Biomechanics of temporo-mandibular joint. Articilator. Movements of Protrusion Retrusion Lateral excursion Opening-Closing

Opening-Closing Translatory movement of the mandibular condyle along the posterior wall of the articular eminence. Protrusion A protrusive movement occurs when the mandible moves forward. Retrusion Retraction of the mandible from any position Lateral excurcion When the mandible moves into a left lateral excurcion the right condyle moves forward and inward (Bennett angle), while the left condyle will shift slightly in a lateroposterior direction(Bennett movement). In this example, the left side is working side and the right side is nonworking side. When the mandible moves into a right lateral excurcion the left condyle moves forward and inward (Bennett angle), while the right condyle will shift slightly in a lateroposterior direction(Bennett movement). In this example, the right side is working side and the left side is nonworking side. Border movements of the mandible The most extreme positions to which the jaw is able to move. Laterally: max 10 mm Opening: 50-60 mm Protrusion: 9mm Retrusion:1 mm Described from sagittal, frontal and horizontal planes. Usually not affected by head or body posture. Mandibular movements Most mandibular movements occur around three dimensions. They include, the transverse(horizontal), vertical(frontal) and sagittal axes. Mandibular movements can be classified as border and intraborder movements. Border movements occuring in all three planes and intraborder movements are all possible movements of the mandible occur within the border envelope.

Extreme movements in the sagittal plane The patient is instructed to move the mandible from centric relation(CR) to centric occlusion(CO), then edge to edge relationship(ER), then the maximum protrusive (MP) and then arc downward to the maximum opening position. Extreme movements in the frontal plane Here the patient is instructed to move the mandible from centric occlusion (CO), then to the maximum right lateral positon, then arc downwards to the maximum mouth opening position. From this, the patient is instructed to arc upward to the maximum left lateral position and then return to centric occlusion(CO). Extreme movements in the horizontal plane Here the patient is instructed to move the mandible from the centric relation position(CR), to the maximum right lateral position, to the maximum protrusive position, to the maximum left lateral position and return to centric. Envelope of Motion When we combine the border movements of all the three planes, we get a three-dimensional space within which mandibular movement is possible. This three-dimensional limiting space is called the envelope of motion. It was first described by Posselt in 1952. Intra-border Movements Intra-border movements occur within the envelope of motion. They are chewing, speech, swallowing and yawning. Determinants movements of the mandibular movements The angle between the sagittal projection of the condylar path and the occlusion plane according to Gizi – 33°. Bennett angle- the angle formed by the sagittal plane and the path of the advancing condyle during lateral movement of the mandible, as viewed in the horizontal plane, equal average 15- 17o.This is the angle between the path of the non-working condyle and the sagittal plane.

The Bennette movement (lateral shift) The bodily shift of the mandible towards the working side during lateral excursion.

Bites The static interarch relashionships, or bites, are the relations of two arches under the strong contraction of the masticatory muscles. All bates are distinguished into two types: 1.the physiological (normal) bites 2. the pathological bites

Orthognatia is characterized by:

1. The overbite, the characteristic of maxillary anterior teeth to overlap the mandibular anterior teeth in a vertical direction by 1-2 mm 2. The overjet the characteristic of maxillary anterior teeth to overlap the mandibular anterior teeth in a horizontal direction by 1-2 mm 3. the interdigitation, the characteristic of each tooth to articulate with two opposing teeth (except for the mandibular central and the maxillary last molars) 4. The distal surface of the upper and lower third molars are situated on one frontal plane 5. The buccal cusps of the lower teeth occlude with the mesiodistal grooves of the upper teeth or, to reverse the description that the lingual cusps of the upper teeth are in contact with the mesiodistal grooves of lower teeth. Functional and nonfunctional cusps 1: functional cusps 2: nonfunctional cusps Buccal upper and Lingual lower cusps do not support occlusion they are the nonfunctional cusps

The articulator The articulator is a mechanical instrument designed to simulate the movements of the mandibular arch in relation to the maxillary arch. These movements are directed and limited by the elements of the articulator that simulates the anatomical determinant of mandibular movement. DEFINITION An articulator may be defined as a mechanical device that represent the temporomandibular joint and jaw members to which maxillary and mandibular casts may be attached to simulate jaw movement. PURPOSES 1.To hold the maxillary and mandibular casts in a determined fixed relationship

2.Mounting of dental casts for diagnosis treatment planning and patient presentation.

3.To simulate the jaw movement like opening and closing.

4.Fabrication of occlusal surfaces for dental restoration.

5.Arrangement of artificial teeth for complete and removable partial denture. Uses 1.To diagnose the state of occlusion in both the natural and artificial dentition.

2.To plan the dental procedures based on the relationship between opposing natural and artificial teeth. 3.To aid in the fabrication of restorations and prosthodontics replacements.

4.To correct and modified complete restorations.

5.To arrange artificial teeth. ADVANTAGES 1.Properly mounted casts allow the operator to better visualize the patients occlusion, especially from lingual view.

2. Patient cooperation is not a factor when using an articulator. Once appropriate interocclusal records are obtained from the patient.

3. A reduces the chair time, patient appointment time. More procedures can be delegated to auxillary personnel.

4. The patients saliva, tongue, and cheeks are not factors when using an articulator BASIC COMPONENT OF AN ARTICULATOR

Upper member – Represent Lower member – Represent mandible CONDYLAR TRACK – CONDYLAR ELEMENT- Vertical Rod (Incisal Pin) Incisal guide table SOME COMMONALY USED ARTICULATOR Mean-Value Articulator Hanau wide VUE articulator Whip – mix articulator Denar articulator Panadent articulator TMJ articulator

HANUA WIDE VUE Semi adjustable ARCON type Accept Face-bow transfer Capable of hinge lateral movements.

Upper member :  & horizontal arm.  Condylar T.Shaped with vertical guidance attached to this. Lower Member :  L-Shaped with horizontal & vertical arm.

 Upper portion of vertical arm contains a roll pin. Which project on the outer surface.

 The condylar shaft attached to inner surface of the vertical arm 12-13 mm anterior to the roll pin.

 The condylar element (metal ball ) is attached to the free end of the condylar shaft. Condylar guidance :

 It is circular structure with a slot in the center

 The condylar element of lower member articulate with this slot also called condylar track.

 The posterior end of this track has a component known as centric stop.

Vertical Rod or Incisal Pin : Helps to keep a fixed distance between the upper & lower member at anterior end.

The pointed tip of vertical rod should rest on the center of incisal guide during articulation Incisal guide table :  It has a customised incisal guide table.

 During articulation it should be flat & the incisal pin should be at in center.

 A pair of lateral wings is present around it. CLASSIFICATION OF ARTICULATORS BASED ON THE ADJUSTABILITY Three Types :-

a. Non – Adjustable b. Semi – Adjustable c. Fully – Adjustable

Adjustability of the articulator The capability of the articulator to closely simulate the movements of the mandible is dependent upon the adjustability of the articulator elements. NON – ADJUSTABLE Can open and close in a fixed horizontal axis. SEMI ADJUSTABLE  Have adjustable sagittal condylar paths, adjustable lateral condylar path.

 Two Type Arcon Type Non arcon Type Arcon articulators The term “arcon”from the words articulator and condyle. The condylar element is attached to the lower member of the articulator and the condylar guidance (mechanical analog of the glenoid fossa) is attached to the upper member. This articulator resembles the temporomandibular joint.

Non-Arcon articulators These articilators have the condylar elements are attached to the upper member of the articulator and the condylar guidance (mechanical analog of the glenoid fossa) is attached to the lower member. This articulator is the revers of the temporomandibular joint.

