Complete denture Fourth appointment

Clinical procedure  Verification of vertical dimension of  Verification of centric jaw relation  Establishment and verification of the protrusive record  Phonation  Esthetics by the dentist  Esthetics by the patient  Determination of color of acrylic resin base Laboratory procedure  Preparation of the trial denture  Disarticulation  Flasking procedures  Dewaxing  Application of separating medium  Mixing of the powder and liquid  Packing  Curing  Cooling  Deflasking  Finishing and polishing the

Verification of vertical dimension of occlusion: Vertical dimension at occlusion- the length of the face when the teeth are in contact and the mandible is in or the teeth are in centric relation. We can varify the vertical dimension using the follwing methods: “Dot” tecnique: Two reference points are marked on the tip of the nose and the tip of the chin then measure the distance between these two points with the mandible in the rest position and in occlusion. The difference between these two measurements is the interocclusal distance «2-4 mm.

Phonation and speech method: The patient is asked to repeatedly pronounce the letter’m’,a certain number of times and the distance between the two reference points is measured immeadiately after the patient stops at this time the mandible is in the rest position. When the patient pronounces «S»or «C» the teeth come very close to each other(fraction of a mm),however,they should not contact The space existing between the position of «M» and «S» is the interocclusal distance which may vary between one individual to the other between 1 to 15 mm.(the average meaning is 2-4 mm).

Verification of centric jaw relation The most posterior relation of the mandible to the maxilla at the established vertical dimension. . The patient should be seated at 45 degree inclined position in the chair . Place maxillary trial dentures in the mouth . Dry the occlusal surfaces of the mandibular teeth with absorbent paper . Soften a sheet of tenax recording wax on the flame , roll it . Cut the softened, rolled wax(approximately 2 to 3 cm in length) and place it in the area of the mandibular posterior teeth . Put the mandibular trial denture in the mouth . Guide the patient to close in the most retruded position short of tooth to tooth contact.The patient should .touch the wax , «bite» or «close» into it . Remove the assembly from the mouth and put mandibular trial denture in cold water. . Place the trial denture on the casts(attaching to the articulator) . Close the articulator by placing the cusps of maxillary posterior teeth in the corresponding indentation of the recording wax . If centric record is correct the maxillary cusps should be seated accurately in the indentation of the recording wax and condyles of the articulator should be contacting the anterior wall of condilar fossae of the articulator. Establishment and verification of the protrusive record . The purpose of this step is to obtain protrusive record from the mouth and verify it with interocclusal soft tenax recording wax. . Place maxillary trial dentures in the mouth . Dry the occlusal surfaces of the mandibular teeth with absorbent paper . Soften a sheet of tenax wax on the flame , roll it . Cut the softened, rolled wax(approximately 2 to 3 cm length) and place it in the area of the mandibular posterior teeth . Put the mandibular trial denture in the mouth and instruct the patient to close the mouth while protruding the mandible to approximate the anterior teeth edge to edge position As soon as the patient`s mandible reaches the desirable position ask the patient to mouth , remove the trial dentures and place them in cold water. Place trial on the casts and check this recording on articulator. Phonation Position of the teeth , thickness of the palate and wax contour of the trial dentures may influence the phonation and the speech.Incorrect vertical dimension may affect the phonation.Unstable trial dentures may result in erroneous phonetic conclusion. Listen carrefully to various words espetially the «s» and «f» sounds. Listen carrefully for whistling during the pronunciation of «s» and «ch» sounds. If necessary modify the thickness of the palatal portion of trial denture,or position of the teeth to correct the phonation. Esthetics by the Dentist The purpose of this step is to evaluate the appearance of the dentures . Determination of color of acrylic resin base Esthetics by the Patient Laboratory procedure: . Final tooth arrangement . Wax contour of complete dentures . Preparation of the trial denture The trial dentures are placed on the cast and sealed to the cast using additional wax.This is done so that the relationship of the trial denture and the cast is not altered during disarticulation . Disarticulation . Flasking procedures The base of the flask is filled with dental plaster (this is the first pour).The cast with the wax pattern is immersed into the plaster-filled base.Once the base is invested,a separating medium is applied in all areas where gypsum is exposed in order to protect the continuity of the membrane.Surface tension reducing agent can be applied over the wax pattern in order to improve the wettability of the second pour of gypsum over the wax pattern.Once the separating medium dries,the body of the flask is placed and fit on the base.

. A mix of dental plaster and poure into the body till the level of the occlusal /incisal surfaces of the teeth.(this is the second pour) . The third pour of dental plaster is poured to fill the body and closed.Excess plaster is allowed to escape out. . After flasking ,the flask is left undisturbed for 30-60 minutes

Dewaxing Dewaxing is done to remove the wax in the wax pattern so that a mould space is created for acrilic to fill-in.It is carried out by placing the flask in boiling water(100C) for 5 minutes,after 5 minutes the flask is taken out of the water bath,the base and the body are carefully separated.The softened wax is flushed out using hot water or a wax solvent or soap solution.  Application of separating medium  Separating medium is applied to the dewaxed mould space prior to packing the acrilic resin.The purposes of this step are:  To prevent water from the mould entering into the acrylic resin.This may affect the rate of polimerization and colour  To prevent monomer penetrating into the mold material,causing plaster to adher to the acrylic resin and producing a rough surface Mixing of powder and liquid Polimer monomer proportion  3:1 by volume  2:1 by weight

Packing Introduction of denture base resin into the mould cavity is termed packing Curing (Polimerisation) Cooling Deflasking Finishing and polishing the dentures

COMPLETE DENTURE THIRD APPOINTMENT

1 Clinical procedures 2 Laboratory procedures

Clinical procedures: 1. Establishment of posterior border of maxillary denture 2. Posterior palatal seal 3 Maxillary occlusal rim 4 Mandibular occlusal rim 5 Establish and check vertical dimension of occlusion 6 Facebow record 7 Mounting maxillary cast on articulator 8 Centric jaw relation record 9 Mounting mandibular cast on articulator 10 Selection of the teeth

