTION Tip of buccal cusp ridge depth of fossae and grooves caused by the incomplete fusion SulcusSulcus of enamel during tooth development (at the white arrow in Tip of lingual cusp Fig. 1-42). Because it is very difficult to remove food debris Tr iangular ridges from these inaccessible fissures, tooth decay (also called © Jones & FIGURE Bartlett 1-36. Learning,This two-cusped LLC premolar has a sulcus between © Jonesdental &caries Bartlett [CARE Learning, eez]) often beginsLLC in the deepest part NOT FORthe SALE buccal andOR lingual DISTRIBUTION cusps. NOTof FOR a fissure SALE or pit OR (seen DISTRIBUTION spreading out within dentin as the

9781284218251_CH01_001_048.indd 28 25/03/20 4:33 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 29

NOT FOR SALE OR DISTRIBUTION NOT FORF SALE OR DISTRIBUTION Fossa developmental grooves (F) F S C M Supplemental grooves (S) S S

Marginal ridge groove (M) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOTA FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

central groove buccal groove

© JonesB & Bartlettbuccal groo Learning,ve LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONmesiobuccal groove D M D M D M distobuccal groove distobuccal triangular © Jones & BartlettL Learning,lingual grooLLCve © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Mandibular molars

mesiobuccal triangular D M groove M D © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC mesiolingual NOT FOR SALE OR DISTRIBUTIONtriangular NOT FOR SALE OR DISTRIBUTION L lingual groove groove lingual groove B Maxillary molars

FIGURE 1-37. A. This two-cusped premolar has developmental (major) and supplemental (extra) occlusal grooves. (Courtesy of © Jones &Drs. Bartlett Richard W . Learning,Huffman and Ruth LLC Paulson.) B. Grooves are labeled© on Jones a mandibular & Bartlett four-cusped Learning, molar (upper leftLLC and center), a NOT FORmandibular SALE OR five-cusped DISTRIBUTION molar (upper right) and a maxillary molar NOTwith four FOR major SALEcusps (lower OR row). DISTRIBUTION The buccal, lingual, and central grooves are considered developmental grooves. The buccal groove extends between the two buccal cusps onto the buccal surface on mandibular molars, and the lingual groove extends between the two lingual cusps onto the lingual surface of maxillary molars. Five- cusped mandibular first molars have three buccal cusps, so there are two developmental grooves: a mesiobuccal groove between the mesiobuccal and distobuccal cusps and a distobuccal groove between the distobuccal and distal cusps. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALEDistobuccal OR triangular DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (fossa) groove Buccal cusp

Distal triangular fossa (red) and pit © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALEMesial ORtriangular DISTRIBUTION fossa (red) and pit

© Jones & FIGURE Bartlett 1-38. Learning,The mesial and LLC Distolingual triangular © Jones & Bartlett Learning, LLC NOT FORdistal SALE fossae OR are DISTRIBUTION outlined in red on (fossa) groove NOT FOR SALE OR DISTRIBUTION this maxillary two-cusped premolar. Lingual cusp

9781284218251_CH01_001_048.indd 29 25/03/20 4:33 PM 30 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning,FOSSAE AND LLC PITS © Jones & Bartlett Learning, LLC NOT FOR SALETwo-cusped OR premolar DISTRIBUTIONThree-cusped premolar NOT FOR SALE OR DISTRIBUTION B mesial fossa B mesial triangular fossa and pit and pit

D M D M distal triangular © Jones & Bartlettfossa Learning, and pit LLC M © JonesD & Bartlett Learning, LLC Mesial Distal distal fossaNOT FOR SALEcentral OR fo ssaDISTRIBUTION and pit fossa NOT FOR SALE fossaOR DISTRIBUTION L and pit L

Four-cusped molar

mesial triangular fossa © Jones & Bartlettand pit Learning, LLC © Jones & Bartlett Learning, LLC Lingual ridge NOT FOR SALEB OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION central fossa and pit FIGURE 1-41. This maxillary canine has a lingual ridge that divides the lingual surface into a mesial fossa and a distal fossa. M distal triangular fossa and pit D © Jones & Bartlett Learning, LLC © Jonesopen, it& is Bartlett like a fissured Learning, groove. LLCWhere two rivers converge NOT FOR SALE OR DISTRIBUTIONL NOT(as FOR when SALE grooves OR or fissures DISTRIBUTION converge), the whirlpools and eddies may have formed a depression, like a fossa, possibly FIGURE 1-39. Fossae and pits are labeled on teeth with two, three, and four cusps. Two-cusped teeth have two fossae (a mesial with a pit at its depth. Needless to say, it is difficult to define and a distal fossa), while three- or four-cusped teeth also have a exactly where a mountain stops and the valley begins, just third fossa called a central fossa. as it would be difficult to define exactly where a tooth cusp © Jones & Bartlett Learning, LLCstops and a sulcus or fossa begins.© Jones Just realize& Bartlett that these Learning, LLC NOT FOR SALE OR DISTRIBUTIONterms are not precise, but that theyNOT are FOR helpful SALE when learning OR DISTRIBUTION dark area between the two black arrows) and described in how to reproduce tooth form during construction of crowns more detail in Chapter 10. These carious pits and fissures and placement of fillings or when learning to finish and pol- are most likely to be located in four areas: at the depth of ish an existing filling. deep grooves and pits on the occlusal surface of posterior teeth,© in Jones buccal grooves & Bartlett that extend Learning, onto the LLCbuccal surface © Jones & Bartlett Learning, LLC B. EXTERNAL MORPHOLOGY OF THE of mandibularNOT FOR molars, SALE in lingual OR DISTRIBUTION grooves that extend onto ANATOMICNOT FOR ROOT SALE OR DISTRIBUTION the lingual surface of maxillary molars, and on the lingual surface of maxillary incisors where the lingual fossa joins the Recall that the anatomic root is the part of a tooth that is cingulum (Fig. 1-43). covered with cementum. The apex of the root is the tip or In summary, if you compare tooth morphology to a peak at the end of the root, often with visible openings called © Jones &mountain Bartlett range, Learning, the mountain LLC peak would be the cusp tip.© Jones & Bartlett Learning, LLC NOT FORRidges SALE emanating OR DISTRIBUTION from the mountain peak are like the cuspNOT FOR SALE OR DISTRIBUTION ridges and triangular ridges. The depression between the mountains is a valley, like the depressions between cusps is a sulcus. The dried river bed at the bottom of the valley is like a groove at the bottom of the sulcus. If the riverbed is cracked © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

lingual pit (if present)

lingual fossa FIGURE 1-42. A cross section of a mandibular molar shows an occlusal groove (white arrow), which actually has a fissure (crack- © Jones & Bartlett Learning, LLC © Joneslike fault) & extendingBartlett through Learning, the outer enamel LLC and into the dentin. NOT FOR FIGURESALE 1-40. OR TheDISTRIBUTION lingual surface of this maxillary lateral incisor NOTThe FOR black SALE arrows show OR how DISTRIBUTION the dental decay spreads out once it shows the shallow lingual fossa and an adjacent lingual pit. reaches softer dentin at the depth of this fissure.

9781284218251_CH01_001_048.indd 30 25/03/20 4:33 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 31

ABC D

FIGURE 1-43. Caries-prone pits and fissures are located in four places arrows( ). A. The occlusal surfaces of posterior teeth. B. The lingual surfaces of maxillary molars. C. The buccal surfaces of mandibular molars. D. The lingual surfaces of maxillary incisors. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

apical foramina, where the nerves and blood vessels enter three-rooted teeth). The furcal region or interradicular into the tooth pulp canals. The cervix [SUR viks] or neck of space is the region or space between two or more roots, © Jones &the Bartlett tooth is the Learning, slightly constricted LLC region surrounding the© Jonesapical &to theBartlett furcation Learning, where the roots LLC divide from the root NOT FORjunction SALE ofOR the DISTRIBUTIONcrown and the root (Fig. 1-44B). NOTtrunk. FOR SALE OR DISTRIBUTION Some new terms apply to multirooted teeth (Fig. 1-44B). The root trunk or trunk base is the part of C. CERVICAL LINE (CEMENTOENAMEL the root of a multirooted molar or two-rooted premolar next to the cementoenamel junction that has not yet split JUNCTION OR CEJ) CURVATURE (like a stubby tree trunk© Jonesbefore it &gives Bartlett off branches). Learning, The LLCWhen viewed from the mesial© or Jones distal aspect, & Bartlett the cervical Learning, LLC furcation [fur CAY shun]NOT is theFOR place SALE on multirooted OR DISTRIBUTION teeth line of a tooth curves (is convex)NOT toward FOR the incisalSALE or OR occlu DISTRIBUTION- where the root trunk divides into separate roots (called a sal surface (Fig. 1-44). In general, the amount of curvature bifurcation on two-rooted teeth and a trifurcation on is greater on the mesial surface than on the distal surface of

Apex of root Apical foramina

Furcal region © Jones & Bartlett Learning, LLC Root© bifurcation Jones & Bartlett Learning, LLC Longitudinal NOT FOR SALERoot OR axis DISTRIBUTION line NOT FOR SALE OR DISTRIBUTION depression on root

Anatomic root Root trunk

© Jones & BartlettCementoenamel Learning, LLC © Jones & Bartlett Learning, LLC Cementum junction Cementoenamel NOT FOR SALE OR DISTRIBUTIONCervix NOTjunction FOR (ce SALErvical OR DISTRIBUTION Cervical line Cervical line line)

NOT FOR SALE OR DISTRIBUTIONAnatomic crown NOT FOR SALE OR DISTRIBUTION A Tip of B cusp