FULLY ADJUSTABLE  Capable of being adjusted to follow the mandibular movement in all direction. They are not used due to their complexity.

Exp. Stuart Gnathoscope Simulator

Casting

Casting is the most commonly used method for the fabrication of metal restorations outside of the mouth. A pattern of the lost tooth structure is made in wax. This is then surrounded by an investment material. After the investment hardens the wax is removed leaving a space or mold. Molten alloy is forced into this mold. The resulting structure is an accurate duplication of the original wax pattern.

Steps in casting

Wax Pattern preparing in technician laboratory is sent in casting laboratory.

I Sprue former

It is made of wax, plastic. Thickness is in proportion to the wax pattern.

There are two basic types of sprues: multiple and single.

The majority of removable partial denture castings require multiple spruing:

Some important points to remember in multiple spruing are as follows.

1. Use a few sprues of large diameter rather than several smaller sprues 2. Keep all sprues as short and direct as possible 3. Avoid abrupt changes in direction, avoid T-shaped junctions as much as possible 4. Reinforce all junctions with additional wax to prevent constrictions in the sprue channel and to prevent V- shaped sections of investment that might break away and be carried into the casting.

The purposes of spruing the wax pattern are

• To create a channel for elimination of wax during burnout • To form a channel for the ingress of molten alloy during casting • To compensate for alloy shrinkage during solidification

II Casting Ring Liner

A ring liner is placed on the inner side of casting ring.

III Investing

An investment can be described as a ceramic material which is suitable for forming a mold into which a metal or alloy is appropriately cast. The procedure for forming the mold is described as”investing”.

Types of investment materials There are three types of investment materials. They all contain silica as the retractor constituent. The type of binder used is different.

1. Gypsum bonded investments: they are used only for casting gold alloys. They can withstand temperature up to 700 C. 2. Phosphate bonded investments: they are used for casting cobalt- chromium alloys. They can withstand high temperatures. 3. Silica bonded investments: they are an alternative to the phosphate bonded investments, for high temperature casting. They are principally used in the casting of base metal alloy partial denture. Investing

Seat the casting ring into the crucible former taking care that there is uniform space around the wax pattern. The pattern should be located near the centre of the ring.

Mix the investment as per the recommended w/p ratio and vibrate. Take some investment on the brush and apply on the wax pattern pushing it forwards from an edge to the deeper parts of the pattern to avoid air bubbles. The ring is reseated on the crucible former and placed on the vibrator and gradually filled with the remaining investment mix. Allow it to set for 1 hour.

The investment for a removable partial denture casting consists of two parts: the investment cast on which the pattern is formed and the outer investment surrounding the cast and pattern. The modern is confined within a metal ring, which may or may not be removed after the outer investment has set.

IV Wax Elimination and Heating (Burnout)

The burnout operation serves three purposes:

1) It drives off moisture in the mold .

2) It vaporizes and this eliminates the pattern, leaving a cavity in the mold.

3) It expands the mold to compensate for contraction of the metal on cooling.

V Casting The method of casting will vary widely with the alloy and equipment being used.

All methods use force to quickly inject the molten metal into the mold cavity. This force may be either centrifugal or air pressure. The former is more commonly used.

The metal may be melted with a gas- oxygen blowtorch or by an electric muffle surrounding the metal.

In some dental laboratories the induction method may be used, which provides a rapid and accurate method of melting the metal.

VI Removing the casting from the investment, sandblasting

VII Finishing and Polishing

Complete edentulous mouth, etiology, clinical picture, anatomotopographic features of edentulous jaws, classification of edentulous jaws, types of oral mucosa. Fixation and stabilization of complete dentures. Theories methods of fixation.

Edentulism is the condition of being toothless to at least some degree; it is the result of tooth loss. Loss of some teeth results in partial edentulism, while loss of all teeth results in complete edentulism. The etiology, or cause of edentulism, can be multifaceted: • 1.Periodontal disease • 2.Tooth decay • 3.Genetic defects • 4.Trauma • 5.Drug use • 6.Malnutrition

Residual alveolar ridge It is defined as ”The portion of the alveolar ridge and its soft tissue covering which remains following the removal of teeth.” It resorbs rapidly following ehxraction and continues throughout life in a reduced rate.The submucosa over the ridge has adequate resiliency to support the denture. The maxilla resorbs in a superioposterior direction, and the mandible resorbs in an inferioanterior direction. Ridge resorption may also alter the form of the ridges , such as bulbous ridges with undercuts or even sharp, thin, knife-edged ridges, depending of which of many possible factors influenced the resorbsion. Classification upper edentulous jaw by Shreder: I type- high alveolar ridge covered normal uniform density of mucosal tissue, well expressed alveolar tubercle,deep U-shaped palate,without maxillary tori. This type ideal for both retention and stability. II type- middle resorption alveolar ridge, middle expressed alveolar tubercle, not deep palate with tori. Not so good for both retention and stability. III type- full resorption alveolar ridge, small size alveolar arch and an alveolar tubercle, flat palate and very big tori. Difficult to achieve good retention and stability. Classification lower edentulous jaw by Keller: I type-well expressed alveolar ridge II type uniform resorption of alveolar ridge. The floor of the mouth is found near the crest of the ridge. III type non uniform resorption of alveolar alveolar ridge, well expressed alveolar ridge in frontal area and resorption of alveolar alveolar ridge in lateral area IV type non uniform resorption of alveolar alveolar ridge, well expressed alveolar ridge in lateral area and resorption of alveolar alveolar ridge in frontal area. The type 1,3 good for both retention and stability The type 2,4 not good for retention and stability The anatomy of the edentulous ridge in the maxilla and mandible is very important for the design of a complete denture. The consistency of the mucosa and the architecture of the underlying bone is different in various parts of the edentulous ridge. Mucous Membrane The entire oral cavity is lined by the oral mucosa. The oral mucosa has two layers namely the mucosa and submucosa. The mucosa has a stratified squamous epithelium. The submucosa varies in thickness and consistency and it is responsible for supporting the denture. When it is thin, it easily gets traumatized. When it is loosely attached, inflamed it gets easily displaced. The colour,condition and the thickness of the mucosa should be examined. The mucosa should have a healthy pink colour. Condition of the mucosa can be classified as: 1.Normal iniform density of mucosal tissue. Investing membrane is firm, but not tense and forms the ideal cushion for the basal seat of the denture. 2.Soft tissues have excessively thick, investing membranes filled with redundant tissue. 3.Soft tissues have a thin investing membrane and are highly susceptible to irritation under pressure. The anatomical landmarks in the maxilla are: Limiting structure: Labial frenum Labial vestibule Buccal frenum Buccal vestibule Hamular notch Posterior palatal seal area. Limiting structure determine and confine the extent of the denture.