Laboratory procedures: 1.Complete teeth set-up 2.Complete wax-up

Establishment of posterior border of maxillary denture Posterior palatal seal Posterior palatal seal (postdam) –the soft tissues along the junction of the hard and soft palates on which pressure within the physiological limits of the tissues can be applied by a denture to aid in the retention of the denture This is the area of the soft palate that contacts the posterior surfaces of the denture base. It prevents air entry between the anterior and posterior vibrating lines Vibrating line -the imaginary line across the posterior part of the palate marking the division between the movable and immovable tissues of the soft palate which can be identified when the movable tissues are moving It is an imaginary line drawn across the palate that marks the beginning of motion in the soft palate, when the individual says «ah» We distinguish  Anterior vibrating line .  Posterior vibrating line

 Anterior vibrating line –is an imaginary line lying at the junction between the immovable tissues over the hard palate and the slightly movable tissues of the soft palate.  Posterior vibrating line - is an imaginary line located at the junction of the soft palate that shows limited movement and soft palate that shows marked movement.

Functions of the posterior palatal seal  Aids in retention by maintaining constant contact with the soft palate during functional movements like speech, mastication and deglutition  Reduces the tendency for gag reflex as it prevents the formation of the gap between the denture base and the soft palate during functional movements  Prevents food accumulation between the posterior border of the denture and the soft palate  Compensates for polymerization shrinkage

Recording the posterior palatal seal is very important for the retention of the denture. A good posterior palatal seal is essential to provide peripheral seal. The denture border should rest on soft and resilient tissues, which can move along with the denture during function and prevent loss of peripheral seal. Refer post dam and vibrating lines for further details. The method used to mark the Post-dam: Palpate hamular notch areas posteriorly to the maxillary tuberosity on both sides.Do the same thing with mouth mirror. The full extent of the hamular notch is marked with an indelible pencil. The hamular notch is a depression situated between the maxillary tuberosity and the hamulus of medial pterygoid plate.  The full extent of the hamular notch is marked with an indelible pencil.  The posterior vibrating line is marked using an indelible pencil by asking the patient to say «ah» in a non –vigorous manner  The line marked in the hamular notch is connected whit the posterior vibrating line using an indelible pencil. This will formed the posterior border of the denture.

 Put the maxillary record base in the mouth  Hold the nostrum of the nose  Ask the patient to blow trough his nose  Thus the indelible markings are transferred to the base

The trial base is seated on the master cast to transfer the markings marked in the patient's mouth to the cast

The anterior vibrating line is marked in the patient's mouth using an indelible pencil by asking the patient to close his nostrils firmly and gently blow trough his nose. The markings are transferred to the master cast as described before for the posterior vibrating line The area between the anterior and posterior vibrating line is scrapped in the master cast to a depth of 1,5-2,0 mm and width is about 6 mm on either side of the mid-palatine raphe. In the region of the mid-palatine raphe,it should be only 0,5 to 1mm in depth and 2 mm in width. Occlusal rims – occluding surfaces built on temporary or permanent denture bases for the purpose of making maxillo-mandibular relation records and arranging teeth. Also –wax form used to establish accurate maxillomandibular relation and for arranging artificial teeth to form the trial denture. Occlusal rims are fabricated to record various maxillo-mandibular relations , lines, vertical and horizontal overlaps, etc. They are usually fabricated to a larger size so that they can be reduced as needed. Maxillary occlusal rim  Use baseplate hard wax for construction of occlusal rims  Take on sheet of baseplate wax,soften thoroughly, and roll it in cigar shape. Then place it on the maxillary record base approximating alveolar ridge Place the maxillary record base with soft oversize occlusal rim in the mouth Take two wooden tongue blades, approximated one of the blades to the imaginary line, passing from the pupil of one eye to the pupil of the other eye. Place the 2 tongue blade on the anterior portion of the soft oclussial rim and mold it until it becomes on the level of the upper lip and parallel to the other tongue blade. Place 1 tongue blade to the imaginary line from the tragus of the ear to the ala of the nose,on the right side of the face.Place 2 tongue blade on the right posterior portion of the soft occlusal rim and mold it until it becomes parallel to the other tongue blade.  Remove the occlusal rim and place it in the cold water bath for 2-3 minutes  With the warm laboratory knife remove the excess wax  The labial wall of the rim should be 9 mm anterior to the incisive papilla to support the lip and about 1 mm below the relaxed lip line in the average patient

 The occlusal rim on the anterior section should be 10mm  The occlusal rim on the posterior section should be 15mm  Use baseplate hard wax for construction of occlusal rims  Take on sheet of baseplate wax,soften thoroughly,and roll it in cigar shape.Then place it on the mandibular record base approximating alveolar ridge.  Place the maxillary record base with soft oversize occlusal rim in the mouth  Ask the patient to close the mouth gently and swallow hard.Repeat this 3 or 4 times Remove the mandubular occlusal rim, place it in cold wather bath and remove the excess parts Place both occlusal rims in the mouth and check. Both rims should be contacting over the all occlusal surfaces

Establish and check vertical dimension of occlusion Vertical jaw relation -the amount of separation between the maxilla and mandible in the frontal plane Vertical jaw relation can be recorded in two positions  Vertical dimension at rest position –the length of the face when the mandible is in rest position  Vertical dimension at occlusion- the length of the face when the teeth are in contact and the mandible is in centric relation or the teeth are in centric relation.

