13. 13. Natural vs. Complete Natural vs. Complete Denture OcclusionDenture Occlusion

Michael Hamada DDSMichael Hamada DDSDivision ofDivision of Advanced Prosthodontics, Advanced Prosthodontics, Biomaterials and Hospital DentistryBiomaterials and Hospital Dentistry

UCLA School of DentistryUCLA School of Dentistry

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Natural Dentition:Organic OcclusionNatural Dentition:Organic Occlusion

Organic occlusions present in a variety of individual tooth size, Organic occlusions present in a variety of individual tooth size, shape, form and alignment, but ideally exhibit certain shape, form and alignment, but ideally exhibit certain characteristic features.characteristic features.

Natural Dentition:Organic OcclusionNatural Dentition:Organic Occlusion

Bilateral Posterior Centric Bilateral Posterior Centric ContactContactAnterior GuidanceAnterior GuidanceMutually Protective Mutually Protective Scheme of OcclusionScheme of Occlusion

Complete Denture OcclusionComplete Denture Occlusion

Likewise, complete denture occlusions present in a Likewise, complete denture occlusions present in a variety of forms, but also exhibit certain common variety of forms, but also exhibit certain common characteristicscharacteristics

Complete Denture OcclusionComplete Denture Occlusion

Bilateral Posterior Centric Bilateral Posterior Centric ContactContactCentralized ForcesCentralized Forces““Balance” to minimize Balance” to minimize tippingtipping

Differences between Natural and Differences between Natural and Complete Denture OcclusionComplete Denture Occlusion

Differences between Natural and Differences between Natural and Complete Denture OcclusionComplete Denture Occlusion

Arise from fundamental differences in– Sensory Feedback Mechanism– Derivation of :

RetentionStabilitySupport

– Reaction of Supporting Structures to Masticatory Forces

Differences between Natural and Differences between Natural and Complete Denture OcclusionComplete Denture Occlusion

Neuromuscular and Sensory Feedback

Precision of feedback may be somewhat compromised following loss of teeth and associated structures

Differences between Natural and Differences between Natural and Complete Denture OcclusionComplete Denture Occlusion

Derivation of Retention, Stability and Support

Fundamental differences between how they derive retention, stability and support dictate differences in occlusion design between natural and CD occlusion

Retention, Stability and SupportRetention, Stability and Support

Denture Bearing Surface

RetentionRetention

– Resistance to dislodgment forces in a vertical direction away from the bearing surface

Retention, Stability and SupportRetention, Stability and Support

Denture Bearing Surface

StabilityStability

– Resistance to laterally oriented dislodgment forces

Retention, Stability and SupportRetention, Stability and Support

Denture Bearing Surface

SupportSupport

– Factors of the Bearing Surface which resist forces in a vertical direction towards the bearing surface

Differences between Natural and Differences between Natural and Complete Denture OcclusionComplete Denture Occlusion

For natural dentition, derived through the periodontium, providing:Sensory Feedback MechanismDifference in reaction of Supporting Structures to Masticatory Forces– Differences in load transfer mechanism and physiology

Derivation of Retention, Stability and Support

Differences between Natural and Differences between Natural and Complete Denture OcclusionComplete Denture Occlusion

Residual Ridge Resorption (RRR)– Non-physiologic compression (as may occur

under denture bases) results in further resorption, as compared to . . .

– Physiologic levels of tension results in apposition (such as that transmitted by loading the PDL through natural dentition)

Mobile bases on mucosaTeeth move as an unitMalocclusion affects entire base immediatelyNon-vertical forces affect all teeth and is traumaticIncising affects all teeth attached to baseBilateral balance is often desired for base stabilityDecreased tactile sense

Retained in PDL

Units move independently

Malocclusion effects not immediate

Non-vertical forces affect only teeth involved and usually well tolerated

Incising doesn’t affect posteriors

Bilateral balance is rare

Tactile sensitivity

Natural Dentition Denture “Dentition”

Differences between Natural and Complete Differences between Natural and Complete Denture OcclusionDenture Occlusion

Because of compromises inherent in restoring the edentulous arch, CD tooth forms and arrangements (i.e. occlusion), should be designed to provide function and aesthetics while MINIMIZING DENTURE BASE TIPPING (LATERAL) FORCES

Denture “Dentition”

Complete Denture OcclusionComplete Denture Occlusion

SummarySummary

Goal of complete denture occlusion is preservation of structure and restoration of function and esthetics

Consequences of tooth loss create anatomic changes which result in differences in derivation of retention, stability and support between natural and complete denture teeth

SummarySummary

The differences in the design of natural and complete denture occlusion are the consequence of differences in the derivation of retention, stability and support

Complete denture form and tooth placement is biomechanical in nature