The anatomical landmarks in the mandible are: Limiting structure: Labial frenum Labial vestibule Buccal frenum Buccal vestibule Lingual frenum Alveololingual sulcus Retromolar pads

Examination of the patient, anamnesis

The objectives of pretreatment evaluation of a patient: 1. Establishment of a diagnosis 2. Determination of underlying medical conditions that may modify the oral condition or the patient’s ability to tolerate treatment 3. Discovery of concomitant illnesses 4. Prevention of medical emergencies associated with dental treatment 5. Establishment of rapport with the patient

There are five elements to a good diagnostic workup for prosthodontic treatment. History Occlusal evaluation Intraoral examination Diagnostic casts Full mouth radiographs. Taking and Recording Histories. Pertinent information brought out while taking the patient's history should be recorded in writing. In taking a history, the dental officer often has an established routine, which he conscientiously follows so that no possible information is overlooked. He may take brief notes and later write the summary to be recorded. Ethical Aspects. Information given by the patient to the dental officer is confidential and is used to enhance professional care. The dental specialist will not reveal confidential information to any person not concerned with the patient's medical or dental health. The essential elements of a patient history 1. Chief complaint 2. History of the present illness 3. medical history 4. Social history 5. Family history 6. dental history

Chief complaint The chief complaint is the reason that the patient is seeking care, as described in the patient’s own words. History of the present illness The history of the present illness is a chronological description of the patient’s symptoms and should include information relative to duration, location, character, and previous treatment. Medical history The medical history includes:  Current status of the patient’s general health  Hospitalizations  Medications  Allergies Current status of the patient’s general health There are a number of oral manifestations of systemic diseases, if discovered while taking the medical history, which must be considered carefully in planning and carrying out the course of treatment. Some of these conditions, including potential dangers and precautions to be taken, are as follows:

Coronary artery disease. Patients with coronary artery disease (disease of the arteries that supply blood to the heart) may experience pressure or pain in the chest called angina pectoris. Pressure or pain occurs when narrowing of the coronary arteries prevents adequate oxygen to the heart muscles. Attacks may be brought on by nervousness and physical or emotional stress. Patients with a known history of angina pectoris should be treated only after every precaution has been taken to minimize nervousness and stress. Usually a physician is consulted before these patients are treated. The patient who has angina pectoris usually carries his own supply of nitro- glycerin. Rheumatic heart disease: Rheumatic fever is a disease that may affect the valves of the heart. Heart valves that have been damaged (rheumatic heart disease) by rheumatic fever are susceptible to infections from bacteria, which may be forced into the bloodstream during extraction of teeth or other dental procedure. Should a patient with a history of rheumatic fever require dental care, the dental specialist normally will consult the patient's physician. High blood pressure (hypertension). The dental specialist normally will consult the patient's physician before surgery or any extensive dental treatment on a patient with elevated blood pressure. Premedication, selection of the anesthetic agent, and the duration and nature of anticipated surgery or dental manipulation all require careful consideration. Generally,a systolic reading above 160 mm of mercury or a diastolic reading above 95 postpones dental treatment and should be cause for referring the patient to his or her physician for evaluation and treatment. Patients with a history of hypertension or coronary artery disease should not receive epinephrine, since this drug has a tendency both to increase heart rate and elevate blood pressure. Diabetes mellitus. Diabetes is a systemic disease in which the body is unable to utilize sugars in the diet because of the lack of insulin in the system. Diabetes may be controlled by periodic injections of insulin, oral medication, or diet, depending on its severity. Periodontal disease is often associated with uncontrolled diabetes. Special consideration must be given in performing surgery or any dental treatment on diabetics because of their tendency to bleed easily and their high susceptibility to infections. Hemophilia. Hemophilia is a rare hereditary condition appearing in males. In hemophilia, there is profuse bleeding due to an inadequate clotting mechanism resulting in prolonged uncontrollable bleeding, even from the slightest cut. Any necessary surgical procedures should be done only with the cooperation of the patient's physician to minimize and to control bleeding. Epilepsy Epilepsy is another condition whose existence should be known. It does not contraindicate dentistry, but the dentist should known of its history in a patient so that appropriate measures can be taken without delay in the event of a seizure while the patient in the chair. Long, fatiguing appointments should be avoided to minimize the possibility of precipitating a seizure. Allergy and hypersensitivity. Patients may be allergic or hypersensitive to any of a number of drugs or materials used in dentistry. The dental specialist must take a thorough history, so that he may avoid the use of drugs and materials to which the patient may have an unfavorable reaction. Hepatitis B. Patients with active hepatitis, or who are carriers of the Hepatitis B virus, can infect the dentist, staff, and other patients. To reduce risk to everyone, strict barrier protection procedures must be enforced (masks, gloves, gowns, and protective eyewear) along with strict aseptic techniques. Hepatitis is a very debilitating disease and causes death in a small percentage of the cases. Therefore, it is recommended that all dental personnel receive the heptavax vaccine to eliminate risk of infection with the Hepatitis B virus.

HIV Infection.

Human Immunodeficiency Virus (HIV) infection, or AIDS as it was originally called, causes death by destroying the patient's immune system. This virus is very difficult to transmit from one person to another. A dental care provider cannot contract an HIV infection through daily contact at the workplace. If you work on an HIV positive patient, the patient is many more times at risk than you are. The reason is the their immune system cannot easily control new and different infections. It is important, then, to have extremely strict aseptic procedures before, during, and after patient care. This reduces the risk to the HIV patient and the possibility of risk to other patients and the dental care providers. Social history The social history includes:  Present and past occupations  Occupations hazards  Smoking, alcohol or drug use  Marital statuse Family history The family history often provides information relative to diseases of genetic origin or diseases that have a familial tendency. Examples include clotting disorders, atherosclerotic heart disease, psychiatric diseases, and diabetes mellitus.

Dental history Allthough other sections in history are important, dental history is the most important all of them. denatl history includs: period of edentulousness pre-treatment records(previous denture, current denture, pre-extraction records radiographs, photografs, etc) expectations of the patient

Clinical examination includes:

 extraoral examination

 intraoral examination. Extraoral examination The patient’s head and neck region should be examined for any pathological condition. Facial colour,tone, hair color, summetry and neuromuscular activity are noted. It includes facial examination, examination of muscle, lip examination, TMJ examination. TMJ Healthy temporomandibular joints function quietly with no evidence of clicking, crepitation, or limitation of movement on opening, closing, or moving lateraly.

Intraoral examination An oral examination should be accomplished in the following sequence: 1.visual examination 2.pain relief and temporary restorations 3.evaluation of teeth and periodontium 4.vitality tests of individual teeth For physical examination of the patients are used following techniques Inspection, the most commonly used techniques, is based on visual evaluation of the patient. Palpation, which involves touching and feeling the patient, is used to determine the consistency and shape of masses in the mouth and neck. Percussion, which involves differences in sound transmission of structure. It does reveal inflammation in the periapical region, specitically, inflammation of the apical part of the periodontal ligament.. Auscultation, the technique of listening to differences in the transmission of sound, is usually accomplished with a stethoscope. In dentistry it is most typically used to listen to changes in sounds emanating from the temporomandibular joint and in taking a patient’s blood pressure. Tooth mobility  Tooth mobility is directly proportional to the integrity of the attachment apparatus ( periodontal disease). The clinician should use two mouth- mirror handles to apply alternating lateral forces in a facial-lingual direction to observe the degree of mobility of the tooth.  First-degree mobility is less than 1 mm of horizontal movement.  Second-degree mobility is about 1-2mm of horizontal movement.  Third-degree mobility is above than 2mm of horizontal movement accompanied by vertical depressibility. Periodontal probes are used to determine the depth and outline of soft tissue pockets.

Diagnostic or Study casts Diagnostic casts of both the arches should be prepared before commencement of treatment. These are often mounted on an anatomic articulator. Study casts are used to:  Permit study of alignment and occlusal relationships of the teeth outside the confines of the patient's mouth.  Provide a duplication of the mouth, which is useful in consultations with other dental officers.  Provide a permanent record of oral conditions as they existed prior to treatment. Radiographs  Information revealed by radiographs includes the following:  (1) Infection and abscesses within the bone and about the roots of the teeth.  (2) Size and shape of roots of teeth to be extracted.  (3) Carious lesions, which cannot be detected in other ways.  (4) Condition of the periodontal bone.  (5) Condition of teeth and bone that have been considered for the support of fixed or removable prosthodontic appliances.  (6) Presence of impacted teeth, supernumerary teeth, or retained roots.