The space between the teeth at rest is called the 'free-way space'. The 'free-way space' exists only at rest. During occlusion , the teeth come in contact with one another and the space is lost. The same relationship should be reproduced in the complete denture. The vertical dimension at occlusion should always be 2-4 mm lesser than the vertical dimension at rest. The vertical dimension at rest should be recorded at the physiological rest position of the mandible. The physiological rest position is influenced by a number of factors and the following considerations are to be remembered while recording it:  The position of the mandible is influenced by gravity and the posture of the head.Hence while recording vertical jaw relation the patient sould be asked to sit upright, with his/her head upright and eyes looking straight in front.  Since we are recording a physiological rest position, all the muscles affecting this record shoud be relaxed.  Presence of any neuromuscular diseases in the patient can influence the rest position.  Incorrect measurement of the rest position can lead to faulty recording of the vertical dimension at occlusion and can lead to injury to the supporting structures and the temporomandibular joint. The following metods can be used to measure the vertical dimension at rest.  Facial measurements after swallowing and relaxing  Tactile sense  Measurement of anatomic landmarks  Speech  Facial expression

Facial measurements after swallowing and relaxing  The patient is asked to sit upright and relax  Two reference points are marked on the tip of the nose and the tip of the chin  The patient is asked to perform functional movements like wetting his and swallowing  After that his mandible will come to its physiological rest position.The distance between the two reference points is measured when the mandible is in its physiological rest position.

Tactile sense  The patient is asked to stand erect and open his mouth wide till he feels discomfort in his muscles of mastication  Next the patient is asked to close his mouth slowly.The patient is instructed to stop closing when he/she feels that his/her muscles are totally relaxed and comfortable  The distance between the two reference points is recorded and compared to the measurement recorded by the swallowing method.

Measurement of anatomic landmarks The distance between the pupil of the eye and the corners of the mouth and the distance between the anterior nasal spine and the lower border of the mandible should be equal when the mandible is in its physiological rest position.

Speech There are two methods by which the rest position can be recorded with the help of speech  The patient is asked to repeatedly pronounce the letter’m’,a certain number of times and the distance between the two reference points is measured immeadiately after the patient stops  The dentist keeps talking to the patient and he measures the distance between the reference immediately after the patient stops talking.

Facial expression The following facial features indicate that the jaw is in its physiological rest position:  Skin around the eyes and chin should be relaxed. It should not be stretched,shiny or wrinkled  The nostrils are relaxed  The upper and lower lips should have a slight contact  Clinical procedure. Face-bow record Face – bow –a calliperlike device which is used to record the relationship of the maxillae and /or the mandible to the temporomandibular joints. Parts of a face-bow  U-shaped frame  Condilar rods  Bite fork  Locking device U -shaped frame It is a U-shaped metallic bar that forms the main frame of the face-bow.All other components are attached to the frame with the help of clamps

Condilar rods These are two small metallic rods on either side of the free end of the U-shaped frame that contacts the skin over the TMJ.They help to locate the hinge axis or the opening axis of the temporomandibular joint.They transfer the hinge axis of the TMJ by attaching to the condilar shaft in the articulator.

Bite fork This is a u-shaped plate, which is attached to the occlusal rims while recording the orientation relation (the jaw relation when the mandible is kept in its most posterior position,it can rotate in the sagittal plane around an imaginary transverse axis passing through or near the condyles) Locking device This part of the face-bow helps to attach the bite fork to the U-shaped frame.This also supports the face- bow,occlusal rims and the casts during articulaton.

Face-bow record  Wrap two sheets of bees wax around facebow fork  Seat maxillary and mandibular occlusal rims in the mouth  Place the facebow fork in the mouth and instruct the patient to close on beeswax  Remove the facebow fork and chill it in cold water bath  Return the fork the mouth and complete the facebow registration by placing the facebow over dots on 13mm anterior to the tragus of the ear on a line to the outer canthus of the eye  Remove the assembly from the mouth.

Mounting maxillary cast on articulator

Articulator Articulator –mechanical device which represents the temporomandibular joints and the jaw members to which maxillary and mandibular casts may be attached to simulate jaw movements. Purpose of an articulator  To hold the maxillary and mandibular casts in a determined fixed relationship.  To simulate the jaw movements like opening and closing.  To produce border movements(extrem lateral and protrusive movements).

Mounting procedure The procedure of attaching the maxillary and mandibular casts to the articulator in their recorded jaw relation is called articulation.The maxillary cast is first articulated after orientation jaw relation with the help of a face- bow. The mandibular cast is articulated after recording the vertical and centric jaw relations.  The face –bow whith its bite fork attached to the maxillary occlusal rim is positioned in the articulator  First , the earpiece of the face-bow is attached to the rollpin of the articulator. This transfers the posterior reference point of the face-bow to the articulator.  After this,the anterior reference point should be positioned.  The face-bow can be stabilized in this position with the help of face-bow support, which will hold it in position.

 The maxillary cast should be placed in slurry water for at least five minutes for better adhesion of the cast to the mounting plaster.  The maxillary cast is placed onto the record base of the occlusal rim.  Once the face-bow support is attached, the upper member of the articulator can be opened.The upper member is oppened completely so that it does not interfere with the placement of the cast  A relatively thick mix of dental plaster is mixed and placed over the maxillary cast.  The upper member of the articulator is closed and the mounting plaster is contoured to obtain a good finish.

Centric jaw relation record Centric jaw relation –the most posterior relation of the mandible to the maxilla at the established vertical dimension.  For this phase the patient should be reclined at 45 degree  Reduce the mandibular rim by 2mm to receive the soft tenax recording wax.

 Soften the recording tenax wax on the flame and roll it to the diameter of 8-10mm  Place the soft tenax wax roll on the mandibular rim and mold with your index finger and thumb the height of about 6mm,triangular in shape,place mandibular trial denture in the mouth.  Instruct and guide the patient to close in centric jaw relation as he displaces about 2mm of the soft wax.Remove and chill in cold water bath.  Remove from the cold water bath  With the warm laboratory knife remove the excess wax

Mounting mandibular cast on articulator

 The mandibular cast is mounted after recording the tentative vertical and centric jaw relations  The articulator with the mounted maxillary cast is inverted to aid in mounting the mandibular cast  The maxillary occlusal rim is placed on the maxillary cast. The mandibular occlusal rim is positioned over the maxillary occlusal rim using the relation records  The mandibular cast is placed on the lower occlusal rim.(It should be soaked in slurry water before mounting).  The mandibular cast is attached to the lower member of the articulator using dental plaster.  Clinical procedure Teeth selection  Selection of tooth material  Selection of shape  Selection of form  Selection of size

Method of selection  Determine patient face form  Determine arch size from the cast  Hold the one central incisor tooth in the aproximate natural position.  after selecting central incisor do the same with the lateral  Select mandibular anterior teeth according to the maxillar.

