evolution of posterior tooth forms / dental implant courses by indian dental academy

EVOLUTION OF POSTERIOR TOOTH FORMSEVOLUTION OF POSTERIOR TOOTH FORMS

INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMYLeader in continuing Dental Leader in continuing Dental EducationEducation www.indiandentalacademy.comwww.indiandentalacademy.com

IntroductionIntroductionHistory of the development of posterior tooth form.History of the development of posterior tooth form.Theories and concepts of occlusionTheories and concepts of occlusionOcclusal schemes used in complete dentureOcclusal schemes used in complete dentureAnatomic and non anatomic teethAnatomic and non anatomic teethSelection and arrangement of posterior teethSelection and arrangement of posterior teethMonoplane arrangement of posterior teethMonoplane arrangement of posterior teethPosterior teeth arrangement of Class II patientsPosterior teeth arrangement of Class II patientsPosterior teeth arrangement of Class III patientsPosterior teeth arrangement of Class III patientsReview of literatureReview of literatureSummary & conclusionSummary & conclusionReferencesReferences

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1 21 2

33

44 5 5


66 77

88


99

10 10


1111

12 12 NON ANATOMIC OR ONON ANATOMIC OR O0 0 CUSPLESS CUSPLESS TEETHTEETH


1313

1414


1515

16 16


1717

18 1918 19


Occlusal Materials for the denturesOcclusal Materials for the dentures The materials available for occlusal posterior tooth forms The materials available for occlusal posterior tooth forms

are are Porcelain Porcelain Acrylic resin Acrylic resin GoldGold Acrylic resin with amalgam stops Acrylic resin with amalgam stops I P N(integrated polymer network)I P N(integrated polymer network)


Nonanatomical or cusp less teeth are generally the choice in the nuetrocentric occlusion

lingualised concept utilises anatomic teeth for the maxillary and monoplane or semianatomic teeth for the mandible


OCCLUSAL SCHEMES FOR COMPLETE DENTURE OCCLUSION

The occlusal scheme or the tooth molds selected for occlusal rehabilitation will depend on the concept of occlusion that has been selected to satisfy the needs of the patient.

The posterior teeth, arrangement according to the occlusal concept selected, should fulfill the dentist's philosophy of occlusion as which appear esthetically pleasing.

Prosthetic tooth anatomy seems to be more important to dentists than to the patients who use the teeth.

In the absence of clear evidence of the benefits of one tooth anatomy compared with others, dentists should use the least complicated procedures and tooth forms that will satisfy their concepts of occlusion and articulation of a mucosal supported dentition


The proponents of anatomic teeth seen dedicated to the The proponents of anatomic teeth seen dedicated to the precision of articulation and the infallibility of meticulous precision of articulation and the infallibility of meticulous maxillomandibular records.maxillomandibular records.

Many claim it is not the cusps that are the problem but the Many claim it is not the cusps that are the problem but the management of the cusps. management of the cusps.

The natural tooth forms with its cusp inclines usually The natural tooth forms with its cusp inclines usually functions in harmony on the working side with its opposing functions in harmony on the working side with its opposing tooth monitored by tooth contacts of incisal guidance, tooth monitored by tooth contacts of incisal guidance, cuspid guidance and group function of posteriors with cuspid guidance and group function of posteriors with proprioceptive information.proprioceptive information.

Arificial posterior teeth are classified accordinglyArificial posterior teeth are classified accordingly

Anatomic teethAnatomic teeth Non anatomic teethNon anatomic teethwww.indiandentalacademy.comwww.indiandentalacademy.com

Harold R Ortman 1971Harold R Ortman 1971 The role of occlusion in the preservation and The role of occlusion in the preservation and prevention in complete denture Prosthodonticsprevention in complete denture ProsthodonticsBecker et al 1977 Lingualised occlusion for removable prosthesis Becker et al 1977 Lingualised occlusion for removable prosthesis Anatomic occlusionAnatomic occlusionAdvantagesAdvantages

Penetrates food more easilyPenetrates food more easilyResists the rotation of denture bases through cusp interdigitationResists the rotation of denture bases through cusp interdigitationProvides better estheticsProvides better estheticsActs as a guide for proper jaw closureActs as a guide for proper jaw closure