History of protodontic, organization of prosthetic service. Propedeutics in prosthodontics, instruments used in prosthodontics

Prosthodontics: Prosthodontics is the branch of dentistry pertaining to the restoration and maintenance of oral functions, comfort, appearance and health of the patient by the restoration of natural teeth and/or the replacement of missing teeth and contiguous oral and maxillofacial tissues with artificial substitutes.

A prosthodontist is a specialist in the restoration and replacement of broken and missing teeth.

Prosthodontic dentistry includes the following services:

1. Fixed prosthodontics 2. Removable prosthodontics(full and partial denture) 3. Implant prosthodontics 4. Maxillofacial prosthodontics

Ancient Greek scholars Hippocrates and Aristotle wrote about dentistry, including treating decayed teeth and gum disease, extracting teeth with forceps, and using wires to stabilize loose teeth and fractured jaws. The first use of dental appliances or bridges,dentures comes from the Etruscans, in northern Italy from as early as 700 BC. They made dentures out of human or other animal teeth. Roman medical writer Cornelius Celsus wrote extensively of oral diseases as well as dental treatments such as narcotic-containing emollients and astringents.

The first European sets of dentures date from the 15th century and most probably existed before that time. They were carved from bone or ivory.

The first book focused solely on dentistry was the "Artzney Buchlein" in 1530, and the first dental textbook written in English was called "Operator for the Teeth" by Charles Allen in 1685. It was between 1650 and 1800 that the science of modern dentistry developed. It is said that the 17th century French physician Pierre Fauchard started dentistry science as we know it today, and he has been named "the father of modern dentistry". Among many of his developments were the extensive use of dental prosthesis, the introduction of dental fillings as a treatment for dental caries.

The first porcelain dentures were made around 1770 by Alexis Duchâteau. In 1791 the first British patent was granted to Nicholas Dubois De Chemant, previously assistant to Duchateau, for De Chemant's Specification, "a composition for the purpose of making of artificial teeth” Single teeth in porcelain were made since 1808. Later dentures were made of vulcanite and then, in the 20th century, acrylic resin and other plastics.

Dental Unit. Construction

Chair

Bracket table

Operation unit:

-engine driven handpieces:mikromotor, turbine, sonic-ultrasonic scaler -siringe:air,water

Operating light

Waterblock:

-suction hoses: saliva ejector, exhauster

SALIVA EJECTORS

Saliva ejector mouthpieces are made to attach at one end to the saliva ejector tubing on the dental unit. The other end rests in the mouth for the evacuation of saliva, blood, water, or debris during dental procedures.

Dental chair

Patient can be seated or laid comfortably: back-rest, foot-rest, head-rest

Programming:

1.comfortable seating (consult, examination)

2.impression taking

3.operation position ( ‘8’, ‘9’,‘10’o’clock positions)

Instruments used in Prosthodontics BASIC DENTAL EXAMINATION SETUP

The basic dental examination setup (figure 1) consists of a mouth mirror, cotton pliers, explorer, periodontal probe, cotton dispenser with cotton, and a saliva ejector. This equipment is used in almost every dental treatment procedure. The water and air syringes are frequently used to remove debris and fluids from tooth surfaces so that they may be examined more accurately. A good light source is also essential to adequate vision in performing any oral diagnostic procedures.

Figure 1 Instruments and materials for basic examination.

1. Mouth Mirrors. Mouth mirrors enable the dental specialist and the dental officer to see, by reflective vision, surfaces of tissues and teeth, which cannot be seen with direct vision. They aid in reflecting light into dark areas in the mouth so tissues and teeth may be more readily seen. They can be used to retract soft tissues of the cheek, tongue, and lips. There are two general types of mouth mirrors: plane glass mirrors in which the reflected image is the same size as the object being viewed, and magnifying mirrors in which the reflective image provides an enlarged view. The type of mirror used depends on the preference of the dental officer.

Mouth mirror.

2. Explorers. Explorers are sharp, pointed metallic instruments so designed that the various surfaces of teeth may be conveniently reached with the explorer point. These instruments are used for diagnostic purposes based on the sense of touch and on mechanical penetration of defects in tooth surfaces. Some diagnostic purposes are: locating caries and enamel defects on the interproximal, occlusal, and other surfaces which are difficult to see by direct vision, locating subgingival calculus, and locating of faulty margins on dental restorations.

Explorers.

3. Cotton Pliers (Forceps ). Cotton pliers are tongs-like, metallic instruments. The working end of a pair of cotton pliers consists of two tapered opposing portions that form a 60-degree angle with their handle. Cotton pliers are used for handling cotton pellets, cotton rolls, small instruments, or other small items placed into or withdrawn from the mouth.

Cotton pliers.

4. Periodontal Probes. Periodontal probes are non-cutting instruments that are used to determine the depth and outline of soft tissue pockets. Most are single-ended; some are double-ended. Periodontal probes have handles, a rounded nib, and a point (or face). The nib is marked with graduations that correspond to millimeters.

Periodontal probe.

MOTOR DRIVEN ROTARY INSTRUMENTS USED FOR CAVITY PREPARATION

Burs

Characteristics. In discussing the preparation of a cavity for restoration in a modern clinic, it is essential that we talk about the many different kinds of burs available to the dentist. They are manufactured in different sizes and shapes suited to the various types and forms of the cavity preparation desired. Four different things about the burs must be known:

1. The shape (name) of the working end

2. The series number of the bur

3. The material of which it is made

4. In which hand piece each type of bur may be used.

Series numbers and bur shapes are associated with each other:

Hand piece.

There are three different hand piece attachments for the burs.

1. Slow-speed straight hand piece (SHP) 2. Slow-speed contra-angle hand piece (AHP) (20000-70000 rotation/minute) 3. High-speed hand pieces (HSHP) or turbine (300000-500000 rotation/minute)

The slow-speed straight hand piece (SHP) accepts a bur with a long shank. This means that the end of the bur that goes into the hand piece is smooth. The shank of the straight hand piece bur is not only longer but also larger than the other burs.

The bur that goes into the slow-speed contra-angle hand piece (AHP) is almost as large around as the straight handpiece bur, but it is much shorter and has a notched end with a groove opposite the working end that fits into the latch attachment on the angle hand piece. The bur for all high-speed hand pieces (HSHP) is smaller and shorter than the other burs. Burs are an essential part of the setup for the dentist performing a restorative procedure. They are the rotary cutting instruments that is used in a cavity preparation procedure.

Bur shapes.

Diamond burs. Diamond burs are used to cut enamel and are manufactured in various sizes and shapes. These instruments create heat during use and require water or air-cooling if used for any length of time.

Diamond burs .

The plenty of time for creation prosthesis is carried out on the cast in the dental laboratory. Denture bases or other dental restorations may be fabricated over these casts.

The impression must be taken for making cast.

Cast. A positive reproduction of the form of the tissues of the maxillae or mandible. After the impression of the tissues has been made, plaster of Paris or gypsum is poured into the impression to form the cast.

Impression. An imprint or negative form of the teeth or other tissues of the oral cavity made in a plastic material that becomes relatively hard or set while in contact with these tissues. Material is poured into this impression to produce a positive form or cast of the recorded tissues.

Impression Tray. Impression trays are carriers for the material used in making impressions of the teeth, alveolar ridges, and adjacent structures. They are manufactured in various sizes and shapes to accommodate the size and shape of the arch, the type of impression material to be used, and the impression technique to be followed.

Spatulas. Spatulas are used for mixing impression material and gypsum and heating and manipulating wax. Laboratory spatulas are made of hard rubber or of metal with wooden handles.

Plaster Bowls. Plaster bowls are made of rubber and are used for mixing impression materials, plaster, gypsum, and investment materials. They are available in four sizes: extra large, large, medium, and small.