 Size of posterior teeth should be harmonized 1. With the size of anterior teeth 2. With the size of arch  Narrow surfaces of the teeth makes the chewing more efficient.Selected artificial posterior teeth should usually be narrower than natural teeth  The available space between maxillary and mandibular archs is an important factor to choosing the length of the posterior teeth

Occlusion

Occlusion is defined as “Any contact between the incising or masticating surfaces of the maxillary and mandibular teeth”. Occlusion is an important factor, which governs the retention and of the complete denture. It is important to know the principles of occlusion before arranging artificial teeth.

Differences between natural and artificial occlusion.

Natural teeth Artificial teeth Natural teeth function independently and each Artificial teeth function as a group and the occlusal individual tooth disperses the occlusal load loads are not individually managed

Malocclusion can be non problematic for a long Malocclusions pose immediate drastic problems time. Non vertical forces are well tolerated Non vertical forces damage the supporting tissues Incising does not affect the posterior teeth Incising will lift the posterior part of the denture The second molar is the favored area for heavy Heavy mastication over the second molar can tilt mastication for better leverage and power or shift the denture base. Bilateral balance is not necessary and usually Bilateral balance is mandatory to produce stability considered a hindrance of the denture

Ideal requirements of complete denture occlusion Complete denture occlusion should fulfill the following characteristics: • Stability of the denture and its occlusion when the mandible is in both centric and eccentric relations • Balanced occlusal contacts (tripod contact) during all eccentric movements • Unlocking (removing interferences) the cusps mesiodistally so that the denture can settle when there is ridge resorption. • The cuspal height should be reduced to control the horizontal forces. • Functional lever balance should be obtained by vertical tooth to ridge crest relationship. (Lever balance is the balance against leverage forces acting on the denture. Presence of positive contact on the opposing side provides lever balance. It differs from bilateral balance in that it does not necessarily require three point contact). • Cutting, penetraiting and shearing efficiency of the occlusal surface equivalent to that of natural dentition • Incisal clearance during posterior functions like chewing. • Minimal area of contact to reduce pressure while crushing food • Sharp ridges, cusps and sluiceways to increase masticating efficiency.

Arrangement of artificial teeth An artificial tooth is set by softening the wax in that portion of the occlusal rim and positioning the tooth on it. Each tooth is attached sealed to the occlusal rim based on the following principles.

Maxillary central incisor • The long axis of the tooth is parallel to the vertical axis when viewed from the front. • The long axis of the tooth is sloping labially when viewed from the side. • The incisal edge of the tooth evenly contacts the occlusal plane

Maxillary lateral incisor • The long axis of the tooth is tilted towards the midline when viewed from the front. • The long axis of the tooth is sloping labially when viewed from the side. The inclination of the slope is greater than that of the central incisor. • The incisal edge is 2 mm above the level of the occlusal plane. And the edge is tilted towards the midline.

Maxillary canine • The long axis of the tooth is parallel to the vertical axis when viewed from the front. A mild mesial tilt is supposed to improve its aesthetics. • The long axis of the tooth is parallel to the vertical axis when viewed from the side. • The cuspal tip of the canine touches the plane of occlusion • The cervical third of the canine should be more prominent than the cuspal third

Maxillary first premolar • The long axis of the tooth is parallel to the vertical axis when viewed from the front. • The long axis of the tooth is parallel to the vertical axis when viewed from the side. • The buccal cusp touches the occlusal plane and the palatal cusp is positioned about 0,5 mm above the occlusal plane. Maxillary second premolar • The long axis of the tooth is parallel to the vertical axis when viewed from the front. • The long axis of the tooth is parallel to the vertical axis when viewed from the side. • Both the buccal and palatal cusps should touch the occlusal plane. Maxillary first molar • The long axis of the tooth is tilted buccally when viewed from the front • The long axis of the tooth is tilted distally when viewed from the side • The mesio-palatal cusp alone should touch the occlusal plane. This arrangement gives rise to the lateral curves. Maxillay second molar It is arranged similar to a first molar except in a higher level • The long axis of the tooth is tilted buccally when viewed from the front • The long axis of the tooth is tilted distally when viewed from the side • The mesio-palatal cusp should be the nearest cusp to the occlusal plane Mandibular central incisor • The long axis of the tooth is parallel to the vertical axis when viewed from the front. • The long axis of the tooth slopes slightly labially when viewed from the side. • The incisal edge of the tooth should be 2mm above the plane occlusion. Mandibular lateral incisor • The long axis of the tooth is parallel to the vertical axis when viewed from the front. • The long axis of the tooth slopes slightly labially when viewed from the side but not so steeply as the central incisor. • The incisal edge of the tooth should be 2mm above the plane occlusion. Mandibular canine • The long axis of the tooth is very slightly tilted lingually when viewed from the front • The long axis of the tooth slopes slightly mesially when viewed from the side. • The canine tip is slightly more than 2mm above the occlusal plane Mandibular first premolar • The long axis of the tooth slopes slightly lingually when viewed from the front • The long axis of the tooth is parallel to the vertical axis when viewed from the side. • The lingual cusp is below the occlusal plane and the buccal cusp should be 2mm above the occlusal plane Mandibular second premolar • The long axis of the tooth slopes slightly lingually when viewed from the front • The long axis of the tooth is parallel to the vertical axis when viewed from the side. • Both the cusps are 2mm above the level of the occlusal plane Mandibular first molar • The long axis of the tooth slopes slightly lingually when viewed from the front • The long axis of the tooth is tilted mesially when viewed from the side • All the cusps are above the level of the first molar with the mesial and lingual cusps being lower than the distal and buccal cusps. 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 . 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. • 2. • 3.Genetic defects • 4.Trauma • 5.Drug use • 6.Malnutrition

Complete denture or full denture is defined as “the replacement of the natural teeth in the arch and their associated parts by artificial substitutes”. It is not a physiological prosthesis.