FIGURE 1-44. A. Root anatomy on a single-rooted canine. B. Root anatomy of a bifurcated (split) root on a maxillary © Jones & Bartlettfirst premolar.Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 31 25/03/20 4:33 PM 32 PART 1 ■ Comparative Tooth Anatomy

© Jones & BartlettTABLE 1-2 Learning, Summary LLC of Curvatures of the Cementoenamel© Jones Junction& Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Proximal surfaces: mesial curvature vs. Generally, teeth have a greater proximal cervical line curvature on distal curvature the mesial than the distal. Proximal surfaces: anterior teeth vs. Proximal cervical line curvatures are greatest on the mesial posterior teeth surfaces of central incisors and, for most teeth, tend to get © Jones & Bartlett Learning,smaller LLC when moving from the anterior© teethJones toward & theBartlett last Learning, LLC NOT FOR SALE OR DISTRIBUTIONmolar where there may be no curvatureNOT at all. FOR SALE OR DISTRIBUTION

CERVICAL LINE Posterior teeth: facial vs. lingual On many posterior teeth, the cervical line is in a more occlusal

(CEMENTOENAMEL (CEMENTOENAMEL surface position on the lingual than on the facial. JUNCTION) CURVATURES

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC the sameNOT tooth, FOR and SALE the amount OR DISTRIBUTIONof curvature is greatest for NOT FOR SALE OR DISTRIBUTION Important Tooth Dimensions to central incisors and diminishes in size for each tooth when TABLE 1-3 Memorize moving distally around each quadrant (Table 1-2). Tooth with longest crown Mandibular canine (Woelfel research: maxillary incisor) © Jones &D. Bartlett RELATIVE Learning, SIZE LLC © Jones & Bartlett Learning, LLC Longest tooth overall Maxillary canine NOT FORIn SALE order ORto document DISTRIBUTION the relative sizes of tooth crownsNOT FOR SALE OR DISTRIBUTION and roots, Dr. Woelfel studied a convenient sample of 4572 Longest root Maxillary canine extracted teeth. His findings are presented in Table 1-7 at Widest crown mesiodistally Mandibular first molar the end of this chapter. This table should not be memo- Widest crown Maxillary first molar rized, but it can be useful when comparing the average buccolingually dimensions of each tooth© Jones and in &order Bartlett to appreciate Learning, the LLC © Jones & Bartlett Learning, LLC wide range of dimensionsNOT for FOR each SALEtooth. A OR summary DISTRIBUTION of Narrowest crown NOTMandibular FOR central SALE incisor OR DISTRIBUTION the most important highlights of that data is presented in mesiodistally Table 1-3. Greatest cervical line curve Mesial of maxillary incisor

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION TERMINOLOGY RELATED TO THE IDEAL TOOTH ALIGNMENT SECTION VII OF TEETH IN DENTAL ARCHES

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORWhen SALE viewed OR DISTRIBUTIONfrom the occlusal aspect, the alignment ofNOT FOR SALE OR DISTRIBUTION teeth within each dental arch is somewhat U shaped or par- abolic like the famous landmark in Missouri, the St. Louis Arch (Fig. 1-45). The incisal edges and the buccal cusp tips follow a curved line around the outer edge of the dental arch; the lingual cusp tips of© the Jones posterior & teethBartlett follow Learning, a curved LLC © Jones & Bartlett Learning, LLC line nearly parallel to theNOT buccal FOR cusp SALEtips. Between OR DISTRIBUTIONthe buc- NOT FOR SALE OR DISTRIBUTION cal and lingual cusps of posterior teeth is the sulcular groove (occlusal sulcus), a V-shaped depression that extends anteroposteriorly through all of the posterior teeth in each quadrant. This sulcular groove is made up of the occlusal sulcuses© of Jones adjacent &posterior Bartlett teeth Learning, in each quadrant LLC (Fig. 1-45). © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION A. MIDROOT AXIS LINE AND TOOTH ALIGNMENT

Themidroot axis line (or root axis line) is an imaginary line FIGURE 1-45. This model of the maxillary dentition with ideal © Jones &through Bartlett the center Learning, of the tooth LLC root. When viewing the facial© Jonesalignment & formBartlett an arch Learning,shape and the ropeLLC of blue wax on the left NOT FORor SALE lingual ORsurface, DISTRIBUTION it can be visualized as a line that dividesNOT half FOR falls withinSALE the ORocclusal DISTRIBUTION sulcus.

9781284218251_CH01_001_048.indd 32 25/03/20 4:33 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 33

RootRoot aaxisxis lilinene © Jones & Bartlett Learning, LLC ApexApex of rooroott © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FORApexApex of SALEroot OR DISTRIBUTION

RRootoot aaxisxis lineline t © Jones & Bartlett Learning, LLCRRootoot aaxisxis linlinee © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Anatomic root Anatomic roo

Cervixrvix CCervicalervical line ementum Cementum C © Jones & Bartlett Learning,((cementoenamelcementoenamel LLC © Jones & Bartlett Learning, LLC junctionjunction)) NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Distal contactt LabialLabial crest Lingual crest n area and crestt Mesial contact of curvature n of curvature of curvaturee area andand crest ((heightheight of contour) ofof curvaturecurvature Cingulum Enamel Enamel mic cro (green) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Anatomic cr ow Anatomic cr ow NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ABA B Tip of cusp

FIGURE 1-46. The midroot axis line is drawn on two views of a canine. A. When viewed from the facial (or lingual), the greatest bulges on the mesial and distal surfaces (crests of curvature) on this canine are the widest points on the crown that touch lines parallel to the midroot axis line. These crests© Jones of curvature & Bartlettare essentially Learning, the same as the LLC contact areas of teeth when they© areJones aligned & ideally Bartlett in the Learning, LLC mouth. Notice that these contact areas are positioned more incisally on the mesial surface than on the distal. B. When viewed from the proximal, the greatest bulgesNOT on the FOR facial SALE and lingual OR surfaces DISTRIBUTION (crests of curvature) are the points on theNOT facial andFOR lingual SALE crown outlineOR DISTRIBUTION that touch lines that are parallel to the midroot axis line. They are located in the cervical third on both the facial surface and on the lingual surface (on the cingulum shaded green) for all anterior teeth.

the bulk© Jones of the root & intoBartlett mesial andLearning, distal halves LLC (Fig. 1-46A). (or cusp tip)© of Jones a maxillary & Bartlettcanine is more Learning, likely to be LLC labial WhenNOT viewing FOR the mesialSALE or OR distal DISTRIBUTION surface, it divides the bulk to the midrootNOT axis FORline (as SALE seen in Fig.OR 1-46B). DISTRIBUTION of the root into facial and lingual halves (Fig. 1-46B). It is an When the posterior teeth in each arch are viewed from important reference line for describing the location of tooth the buccal aspect as in Figure 1-47, notice that posterior teeth landmarks. For example, you will learn that the incisal ridge are not aligned exactly parallel to one another and all cusp

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-47. A wax strip placed between stone models of the maxillary and mandibular teeth demonstrates the anteroposterior curve (curve of Spee), which is concave in the mandibular arch but convex in the maxillary arch. © Jones &Note Bartlett the difference Learning, in the axial LLCalignment of the teeth © Jones & Bartlett Learning, LLC NOT FORwithin SALE each OR arch demonstratedDISTRIBUTION by the axial lines placed on NOT FOR SALE OR DISTRIBUTION the third molars and on the first premolars.

9781284218251_CH01_001_048.indd 33 25/03/20 4:33 PM 34 PART 1 ■ Comparative Tooth Anatomy