Mold and Shade Guides. Denture teeth and facings are made in a variety of sizes, forms, and shades by many tooth manufacturers. Size and form are identified by letter or number as are the shades.

Impression

Dental impression is a negative record of hard and soft tissues, which are on denture bearing area and his borders.

Denture bearing area

Denture bearing area is a complex of organs and tissues, which are in direct contact with dental prosthesis.

Desirable Properties for impression

 The high quality impression should reflect accurately all elements of denture bearing area and surrounding him tissues.

 There mustn't be bubbles, pores, guy lines and other defects on the surface of impression.

 Reflection of dental arch or alveolar ridge in impression must be located in the middle of the tray borders.

 The margins of impression must be properly reflected.

Die

The positive reproduction of a single tooth is described is a die.

Cast or Model

The positive reproduction of several teeth or a whole arch – cast or model.

Cast is poured from the impression.

Types of models

• Working models are used for making prosthesis. They must be made from hard or extra hard types of gypsum and accurately reproduce denture bearing area. • Auxiliary models are for reflecting antagonist teeth for full reproduction of clinical situation in mouth cavity. • Diagnostic models are for making diagnosis in complicated clinical situations, treatment planning. • Control models are necessary for evaluation of treatment effectiveness.

We can choose different types of impressions depending on the purpose of model and clinical condition of mouth cavity.

Anatomical impression

Anatomical (primary) impression is static reflection of denture bearing area and surrounding tissues.

It is usable for all types of prosthodontic constructions.

Functional impression

Functional (secondary) impression is for removable denture making.

For the formation of the impression borders individual trays are used during active and passive movement of soft tissues.

Compressive impression

Compressive impression is used in case of normal mucous membrane with uniformly expressed medium submucous membrane (wherever present).

Decompressive impression

Decompressive impression is for atrophic or hypertrophic mucous membrane.

We can reach various degrees of compression by making perforations on impression tray and using impression materials with different muco-compressive properties.

Types of impression trays

1. Prefabricated 2. Individual (custom made)

For non-perforated impression trays we use special adhesive material, because there is no mechanical fixation of impression materials compared to perforated trays.

Prefabricated impression trays can also be for edentulous jaws.

They are with short and rounded boards.

Sizes 7, 8, 9, 10

Prefabricated impression trays for bite registration and for both jaws reproduction.

Individual or Custom made trays

Impression materials

 It should have pleasant taste, odour and esthetic color.

 It should not contain any toxic or irritating ingredients.

 It should be economical.

 It should be easy to use with the minimum of equipments.

 It should possess a satisfactory consistency and texture.

 It should have an adequate strength so that it will not break or tear while removing from the mouth.

 It should exhibit dimensional stability over humidity and temperature ranges.

 It should be compatible with the die and cast materials.

 It should faithfully reproduce the tissues of mouth.

Rigid impression materials

Rigid impression materials are those that set into rigid consistency.

Although rigid impression materials may be capable of recording tooth and tissue details accurately, they cannot be removed from the mouth without fracture and reassembly.

Nowadays we mostly use gypsum for making models.

Zinc oxide eugenol rigid impression material

 Available as two pasts – base and catalyst.

 They are not used as primary impression materials.

 They should never be used for impressions that include remaining natural teeth.

 Zinc oxide eugenol being rigid substance, can be used as secondary impression material for complete dentures with custom trays.

Thermoplastic materials

 Thermoplastic impression materials are those that become plastic at higher temperatures and resume their original form when cooled.

 This material is most often used for border correction (border molding) of custom impression trays for Kennedy Class I and II removable partial denture bases and complete dentures.

Agar hydrocolloid

 Agar is an organic hydrocolloid extracted from certain types of seaweeds.

 Agar is a reversible hydrocolloid.

 Since it is reversible, it can be reused.

 It is used for full mouth impression without deep undercuts.

 Nowadays, widely used for cast duplication.

Alginate

 It is an irreversible elastic hydrocolloid.

 It is a mucous extract from certain brown seaweeds.

 Used for making diagnostic casts, orthodontic treatment casts, auxiliary casts and casts for making temporary crowns.

 For making preliminary impression.

Elastomeric impression materials

According to viscosity

1. Putty

2. Heavy-body

3. Medium (regular)

4. Light body

5. Very light body

Polysulfide and Polyether

Polysulfide (Thiokol) impression materials can be used for final impression during complete denture making.

Polyether impression materials can also be used for functional impression and for monophase anatomical impression.

Silicone

The silicone impression materials are more accurate and easier to use than the other elastic impression materials. There are two types of silicones:

 C - silicone (condensation silicones)

 A- silicone (addition reaction silicones)

C – silicone

C - silicone - Condensation silicones: process of polycondensation . During the process some small molecules evaporate (e.g. alcohol).

A- silicone

A- silicone – addition silicone: the addition reaction is the most accurate of the elastic impression materials. During this process there are not evaporating molecules.

There are special A- silicone materials for bight registration.

Monophase impression

Use one type of material: viscosity– medium or light.

Double mix technique

 A suitable stock tray is selected.

 Tray adhesive is applied uniformly into the tray.

 Putty impression material is mixed and made into a rope and loaded onto the tray.

 Making and removing the impression.

 The impression is additionally relieved by scraping the areas, which cover the tooth preparation.

 The light body material is then syringed over the putty impression and also over the tooth preparation.

 The final impression will contain the accurate details recorded by the light body materials. Single mix technique

 In this procedure both materials (light body and putty) are used simultaneously.

 The putty material is loaded into the stock tray.

 The light body material is syringed around the prepared tooth.

 A full mouth impression is made using the loaded stock

Casting

1. Sprue former

2. Casting Ring Liner

3. Investing

4. Wax Elimination and Heating (Burnout)

5. Casting

6. Removing the casting from the investment, sandblasting

7. Finishing and Polishing

Wax pattern is prepared in technician laboratory and sent to casting laboratory.

Sprue former

The purposes of spruing the wax pattern are:

To create a channel for elimination of wax during burnout

To form a channel for the ingress of molten alloy during casting

To compensate for alloy shrinkage during solidification Casting Ring Liner putting

Investing: filing by investment materials

Wax Elimination and Heating (Burnout)

The burnout operation serves three purposes:

 1) It drives off moisture in the mold .

 2) It vaporizes and this eliminates the pattern, leaving a cavity in the mold.

 3) It expands the mold to compensate for contraction of the metal on cooling.

Casting: inserting melted alloy into the mold. Cooling.

Removing the casting from the investment

Sandblasting

Cutting sprue formers

Finishing and Polishing

Fixed partial dentures

A fixed partial denture is “A partial denture that is cemented to natural teeth or roots which furnish the primary support to the prosthesis”. A fixed prosthesis is “ A restoration or replacement which is attached by a cementing medium to natural teeth, roots, implants”. These dentures are often termed as BRIDGES. Fixed partial dentures are fabricates in a complex manner. The prosthesis is cemented to the supporting teeth and cannot be removed by the patient.

Common terms used in fixed prosthodontic

Crown Laminate veneers or facial veneers Inlay Onlay Abutment Pontic Connectors

Crown is a cemented extracoronal restoration that covers or veneers the outer surface of the clinical crown. The primary function of a crown is to protect the underlying tooth structure and restore the function, form and aesthetics.

We know three types of the crowns – 1. clinical crowns depicts the intraorally visible tooth structure 2. anatomical crowns depicts the area of the tooth covered by enamel 3. artificial crowns. If the prosthetic crown covers all five surfaces of the clinical crown it is referred to as a Full veneer crown (FVC). If the prosthetic crown does not cover the entire clinical crown, it is referred to as a Partial veneer crown (PVC).