DisadvantagesDisadvantagesMore occlusal disharmony during settling and difficult to correct More occlusal disharmony during settling and difficult to correct by adjustmentby adjustmentPrecise jaw closure and base stability required for interdigitationPrecise jaw closure and base stability required for interdigitationIncreased horizontal forcesIncreased horizontal forcesDifficult to adapt to abnormal jaw relationshipsDifficult to adapt to abnormal jaw relationships


Nonanatomic occlusionNonanatomic occlusionAdvantagesAdvantages

Does not lock the mandible in one positionDoes not lock the mandible in one positionPermits the use of less time consuming techniques.Permits the use of less time consuming techniques.Minimizes horizontal stress because of the absence of Minimizes horizontal stress because of the absence of inclined planesinclined planesAdapts easily to Classes II and III jaw relationsAdapts easily to Classes II and III jaw relationsMore easily adjusted after changes in vertical and More easily adjusted after changes in vertical and horizontal relationshorizontal relationsEasier to arrange in cross biteEasier to arrange in cross bite

DisadvantagesDisadvantagesPoor estheticsPoor estheticsDecreased masticatory efficiencyDecreased masticatory efficiencyMore difficult to obtained balanced occlusionMore difficult to obtained balanced occlusionPsychological Psychological


Harold R. Ortman (1971) ….Harold R. Ortman (1971) ….Evaluation of the occlusal formsEvaluation of the occlusal forms

Payne and Trapozzano and Lazzari ……Payne and Trapozzano and Lazzari ……Kydd…..Kydd…..Sauser and Yurkstas……..Sauser and Yurkstas……..Brewer and co-workers……..Brewer and co-workers……..

Julian B. Woelfel, Chester M. Winter and Takayashi Igarashi (1976) conducted a five year cephalometric study of mandibular ridge resorption with different posterior occlusal forms. Three groups of patients were selected,

one group of patient flat-cusped rational posterior teeth were used.

Second group, semianatomic 20° posterior teeth were set with a buccolingual reverse curve.

Third group of patient given anatomic 33° posterior teeth….www.indiandentalacademy.comwww.indiandentalacademy.com

Payne, discussed the selection of artificial posterior tooth Payne, discussed the selection of artificial posterior tooth forms. forms. ““The dentist must be versatile and capable of making The dentist must be versatile and capable of making intelligent compromises”. intelligent compromises”.

There are three basic schemes of posterior occlusionThere are three basic schemes of posterior occlusion

The spherical The spherical

The flat The flat

The reverseThe reversewww.indiandentalacademy.comwww.indiandentalacademy.com

Factors influencing function of anatomic and non-anatomic Factors influencing function of anatomic and non-anatomic teethteeth

Efficiency…Efficiency…Directional forces…Directional forces…Horizontal stress…Horizontal stress…Stability..Stability..


Balanced occlusionBalanced occlusion

Is the stable simultaneous contact of the opposing upper Is the stable simultaneous contact of the opposing upper and lower teeth in centric relation position and a continuous and lower teeth in centric relation position and a continuous smooth bilateral gliding from this position to any eccentric smooth bilateral gliding from this position to any eccentric position within the normal range of mandibular functionposition within the normal range of mandibular functionFurthermore,this balance must be in harmony with the Furthermore,this balance must be in harmony with the temporomandibular joints and with the neuromuscular temporomandibular joints and with the neuromuscular activity.activity.Ellsworth Kelly 1977 Centric relation,centric occlusion and Ellsworth Kelly 1977 Centric relation,centric occlusion and posterior tooth forms and arrangementposterior tooth forms and arrangement


Bilateral balance in cusped teeth depends on the hanau’s Bilateral balance in cusped teeth depends on the hanau’s quint- quint- The condylar inclinationThe condylar inclinationThe incisal guidanceThe incisal guidanceThe compensatory curveThe compensatory curveThe cuspal inclination The cuspal inclination The occlusal plane The occlusal plane


BALANCE CAN BE ATTAINED IN NON ANATOMICAL TEETH AS WELLBALANCE CAN BE ATTAINED IN NON ANATOMICAL TEETH AS WELLChastain et al 1955 The Cuspless Centralised Occlusal Pattern…Chastain et al 1955 The Cuspless Centralised Occlusal Pattern…

Balancing ramps or elements are provided by inclining the occlusal plane and an flat incisal Balancing ramps or elements are provided by inclining the occlusal plane and an flat incisal guidanceguidance

This form of occlusion tends to magnify the stresses created, because the forces delivered somewhat at right This form of occlusion tends to magnify the stresses created, because the forces delivered somewhat at right angles to the occlusal surface are of butting action.angles to the occlusal surface are of butting action.The forces against the lower denture are not only exerted, such a direction as to tip it, but will drive it to one The forces against the lower denture are not only exerted, such a direction as to tip it, but will drive it to one side against the poorly formed and sensitive tissues of the mylohyoid ridge. side against the poorly formed and sensitive tissues of the mylohyoid ridge.