FIGURE 1-48. Dental stone casts viewed from the distal with a wax strip used to demonstrate the mediolateral curve (of Wilson). It is convex in the maxillary arch, but concave in the mandibular arch. Note the red lines that denote posterior tooth alignment within each arch: maxillary molar crowns tilt toward the facial, and mandibular molar crowns tilt toward the lingual. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC tips inNOT a quadrant FOR doSALE not normally OR DISTRIBUTION fall along a ruler-straight mediolateralNOT curve FORof the maxillarySALE OR arch DISTRIBUTION is convex, whereas line. The axial alignment changes gradually from posterior that of the mandibular arch is concave (Fig. 1-48). to anterior teeth, which is evident when you compare the alignment of the mandibular third molar (tipped noticeably more to the mesial) than on the first premolar. Subsequently, B. CREST OF CURVATURE (HEIGHT OF © Jones &if youBartlett were to Learning,connect the buccal LLC cusp tips with a line, a grad©- JonesCONTOUR) & Bartlett ONLearning, THE FACIAL LLC AND NOT FORual SALE anteroposterior OR DISTRIBUTION curve (curve of Spee) is evident (seeNOT FORLINGUAL SALE ORSURFACE DISTRIBUTION Fig. 1-47). This curve is convex in the maxillary arch, while The shape and extent of the greatest bulge on the facial and the curve is concave in the mandibular arch. lingual crown surfaces help determine the direction that food When viewed from the distal, maxillary posterior teeth particles are deflected as they are crushed between tooth sur- are axially tilted facially within the maxillary arch, whereas faces when chewing. When we chew food, these natural tooth mandibular posterior teeth© Jones are tilted &lingually Bartlett within Learning, the man- LLC © Jones & Bartlett Learning, LLC convexities divert food away from the thin free gingiva and dibular arch (Fig. 1-48).NOT Therefore, FOR in theSALE mouth OR, lingual DISTRIBUTION cusps NOT FOR SALE OR DISTRIBUTION gingiva sulcus surrounding the cervix of the tooth and toward of maxillary posterior teeth appear longer than the buccal the firmer tissues of the mouth, thus minimizing trauma to cusps, while the lingual cusps of mandibular posterior teeth the gingiva. If teeth were flat facially and lingually, food could appear shorter than the buccal cusps due to the lingual tilting more likely damage the gingiva (Fig. 1-50). Needless to say, it is within the mandible. However, to avoid confusion, you need best for the dentist, dental hygienist, and/or dental technician to realize© Jones that later & in Bartlett the book, Learning,you will learn LLCthat when you © Jones & Bartlett Learning, LLC to reproduce and maintain these natural convexities when holdNOT a mandibular FOR SALEmolar in ORyour DISTRIBUTIONhand with the midroot axis NOT FOR SALE OR DISTRIBUTION restoring a tooth, when finishing and polishing fillings near aligned vertically, the lingual cusps of mandibular molars are the gum line, or when contouring a replacement tooth crown. actually slightly longer than buccal cusps (Fig. 1-49). When a The facial or lingual crest of curvature (height of con- line connects the buccal and lingual cusps of the same type tour) is the point on a crown outline where a line drawn par- of molars and premolars on opposite sides of the arch, this allel to the midroot axis line touches the greatest bulge on © Jones &side-to-side Bartlett curve Learning, is the mediolateral LLC curve (of Wilson). The© Jones & Bartlett Learning, LLC the crown (Fig. 1-51). It is usually located in either the cervi- NOT FOR SALE OR DISTRIBUTION NOTcal FOR third SALE or the middle OR DISTRIBUTION third, normally not in the occlusal or incisal third. When viewed from the proximal, the location of the crest of curvature on the facial surface on both anterior and posterior tooth crowns is normally located in the B L B L © Jones & Bartlett Learning, LLCcervical third. The location of© the Jones lingual crest& Bartlett of curvature Learning, LLC depends on whether the tooth is anterior or posterior. The NOT FOR SALE OR DISTRIBUTIONlingual crest of curvature on anteriorNOT FORteeth is SALE in the cervicalOR DISTRIBUTION third, on the cingulum (Fig. 1-46B). The lingual crest of curvature on posterior teeth is most often located in the middle third (Fig. 1-51). Refer to Table 1-4 for a summary of the © Jones & Bartlett Learning, LLC location of the© Jonesfacial and & lingual Bartlett heights Learning, of contour for LLC anterior teeth compared to posterior teeth. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

C. CONTACT AREAS (OR PROXIMAL CRESTS OF CURVATURE) FIGURE 1-49. This mandibular second molar with its mid-root axis © Jones &aligned Bartlett vertically Learning, (left drawing) hasLLC lingual roots that appear longer©, JonesWhen &the Bartlett teeth are Learning,in normal, ideal LLC alignment within an NOT FORwhereas SALE the OR same DISTRIBUTION tooth with the midroot axis tipped lingually, as itNOT arch FOR and SALE viewed directlyOR DISTRIBUTION toward the facial or lingual surfaces, would be in the mandible, has lingual cusps that appear shorter. the location of the mesial or distal greatest bulges or crests

9781284218251_CH01_001_048.indd 34 25/03/20 4:34 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 35

FIGURE 1-50. A. Normal facial and lingual crests of curvature help divert food away© Jones from the & gingival Bartlett sulcus. Learning, LLC © Jones & Bartlett Learning, LLC B. When crests of curvature are not adequate,NOT food FOR can more SALE readily OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION damage the gingival sulcus. AB

Midroot axis line (in red)

Crest of curvature (cervical third) FIGURE 1-51. On the proximal view of this Crest of curvature (middle third) premolar, the buccal crest of curvature (height © Jones &of Bartlettcontour) is located Learning, in the cervical LLC third, while © Jones & Bartlett Learning, LLC the lingual height of contour is located more NOT FORocclusally, SALE inOR the middleDISTRIBUTION third. This is typical of NOT FOR SALE OR DISTRIBUTION most posterior teeth.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Summary of the Location of Facial and Lingual Heights of Contour (Greatest Bulge) of the Crown TABLE 1-4 (BestNOT Seen FOR from SALE the Proximal OR DISTRIBUTION View) NOT FOR SALE OR DISTRIBUTION

FACIAL (HEIGHT OF CONTOUR) LINGUAL (HEIGHT OF CONTOUR)

Anterior teeth (incisors and canines) Cervical third Cervical third (on cingulum) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC PosteriorNOT teethFOR (premolars SALE ORand molars) DISTRIBUTION Cervical third NOT FORIn SALEor near middle OR DISTRIBUTIONthird General learning guidelines: 1. Facial crest of curvature for all teeth is in cervical third. 2. Lingual crest of curvature for all anterior teeth is in the cervical third (on the cingulum). 3. Lingual crest of curvature for posterior teeth is in the middle third (slightly more occlusal in mandibular teeth due to the lingual tilt of the crown). © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 35 25/03/20 4:34 PM 36 PART 1 ■ Comparative Tooth Anatomy

Distal contact Mesial contact © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

FIGURE 1-52. The mesial and distal contact areas seen on the occlusal view of this two-cusped maxillary premolar are Lingual cusp located buccal to the center of the tooth buccolingually, which © Jones & Bartlett Learning,Crest of cur LLCvature is typical ©of mostJones posterior & Bartlettteeth. Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

of curvature is essentially the same location as contact areas • When chewing, tooth contacts help prevent food where two adjacent teeth touch (labeled on a canine from the from being forced between the teeth where it could facial view in Fig. 1-46A and on a premolar from the occlusal contribute to decay and gum and bone disease © Jones &view Bartlett in Fig. 1-52 Learning,). LLC © Jones(periodontal & Bartlett disease). Learning, Further, youLLC must be able to pass NOT FOR SALEIn a youngOR DISTRIBUTION person, contacts between teeth start offNOT FORfloss SALE through OR each DISTRIBUTION contact area in order to clean the between recently erupted teeth as contact points. Then, as proximal surfaces, which are otherwise inaccessible to the teeth rub together during function, these points become the toothbrush. somewhat flattened and truly become contact areas. (It has • Contact protects the thin interdental papillae of the been shown by careful measurements that by age 40 in a gingiva by diverting food buccally and lingually. healthy mouth with a complete© Jones dentition, & Bartlett a total Learning,of 10 mm LLC © Jones & Bartlett Learning, LLC A diastema [di ah STEE mah] is a space that exists of enamel has been wornNOT off FORthe contact SALE areas OR of allDISTRIBUTION teeth in NOT FOR SALE OR DISTRIBUTION between two adjacent teeth in the same arch that is not the an entire arch. This averages 0.38 mm per contact area on result of a missing tooth. It is most commonly seen between each tooth and certainly emphasizes the amount of proximal the maxillary right and left central incisors, but can occur wear that occurs. Therefore, we would expect contact areas between any teeth (Fig. 1-53A and B). on teeth of older people to be large and somewhat flattened.) When learning the normal location of the proximal con- The© Jones proximal & contactBartlett of eachLearning, tooth with LLC the adjacent © Jones & Bartlett Learning, LLC tacts for each type of tooth, it will be helpful to learn the teethNOT has several FOR important SALE ORfunctions: DISTRIBUTION NOT FOR SALE OR DISTRIBUTION following general guidelines that apply to most permanent • The positive contact of all teeth within each dental arch teeth. Exceptions to these general rules will be presented in stabilizes the position of teeth within each arch. later chapters.

FIGURE 1-53. A. This stone model has a space between maxillary central incisors called a diastema. B. On these primary teeth, there is an obvious diastema between the maxillary central incisors. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 36 25/03/20 4:34 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 37

FIGURE© Jones1-54. A. These& Bartlett maxillary teethLearning, LLC © Jones & Bartlett Learning, LLC are alignedNOT to FOR demonstrate SALE the ORlocation DISTRIBUTION of NOT FOR SALE OR DISTRIBUTION proximal contacts: contacts are more incisal (near the incisal edge) on the central incisor, but are located progressively more cervical as you move posteriorly to the third molars. © Jones &B. BartlettProximal contacts Learning, between the LLC central © Jones & Bartlett Learning, LLC incisors are very close to the incisal edge at the NOT FORmidline SALE (most OR incisal DISTRIBUTION between the mandibular NOT FOR SALE OR DISTRIBUTION incisors), but more cervical as you move posteriorly. B

