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The Ideal Occlusion.

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Presentation on theme: "The Ideal Occlusion."— Presentation transcript:

1 The Ideal Occlusion

2 Ideal Morphologic Occlusion
Posterior Teeth Angle I Contact Normal buccal overjet Anterior Teeth AP mm Hor OJ Vertical mm Ver OB, 50% Transverse Midlines aligned

3 Ideal Functional Occlusion
Intercuspal Position: CR jaw position Simultaneous posterior contact Axial loading of posterior teeth Lighter contact of anterior teeth Anterior Excursive Guidance: Canine Guidance/ or Group Function Nonworking: NO contact 3. Protrusion: NO posterior contact

4 My first patient in the clinic!

5 Biologic Variation of Occlusion

6 I. Morphologic Variation Brunelle JA et al
I. Morphologic Variation Brunelle JA et al.: Prevalence and distribution of selected occlusal characteristics in the US Population, , J Dent Res 1996;75: Third National Health and Nutrition Examination Survey (NHANES III) Age: 8-11 & y/o n= 11,000 Hx of ortho tx: 20% Crowding: Children 48-58% & Adults 57-67%

7 A. Sagittal Plane (Children and Youths)
Angle I Normal: 30% Angle I Malocclusion: 55% Angle II Malocclusion: 15% Angle III Malocclusion: 1%

8 B. Horizontal Plane (Transverse)
Posterior Crossbite: 9.1%

9 High Mandibular Plane Angle
Tall lower face Smile: maxillary teeth and gingival visible Lips postured to seal Anterior open bite tendency

10 Low Mandibular Plane Angle
Short lower face Smile: Minimal maxillary tooth visibility Lower lip everted Deep bite tendency

11 C. Vertical Plane Open Bite (≥ 0 mm): < 3%
Vertical Deep Bite (>5 mm): 16 %

12 D. Racial Differences: Asian: increased Angle III prevalence
Afro-American: 10% anterior open bite Northern European: increased prevalence of vertical deep bite, increased prevalence Angle II

13 II. Functional Occlusal Variation

14 A. CR/IP (CO) Slide Slide Prevalence: >90%
Horizontal Component: Usually mm Lateral Component: 25% (Rieder CE: J Prosthet Dent 39: , 1978; n=323)

15 1. Working Side Contacts:
Great Variation: Combination of guidance schemes typical. Average # of contacting teeth 2 with one being the canine. (Woda AV et al., J Prosthet Dent 1979;42:

16 1. Working Side Contacts:
Great Variation: One sample identified 2% with bilateral canine guidance and 18% with unilateral canine guidance. (Ingerval B, Archs Oral Biol 1977;17: )

17 Skeletal Variation of Occlusion

18 Skeletal Effect: Canine Guidance: tend to have mandibular plane angle < 24o Group Function: tend to have a mandibular plane angle > 24o (DiPietro GJ: J Prosthet Dent 38: , 1977; n=112)

19 2. Nonworking Side Contacts:
Nonworking contacts identified in > 60% of a sample (Ingervall B, Archs Oral Biol 17: , 1977)

20 2. Nonworking Side Contacts:
Nonworking interferences (contact only on the nonworking side) identified in 8% of a study sample (Ingervall B, Archs Oral Biol 17: , 1977)

21 C. Intercuspal Position Contacts: Ideal
Size: small circular areas ≤ 1 mm diameter Location: cusp tips to flat fossae & marginal ridges; or balanced inclines. Number: n=26 or 66

22 C. IP Contact Biological Variation (Riise C & Ericsson SG: J Oral Rehabil 10:473-480, 1983.)
Size: large irregular areas Location: on cuspal inclines Number: average of 2 contacts/ molar, 1 contact/ premolar and <1 contact/ anterior tooth

23 Homo sapiens exhibit greater occlusal variation than any other primate

24 III. Biomechanical System
Great population variability Masticatory system very adaptable to this variation but exhibits greater adaptive capacity with slow developmental change as compared to rapid change, I.e. restorative dentistry.

25 III. Biomechanical System
Restorative Treatment: We as dentists can not control the biological adaptability but we can control mechanical characteristics. Therefore restorations are fabricated to an ideal occlusion within the scope or extent of the treatment.

26 Objectives CR Adjustment: Intercuspal Occlusion
Eliminate CR-IP slide, “create new IP in CR” VDO slightly closed from original IP VDO Simultaneous posterior contact Axial loading of posterior teeth Anterior lighter contact

27 Occlusal Adjustment: A Method
Goal: All centric cusps contacting and every posterior tooth pair holding shimstock.

28 Thank you!

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