Theories of occlusionTheories of occlusionSpherical theory,…Conical theory…Bonvill triangle theory…


Spherical theory of occlusionSpherical theory of occlusionEdgar et al 2002 Edgar et al 2002 The history of articulators:A clinical history The history of articulators:A clinical history of articulators based on geometric theories of mandibular of articulators based on geometric theories of mandibular movementmovement

This was given by Monson and the concept was derived from This was given by Monson and the concept was derived from an idea by Vonspee. an idea by Vonspee.

Positioning of teeth with anterioposterior and medio-lateral Positioning of teeth with anterioposterior and medio-lateral inclines in harmony with a spherical surface. Some times inclines in harmony with a spherical surface. Some times referred to as having Monson curve.referred to as having Monson curve.


The effect of Bonwills equilateral triangle theoryThe effect of Bonwills equilateral triangle theory

Finn Tenges Christensen (1959) The Effect Of Bonvill’s Finn Tenges Christensen (1959) The Effect Of Bonvill’s Triangle On Complete DenturesTriangle On Complete Dentures

The construction of average articulators is generally in The construction of average articulators is generally in accordance with Bonwill’s theory, and Monson’s pyramid accordance with Bonwill’s theory, and Monson’s pyramid is based also on Bonwill’s triangle.is based also on Bonwill’s triangle.

The sides are assumed to be 100mm in length. The The sides are assumed to be 100mm in length. The height of the triangle is consequently equal to 100mm X height of the triangle is consequently equal to 100mm X sine 60 degrees. sine 60 degrees.


Christensens phenomenonChristensens phenomenon The supposition for the calculation of the christensen’s The supposition for the calculation of the christensen’s

angle is a straight condylar path with a common inclination angle is a straight condylar path with a common inclination on each sideon each side

The incisal point in protrution is assumed to be displaced The incisal point in protrution is assumed to be displaced into or parellel with the maxillary occlusal rim with flat into or parellel with the maxillary occlusal rim with flat occluding surfaces when there is no inclination of the incisal occluding surfaces when there is no inclination of the incisal guidance and no compensating curve of occlusionguidance and no compensating curve of occlusion

The size of the christensens angle decreases if the height of The size of the christensens angle decreases if the height of the bonvill’s triangle increasesthe bonvill’s triangle increases


Organic occlusionOrganic occlusion

It is that concept where in any jaw movement away from It is that concept where in any jaw movement away from centric occlusion will result in separation of all posterior teeth.centric occlusion will result in separation of all posterior teeth.

The ridge and groove directions of the posterior teeth are The ridge and groove directions of the posterior teeth are determined as result of the movements of the condyles. The determined as result of the movements of the condyles. The cusp height, fossa depth of posterior teeth and the proper cusp height, fossa depth of posterior teeth and the proper concavity at the lingual surfaces of the maxillary anterior concavity at the lingual surfaces of the maxillary anterior teeth are determined as a result of mandibular movements.teeth are determined as a result of mandibular movements.

The aim of this occlusion is to relate the occlusal elements of The aim of this occlusion is to relate the occlusal elements of teeth so that the teeth will be in harmony with the muscles teeth so that the teeth will be in harmony with the muscles and joints in function. and joints in function.


In organic occlusion three phases of mutually interdependent In organic occlusion three phases of mutually interdependent protection are present. protection are present.

The posterior teeth should protect the anterior in the The posterior teeth should protect the anterior in the centric occlusal position.centric occlusal position.

The maxillary incisors should have vertical overlap The maxillary incisors should have vertical overlap sufficient to provide separation of the posterior teeth when sufficient to provide separation of the posterior teeth when the incisors are in edge to edge contact. the incisors are in edge to edge contact.

In lateral mandibular position outside the masticatory In lateral mandibular position outside the masticatory movements, the cuspids should prevent contact of all other movements, the cuspids should prevent contact of all other teeth. teeth.