Function of a Complete denture: 1.AESTHETICS: The complete denture should restore the lost facial contours, vertical dimension, etc. 2.MASTICATION: A complete denture should have proper balanced occlusion in order to enhance the stability of the denture. 3.PHONETICS: One of the most important functions of a denture is to restore the speech of the patient. Indications for a Full Denture . The patient is edentulous . The remaining teeth cannot be saved . The remaining teeth cannot support a removable partial denture and no acceptable . The patient refuse alternative treatment recommendations.

Contraindications for a Full Denture . Another acceptable alternative is available. . The patient is hypersensitive to denture materials . The patient is not interested in replacing missing teeth. .

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

Prosthodontic principles of dentures Retention is the principle that describes how well the denture resists the force of gravity, adhesiveness of foods and the forces associated with the opening of the jaws. Denture is prevented from moving in the vertical plane. Stabily is defined as “the quality of a denture to be firm or constant to resist displacement by functional stresses. Stability is the principle that describes how well the denture base is prevented from moving in the horizontal plane, withstands horisontal forces The factors that affect retention can be classified as: • Anatomical factors • Physiological factors • Physical factors • Mechanical factors • Muscular factors

Anatomical factors The various anatomical factors that affect retention, are: 1. Size of denture-bearing area Retention increases with increase in size of the denture-bearing area. Maxillary dentures have more retention than mandibular dentures. 2. Quality of the denture-bearing area.

Physiological factors The viscosity of saliva determines retention. Thick and ropy saliva gets accumulated between the tissue surface of the denture and the palate leading to loss of retention. Thin and watery saliva can also lead to loss of retention.

Physical factors The various physical factors which affect retention, are 1. Adhesion 2. Cohesion 3. Interfacial surface tension. 4. Atmospheric pressure and peripheral seal Adhesion is defined as “The physical attraction of unlike molecules to one another”. The role of saliva is very important for adhesion. Saliva wets the tissue of the denture and the mucosa. A thin film of saliva formed between the denture and the tissue surface. This thin film helps to hold the denture to the mucosa. In patients with xerostomia, adhesion does not play a major role. Cohesion is defined as “The physical attraction of like molecules to each other” The cohesive forces act within the thin film of saliva. Interfacial surface tension. It is defined as “the tension or resistance to separation possessed by the film of liquid between two well-adapted surfaces. This forces are found within the thin film of saliva separating the denture base from the tissues. This film of saliva tends to resist the displacing forces, which tend to separate the denture from the tissue. It plays a major role in the retention of a maxillary denture.

Atmospheric pressure and peripheral seal. Peripherial seal is the area of contact between the peripheral borders of the denture and the resilient limiting structures. This peripherial seal prevents air entry between the denture surface and the soft tissue. Hence, a low pressure is maintained within the space between the denture and soft tissue. Peripheral seal is the most important factor for providing retention. To achieve good peripheral seal, the denture borders should rest on soft and resilient tissue. When displacing forces act on the denture, a partial vacuum is produced between the denture and the soft tissue, which aids in retention. Mechanical factors The various mechanical factors, which aid in retention, are: Implants Magnetic forces. Intramucosal magnets aid in increasing retention of highly-resorbed ridge. Denture adhesives They are available as creams or gels or powders. They should be coated on the tissue surface before wearing the denture. Suction chambers and suction discs In the past suction chambers in the maxillary dentures were used to aid in retention. The suction chamber creates an area of negative pressure, which increases retention. They are avoided now due to their potency for creating palatal hyperplasia.

Muscular factors The muscles apply supplementary retentive forces on the denture. There is a balance between the forces acting from the buccal musculature and the tongue.

The various factors affecting stability are: Vertical height of the residual ridge The residual ridge should have sufficient vertical height to obtain good stability. Highly resorbed ridges offer the least stability. Quality of soft tissue covering the ridge The ridge should provide a firm soft tissue base with adequate submucosa to offer good stability. Flabby tissues with excessive submucosa offer poor stability. Quality of impression Arrangement of teeth The postion of the teeth and their occlusion play an important role in the stability of denture. Contour of the polished surfaces. The polished surfaces of the denture should be harmonious with the oral structures. They should not interfere with the action of the oral musculature.

Fifth appointment

Clinical procedure . Detection of pressure areas and their corrections . Detection of over extended borders and their corrections . Centric relation record . Remount mandibular cast . Verification of centric record . Correction of occlusal disharmonies . Home care instructions . Appointment for 1st and 2nd check ups and adjustments Laboratory procedure 1.Make a plaster index of the maxillary artificial teeth to preserve the facebow mounting. 2.Recover and polish maxillary denture 3.Recover and polish mandibular denture 4.Block out the undercuts of both maxillary and mandibular denture. 5.Make plaster mounting casts for both dentures 6.Check the dentures before the patient arrives.

Examining the dentures . Before inserting the denture, the clinician should feel the borders of the denture to check for any sharp projectios or rough ends . The tissue surface of the denture is examined for the presence of voids and nodules. Speech . One of the most challenging functions that should be reproduced in a denture is speech. . dentures play different roles in the production of different sounds. . The sounds ( b,p,m) are controlled by the lip and become defective due to the absence of lip support or alteration in vertical dimension at occlusion

Occlusal harmony Before insertion, occlusal harmony is evaluated in the lab by remounting in an articulator. All major occlusal errors are usually corrected in the lab. Usually occlusal disharmony is not corrected during the insertion appointment. The patient is asked to wear the denture continuously for 24 hours and then the occlusal corrections are made.