• When viewing teeth from the facial, contact areas are located in one of three© Jones places: in & the Bartlett incisal (or Learning, occlusal) LLCD. EMBRASURE SPACES© Jones & Bartlett Learning, LLC third, at the junctionNOT of the incisalFOR (orSALE occlusal) OR and DISTRIBUTION middle When adjacent teeth contact, theNOT continuous FOR SALE space that OR sur DISTRIBUTION- thirds, or in the middle third of the crown. Contact areas rounds each contact area can be divided into four somewhat are not normally located in the cervical third. triangular embrasure spaces. These spaces are narrow- • On most teeth, the mesial contact is more incisal or est closest to the contact area where the teeth are in tight occlusal than its distal contact (Fig. 1-54A). contact, but due to the tapered shape and rounded corners • In© ge Jonesneral, proximal & Bartlett contacts Learning, are closer LLCto the biting/ of most teeth,© Jonesthese spaces & Bartlettwiden facially Learning, to form a LLCbuccal chewingNOT FORsurface SALE on anterior OR DISTRIBUTION teeth than are posterior or labial embrasureNOT FOR space SALE and lingually OR DISTRIBUTION to form a lingual teeth. The mesial contact areas on central incisors are embrasure space and widen occlusally (or incisally) to form positioned near the incisal edge, closest to the biting/ a small occlusal or incisal embrasure space. The fourth space, chewing surfaces (Fig. 1-54B), while contacts on molars cervical to the contact area, is properly called the interproxi- are located closer to the middle of the crown, the farthest mal space. © Jones & Bartlettfrom the chewing Learning, surface. LLC © JonesThe & lingual Bartlett embrasure Learning, is ordinarily LLC larger or longer NOT FOR• SALE When ORviewing DISTRIBUTION posterior teeth from the occlusal view,NOT than FOR the SALE facial embrasure OR DISTRIBUTION because most teeth are narrower contacts are often located slightly to the facial of the tooth (have less bulk) in the lingual half than on the facial half midline buccolingually (Fig. 1-55). and because their contact points are most often located • When viewing anterior teeth from the incisal view, facial to the faciolingual midline of the crown. See the dif- contacts are nearly centered faciolingually (Fig. 1-55). ference in the embrasure space sizes in Figure 1-56. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURENOT 1-55. FOR These SALE maxillary OR teeth DISTRIBUTION are NOT FOR SALE OR DISTRIBUTION aligned to demonstrate the location of proximal contacts when viewed from the occlusal. Between posterior teeth, the contacts are located buccal to the middle of the teeth © Jones &buccolingually. Bartlett BetweenLearning, anterior LLC teeth, the © Jones & Bartlett Learning, LLC NOT FORcontacts SALE are OR located DISTRIBUTION near the center of the NOT FOR SALE OR DISTRIBUTION teeth faciolingually.

9781284218251_CH01_001_048.indd 37 25/03/20 4:34 PM 38 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC © Jonesbut occlusal & Bartlett to their contactLearning, area. This LLC is the space where we NOT FOR SALE OR DISTRIBUTION NOTplace FOR the SALE dental flossOR DISTRIBUTIONbefore passing it through the contact area to clean tooth surfaces in the interproximal space. When viewed from the facial or lingual, the triangular- shaped interproximal space is bounded by the proximal surfaces of adjacent teeth, with the apex of the triangle at the © Jones & Bartlett Learning, LLCcontact between two teeth (Fig.© Jones1-57A and & BBartlett). In a mouth Learning, LLC NOT FOR SALE OR DISTRIBUTIONwith healthy periodontium, thisNOT space FOR is completely SALE OR filled DISTRIBUTION with the interdental papilla (Fig. 1-57C). Sometimes, this interproximal space is referred to as the cervical or gingival FIGURE 1-56. When viewed from the occlusal, the lingual embrasure. embrasure spaces of posterior teeth are larger than the buccal Excellent proximal contacts and well-formed crown embrasure© Jones spaces & due Bartlett to the taper Learning, of the teeth narrower LLC toward contours forming© Jones the proximal & Bartlett embrasure Learning, spaces serve LLC to the lingual and the location of the proximal contacts buccal to the NOT FOR SALE OR DISTRIBUTION direct food awayNOT from FOR the gingiva.SALE WhenOR DISTRIBUTION the embrasures are midline faciolingually. incorrectly shaped (as with a poorly contoured dental resto- ration), or when there is a space between the teeth, fibrous The occlusal or incisal embrasure is usually shallow food may readily lodge in the interproximal spaces requir- from the occlusal surface or incisal edge to the contact areas ing frequent use of dental floss or toothpicks for its removal. © Jones &and Bartlett is narrower Learning, faciolingually LLC on anterior teeth but broader© JonesThis food& Bartlett impaction Learning, is not only LLCan annoyance, but it can NOT FORon SALE posterior OR teeth. DISTRIBUTION The occlusal embrasure on posterior teethNOT contribute FOR SALE to the OR formation DISTRIBUTION of periodontal disease (bone is the small area between the marginal ridges of adjacent teeth loss) and dental decay.

FIGURE 1-57. A. The mandibular teeth are aligned to demonstrate the A interproximal spaces (or cervical © Jones & Bartlett Learning, LLC Interdental papilla © Jones & Bartlett Learning, LLC Incisal embrasure spaces) located between NOT FOR SALEembrasure OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION space each pair of contacting teeth. B. This close-up of mandibular incisors in a skull (without tissue) shows the interproximal space cervical to the Interproximal proximal contact (gingival embrasure © Jones & Bartlett Learning,space LLC (cervical © Jones & Bartlett Learning,space). The veryLLC small triangular space embrasure above the proximal contact is the incisal NOT FOR SALE OR DISTRIBUTIONspace) NOT FOR SALE OR DISTRIBUTION embrasure space. C. The interproximal spaces between these maxillary teeth are filled with healthy gingiva called B C interdental papillae. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION REVIEW Questions

These questions were designed to help you confirm that you 2. Which ridges help to surround the perimeter of the understand the terms and concepts presented in this section. occlusal surface (occlusal table) of a two-cusped More© than Jones one answer & Bartlett may be correct.Learning, LLC premolar?© Jones & Bartlett Learning, LLC 1. WhiNOTch ofFOR the following SALE bumpsOR DISTRIBUTION or ridges is NOT likely to a. MesialNOT marginal FOR ridge SALE OR DISTRIBUTION be found on a maxillary premolar? b. Distal marginal ridge c. Mesial cusp ridge of the buccal cusp a. Oblique ridge d. Distal cusp ridge of the lingual cusp b. Cingulum e. Transverse ridge © Jones & Bartlettc. Mesial Learning,marginal ridge LLC © Jones & Bartlett Learning, LLC NOT FOR SALEd. Tra ORnsverse DISTRIBUTION ridge NOT FOR SALE OR DISTRIBUTION e. Triangular ridge

9781284218251_CH01_001_048.indd 38 25/03/20 4:35 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 39

© Jones &3. Bartlett On a two-cusped Learning, premolar, LLC which ridges meet to form ©a Jones6. Whe &n Bartlett viewed from Learning, the proximal LLC views, what is the NOT FOR SALEtransverse OR ridge? DISTRIBUTION NOT FORlocation SALE of the OR greatest DISTRIBUTION bulge (crest of curvature or height a. Buccal ridge of the buccal cusp of contour) on the facial surface of all teeth? b. Triangular ridge of the lingual cusp a. Occlusal third c. Triangular ridge of the mesiolingual cusp b. Lingual third d. Triangular ridge of the buccal cusp c. Buccal third e. Cervical ridge of© the Jones buccal cusp& Bartlett Learning, LLCd. Middle third © Jones & Bartlett Learning, LLC e. Cervical third 4. Which of the followingNOT is FOR (are) SALENOT a cuspOR foundDISTRIBUTION on NOT FOR SALE OR DISTRIBUTION three-cusped type premolars? 7. Which space(s) contain(s) the part of the gingiva known a. Mesiobuccal as the interdental papilla? b. Distobuccal a. Buccal embrasure c.© Bucc Jonesal & Bartlett Learning, LLC b. Occlusal© Jones embrasure & Bartlett Learning, LLC d.NOT Mesio FORlingual SALE OR DISTRIBUTION c. LingualNOT embrasure FOR SALE OR DISTRIBUTION e. Distolingual d. Cervical embrasure e. Interproximal space 5. What is the correct order of anatomic landmarks of a tooth with two roots from the cementoenamel junction to the root tip? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC a. Cervix, trunk, furcation, apex NOT FOR SALEb. Trun ORk, cervix, DISTRIBUTION furcation, apex NOT FOR SALE OR DISTRIBUTION c. Trunk, furcation, cervix, apex d. Cervix, trunk, apex, furcation

e. Furcation, trunk, cervix, apex

1–a, b; 2–a, b, c, d; 3–b, d; 4–a, b; 5–a; 6–e; 7–d, e 7–d, 6–e; 5–a; b; 4–a, d; 3–b, d; c, b, 2–a, b; 1–a, © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,ANSWERS: LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Occlusion [ah KLOO zhun] in dentistry refers to the rela- mandibular teeth to the maxillary teeth will be presented in © Jones &tionship Bartlett of theLearning, upper and LLC lower teeth when they close© Jonesthis section. & Bartlett Learning, LLC NOT FORtogether SALE orOR contact DISTRIBUTION one another during function or rest.NOT FORTooth SALE relationships OR DISTRIBUTION were described and classified as Therefore, occlusion involves the contacting of occlusal and classes I, II, and III in the early 1900s by Edward H. Angle. incisal surfaces of opposing maxillary and mandibular teeth. He classified ideal occlusion as class I and defined it based The word occlude literally means to close up or shut, as in on the relationship between the maxillary and mandibular closing your teeth together. dental arches. When defining class I occlusion, the teeth It is important to learn© Jones the relationships & Bartlett of teeth Learning, in ideal LLCshould be closed together in ©their Jones maximum & Bartlett intercuspal Learning, LLC occlusion in order to identifyNOT malocclusionsFOR SALE that OR could DISTRIBUTION con- position, or best fitting togetherNOT of FORthe teeth, SALE as shown OR DISTRIBUTIONin tribute to dental problems. The importance of proper occlu- Figure 1-58. This relationship can be achieved on handheld sion cannot be overestimated. It is essential for both dental models when the maxillary teeth fit as tightly as possible health and general health and for a patient’s comfort and abil- against the mandibular teeth (i.e., are most stable). The fol- ity to speak, chew, and enjoy food. Understanding occlusion lowing specific tooth relationships define class I ideal occlu- requires© Jones a knowledge & Bartlett not only Learning, of the relation LLC of the lower sion in the adult© Jones dentition: & Bartlett Learning, LLC jaw NOTto the upperFOR jawSALE but also OR of DISTRIBUTION the jaw joints, their com- NOT FOR SALE OR DISTRIBUTION • Horizontal overlap of anterior teeth: The incisal edges plexities, and the muscles, nerves, ligaments, and soft tissues of maxillary anterior teeth horizontally overlap the that affect the position of the mandible. These topics will be mandibular teeth such that the incisal edges of maxillary covered in much more depth in Chapter 9. The arrangement teeth are labial to the incisal edges of mandibular teeth of teeth within the dental arches (alignment, proximal con- (best seen in Fig. 1-58). © Jones &tacts, Bartlett and embrasure Learning, spaces) LLC has been discussed in the previ©- Jones & Bartlett Learning, LLC • Vertical overlap of anterior teeth: The incisal edges NOT FORous SALE section OR of thisDISTRIBUTION chapter, and the ideal relationship of theNOT FOR SALE OR DISTRIBUTION of the maxillary anterior teeth extend below (overlap