Lineal occlusionLineal occlusion

Donald G. Gronas (1974) Lineal Occlusal Concepts For Donald G. Gronas (1974) Lineal Occlusal Concepts For Complete DenturesComplete DenturesStraight line of points or knife-edge contacts on artificial Straight line of points or knife-edge contacts on artificial teeth in one arch occluding with flat nonanatomic teeth in teeth in one arch occluding with flat nonanatomic teeth in the opposing arch has been suggested as a means of the opposing arch has been suggested as a means of reducing unfavourable occlusal forces and simplifying reducing unfavourable occlusal forces and simplifying occlusal adjustment in complete denture. occlusal adjustment in complete denture.


His literature has supported the use of linear (also known as lineal) occlusion to enhance the stability of complete denture prosthesis

Noninterceptive occlusion (linear occlusion) requires that there should be no interference or interception with mandibular movement in protrusive or lateral excursions.

Richard A. Williamson,DDS, 2004 Maximizing Mandibular Richard A. Williamson,DDS, 2004 Maximizing Mandibular Prosthesis Stability Utilizing Linear Occlusion, Occlusal Prosthesis Stability Utilizing Linear Occlusion, Occlusal Plane Selection, and Centric RecordingPlane Selection, and Centric Recording


Combinations of occlusal forms used for lineal occlusionCombinations of occlusal forms used for lineal occlusionNonanatomic maxillary porcelain teeth opposing Nonanatomic maxillary porcelain teeth opposing mandibular porcelain lineal teeth. …mandibular porcelain lineal teeth. …Nonanatomic maxillary plastic teeth (modified)opposing Nonanatomic maxillary plastic teeth (modified)opposing mandibular plastic lineal teeth (modified)….mandibular plastic lineal teeth (modified)….Nonanatomic maxillary plastic teeth (modified)opposing Nonanatomic maxillary plastic teeth (modified)opposing mandibular porcelain lineal teeth….mandibular porcelain lineal teeth….Anatomic maxillary porcelain teeth opposing Anatomic maxillary porcelain teeth opposing nonanatomic mandibular plastic teeth…nonanatomic mandibular plastic teeth…


Tooth positioning for lineal occlusionTooth positioning for lineal occlusionThe mandibular incisors establish the anterior end of the The mandibular incisors establish the anterior end of the occlusal plane. occlusal plane. The posterior landmark is usually the top one third of the The posterior landmark is usually the top one third of the retromolar pad. retromolar pad. The occlusal plane should be kept as high posteriorly as The occlusal plane should be kept as high posteriorly as practical to aid in developing protrusive balancing practical to aid in developing protrusive balancing contacts with a flat plane of occlusion.contacts with a flat plane of occlusion.


Lingualized occlusionLingualized occlusion

Curtis M. Becker 1977 Lingualised Occlusion For Removable Curtis M. Becker 1977 Lingualised Occlusion For Removable ProsthodonticsProsthodontics stated that occlusal forms can be classified into three stated that occlusal forms can be classified into three major groups:major groups:

Anatomic – 30 degree cuspsAnatomic – 30 degree cuspsSemianatomic – 20 degree cuspsSemianatomic – 20 degree cuspsNonanatomic or cuspless – 0 degree cuspNonanatomic or cuspless – 0 degree cusp

The basic concepts of lingualized occlusion were first The basic concepts of lingualized occlusion were first suggested by Payne. suggested by Payne.

Pound discussed a similar occlusal concept and used the Pound discussed a similar occlusal concept and used the term “lingualized occlusionterm “lingualized occlusion. .


Indications for lingualized occlusionIndications for lingualized occlusionLingualized occlusion can be used in most denture combinations. Lingualized occlusion can be used in most denture combinations.

It is particularly helpful when the patient places high priority on esthetics It is particularly helpful when the patient places high priority on esthetics but nonanatomic occlusal scheme is indicated by oral conditions such as but nonanatomic occlusal scheme is indicated by oral conditions such as severe alveolar resorption, a Class II jaw relationship, or displaceable severe alveolar resorption, a Class II jaw relationship, or displaceable supporting tissue. supporting tissue.

If the nonanatomic occlusal scheme is used, esthetics in the premolar If the nonanatomic occlusal scheme is used, esthetics in the premolar region are compromised. region are compromised.

With lingualized occlusion, the esthetic result is greatly improved while still With lingualized occlusion, the esthetic result is greatly improved while still maintaining the advantages of a nonanatomic system. maintaining the advantages of a nonanatomic system.