A crown that is used as a part of the fixed partial denture for retention and support from the abutment tooth is called as a Retainer.

Abutment – It is any tooth, root or implant which gives attachment and support to the fixed partial denture Pontic –The artificial tooth that replaces a missing tooth in a fixed partial denture is called a pontic. Pontics are attached to the retainers. All forces acting on the pontic are transferred to the abutment through the retainers.

Connectors – It is the connection that exists between the pontic and retainer. They may be rigid or non-rigid. Rigid connectors are immovable attachments between the pontic and retainer. Ex. Solder joints. Non-rigid connectors are movable attachments with a key-keyway mechanism. Ex precision attachments.

Classification of partial adentia. External clinical features • Lips’ retraction, especially upper lip • Buccal retraction, in case of masticatory tooth absence • The lowering of the vertical dimension of the face, in loss of mastication teeth of both jaws. • Angular cheilitis development • Big amplitude of vertical movement of the lower jaw during swallowing Complaints If the defect is located in frontal part of dental arch. • Esthetical dissatisfaction • Diction impairment • Saliva sprinkle during speech • Impossibility to bite off If the defect is located in lateral part of dental arch. • Mastication impairment • Damage of the gum mucous and pain • Esthetical dissatisfaction in case of absence Anamnestic data • Causes of the tooth loss • Dates of the tooth loss • If the patient has had prosthodontic prosthesis and the type of construction Patient’s examination • Type of defect • Extension of defect • Availability of antogonists’ pair. • Condition of periodont and hard tissues of the preserved teeth • Occlusal curve Additional methods of examination • Palpation • Soundation • Determination of the tooth agility • X-Ray examination of all probable abutment teeth Results of tooth partial loss • Impairment of continuity of dental arch and defect formation • Development of 2 group of teeth: functional, and non-functional • Functional overloading of some tooth groups • Dental arch deformation • Mastication, speech and esthetic impairment • TMJ and masticator muscles functional impairment Defects can be • Limited or involved • Unlimited or terminal Several classifications of partially edentulous arches have been proposed. This variety has leаd to some confusion and disagreement concerning which classification best describes all possible configurations and should be adopted. The Kennedy method of classification is probably the most widely accepted classification of partially edentulous arches today. Kennedy classification The Kennedy method of classification was originally proposed by Dr. Edward KENNEDY in 1925. It attempts to classify the partially edentulous arch in a manner suggests certain principles of design for a given situation. Kennedy divided all partially edentulous arches into four basic classes. Edentulous areas other than those determining the basic classes were designated as modification spaces. The following is the Kennedy classification. Class I –Bilateral terminal adention (edentulous areas located posterior to the natural teeth) Class II – a unilateral terminal adention (edentulous areas located posterior to the remaining natural teeth) Class III – a unilateral involved adention (edentulous areas with natural teeth remaining both anterior and posterior to it). Class IV - invovlved adention in frontal part of dental arch. (it is single, but bilateral (crossing the midline), edentulous area located anterior to the remaining teeth).

Classification defects by size • minor – in absence of 1-3- adjacent teeth • moderate - in absence of 4-6 adjacent teeth • large - in absence of 7-13- adjacent teeth

Reserved force of periodont Perioodnt ability for increased functional adaptation

Causes of functional overloading • Bite’s anomaly, common deep bite • Partial absence of teeth • mixed function of frontal teeth • pathological dental abrasion • mistakes in preparing prosthesis – increase of bite, wrong clasp system etc. • bruxizm • acute and chronic apical periodontitis Functional overloading can be different • by influence force value • by direction • by duration • combined Clinical features of functional overloading • increased enamel and abrasion, which are in traumatic occlusal condition • dislodgement(displacement) of teeth in different directions • pathological movements of teeth • development of periodontal pockets • gingivitis By X-ray exam • enlargement (deformation) of periodontal slit • atrophy of dental alveoli • osseos pocket formation on the side of inclination Traumatic occlusion • primary • secondary For primary traumatic occlusion is typical • Local character of pathological process • No purelent discharge from pathological pockets • Hyperemic gingival edge not detached from the tooth • Radially dystrophy of periodont is noted only in the region of functional overloading

Temporo-mandibular joint, structure, muscular system.

Structure of the Stomatognathic System (Determinants of Occlusion)  Dentition  Periodontium  Temporomandibular joint (TMI)  Neuromuscular system The temporomandibular joint (TMJ)  Freely movable diarthrodial articulation between the condyle of the mandible and the squamous portion of the temporomandibular bone

 The TMJ of one side cannot function without the movement of the contralateral joint  Articulating surfaces are covered with fibrous nerve free and nonvascular connective tissue

The joint exibits two types of movements:

 rotation (hinge movement)

 translation (gliding movement)

Articular disk divides the joint space into separate  superior compartment

and

 inferior compartments The lower compartment shows hinge movement. During hinge movement the condyle moves against the articular disc and the glenoid fossa . The upper compartment shows anteriorposterior gliding movement. During this movement the condyle and the articular disc move against the glenoid fossa .

Jaw closing muscles  Masseter muscle  Temporalis muscle  Medial pterygoid muscle Jaw opening muscles  Mylohyoideus muscle  Geniohyoideus muscle  Anterior digastric muscle The movements of mandible forward is realized by bilateral contraction of lateral pterygoid muscles The movements of mandible left or right is realized by one-sided contraction of lateral pterygoid muscles When the mandible moves into a left lateral excursion is contraction the right side of lateral pterygoid muscles When the mandible moves into a right lateral excursion is contraction the left side of lateral pterygoid muscles Articulation The relations of upper and lower teeth to each other during mandibular movements. Occlusion The relation of the maxillary and the mandibular teeth when in functional contact during activity of the mandible. Centric occlusion The position of the mandibule when the relationship of opposing occlusial surfaces (natural teeth or denture teeh) provides for maximum planned contact and intercuspation (ICP). Centric relation The most retruded relation of the mandible to the maxilla when the condyles are in the most posterior unstrained position in the glenoid fossae. The relationship of the mandibule to the maxillae when the condyles are in their most superior position, with the central baering area of the articular disks in contact with the articular surface of the condyles and with the articular eminences. Retruded Contact Position (RCP)  Contact position between the teeth in CENTRIC RELATION.  In general only one contact between the teeth exists at the region on both sides of the dental arch. ICP(CO) relative to RCP(CR)  ICP identical with RCP in 10-14% of the population  A larger percentage of individuals have a difference of approximately 0.1-1.5 mm vertically, 0.1 to 1 mm horizontally, less than 1mm transversally Rest position of the mandible  The physiologic resting position of the mandible when the individual is sitting or standing in an upright position (postural rest position), as determined by the muscles and other tissues that attach to the mandible.  Myographically small tonic activity can be detected in the muscles.  Lips are in contact Occlusal vertical dimension (OVD):

The vertical dimension of the face as determined by a midline vertical measurement of the face between two points above and below the mouth when the mandibule is in centric occlusion. Rest vertical dimension (RVD): The vertical dimension of the face when the mandible is in postural rest position. Free way space (Interocclusal distance ) The distance between the occluding surfaces of the maxillary and mandibular teeth , when the mandible is in rest position,commonly 2 to 4 mm less than the RVD

Tooth Anatomy

Common terminology

Anatomical crown is the part of the tooth, which is covered with enamel.

Clinical crown is the part of the tooth that is visible in the oral cavity. The length of the clinical crown may not fully reflect the anatomical crown length. The clinical crown length can be changed during lifetime.

Anatomical root is the part of the tooth that is covered with cementum.

Clinical root is the part that is not visible in the mouth.

