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!