Lingualized occlusion also can be used effectively when a complete denture Lingualized occlusion also can be used effectively when a complete denture opposes a removable partial denture. opposes a removable partial denture.


Principles of lingualized occlusionPrinciples of lingualized occlusionAnatomic posterior (30 or 33°) teeth are used for the maxillary denture. Anatomic posterior (30 or 33°) teeth are used for the maxillary denture. Tooth forms with prominent lingual cusps are helpful.Tooth forms with prominent lingual cusps are helpful.Nonanatomic or semianatomic teeth are used for the mandibular denture. Nonanatomic or semianatomic teeth are used for the mandibular denture. Either a shallow or flat cusp form is used. A narrow occlusal table is Either a shallow or flat cusp form is used. A narrow occlusal table is preferred wherever resorption of the residual ridges has occurred. preferred wherever resorption of the residual ridges has occurred. Modification of the mandibular posterior teeth is accomplished by selective Modification of the mandibular posterior teeth is accomplished by selective grinding which is always necessary regardless of specific tooth or material.grinding which is always necessary regardless of specific tooth or material.Maxillary lingual cusps should contact mandibular teeth in centric occlusion.Maxillary lingual cusps should contact mandibular teeth in centric occlusion.Balancing and working contacts should occur only on the maxillary lingual Balancing and working contacts should occur only on the maxillary lingual cusps.cusps.Protrusive balancing contacts should occur only between the maxillary Protrusive balancing contacts should occur only between the maxillary lingual cusps and the lower teeth.lingual cusps and the lower teeth.


Advantages of Advantages of lingualized occlusionlingualized occlusion– Most of the advantages attributed Most of the advantages attributed

to both the anatomic and to both the anatomic and nonanatomic forms are retained. nonanatomic forms are retained.

– Cusp form is more natural in Cusp form is more natural in appearance compared to appearance compared to nonanatomic tooth form. nonanatomic tooth form.

– Good penetration of the food bolus Good penetration of the food bolus is possible. is possible.

– Bilateral mechanical balanced Bilateral mechanical balanced occlusion is readily obtained for a occlusion is readily obtained for a region around centric relation. region around centric relation.

– Vertical forces are centralized on Vertical forces are centralized on the mandibular teeth.the mandibular teeth.


Lingualized occlusion with cutter barsLingualized occlusion with cutter bars– The use of posterior teeth with metal blades has been The use of posterior teeth with metal blades has been

advocated by numerous authors. advocated by numerous authors. – The procedure usually recommended is to place the The procedure usually recommended is to place the

metal bladed teeth on the maxillary denture and metal bladed teeth on the maxillary denture and porcelain nonanatomic teeth on the mandibular denture. porcelain nonanatomic teeth on the mandibular denture.

– The principles of lingualized occlusion can be applied The principles of lingualized occlusion can be applied when maxillary anatomic teeth oppose that mandibular when maxillary anatomic teeth oppose that mandibular teeth with metal blades.teeth with metal blades.


Arranging Anatomical Teeth to a Balanced Articulation


Honorato Villa (1959)Honorato Villa (1959) described a technique for described a technique for arranging posterior teeth according to the elliptical arranging posterior teeth according to the elliptical principle. principle. A path tracer was designed which not only traces the paths A path tracer was designed which not only traces the paths that will determine the exact position of each posterior that will determine the exact position of each posterior tooth but also brings out the deficiencies in incorrectly tooth but also brings out the deficiencies in incorrectly designed posterior teeth.designed posterior teeth.


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http://websupport1.citytech.cuny.edu/Dept/Dental/cfrith/FDPART1/sld001.htm

2 Arranging nonanatomical mandibular Posterior Teeth to Balanced ArticulationAnteroposterior and mediolateral compensating curves permits the establishment of a balanced articulation. …

In such arrangements, the mandibular teeth usually are arranged first followed by the maxillary teeth. ……..

The use of the several reference lines and guides developed for the anatomical arrangement also are used with the nonanatomical teeth……. The major difference is in the positioning of the mandibular posterior teeth to develop the compensating curves…..


3 Arranging Nonanatomical Teeth to Monoplane Articulation

With this concept of occlusion, there is no attempt to eliminate deflective occlusal contacts in lateral or protrusive excursions.