Detection and correction of pressure areas. 1.Apply pressure indicating paste (PIP) on the tissue bearing surfaces of both dentures, this should be very thin, uniform in thickness almost transparent and all the strokes of the brush in one direction. . 2. Place one denture at a time in mouth, press it hard with your finger. then remove it and mark the possible pressure areas, detected by the PIP, with indelible pencil. . 3.Relieve the indicated pressure areas with acrylic bur.

Detection of over extended borders and their correction . 1. Place one denture at a time and check for over extension by sight. Check freedom of frenum and muscle attachments. . 2. Apply PIP on the border. . 3. For buccal and labial regions of maxillary and mandibular dentures, place the dentures in the mouth one at a time, hold with your finger and ask the patient to open his mouth wide. . 4.For the mandible lingual areas place the denture in the mouth, hold down your finger and ask the patient to protrude his tongue to register possible over extended areas. . 5.Make the necessary corrections of the over extension, one section at a time.

Centric Relation Record . 1.Have the patient close five minutes on cotton rolls placed across the first molar region (This will help to seat the dentures) . 2.Remove the lower denture, dry occlusal surfaces. Place the soft Tenax wax roll in the central fossae of the lower teeth. Return to the mouth. Have the patient close in centric relation position. Remove the assembly from the mouth and chill wax record by placing the denture in a cold water.

Remount of Mandibular cast Mount the lower plaster cast in correct relation to the maxillary denture.(Use sticky wax to lute all units together) The plaster mounting cast for the maxillary denture should be on the articulator.

Verification of centric relation record . Repeat previous step( centric relation record) and check the accuracy of the mounting by closing the articulator in centric relation.If the mounting does not accept the record accurately, repeat the record several time and remount if a consistent error in mounting is evident. . Verification of protrusive record . Verify the protrusive record by the check bite technique using soft Tenax wax placed on the posterior teeth. . Barring any technical errors, and if the facebow record is not changed, condylar inclinations should be about the same as at the 4th appointment.

Correction of occlusal disharmonies Correct and refine the occlusal in centric and eccentric positions

Home care instruction Give the instructions to the patient regarding the wearing, care and expected health servicing of the denture.

Post insertion visits and adjustments . The new dentures should be reevaluated and if necessary adjusted at least twice; . First one,2 to 3 days after placement of the denture, the second one, 6 to 7 days after placement of the denture . First post insertion visit and adjustments . This appointment is made preferably within 24 hours of placement of denture. . At the beginning of the appointment you should listen to patient complaint and description of the existing discomfort. . Try to distinguish between real discomfort caused by the dentures and peculiar feeling characteristic of patient wearing dentures for the first time. . Perform detailed visual examination, with good light and mouth mirror, of all denture bearing areas especially the areas which are indicated by the patient that causes discomfort . Apply PIP to detect pressure areas . Correct the possible pressure areas and over extensions . Repeat thеsе steps several times if necessary . Finish the dentures by polishing the borders if they have been adjusted.

. Second post insertion visit and adjustments . Appointment for 2nd check up and adjustment is made usually 6 to 7 days after placement of denture. . Objective of this appointment is to relieve all the discomforts, check the stability and retention of the dentures and make necessary corrections. . Home care instructions are given and the necessity of yearly examinations is discussed.

First appointment of fabrication complete denture

The goal of this appointment ismaking a preliminary impression and fabrication of custom (individual) trays. Clinical procedures: Selection of impression trays Modification of impression trays, if needed Preliminary alginate impression Labotarory procedures: Pouring of preliminary impression (as soon as possible) Separation of preliminary impression cast and block-out of undercuts Fabrication of custom trays The lesion should be cured and the tissue should be given adequate rest for sufficient healing. Clinical procedures: Selection of trays Select trays that seem slightly larger than needed A large tray is necessary in order to secure an over extended impression of the patient’s arch, include the tuberosites and retromolar pads. Materials and instrument set-up  Alginate  Tray Adhesive  Edentulous stock trays  Rubber mixing bowl  Round edge spatula  Periphery wax  Mouth mirror  Water bath Stock tray for the edentulous mouth: -range of sizes and shapes -metal, plastic -perforated, non-perforated

1. Select a stock tray 2. Add periphery wax to borders The patient’s existing denture can be used to help select an appropriate size tray. In most cases trays should be modified by pliers or with wax ( beading wax).

Alginate mixing in a plaster bowl using a plaster spatula Mix alginate thoroughly for one minute being careful to rotate the bowl and incorporate all the powder. Fill the tray with a plaster spatula. Both maxillary and mandibular impressions are made by placing anterior part first, line up middle of tray with labial frenum, then place the posterior part. For maxillary impression the dentist should stand behind the parient,sitting in upright position and for mandibular impression – in front of patient sitting at the 45degree . The impression tray should be held by the dentist until the final setting of the alginate. For maxillary impression the dentist should stand behind the parient and for mandibular impression – in front of patient. Make the Impression • Rotate tray into position • Seat posterior portion first • Gently border mold the impression Completed Preliminary Impressions -Should have no major pressure spots or voids -Should capture all peripheral extensions Alginate impression should be removed only after complete setting of alginate. The patient should be instructed not to use old dentures at least 24 hours before next appointment (for final impression). Laboratory procedures Wash the saliva from the impression Mix the mineral white, complete the impression with it and wait for complete setting of the stone, than separate cast from the impression and trim borders so the whole depth of the border of the cast is exposed. Outline the casts with a pencil Maxillary 1. Draw a line thru hamular notches and distal to the fovae 2. Extend the line around cast where soft tissue start to reflect away from ridge height 3. Keep above the frenum attachments Mandibular 1. Draw line down crest of the ridge 2. Extend the line around cast where soft tissue start to reflect away from ridge height 3. Keep above the frenum attachments Fixation the cast on the surveyor at the 45 degree angle to the path of insertion Block out undercuts and parallel sides with wax. Infliction of insulating varnish on cast surface and wait to dry it. Drip monomer and sprinkle polymer on cast until 2mm thickness is achieved Trim the trays to the lines drawn on the cast. Clean all the wax inside of the tray. Also clean the wax from the preliminary cast. The borders of the tray should be 2mm in thickness.