9781284218251_CH01_001_048.indd 39 25/03/20 4:35 PM 40 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-58. Dental stone casts with adult teeth fitting together in the maximum intercuspal position (tightest fit). Notice that, from this view, each tooth has the © Jones & Bartlett Learning,Anteroposterior LLC curve potential for ©contacting Jones two & opposing Bartlett teeth Learning, LLC (curve of Spee) NOT FOR SALE OR DISTRIBUTION except the maxillaryNOT FORthird molar. SALE The vertical OR DISTRIBUTION red line marks the relationship of first molars in class I occlusion: the mesiobuccal cusp of the maxillary first molar occludes in the mesiobuccal groove of the mandibular first molar. Also, the maxillary canine fits into the © Jones & Bartlett Learning, LLC © Jonesfacial embrasure& Bartlett between Learning, the mandibular LLC NOT FOR SALE OR DISTRIBUTION NOT canineFOR and SALE first premolar. OR DISTRIBUTION

vertically) the incisal edges of the mandibular teeth so • The lingual cusp tips and lingual surfaces of the that, when viewed from the facial, part of the incisal mandibular teeth are lingual to those in the maxillary © Jones & Bartlettportion of Learning,mandibular incisors LLC is hidden from view by the© Jones &arch. Bartlett Learning, LLC NOT FOR SALEoverlapping OR DISTRIBUTIONmaxillary incisors (Fig. 1-59). NOT• FORRelative SALE alignment OR DISTRIBUTION: The vertical (long) axis midline of • Relationship of posterior teeth: Maxillary posterior teeth each maxillary tooth is slightly distal to the vertical axis are positioned slightly buccal to mandibular posterior of its corresponding mandibular tooth type so that: teeth (Fig. 1-60) so that: • The tip of the mesiobuccal cusp of the maxillary first • The uccalb cusp tips and buccal surfaces of the molar is aligned directly over the mesiobuccal groove maxillary teeth are© Jonesbuccal to & those Bartlett in the mandibular Learning, LLC (the mesial of two buccal© grooves)Jones on & the Bartlett mandibular Learning, LLC arch. NOT FOR SALE OR DISTRIBUTIONfirst molar (the mesiobuccalNOT cuspFOR of toothSALE 14 ORfits intoDISTRIBUTION • The lingual cusps of maxillary teeth rest in occlusal the mesiobuccal groove of tooth 19 in Fig. 1-61). This sulcuses and fossae of the mandibular teeth. relationship of first molars (the first permanent teeth • The buccal cusps of the mandibular teeth rest in the to erupt) is a key factor in the definition of class I occlusal sulcuses and fossae of the maxillary teeth. occlusion. Further, the maxillary canine fits into the © Jones & Bartlett Learning, LLC facial© embrasure Jones between& Bartlett the mandibular Learning, canine LLC and NOT FOR SALE OR DISTRIBUTION first NOTpremolar. FOR SALE OR DISTRIBUTION • Most teeth in an ideal dental arch have the potential for occluding with two teeth in the opposing arch. For example, the distal surface of the maxillary first

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Buccal surface NOT FOR SALE OR DISTRIBUTIONLingual surface NOT FOR SALEof maxilla ORry DISTRIBUTION of maxillary molar FIGURE 1-59. Maxillary and mandibular teeth of the permanent molar L B dentition are in the maximum intercuspal position. Observe the B interproximal spaces filled with the interdental papillae L between each pair of teeth. Notice how each tooth is in contact Lingual surface with ©its adjacentJones teeth, & Bartlettand how the Learning, midline between LLC proximal of mandibular© Jones & Bartlett Learning,Buccal LLC surface molar of mandibular contactsNOT of the FOR maxillary SALE central OR incisors DISTRIBUTION lines up with the midline NOT FOR SALE OR DISTRIBUTIONmolar between proximal contacts of the mandibular central incisors. Also, note how the incisal edges of maxillary anterior teeth overlap (vertical overlap) and hide the incisal edges of the mandibular anterior teeth, and how each of the relatively wide maxillary central © Jones &incisors Bartlett overlaps Learning, not only the narrow LLC mandibular central incisor but© Jones FIGURE & 1-60. Bartlett This proximal Learning, view of a maxillaryLLC and mandibular also part of the mandibular lateral incisor (e.g., tooth 9 overlaps molar in normal interarch alignment reveals the alignment and NOT FORtooth SALE 24 and OR part DISTRIBUTION of 23). NOTposition FOR ofSALE buccal and OR lingual DISTRIBUTION cusps in ideal occlusion.

9781284218251_CH01_001_048.indd 40 25/03/20 4:35 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 41

© Jones & Bartlett Learning, LLC © Jones &premolar Bartlett (tooth Learning, 12 in Fig. 1-61)LLC is posterior to the NOT FOR SALE OR DISTRIBUTION NOT FORdistal SALE surface OR of DISTRIBUTION the mandibular first premolar (tooth 21), and therefore, tooth 12 occludes with both the mandibular first and second premolar (teeth 20 and 10 11 9 12 13 14 15 21). Exceptions to this rule include the mandibular 18 central incisor, which, due to its size and location, 25 24 23 22 © Jones21 20& Bartlett19 Learning, LLC only occludes with the© maxillary Jones central & Bartlett incisor Learning,(as LLC NOT FOR SALE OR DISTRIBUTIONseen in Fig. 1-59), andNOT the maxillaryFOR SALE third ORmolar, DISTRIBUTION which only occludes with the mandibular third molar (Fig. 1-58). To summarize, ideal occlusion involves a class I relation- FIGURE 1-61. The left cheek has been drawn back to reveal ship between the maxillary and mandibular first molars in how each of these maxillary teeth occludes with two opposing mandibular© Jones teeth. T ooth& Bartlett 19 has two Learning, buccal grooves: LLCmesiobuccal maximum intercuspal© Jones position. & Bartlett Also, Learning,ideally, there LLCshould (with NOTa buccal FOR filling) SALEand distobuccal OR DISTRIBUTION (not visible). Note that the be no large flattenedNOT FOR chewing SALE surfaces OR (facets)DISTRIBUTION and no tooth mesiobuccal cusp of the maxillary first molar (tooth 14) occludes grinding (bruxing) habits, bone loss, crooked teeth, loose with the mesiobuccal groove on the mandibular first molar (19) teeth, or joint pain.1 Classes II and III of occlusion and mal- and that the maxillary canine (11) fits into the facial embrasure occlusion (literally meaning bad occlusion) will be discussed between the mandibular canine (22) and the first premolar (21). in detail in Chapter 9. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION REVIEW Questions about Occlusion

These questions are to help you confirm that you understand 2. Where do lingual cusps of maxillary teeth occlude in the terms and concepts© presented Jones in & this Bartlett section. Learning,More than LLCideal class I occlusion? © Jones & Bartlett Learning, LLC one answer may be correct.NOT FOR SALE OR DISTRIBUTIONa. In the buccal embrasureNOT space FOR between SALE mandibular OR DISTRIBUTION 1. Ideal class I occlusion involves an important first teeth permanent molar relationship where the mesiobuccal b. In the lingual embrasure space between mandibular cusp of the maxillary first molar is located within the teeth c. In occlusal fossae of mandibular teeth a.© MesJonesiobuccal & grooveBartlett of the Learning, mandibular LLCfirst molar. © Jones & Bartlett Learning, LLC b.NOT Distobuccal FOR SALEgroove of OR the mandibularDISTRIBUTION first molar. NOT FOR SALE OR DISTRIBUTION c. Buccal groove of the mandibular second molar. d. Mesiobuccal groove of the mandibular second molar.

e. Distobuccal groove of the mandibular second molar.