However, some deflective occlusal contacts of the posterior teeth will be experienced


Arranging Mandibular Posterior Teeth to Lingualized Articulation.

Myerson Lingualized, Integration (MLI) molds represent an occlusion scheme designed for this concept.

It has been suggested that these molds will provide maximum intercuspation, an absence of deflective occlusion contacts, adequate cusp height for selective occlusal reshaping, and a natural and pleasing appearance

.

The MLI teeth are available in two posterior tooth molds: (1) controlled contact (CC) and (2) maximum contact MC molds


Arranging the Maximum Contact Mold

In the arrangement of the MC mold, the maxillary teeth are positioned with the incisal pin slightly open when the lingual cusps are in contact with their mandibular antagonists.

The prominence of the maxillary lingual cusps will require some occlusal reshaping of the central fossae and marginal ridges of the lower teeth to establish maximum intercuspation.

After each maxillary tooth is positioned, a thin sheet of articulating paper is interposed between the tooth and its mandibular antagonist.

The articulator is closed, marking the first contact point.

The contact point on the occlusal surface of the mandibular tooth is enlarged by grinding with a round bur to permit the lingual cusp to obtain positive seating with the lower tooth.

This process is continued until maximum interdigitation is achieved and the incisal pin is in contact with the incisal table.


POSTERIOR TEETH ARRANGEMENT FOR CLASS II RELATION SHIP


The lower ridge is small and markedly inside the upper ridge .

The anterior teeth exhibit a pronounced horizontal overlap when they are arranged properly for esthetics .

The vertical overlap should be kept as small as esthetics and phonetics will allow in order to establish an incisal guidance as shallow as possible .

In most of these cases, the horizontal overlap is great enough to accommodate for mastication without the anterior teeth interfering during the function of mastication on the posterior teeth.


The small arch of the lower ridge retruded to a position inside the upper makes it impossible to obtain the correct upper and lower canine relationship.

The lower canine is inside the upper arch of teeth and is more distal in its relationship to the upper canine than in class I .This gives a tooth-on-tooth vertical relationship to the posterior teeth that can be articulated to establish a stable centric and eccentric occlusion after special grinding procedures


Setting the Mandibular Posterior TeethSetting the Mandibular Posterior TeethThe same criteria described for setting lower teeth are The same criteria described for setting lower teeth are

applied to this case. applied to this case.

The lower anteriors were set for lip support and the first The lower anteriors were set for lip support and the first premolar follows the arch contour established by them so premolar follows the arch contour established by them so that the modiolus is supported. that the modiolus is supported.

Any attempt to set the lower anterior or posterior teeth to an Any attempt to set the lower anterior or posterior teeth to an exaggerated labial or buccal position in relation to the lower exaggerated labial or buccal position in relation to the lower ridge is contraindicated because it will create an unfavorable ridge is contraindicated because it will create an unfavorable lever action on the lower denture base during functionlever action on the lower denture base during function..


Either anatomic, modified anatomic, or non anatomic teeth can be used for these retrusive cases. The selection of the occlusal form is based on the same factors of ridge strength, form, and interridge space as for the normal ridge relation. Because the lower ridge in these patients is usually small and weak in relation to the upper, the buccolingual inclines are modified to a shallow angulation, or nonanatomic teeth are selected.

After the lower premolars are initially set, the upper first premolar is temporarily set to evaluate its position. It will have a marked buccal overlap with the upper lingual cusp usually opposing the lower buccal cusp.


Grinding Modifications for Upper Posterior Teeth

The upper anatomic or modified anatomic teeth are initially ground to eliminate all mesiodistal interlocking transverse ridges and cusp heights. The buccal cusps are shortened progressively from the premolars to the molars

The maxillary premolars need additional special grinding on the lingual cusp to create a flat stable platform for centric occlusal contact with the lower premolars

Setting the Upper Posterior Teeth

Before the upper posterior teeth are set the incisal guide pin must be checked for the proper occluding vertical dimension.

The condylar locks are opened so that eccentric excursions can be made into right lateral, left lateral, and protrusive positions.

The incisal guidance should be set for most patients so that the anterior teeth just clear during these excursions.


POSTERIOR ARRANGEMENT FOR CLASS III RELATIONSHIP

The usual approach to the arrangement of the anterior teeth for the class III is to set the upper anteriors as far forward as esthetics requires for the support of the upper lip and to set the lower anteriors as far lingual on the ridge as possible without interfering with the tongue .