Anatomical neck (C.E.J Cement - Enamel Junction) is a boundary of the anatomical crown and anatomical root.

Periodontal fibers (P.D.L.) are collagen fibers that connect root to the alveolar bone.

Gingiva, Gum is connective tissue that covers the jaw bone up to the level of the clinical crown.

Biological width (about 2 mm) is the distance between the crista of alveolar bone and the floor of gingival sulcus. It consists of two parts: connective tissue attachment (1.07 mm) and epithelial junction (0,97 mm).

Dental arches

Teeth arrangement in alveolar bone is such that there are occurring different curves at various levels (curves of Spee and Wilson).

Due to such regular arrangement distribution of chewing pressure on the teeth becomes balanced and minimal.

Spee Curve

We study this curve in a parasagital plane. Curve occurs when the cutting edges of the teeth, tips of the canines and tips of premolars’ and molars’ vestibular cusps are connected to each other by imaginary line.

Wilson Curve

This curve we study in frontal plane at the level of premolars and molars. It occurs when the imaginary line connects apex of mandibular buccal cusp and an apex of lingual cusp and the curve continues until the next side of the same teeth, the same name cusps.

1

Such teeth arrangement (maxillary teeth to vestibular slope, mandibular teeth of the lingual slope) provides smooth teeth sliding during lateral movements, and makes it balanced and smooth, without any obstructions.

Teeth axis is usually forming the straight angle with the tooth occlusion surface, when each tooth and jaw axis are forming an imaginary angle.

The roots of the upper incisors from vestibulo-oral plane strongly bent to the oral side, and have slight bent to medial side from medio-distal corner. Canines are exception, their roots bent strongly to the distal side.

Roots of maxillary premolars and molars from vestibulo-oral plane bend to the oral side, and from medio-distal plane to the distal.

Roots of the mandibular incisors are strongly bent in favor of the oral side, and from medio- distal plane of almost 90 degrees have slight bent to medial side, whereas canines have slight bent to the distal side.

Premolars roots are slightly bent to the distal side, P1- also to oral and P2- to the vestibular side.

Molars roots have greater angle of bent toward the distal side, as well as to the vestibular side.

Interdental contact points (contact area)

In a teeth arch each tooth gets into contact with neighboring 2 teeth, with the exception of the 8th teeth that have contact only by medial side. All teeth interdental contacts occur with medially located tooth distal surface and distal tooth medial area, except for two central incisors that are contacting each other by two medial areas. The contact between the teeth at the first is a point, which later becomes the larger surface area, because of teeth wear. Thus the interdental space is decreased, which causes teeth medialisation. Correct location of contact points causes the teeth to be stable and to resists deformations under the action of different types of masticatory forces. Correctly located contact points contribute to the prevention of food accumulation in interdental spaces. If there is an imaginary line connecting interdental contact points, the curve will be formed, that follows the Spee Curve. Observing contact points from vestibulo-oral side it becomes clear that the points are located at the middle 1/3 level of the tooth anatomical crown. Triangular interdental spaces are formed below the interdental contacts between two neighboring teeth. It is covered by interdental papilla, which protects the alveolar bone crest.

2

Incisors

Numeration according to FDI N 11, 12, 21, 22, 31, 32, 41, 42

Functions

1) Cutting

2) Aesthetics

3) Speaking

The Upper Central Incisor

According to FDI Teeth N 11,21

Vestibular surface has a wide cutting edge and 3 mamelons

-medial mamelon has strongly expressed angle,

-middle mamelon after rising becomes flat,

-distal mamelon edge has rounded end.

Conical root has slight bent to the distal side.

Palatal surface

-looks like a spoon,

-in a center has lingual fossa, which is limited to medial and distal side by marginal pads.

Medial surface

-It has a triangular shape,

-contact cervical area begins from about cervical 1/3 and ends at the cutting edge, has a rounded shape.

Distal surface is similar to medial surface, but smaller, contact area with less rounded and shorter.

Cutting edge is straight.

3

The Upper Lateral Incisors

According to FDI Teeth N 12, 22

They are basically similar to the central incisors, but of smaller size.

There are basically 3 mamelons on the vestibular surface.

Medial contact is more rounded and longer.

Palatal surface has deeper depression (blind gap), has protruding marginal pads.

The cutting edge is straight, distal angle more rounded.

Top of distal root often is bent to the distal side, and the tooth axis a little bit to the medial side.

Lower Central Incisors

According to FDI Teeth N 31, 41

The smallest from all incisors.

Vestibular surface

-bilateral symmetry,

-3 mamelons (medial and distal mamelons have equal protrusion),

-teeth axis coincides with the jaw axis,

-the widest part of the crown is the cutting edge.

Lingual surface

- Slight depression and lateral marginal pads.

Medial and distal contacts are starting from the 1/3 of the lower level and ending at the incisor edge.

The root is compressed in medio-distal direction, in 40-50% of cases has two root canals, the top is bent toward the lingual side.

Lower Lateral Incisors

According to FDI Teeth N 32, 42

4

Vestibular surface,

- It's wider than central,

-avoid bilateral symmetry,

-crowns’ widest part has a more cervical location.

Lingual and medial surfaces are alike to central incisor.

Distal surface edge is more pronounced and rounded.

Cutting edge on the distal side turns down.

The root is like the root of the central incisor.

Canines

According to FDI teeth N 13, 23, 33, 43

Vestibular surface has 3 mamelons, a central mamelon forms the main protrusion of crown, which is even more expressed in middle 1/3.

The cutting edge is divided into 2 slopes by the crista. Medial slope is shorter than distal.

Medial contact area creates a linear contact with the lateral incisor, and the distal contact area is rounded and forms surface contact with .

The lower canines in comparison with the upper canines have the same or greater crown longitudinal sizes.

When looking at the front profile on the upper and lower canines they look like 1st premolars.

Upper canine root is rounded, the lower canine root is compressed in medio-distal direction. Both roots are the longest of teeth, with the crown can reach up to 31 mm.

Premolars

Have more than 2 cusps. The one of them is buccal and one or two lingual.

Maxillary premolars crown is wider in medio-distal direction than in vestibulo-oral. Mandibular premolars crown width is the same in both directions.

5

Upper First Premolars

According to FDI teeth N14, 24

Vestibular surface looks like a canine, but smaller, and bigger than 15, 25 teeth.

Buccal cusp top in a middle of tooth line has a distal location.

Medial slope is longer and straighter than the distal slope.

There are 3 mamelons in vestibular surface, the most pronounced is the middle mamelon. These three are joined together in middle 1/3 of the crown creating crowns’ vestibular equator.

Palatal surface

- watching crowns’ palatal surface the cheek cusp external borders are found,

-palatal cusp top coincides with the middle axis of the tooth,

- palatal cusp medial and distal slopes are equal to each other,

- palatal surface is smooth and free from mamelons.

Medial surface

-the palatal and vestibular roots are visible,

-vestibular cusp is bigger than palatal one,

-contact point begins from occlusion 1/3 up to the middle 1/3 end of the border, after which begins the tooth surface medial depression and continues until the roots bifurcation.

-bifurcation is in anatomical root apical 1/3 part.

Distal surface

-Mainly resembles medial surface picture,

-contact area is mainly located in crown middle 1/3 level,

-tooth equator is weaker expressed.

Occlusion surface

-pentagonal shape

-central fissure passes through the crown middle part, reaches to distal and medial contacts and divides V-shaped to form corresponding fossa,

6

-medial fossa is deeper than distal,

-vestibular and palatine cusps are divided into two medial and distal slopes.

Upper Second Premolar

According to FDI teeth N15, 25

Vestibular surface

-resembles the N14- in shape, but smaller in size,

-medial-occlusion and distal- occlusion slopes are less pronounced.