1–a; 2–c 1–a; ANSWERS: © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

SECTION IX TOOTH DEVELOPMENT FROM LOBES © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Tooth crowns develop from lobes or primary growth cen- from four lobes: three facial lobes and one lingual lobe ters (Fig. 1-62). Most normal teeth show evidence of hav- forming the cingulum. ing developed from three to five lobes. As a general rule, the As on anterior teeth, the facial portion of the facial cusp facial© portion Jones of anterior& Bartlett teeth Learning,(incisors and canines)LLC forms of a premolar© formsJones from & three Bartlett lobes, oftenLearning, evident byLLC a buc- from three lobes, and the lingual cingulum area forms from cal ridge and a depression on either side dividing the facial one NOTlobe. Evidence FOR SALE of three OR facial DISTRIBUTION lobes can sometimes be surface intoNOT three parts.FOR EachSALE lingual OR cusp DISTRIBUTION forms from one seen as a labial ridge separated from the rest of the facial lobe. Therefore, a two-cusp-type premolar forms from four surface by two shallow depressions dividing the facial sur- lobes: three facial and one lingual, the same as for an anterior face into three parts (seen clearly on a maxillary central tooth. However, a three-cusp-type premolar with two lingual © Jones &incisor Bartlett in Fig. Learning, 1-63A) or three LLC mamelons on an incisal edge© Jonescusps forms& Bartlett from five Learning, lobes: three facialLLC and two lingual, one (Fig. 1-63B). To summarize, anterior teeth normally develop for each lingual cusp. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 41 25/03/20 4:35 PM 42 PART 1 ■ Comparative Tooth Anatomy

E F G

FIGURE 1-62. Lobes or primary anatomic divisions on teeth. Drawings (A), (B), and (C) show the facial, mesial, and incisal views of a maxillary central incisor that,© likeJones all anterior & Bartlett teeth, forms Learning, from four lobes. LLC The lingual cingulum develops from© oneJones lobe (labeled & Bartlett 4) seen inLearning, LLC views (B) and (C). MamelonsNOT may FOR appear SALE on the incisal OR edge DISTRIBUTION of newly erupted incisors, an indication of theNOT three labialFOR lobes. SALE Drawings OR (D) DISTRIBUTION and (G) are the mesial and occlusal view of a two-cusped premolar that also forms from four lobes. As with anterior teeth, the facial cusp forms from three lobes, and one lingual lobe forms the lingual cusp. The divisions between the facial and lingual lobes are evidenced by the marginal ridge developmental grooves. Each cusp of a molar is formed by one lobe. Drawing (E) is a mandibular first molar with five lobes, three buccal, and two lingual, which is one lobe per cusp. Drawing (F) is a maxillary first molar with three larger lobes and one smaller lobe, ©or oneJones per cusp. & BartlettA very small fifthLearning, (Carabelli) LLCcusp, when large enough, may have© formed Jones from & a Bartlettseparate lobe. Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

As a general rule, each molar cusp forms from one lobe. Two types of tooth unusual occurrences (called anoma- For example, maxillary or mandibular molars with five cusps lies), peg-shaped maxillary lateral incisors (seen later in form from five lobes, and those with four cusps form from Chapter 11) and some extra teeth (also called supernumer- © Jones &four Bartlett lobes. Some Learning, maxillary molarsLLC have as few as three cusps© Jonesary teeth), & Bartlett form from Learning, less than three LLC lobes. Guidelines for NOT FORand SALE form ORfrom DISTRIBUTIONthree lobes. A small fifth cusp (of Carabelli)NOT determining FOR SALE the ORnumber DISTRIBUTION of lobes that form each tooth are may also be present on some maxillary molars, and when it presented in Table 1-5. is large, it may have formed from a separate lobe.

Two © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC depressionsNOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

FIGURE 1-63. A. The light reflecting off of this maxillary central incisor reveals the three bulges reflecting the formation of the facial surface by three facial lobes. The © Jones & Bartlett Learning, LLC © Jones &three Bartlett bulges are Learning, separated by twoLLC depressions. B. This NOT FOR SALE ORAB DISTRIBUTION NOT FOR mandibularSALE OR incisor DISTRIBUTION with three mamelons reflects its Three bulges formation from three facial lobes.

9781284218251_CH01_001_048.indd 42 25/03/20 4:35 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 43

© Jones & BartlettTABLE 1-5 Learning, Guidelines LLC for Determining the Number© Jones of Lobes & Forming Bartlett Adult Learning, Tooth LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION TOOTH CLASS NO. LINGUAL CUSPS OR CINGULUM NO. OF LOBES (FACIAL AND LINGUAL) All anterior teeth 1 Cingulum 3 + 1 = 4 Two-cusped premolars 1 lingual 3 + 1 = 4 Three-cusped premolars 2 lingual 3 + 2 = 5

ANTERIOR © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC TEETH ANDTEETH PREMOLARS NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Guideline for determining the number of lobes for anterior teeth and premolars: Number of lobes = 3 facial lobes + 1 lobe per lingual cusp or cingulum

MOLAR BY NUMBER OF CUSPS NO. TOTAL CUSPS NO. OF LOBES © JonesThree-cusped & Bartlett molars Learning, LLC3 © Jones3 & Bartlett Learning, LLC Four-cusped molars 4 4 NOT FORFive-cusped SALE molars OR (including DISTRIBUTION 5 NOT 5FOR SALE OR DISTRIBUTION MOLARS large Carabelli cusps) Guideline for determining the number of molar lobes: Number of molar lobes = 1 per cusp (including Carabelli if large) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

REVIEW Questions about Lobes

These questions were ©designed Jones to &help Bartlett you confirm Learning, that you LLC4. How many developmental© Joneslobes form & Bartletta mandibular Learning, LLC understand the terms andNOT concepts FOR presented SALE inOR this DISTRIBUTION section. lateral incisor? NOT FOR SALE OR DISTRIBUTION More than one answer may be correct. a. 1 1. How many developmental lobes form a premolar with b. 2 two cusps (one buccal cusp and one lingual cusp)? c. 3 d. 4 a.© 1Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC e. 5 b.NOT 2 FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION c. 3 5. What separates the portions of tooth formed by different d. 4 lobes? e. 5 a. Supplemental grooves 2. How many developmental lobes form a maxillary molar b. Mamelons © Jones & Bartlettwith three Learning, cusps (two buccal LLC cusps and one lingual cusp)?© Jonesc. &Cus Bartlettp ridges Learning, LLC d. Transverse ridges NOT FOR SALEa. 1 OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION e. Developmental grooves b. 2 c. 3 d. 4 e. 5 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 3. How many developmentalNOT FOR lobes SALE form a ORthree-cusped DISTRIBUTION NOT FOR SALE OR DISTRIBUTION premolar with one buccal cusp and two lingual cusps? a. 1 b. 2 c. 3 d.© 4Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

e.NOT 5 FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

1–d; 2–c; 3–c; 4–d; 5–e 4–d; 3–c; 2–c; 1–d; ANSWERS:

9781284218251_CH01_001_048.indd 43 25/03/20 4:35 PM 44 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC INTERESTING VARIATIONS IN ANIMAL TEETH COMPARED TO NOT FOR SALESECTION OR DISTRIBUTION X NOT FOR SALE OR DISTRIBUTION HUMAN TEETH USING DENTAL FORMULAE

A dental formula for the human primary dentition can be 2 1 2 3 © Jones & Bartlett Learning, LLCICPM Mu= 88pper an©dl Jonesower teet &hi Bartlettneach Learning, LLC represented by placing the abbreviation for incisors (I) fol- 2 1 2 3 lowed by an upper numberNOT FORrepresenting SALE the OR number DISTRIBUTION of quadrant, 32NOT teeth FOR in all fourSALE quadrants OR DISTRIBUTION incisors in an upper quadrant over a bottom number repre- senting the number of incisors in a lower quadrant (I 2/2), It is interesting to note that the dentition of animals can then the number of canines (C) in an upper and lower quad- be represented by the same type of formula as described rant (C1/1), and then the number of molars (M) in an upper above. Look at the formulas for animals in Table 1-6, and lower© Jones quadrant & Bartlett(M2/2). The Learning, formula used LLC to represent and note that© Jones cows have & Bartlett no upper Learning, incisors or LLCupper teethNOT in the FORhuman SALEprimary ORdentition DISTRIBUTION is as follows: canines. TheyNOT have FOR three upperSALE and OR three DISTRIBUTION lower premolars on each side. Did you know that dogs have twice as many 2 1 2 ICMu= 55pper andlower teethineachquadrant; premolars as humans if you include uppers and lowers, 2 1 2 as well as the right and left sides? Did you know that 20 teethinall foourquadrants the tusks on an elephant are maxillary central incisors? © Jones & BartlettThe dental Learning, formula for LLC the human permanent denti©- JonesElephants & Bartlett have the Learning,largest diastema LLC in the world, large NOT FORtion, SALE adding OR the DISTRIBUTION new abbreviation for premolars (PM), is asNOT enough FOR SALEfor the OR massive DISTRIBUTION trunk between their central follows: incisors.

TABLE 1-6 Some Dental Formulae (Order of Teeth per Quadrant) and Interesting Facts about Teeth in Animals2–4 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 2 1 2 3 1 0 1 3 Humans, Old World monkeys,NOT FOR SALEIC2 1 P 2OR DISTRIBUTIONM 3 Porcupines and beavers NOT ICFOR1 0 P 1 SALE ORM 3 DISTRIBUTION and apes

2 1 3 3 3 1 4 2 New World monkeys IC2 1 P 3 M 3 Bears and pandas IC3 1 P 4 M 3

3 1 4 2 1 0 2 3 Dogs, wolves, and foxes IC3 1 P 4 M 3 Squirrels IC1 0 P 1 M 3 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Cats IC3 1 P 3 M 1 Rabbit‡ IC2 0 P 3 M 3 NOT FOR SALE OR DISTRIBUTION3 1 2 1 NOT FOR SALE OR1 DISTRIBUTION0 2 3

0 0 3 3 1 0 0 3 Cows IC3 1 P 3 M 3 Mice and rats IC1 0 P 0 M 3

* 3 1 4 3 3 1 4 3 Horses and zebra IC3 1 P 4 M 3 Moles IC3 1 P 4 M 3 Walruses IC1 1 P 3 M 0 Vampire bats IC1 1 P 2 M 0 © Jones & Bartlett Learning, LLC 0 1 3 © 0Jones & Bartlett Learning, LLC2 1 3 0