The patient treated with this basic approach looks less prognathic and the anterior teeth, except for the very pronounced class III relationship, can be set edge-to-edge .

This procedure creates no particular problem in establishing the proper relationship between the upper and lower canines. It permits an anatomically normal ,vertical interdigitated relationship for the posterior teeth.


…The crossing point of this occlusion depends on the buccolingual vertical relationship of each case.

The crossing over of the upper posterior tooth occurs when a conventional occlusal relationship would position the upper tooth too far to the buccal

In this errant position, the tooth would create unfavorable displacing leverage on the upper base during function. It would also impinge on the buccal mucosa, which would result in additional displacing forces acting on the teeth and denture base.

Cheek biting is also common with teeth positioned too far to the buccal


Selection of Posterior TeethThe same indications for the selection of the size and the modification of

the occlusal form for the conventional case hold for this type of ridge relationship.

However, it is the upper ridge that is primarily considered since it is always the smaller and usually the weaker ridge.

When the lower ridge is markedly resorbed a nonanatomic teeth is

indicated .

The buccolingual and mesiodistal relation of the upper and lower posteriors is not as critical with this type of occlusion .


Grinding Modifications for Upper Posterior TeethEach upper posterior tooth is modified before it is set. The

transverse ridges are flattened to eliminate the mesiodistal interlocking potential of the anatomic tooth.Special additional individual tooth grinding is necessary as the teeth are set. It depends on the tooth that initiates the crossing over of the occlusion.

When this occurs, the upper tooth is flattened both on buccal and lingual cusps to establish a static centric occlusal contact with the lower tooth .

The teeth in cross bite relation need additional modification by grinding on the upper buccal cusps. They must be rounded to occlude in the modified central fossa of the lower.


Setting the Upper Posterior Teeth

• The upper first premolar can usually be set in conventional relationship to the lower premolars. The upper lingual cusp is set in the common central fossa of the modified lower premolars .

• It should be in a complimentary esthetic position in relation to the upper canine and should establish a normal arch form.

• The second premolar usually requires special consideration because it starts the crossover to the cross-bite occlusal relation.

• The upper buccal and lingual cusps are flattened. When it is properly set in relation to the upper ridge, the articulator is closed to evaluate its occluding position with the lower teeth.

• The lower teeth must now be flattened on the buccal and lingual cusp inclines so that a stable occlusal contact is established when the articulator is closed to the occluding vertical dimension .


The upper first and second molars are set in a cross-bite relation, which puts the rounded upper buccal cusps in the lower central fossa. This position of the upper molar teeth provides for a compatible arch form of teeth in relation to the maxilla and provides a favorable leverage system during function.

The crossing point can vary from case to case, depending on the degree of prognathism and the residual ridge relationship. It may not be bilaterally symmetric. When the basic concepts of acceptable arch form, biomechanical principles, and tooth modification are applied intelligently, any degree of prognathism and aberrant ridge relation can be successfully managed either with modified anatomic or nonanatomic teeth.


Arrangement of posterior teeth in abnormal Arrangement of posterior teeth in abnormal jaw relationsjaw relations

Various methods of correction may be employedVarious methods of correction may be employed


SUMMARY AND CONCLUSIONSUMMARY AND CONCLUSIONThe nature of the supporting structures for complete The nature of the supporting structures for complete dentues and the forces directed to to them by the occlusion dentues and the forces directed to to them by the occlusion creates a special biomechanical problemcreates a special biomechanical problemBiologic,physiologic,and mechanical principles need to be Biologic,physiologic,and mechanical principles need to be considered and carefully coordinated in this new man made considered and carefully coordinated in this new man made occlusionocclusionThe first concern is the health and preservation of the The first concern is the health and preservation of the supporting tissuessupporting tissuesApply all the factors that favour the stability of the base Apply all the factors that favour the stability of the base and design the occlusion to function optimally in relation to and design the occlusion to function optimally in relation to the forces of masticationthe forces of masticationIf you elect to use cusped teeth because you believe in If you elect to use cusped teeth because you believe in their merits, be prepared to apply the necessary geometric their merits, be prepared to apply the necessary geometric controlls of balanced occlusion on an adjustable articulatorcontrolls of balanced occlusion on an adjustable articulatorNon anatomic teeth do not need all these exacting jaw Non anatomic teeth do not need all these exacting jaw records and instrumentation, but only a common starting records and instrumentation, but only a common starting point for all artificial occlusion-the position of centric point for all artificial occlusion-the position of centric relationrelation


REFERENCESREFERENCES

Sheldon Winkler: Essential of complete denture prosthodontics, 2nd Edition.