Patient medical evaluation, examination. Extra oral and intra oral examination. Preparation of oral cavity for complete dentures.

Diagnosis and treatment planning are the most important parameters in the successful managment of a patient. Inadequate diagnosis and treatment planning are the major reasons behind the failure of a complete denture. Patient evaluation is the first step to be carried out in treating a patient. The dentist should begin evaluating the patient as soon as he/she enters the clinic. This is to obtain a clear idea of what type of treatment is necessary for the patient.

Medical and Dental History Questionnaires

Intra- and Extra-oral Exam Detection, assessment, and treatment of oral lesions and disease

Prosthodontic assessment Clinical factors influencing stability, retention, and support of complete dentures Denture assessment Prognosis

History taking is a systematic procedure for collecting the details of the patient to do a proper treatment planning. Medical history The following medical condition should be ruled out before beginnig the prosthetic treatment. Debilitating Diseases Complete denture patients, most of whom are geriatric may are suffered Debilitating Diseases like diabetes, blood dyscrasias and tuberculous. These patients require specific instructions on denture/tissue care. Cardiovascular Diseses It is always advisable to consult the patient’s cardiologist before treatment. cardiatiac patients will require shorter appointments. Diseases of the Joints the most common diseases of the joint in old age is osteoarthritis. Osteoarthritis plays an important role in complete denture construction when it affects the TMJ. with limited mouth opening and painful movements of the jow, it becomes necessary to use special impression trays. Dental History Although other sections in history are important, dental history is the most important all of them. Chief complaint It should be recorded in the patient’s own words. It gives ideas about patient’s psychology. Expectations The patient should be asked about his/her expectations. The dentist should evaluate the patient’s expectations and classify them as realistic and unlealistic. Period of Edentulousness This data gives imformation about the amount and pattern of bone resorbtion. The cause for the tooth loss should be enquired. Pre-treatment Records The pre-treatment record is a very valuable information. Pre-treatment Records include information about the previous denture, current denture, pre-extraction records( radiographs, photografs, etc), diagnostic casts. Clinical examination It includes extraoral and 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. When there are no teeth present in the mouth, the natural vertical dimension of occlusion is lost and the mouth as a tendency to overclose. This causes the cheeks to exhibit a "sunken-in" appearance and wrinkle lines to form at the commisures. Additionally, the anterior teeth, when present, serve to properly support the lips and provide for certain esthetic features, such as an acute nasiolabial angle. Loss of muscle tone and skin elasticity due to old age, when most individuals begin to experience edentulism, tend to further exacerbate this condition.

Intraoral examination The condition of the existing teeth is of important for denture. The condition, colour and thickness of the mucosa should be examined. The viscosity of the saliva should be determined. saliva can be classified as: Normal quality and quantity of saliva. Cohesive and adhesive properties are ideal. Excessive saliva. Contains much mucus. Xerostomia. Remaining saliva is mucinous. Alveolar Ridge. While examining the residual alveolar ridge the arch size, shape. Ridge contour should be noted. Ridge defects include exostosis that may pose a problem while fabricating complete denture.Bony undercuts do not help in retention. Bony undercuts are seen both in the maxilla and in the mandible. In the maxillary arch they are found in the anterior region of the tuberosities. In tne mandibular arch the area under the mylohyoid ridge acts as an undercut. Torus are abnormal bony prominences found in the middle of the palatal vault. it is not necessary to remove maxilarry torus surgically unless they are very big. It is common to find flabby tissue covering the crest of the alveolar ridges. These movable tissues tend to cause movement of the denture when forces are applied. The most common hyperplastic lesions are epulis papillary hyperplasia of the mucosa. treatment for these lesions includes rest, tissue conditioning and denture adjustments or surgery. The shape of the palate should be examined. It is important to observe the relationship of the soft palate to the hard palate. The tongue should be examined for the size. Presence of a large tongue decreases the stability of the denture. A small tongue does not provide adequate lingual seal the relationship of the floor of the mouth to the crest of the ridge is crucial in determine of the prognosis of the lower complete denture. In some cases, the floor of the mouth is found near the crest of the ridge, especially in the sublingual and mylohyoid region. This decreases the stability and retention of the denture.

The radiograph of choice for the examination of a completely edentulous patient is panoramic radiograph. A panoramic x-ray will show all the bony areas, and along with a clinical exam can uncover any hidden problems and allow for a proper diagnosis. Some of the things we look for in a denture exam are:

o Retained tooth roots o Hard and soft tissue lesions o Hyperplastic (loose tissue) o Size of the ridges o Jaw relationship o Oral Cancer

o

Preparation of oral cavity for complete dentures.

Some patients may have abnormal landmarks, which are unfavourable for placing a denture. These unfavourable tissues should be corrected before making the primary impession. Procedures that involve the correction of these soft tissues abnormalities are known as preprosthetic surgical procedures. Preprosthetic surgical procedures enhance the success of the denture. Some of the common preprosthetic procedures are: 1.Labial frenectomy. 2.Lingual frenectomy. 3.Excision of denture granulomas. 4.Excision of flabby tissue. 5.Reduction of enlarged tuberosity. 6.Excision of hyperplastic retromolar pad. 7.Alveoloplasty. 8.Alveolectomy 9.Reduction of mylohyoid ridge. 10.Excision of tory 11.Vestibuloplasty. 12.Lowering the mental foramen. 13Implants.