NOT FOR SALE OR† DISTRIBUTION 1 0 † 3 NOT3 FOR SALE OR DISTRIBUTION3 1 3 3 Elephants IC0 0 Dm 3 M 3 Shrews IC1 1 P 1 M 3

*Pigs and hippopotami have the same formula, except that they have two or three upper and two or three lower incisors. †Elephants have deciduous molars (Dm) but no premolars. An elephant’s skull is not larger than necessary to house its brain. The size is needed to provide mechanical support for the tusks (one third of their length is embedded in the skull) and the enormous molars. Each molar weighs about 9 pounds and is 5 nearly a foot long mesiodistally© onJones the occlusal & surface.Bartlett Tusks (theLearning, central incisors) LLC can be as long as 1½ feet and weigh© 440 Jones pounds. & Bartlett Learning, LLC ‡Guinea pigs have the same formula, except that they have only one maxillary incisor. The beaver has four strong curvedNOT incisors. FOR They SALE have very ORhard, brightDISTRIBUTION orange enamel on the labial surface and much softerNOT exposed FOR dentin SALE on the lingual OR DISTRIBUTION surface. As the dentin wears off, this leaves very sharp cutting edges of enamel. The incisors continue to grow throughout life. The posterior teeth have flat, rough edges on the occlusal surface, and they stop growing at 2 years of age. There is a large diastema immediately posterior to the incisors, and flaps of skin fold inward and meet behind the incisors to seal off the back part of the mouth during gnawing. Therefore, splinters are kept out. The flaps of skin relax for eating and drinking. The shrew has two hooked cusps on the upper first incisor. Its primary dentition is shed in utero. The shrew’s 1- to 1½-year life span is limited by the wear on their© Jonesmolars. Death & occursBartlett by starvation Learning, once the molars LLC wear out. Also, their small body can ©store Jones only enough & foodBartlett for 1 to 2 Learning,h, so they must feed LLC almostNOT continually. FOR Their SALE diet consists OR of smallDISTRIBUTION invertebrates, woodlice, and fruit. NOT FOR SALE OR DISTRIBUTION The vampire bat has large canines, but its highly specialized upper incisors, which are V shaped and razor edged, are what remove a piece of the victim’s skin. The bat’s saliva contains an anticoagulant, and its tongue rolls up in a tube to suck or lap the exuding blood. Some vertebrates do not have any teeth (complete anodontia) but have descended from ancestors that possessed teeth. Birds have beaks but depend on a gizzard to do the grinding that molars would usually perform. Turtles have heavy jaw coverings, which are thin edged in the incisor region and wide posteriorly for crushing. The duck-billed platypus has its early-life teeth replaced by keratinous plates, which it uses to crush aquatic insects, crustaceans, © Jones &and Bartlett mollusks. The Learning, whalebone whale LLC and anteaters also have no teeth, but© their Jones diets do not& requireBartlett chewing. Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 44 25/03/20 4:36 PM LEARNING EXERCISE 3 (continued) LEARNING EXERCISE 1

© Jones & SketchBartlett a tooth Learning, and adjacent gingivaLLC in cross section, and label © Jones & Bartlett Learning, LLC NOT FOR SALEthe following OR DISTRIBUTIONstructures: enamel, dentin, cementum, root NOT FOR SALE BEGINOR DISTRIBUTIONHERE canal, pulp chamber, apical foramen location, dentinoenamel First junction, cementoenamel junction, dentinocemental junction, molars periodontal ligament space, alveolar bone, gingiva, gingival sulcus, anatomic crown, and anatomic root. Use Figures 1-10 and 1-12 as a guide. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTION FIGURE 1-65. As per the directionsNOT for FOR this learning SALE exercise, OR DISTRIBUTION name each structure. Then identify the same teeth using the International System, then the Palmer System. LEARNING EXERCISE 2 a k Identify© Jones the teeth & visible Bartlett in Figure Learning, 1-64 using theLLC Universal b © Jones & Bartlett Learning, LLC NumberingNOT FOR System. SALE Remember OR DISTRIBUTION that as you are viewing c NOT FOR SALE OR DISTRIBUTION this mouth, the left side of the photograph is the right side j of the mouth. Begin with the second molar in the maxillary d arch and continue to the central incisor. Then drop to i the mandibular central incisor and continue numbering © Jones & backBartlett to the Learning, mandibular secondLLC molar. Compare your © Jones & Bartlett Learning, LLC NOT FOR SALEresponses OR to DISTRIBUTIONthe answers that follow. Then identify the NOT FOR SALE OR DISTRIBUTION same teeth using the International System and finally the Palmer System. efgh FIGURE 1-66. As per the directions for this learning BEGIN HERE exercise, name each structure on this mandibular left second © Jones & Bartlett Learning, LLCpremolar with three cusps (cusp© tips Jones denoted & by Bartlettthree small Learning, LLC circles) and this mandibular left first molar with five cusps Second NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION molars (cusp tips denoted by five small circles).

Answers: Universal tooth numbers for teeth in order: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14; then 19 for © Jones & Bartlett Learning, LLC mandibular© Jones first molar, & Bartlett 20, 21, 22, Learning,23, 24, 25, 26, LLC 27, NOT FOR SALE OR DISTRIBUTION 28, 29,NOT 30. The FOR correct SALE numbers OR using DISTRIBUTION the International FIGURE 1-64. As per the directions for this learning exercise, System are as follows: 16, 15, 14, 13, 12, 11, 21, 22, identify all visible teeth using the Universal number. Then 23, 24, 25, 26; then 36 for mandibular left first molar, identify the same teeth using the International System, then 35, 34, 33, 32, 31, 41, 42, 43, 44, 45, 46. Then use the Palmer System. Table 1-1 to confirm the correct method for identifying © Jones & Bartlett Learning, LLC © Joneseach & Bartlett of these teeth Learning, using the Palmer LLC System. NOT FOR SALEAnswers. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Universal tooth numbers for teeth in order: 2, 3, 4, 5, 6, 7, 8; 25 for central incisor, 26, 27, 28, 29, 30, 31. The correct numbers using the International LEARNING EXERCISE 4 System are 17, 16, 15, 14, 13, 12, 11; 41 for central incisor, 42, 43, 44, ©45, Jones 46, 47. Then, & Bartlett use Table Learning,1-1 LLCOne tooth in Figure 1-66 is© aJones mandibular & Bartlettleft second Learning, LLC to confirm the correct method for identifying each of premolar with three cusps (cusp tips are indicated by the these teeth using theNOT Palmer FOR System. SALE OR DISTRIBUTIONthree small circles), and the otherNOT tooth FOR is a mandibular SALE OR left DISTRIBUTION first molar with five cusps (cusp tips indicated by five small circles). Based on this information, you should be able to identify each of the structures (except maybe i) indicated in Figure 1-66. Confirm your answers below. © JonesLEARNING & Bartlett Learning,EXERCISE LLC 3 © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION Answers:NOT (a) LingualFOR groove;SALE (b) OR mesial DISTRIBUTION pit; (c) mesial marginal ridge; (d) mesial cusp ridge of the buccal Identify the teeth visible in Figure 1-65 using the Universal cusp; (e) triangular ridge of the buccal cusp; (f) distal Numbering System, beginning with the maxillary first molar cusp ridge of the mesiobuccal cusp; (g) mesiobuccal on the left side of the photograph, and continue numbering groove; (h) distobuccal groove; (i) distal cusp tip; (j) through the maxillary first molar on the right side. Then drop transverse ridge made up of the triangular ridges of © Jones & downBartlett to the Learning,mandibular first LLC molar and continue numbering © Jonesthe & distobuccalBartlett cusp Learning, and the distolingual LLC cusp; (k) NOT FOR SALEthrough ORthe first DISTRIBUTION molar on the other side Fig.( 1-66). NOT FORmesial SALE marginal OR ridge DISTRIBUTION groove.

9781284218251_CH01_001_048.indd 45 25/03/20 4:36 PM 46 PART 1 ■ Comparative Tooth Anatomy

1. A. Using good light source (like a small flashlight), a large mirror (magnifying if possible), and a small, clean disposable dental mirror (which© Jones can be & purchased Bartlett from Learning, most drug stores), LLC evaluate the facial and lingual© Jones surfaces & of Bartlett a maxillary Learning, LLC right lateral incisorNOT in FOR your own SALE mouth. OR Describe DISTRIBUTION the tooth in as much detail as possibleNOT trying FORto use asSALE many of OR the DISTRIBUTION terms presented in this chapter as possible. Underline each term you use. For example, “There is a pit on the lingual or palatal surface in the cervical or gingival third in the lingual fossa adjacent to the cingulum that is deeply stained.” B. Repeat this exercise for the maxillary left lateral incisor, then the maxillary right central incisor, and finally the maxillary left central incisor. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 2. NOTThis xercisee FOR isSALE designed OR to assureDISTRIBUTION student mastery of the three commonNOT systems FOR used SALEto identify OR teeth. DISTRIBUTION A. In the chart that follows, record the Universal tooth number to identify each of the four permanent first molars. Next, identify each of these teeth using the International System. Finally, use the Palmer System.