Palatal surface

-shape is alike N14.

Medial surface

-palatal and vestibular cusps have equal height,

-anatomical crown does not have depression,

-contact area is in middle 1/3 part.

Distal surface

-palatal and vestibular cusps have equal height,

-mainly is seen one root with one or two root canals.

Occlusion surface

-has six angles, and looks more rounded, as the cheek and palatal cusps are located closer to the middle line,

-central fissure short and deep,

-it has numerous small fissures.

Lower First Premolar

According to FDI teeth N34, 44

7

Vestibular surface

-Mainly repeats canine appearance,

-the cheek cusp top is in a middle,

-medial slope is shorter than distal,

-crown has 3 mamelons which are connected to each other at cervical 1/3, where they form a crown vestibular equator,

-it has a conical root.

Lingual surface

-lingual cusp has a triangular shape,

- cheek cusp`s lingual slope is visible well, equators of medial and distal contacts too,

-lingual cusp`s medial slope is shorter than the distal slope.

-lingual cusp`s top is located more medially than a tooth axis,

-root has a cone-shaped structure, the top has distal bent.

Medial surface

-occlusion surface is inclined to the lingual side,

-crown vestibular equator is in the lower 1/3,

-medial contact area is in the middle 1/3,

-lingual equator is the lower border of upper 1/3,

-lingual cusp`s top height is less than the height of the cheek cusp,

-root has a conical shape, the top coinciding with the central axis of the tooth.

Distal surface

-Mainly repeats medial picture,

-contact point is more expressed.

Occlusion surface

-cheek cusp`s top is near the crown middle line,

8

-fissure between cusps is Y- shape,

-expressed fissure.

Lower Second Premolar

According to FDI Teeth N 35, 45

Vestibular surface repeats the same image.

Lingual surface

-lingual cusp has two tops, the distal one is higher located.

Medial and distal surfaces repeat the same image.

Occlusion surface

-It has quadrangular shape,

-fissure between cusps is the Y-, H- or U- shaped in appearance, located in the center.

Upper Molars

General Characteristics

-they are chewing teeth,

-mainly have more than 3 cusps (2 cheek , 1 or more palatal),

-2 or 3 roots (2 cheek, palatal 1)

-crown width BP> MD,

-cusps MB> DP,

-beginning from the first to 3rd molars roots tops become closer to each other.

Upper First Molar

According to FDI Teeth N 16, 26

Vestibular surface

9

-MB and DB cusps height is equal,

-MB wider than DB cusp,

-MB and DB cusps are separated by a groove, which ends by blind hole,

-crowns’ equator is in cervical 1/3 level, middle and upper 2/3 are flat,

-3 roots are visible, and the MB and DB roots are pointed towards each other.

Palatal surface

-Two cusps are uneven. MP cusp forms 3/5 of the crown,

-DP cusp is more rounded, smaller and thinner (more expressed than the same cusps in upper M2, and M3)

-the groove between cusps is located distally from the center of the tooth,

-medial angle is more rounded and distal more flat.

Medial surface

-This area is the largest contact surface area of all the teeth,

-MP cusp larger than MB cusp,

- equator is well expressed in the vestibular part of the crown in the lower 1/3,

-palatal surface is proportionate convex,

-contact point is located in the upper and middle 1/3, while the lower 1/3 is depressed or flat.

Distal surface

-DB cusp more convex than the DP cusp,

-medial cusps’ very small part is visible,

- equator is well expressed in vestibular part, located in the crowns’ lower 1/3,

-palatal surface is proportionate convex,

-distal contact proportionate convex and forms a large contact area.

Occlusion surface

-It has rhombus form,

10

-MB and DP angles are sharp, and MP and DB are obtuse angles,

-cheek surface 1/3 and palatal surface 1/2 are visible,

-mainly has 4 cusps and one small cusp, which is known as Carabelli cusp,

-intercuspidal fissure has H- form and divides tooth asymmetrically,

-each cusp has 2 slopes,

-MP cusp, which is the largest, has a flat top,

-DP cusp is the smallest and the dimensions are very variable,

-MB cusp is relatively sharp knoll, and its size is less than MP cusp only,

-DB cusp has sharpest top and in size it is the 3rd one.

Basically it has three roots, but in 90-93% of cases there are four root canals.

Upper Second Molar

According to FDI Teeth N 17, 27

Vestibular surface

-It has a smaller surface area than the N 16, 26,

-DB cusp is less convex,

-distal root is tilted to the cheek side.

Palatal surface

-DP cusp is smaller and shorter than a N16, 26,

-P root is weakly bent toward the distal side,

-Carabelli cusp is missing.

Medial and distal surfaces

-slightly pronounced vestibular equator,

- palatal cusps are smoother and straighter,

-contact surfaces are smooth and slightly concave in the middle 1/3rd level.

11

Occlusion surface

-chewing surface is smaller,

-MB and DP angles are sharp,

-MP and DB angles are blunt,

Central fissure is like the letter H, and the two blind holes occur in slopes.

Roots are three in number, but sometimes, there are also two, rarely one root options.

The lower jaw molars

Lower First Molar

According to FDI Teeth N 36, 46

Vestibular surface

-is formed by the MB, DB and D cusps,

-there are fissures between cusps, which ends in 2 blind holes in crowns’ middle 1/3,

-medial and distal contacts are flat in the middle 1/3, then they are depressed, therefore the main equator of the tooth emerges in the middle 1/3,

It has two roots that in apical 1/3 turn to the distal side.

Lingual surface

-is formed by the ML and DL cusps, which are equal to each other,

-intercuspidal fissure runs through the central axis of the tooth,

-medial and distal contacts are flat in the middle 1/3, then they are depressed, therefore the main equator of the tooth emerges in the middle 1/3 sets.

Medial surface

-ML cusp slightly higher than MB cusp,

-vestibular equator is in the lower border of middle 1/3 part of the tooth, but in the lingual side of the tooth equator is located in the lower level of upper 1/3,

-medial contact is flat,

12

- root has funnel like shape.

Distal surface

- the DL, DB and D cusps are seen, as well as distal intercuspidal fissure,

-in the vestibular part of the tooth an equator is in the lower border of the middle 1/3-rd, and in the lingual side of the tooth an equator is located in the lower level of upper 1/3-rd,

- root has funnel like shape.

Occlusion surface

-It has 5 cusps: MB, DB, D, ML, DL,

-intercuspidal fissure is like cross,

-medial contact is wider than distal,

-vestibular wall longer than lingual.

The roots are usually two with three or four root canals.

Lower Second Molar

According to FDI Teeth N 37, 47

Vestibular Surface

-tooth is smaller than the previous one,

-it has 2 cusps and one intercuspidal groove which coincides with the middle line of the tooth,

- equator is slightly expressed in medial and distal contacts,

-roots are located closer to each other than the N36, 46 teeth roots, and are more inclined to distal,

Language surface

-anatomical crown is smaller than in the vestibular side,

-it has 2 cusps and one intercuspidal groove which coincides with the middle line of the tooth,

-cusps width is smaller than in vestibular side, and thus aproksimal surfaces become a bit visible.

Medial Surface

13

-contact surface is flat, like the N 36,

-roots are sharpened, apical part is slightly bending to cheek side.

Distal surface

-D cusp is absent,

-contact surface is flat,

-root apical part is thinner and bent to the more distal,

Occlusion surface

-cross fissure divides into 4 cusps,

-medial and distal contacts have equal surfaces,

-vestibular and lingual walls length is also equal,

-M and D depressions slightly expressed.

Roots are two in number, manly, sometimes three or one options are known. Root canals mainly are three, sometimes four , two or one options are possible.

14