Zarb Bolender: Prosthodontic treatment for edentulous patients, 12th edition.

John J. Sherry: Complete denture prosthodontics, 3rd edition.

Rudd and Marrow: Dental laboratory procedures-complete denture, Vol.1, 2nd edition.

Brein R. Lang: Dental clinics of North America, July 2004.

Hamish Thomson: Occlusion, 2nd edition.

Finn Tengs Christensen: Effect of Bonwill’s triangle on complete dentures. JPD 9: 791; 1959.www.indiandentalacademy.comwww.indiandentalacademy.com

Harold OrtmanHarold Ortman: Role of occlusion in preservation and prevention in : Role of occlusion in preservation and prevention in complete denture prosthodontics, JPD 1971.complete denture prosthodontics, JPD 1971.Arthur R. RoraffArthur R. Roraff: Arranging artificial teeth according to anatomic : Arranging artificial teeth according to anatomic landmarks, JPD 38: 120; 1977.landmarks, JPD 38: 120; 1977.Donald G. GronesDonald G. Grones: Lineal occlusal concepts for complete dentures, JPD 32: : Lineal occlusal concepts for complete dentures, JPD 32: 122; 1974.122; 1974.B.K. Goyal, K. BhargavaB.K. Goyal, K. Bhargava: Arrangement of artificial teeth in abnormal jaw : Arrangement of artificial teeth in abnormal jaw relation – Maxillary protrusion and wider upper arch, JPD 32: 107; 1974.relation – Maxillary protrusion and wider upper arch, JPD 32: 107; 1974.Julian V. Walpel, Christer M WinterJulian V. Walpel, Christer M Winter: 5 years cephalometric study of : 5 years cephalometric study of mandibular ridge resorption with different posterior occlusal forms, JPD, 36: mandibular ridge resorption with different posterior occlusal forms, JPD, 36: 602; 1976.602; 1976.Honarato Villa A.:Honarato Villa A.: Technique for arranging posterior teeth, JPD 9: 803; Technique for arranging posterior teeth, JPD 9: 803; 1959.1959.Honarato Villa A.:Honarato Villa A.: Adaptability of posterior teeth, JPD 9: 810; 1959. Adaptability of posterior teeth, JPD 9: 810; 1959.


Julian B. Woelfel, Judson C. Hickey:Julian B. Woelfel, Judson C. Hickey: Effect of posterior Effect of posterior tooth form on jaw and denture movement. JPD 12: 922; 1962.tooth form on jaw and denture movement. JPD 12: 922; 1962.Ben L. Faber:Ben L. Faber: Comparison of an anatomic versus physiologic Comparison of an anatomic versus physiologic method of posterior tooth placement for complete dentures, method of posterior tooth placement for complete dentures, JPD 67; 410: 1992.JPD 67; 410: 1992.M.A. Pleasure:M.A. Pleasure: Anatomic versus nonanatomic teeth, JPD 3: Anatomic versus nonanatomic teeth, JPD 3: 747; 1953.747; 1953.SS.Howard Payne:.Howard Payne: Selective occlusion, JPD 5: 301; 1955. Selective occlusion, JPD 5: 301; 1955.Brien R. Lang:Brien R. Lang: A practical approach to restoring occlusion for A practical approach to restoring occlusion for edentulous patients – Part I, guiding principles of tooth edentulous patients – Part I, guiding principles of tooth selection, JPD 50; 455: 1983.selection, JPD 50; 455: 1983.Curtis M. Becker:Curtis M. Becker: Lingualized occlusion for removable Lingualized occlusion for removable prosthodontics, JPD 38: 601; 1977.prosthodontics, JPD 38: 601; 1977.Wilbur Ojenson:Wilbur Ojenson: Occlusion for the Class II jaw relation Occlusion for the Class II jaw relation patient, JPD 64; 432: 1990.patient, JPD 64; 432: 1990.Wilbur Ojenson:Wilbur Ojenson: Occlusion for the Class III jaw relation Occlusion for the Class III jaw relation patient, JPD 64; 566: 1990.patient, JPD 64; 566: 1990.