Maxillary Right Maxillary Left Mandibular Left Mandibular Right © Jones & Bartlett Learning, LLCFirst Molar First© Molar Jones & BartlettFirst Molar Learning, LLCFirst Molar NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Universal International Palmer © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC B. In this chart, record the correct answers for each of the four permanent central incisors. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Maxillary Right Maxillary Left Central Mandibular Left Mandibular Right Central Incisor Incisor Central Incisor Central Incisor

3. Obtain a model of someone’s complete adult dentition from your dentist or orthodontist. Evaluate the shape of each tooth to confirm which teeth are present. On this model, answer each of the following questions: Do all incisors have © Jones & Bartlettmarginal Learning, ridges and lingual LLC fossa? Do the maxillary canines© Jones have distinct& Bartlett facial ridges? Learning, Do they LLC have a distinct lingual NOT FOR SALEridge? OR Do DISTRIBUTIONmandibular canines have distinct marginalNOT ridges FOR and lingual SALE fossae? OR DoDISTRIBUTION any of the premolars have three cusps? If so, are they mandibular second premolars? Do any premolars have a lingual cusp that is so short it is almost nonexistent? If so, are they mandibular first premolars? Do all first molars have five cusps? What are their Universal numbers?

REFERENCES GENERAL REFERENCES

1. Ash MM. Wheeler’s dental anatomy, physiology, and occlusion. Jordan R, Abrams L, Kraus B. Kraus’ dental anatomy and occlusion. 7th ed. Philadelphia, PA: W.B. Saunders, 1993. St. Louis, MO: Mosby Year Book, 1992. 2. Osbo© Jonesrn JR, ed. & Dental Bartlett anatomy Learning, and embryology. LLC Oxford, UK: Melfi RC. Oral© Jonesembryology & andBartlett microscopic Learning, anatomy, a textbookLLC BlackwellNOT FOR Scientific SALE Publications, OR DISTRIBUTION 1981:133. for studentsNOT in FORdental hygiene.SALE 10thOR ed.DISTRIBUTION Philadelphia, PA: 3. Palmer RS. Elephants. In: Richard Harmon, ed. World book Lippincott Williams & Wilkins, 2000. encyclopedia. Vol. 6. Chicago, IL: World Book, Inc., 1979:178C. Renner RP. An introduction to dental anatomy and esthetics. 4. Brant D. Beavers. In: Richard Harmon, ed. World book Chicago, IL: Quintessence Publishing, 1985. encyclopedia. Vol. 2. Chicago, IL: World Book, Inc., 1979:147. © Jones & 5.Bartlett Zoo books: Learning, elephants. Wildlife LLC Education Limited. San Diego,© Jones & Bartlett Learning, LLC CA: Frye & Smith, 1980:14. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284218251_CH01_001_048.indd 46 25/03/20 4:36 PM CHAPTER 1 ■ Basic Terminology for Understanding Tooth Morphology 47

© Jones &1. Bartlett Advanced Learning, Topics about LLC the Embryology and © Jonesand dentin. & Bartlett Odontoblasts Learning, can continue LLC to form new dentin NOT FOR SALEMineral OR Content DISTRIBUTION of Tooth Tissues NOTover FOR a lifetime SALE (called OR secondaryDISTRIBUTION dentin), and when a tooth is traumatized (as from decay), the odontoblasts can form a When you study tooth embryology, you will learn that there type of dentin called reparative dentin. are three cell layers in the forming embryo: the outer ecto- The three tooth tissues differ in their hardness since each derm, the middle mesoderm, and the inner endoderm. contains a different amount of mineral content, primar- Some outer ectodermal© cells Jones form an& enamelBartlett organ. Learning, Enamel LLCily hydroxyapetite. Enamel, the© Joneshardest tissue, & Bartlett is 95% calLearning,- LLC develops from the enamel organ (ectoderm) and is a product NOT FOR SALE OR DISTRIBUTIONcium hydroxyapetite (mineralizedNOT and FOR calcified) SALE and OR only DISTRIBUTION of specialized epithelial cells called ameloblasts [ah MEL o 5% water and enamel matrix. Mature dentin is composed blasts]. Some mesodermal cells form a dental sac with spe- of about 70% calcium hydroxyapetite, 18% organic matter cialized cells called cementoblasts [se MEN toe blasts] that (collagen fibers), and 12% water. Cementum is composed of produce cementum. Other mesodermal cells form a dental 65% calcium hydroxyapetite, 35% organic matter (collagen papilla© withJones specialized & Bartlett cells called Learning, odontoblasts LLC [o DON fibers), and ©12% Jones water. (Another& Bartlett author, Learning, Melfi, states LLCthat the tow blasts] that produce dentin. Odontoblasts, dentin- mineral content of cementum is only about 50%.) buildingNOT cells, FOR are locatedSALE at OR the DISTRIBUTIONjunction between the pulp NOT FOR SALE OR DISTRIBUTION

D r . W o e l f e l ’ s O r i g i n a l R e s e a r c h D a t a © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Data obtained from Dr. Woelfel’s original research on tooth On maxillary molars with two buccal and one lingual root, the dimensions were used to draw conclusions throughout this measurements were taken to the tip of the longest buccal root, book. Average measurements obtained on a sample of 4572 usually the mesiobuccal. On mandibular molars with two roots, extracted teeth obtained© fromJones dentists & Bartlett in Ohio fromLearning, 1974 LLCa mesial and distal, the measurement© Jones was taken & Bartlett to the apex Learning, of LLC through 1979 are presented here in Table 1-7. Root lengths the longest root, usually the mesial root. On two-rooted premo- were measured from theNOT cervical FOR line SALEto the apex OR of DISTRIBUTIONthe root. lars, measurements were taken toNOT the apex FOR of the SALE buccal ORroot. DISTRIBUTION

9781284218251_CH01_001_048.indd 47 25/03/20 4:36 PM 48 PART 1 ■ Comparative Tooth Anatomy

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 0.97 0.80 0.2 0.5 0.2 0.6 0.2 0.6 1.9 1.5 0.2 0.7 0.3 1.6 2.3 1.6 0.2 1.4 DISTAL DISTAL CERVICAL CERVICAL CURVE (MM)

NOTH FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 0.5 0.8 0.4 0.9 0.6 0.9 2.5 2.1 0.5 1.1 0.7 2.8 2.4 2.0 0.5 2.1 MESIAL MESIAL CERVICAL CERVICAL CURVE (MM)

G 7.7 7.0 7.1 7.7 7.5 11.5 11.1 10.4 11.4 10.7 WIDTH WIDTH CROWN CROWN © Jones & Bartlett Learning,FL (MM) LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 7.9 7.2 7.6 5.0 8.2 4.8 4.8 9.2 8.2 3.5 5.79.2 5.4 10.2 9.0 5.6 8.1 WIDTH WIDTH CERVIX CERVIX MD (MM)

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION E NOT F FOR SALE OR DISTRIBUTION 7.1 7.0 7.1 7.6 5.3 8.23 6.11 9.20 8.48 1.40 9.2 11.4 WIDTH WIDTH CROWN CROWN MD (MM)

NOT FOR OVERALL SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

1.43 20.8 1.55 1.83 20.9 1.62 21.61 8.17 6.24 8.22 7.44 1.20 1.72 20.1 10.4 1.49 1.80 22.1 1.57 18.2 11.3 9.2 10.1 8.9 1.82 21.2 6.6 4.7 9.0 8.1 1.70 20.0 9.8 1.64 22.4 1.37 22.5 6.6 4.7 6.2 5.8 1.43 22.1 5.71.82 3.8 20.6 6.1 10.8 5.8 9.1 9.9 8.8 1.56 21.5 1.16 23.6 8.6 6.4 1.45 25.9 6.8 5.2 1.56 RATIO CROWN CROWN © Jones & BartlettROOT-TO- Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION C (MM) ROOT ROOT LENGTH LENGTH 14.0 M root 14.0 D 13.0 12.9 MB root 12.9 DB 12.2 L 13.7 10.8 MB root 10.8 DB 10.1 L 11.2 16.5 11.8 M root 11.8 D 10.8 14.0 12.9 MB root 12.9 DB 12.1 L 13.5 13.9 M root 13.9 D 13.0 13.0 © Jones & Bartlett Learning, LLC 15.9 © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION A B 7.7 7.5 7.2 7.5 7.7 7.6 7.7 8.8 12.6 8.8 14.4 9.8 13.4 9.4 13.5 8.6 13.4 10.6 11.0 11.2 (MM) CROWN CROWN LENGTH LENGTH

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Average Measurements on 4572 Extracted Teeth Obtained From Ohio Dentists during a Study by Dr. Woelfel and his First-Year Dental Hygiene and his First-Year Woelfel Ohio Dentists during a Study by Dr. Obtained From Extracted Teeth Measurements on 4572 Average 1974–1979 Students of the Ohio State University College Dentistry, NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

-7

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC TABLE 1 TABLE MANDIBULAR TEETH Central incisor (226) Avg. for 2392 upper teeth for 2392 Avg. 8.77 13.36 First molar (281) Avg. for 2180 lower teeth for 2180 Avg. 8.62 13.85 First molar (308) Third molar (305) Third Second premolar (227) 8.2 14.7 Canine (321) Canine (316) molar (262) Third Second premolar (224) Second molar (309) First premolar (238) Lateral incisor (295) Lateral incisor (234) Second molar (296) First premolar (234) NOT FOR SALE OR DISTRIBUTIONMAXILLARY TEETH Central incisor (398) NOT FOR SALE OR DISTRIBUTION

Size ranges are shown in tables each chapter. Surface Abbreviations: D, distal; DB, distobuccal; FL, faciolingually; L, lingual; M, mesial; MB, mesiobuccal; MD, mesiodistal. for Tooth Key widest crown mesiodistally; G, faciolingually; H, greatest cervical line curve. B, longest crown by Kraus; C, root: D, tooth overall; E, narrowest mesiodistally; F, A, longest crown by Woelfel;

9781284218251_CH01_001_048.indd 48 25/03/20 4:36 PM