Mouth preparation includes all the measures taken to correct tissue discrepancies that pose a difficulty in placement of a denture. Ulcer,lesion and abscess, etc. require immediate attention. the lesion should be cured and the tissue should be given adequate rest for sufficient healing.For patients with normal tissue, 48-hour rest with frequent tissue massage is sufficient. The patient should be advised to stop wearing the existing dentures. Removal Retained Dentition. The decision to remove or preserve the tooth is planned during treatment planning. An OPG gives a clear idea about the status of remaining dentition.All retained roots should be removed especially if there is any sign of pathology. Asymptomatic roots which are present deep in the bone,whose removal can result in a large bony defect, can be cautiously left untouched. Correction of hypermobile ridge tissue. Hypermobile tissues result due to excessive residual ridge resorption. Small areas of hupermobile tissue, which may not affect the functioning of the denture can be left untouched. Large pendulous hypermobile tissues should be removed. Removal of hypertrophic maxillary labial frenum. If the frenal attachment is high, but not close to the crest of the ridge, it is not mandatory to do any surgical procedure. In a case of a highly attached frenum where relief of the labial notch can be break the peripherial seal of the denture, surgical treatment is recommended. Removal of hypertrophic lingual frenum. Frenectomy is indicated for cases with a hypertrophic lingual frenum. Treatment of epulis fissuratum. Due to overextension of the denture flanges. Is is dose not require any special treatment. Shortening and smoothening the denture border is sufficient. Reduction of maxillary tuberosity. A wide tuberosity is easier to reduce compared to vertically large tuberosity. Excision of tori These are small bony projection of unknown etiology, which grow to their maximum size by the end of third decade of life. Indications for removal of maxillary tori: Interference of speech Loss of posterior palatal seal Poor denture stability. Vestiboloplasty It is a surgical procedure to increase the vestibular depth. Management of prominent mylohyoid and internal oblique ridge. Internal oblique anf mylohyoid ridge are seen in the lingual surfaces of the mandible. Sometimes they become very prominent due to ridge resorbtion. They should be surgically reduced when there is repeated ulceration, loss of peripheral seal, etc.

Second appointment of fabrication complete denture The goal of this appointment is: Border molding of individual trays, making final (functional) impression, Boxing impressions and fabrication of record bases

Clinical procedures: Check and modify the custom trays Border molding of the tray Makes holes in the palate Application of adhesive to the tray Makes final impression

Labotarory procedures Boxing impressions Pouring of impressions Trimming of the final casts Block-out undercuts Fabrication of record bases

Modification of the individual trays Patient’s oral soft tissues have to be in a health condition and in their normal form. Evaluate extention of all buccal and labial borders of the tray observing distance from ridge crest to buccal and labial reflections when the patient’s lips and cheeks are relaxed and in a near normal position. Place the tray in the mouth, mark and shorten borders of the tray if necessary. All the frenal attachments have to be free Maxillary tray should extend into hamular notch areas and include fovae, mandibular tray should cover the retromolar pads area and extend into the retromylohyoid space. The tray should not be dislodged by extreme movements of the border tissues except in the patient with very low ridges. Avoid over extension by manipulating border tissues.

Clinical procedures Check and modify the maxillary custom tray Place the tray in the mouth, mark and shorten all borders if necessary. Establish desired extension and thickness of all denture borders by using green stick modeling compound. (use the warm water bath for tempering). Word rapidly.

Border molding of the maxillary tray. The border molding of maxillary tray in accomplished in four sections. N3

левая правая 1 N 2 N

N4

Place the compound generously on the edge and outside of the dry tray. Try not to allow the material to extend inside the tray, except the posterior palatal seal area, and labial portion, near the border from cuspid to cuspid.

Border molding of the mandibular tray.

The border molding of the mandibular tray is accomplished in six section.

Sequence of the border molding of the mandibular tray

Both maxillary and mandibular impressions are made by placing anterior part first, line up middle of tray with labial frenum, then place the posterior part. The impression tray should be held by the dentist until the final setting of the alginate. For maxillary impression the dentist should stand behind the parient and for mandibular impression – in front of patient.

Establish the proper extension and thickness of all borders with green stick compound. When placing compound on the buccal border, use extreme opening of the mouth to establish this border. When placing compound on the linqual border, use extreme movements of the tonque to establish this border. Place finger on outside of the face and see if the tray extends beyond the buccal shelf. Shorten if necessary. Do not over extend into the masseter muscle. Place compound on the inside of the tray in the retromylohyoid region. Do not permit compound on the pad. Check over extension on the linqual by having the patient open wide and protrude the tonque. Do not overextend in the anterior region of the linqua. Completed tray should remain stable during normal tonque movements.

Make 2 holes in the tray with a #8 round bur in the area of the incisive foramen and the middle of the hard palate for upper individual trays. The materials of choice for a secondary impression are zinc oxide eugenol impression paste or medium bodied elastomeric impression materials.

Seating maxillary impression tray and final impression retract the upper lip with labial frenum in direct view, seat anterior labial notch of the tray around labial frenum with index finger on either side of the tray in the first molar area, vibrate tray up and back into position until impression material runs freely through the holes in the palate. The modeling compound in the posterior palatal seal area should be in close contact with tissues. Shift thumb to tray handle to keep tray from coming forward. The pressure on the tray should be straight back. Shift crooked index finger of the same hand so the tip of the finger is over the hole in the center of the palate. The pressure on the crooked ginger should be straight up. Have patient relax upper lip and gently let it fall so the labial frenum falls down into the labial notch of the tray. Hold in place for ten minutes for rubber base. The dentist should not shift his weight or talk distractingly during this time to prevent undue movement of the tray.

Seating mandibular impression tray and final impression Be sure the impression material is placed evently throughout the tray about 2 mm. thick and that it covers all borders. Spatulate on mixing pad. Mix according to the manufacturers direction. Seat tray, front part first, with index finger of each hand. Lift lip up and hold it against tray handle with thumbs. Retract the cheek on both sides with your index fingers Have patient touch handle of the tray with his tongue and keep it there while the material will set Apply some adhezive over the all surface of individual trays. Wipe the saliva with piece of gauzes.

Laboratory procedure All impressions should be boxed and poured as soon as possible. Boxing impressions Box so all borders are preserved – 3mm. from borders -5mm land area. Use sticky wax on rubber base as adhesive Box mandibular impression so the heels are strong. 2 or possibly three thickness of beading wax are necessary in this region.