The Ideal Occlusion

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The Ideal Occlusion
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Ideal Morphologic Occlusion

• Posterior Teeth
• Angle I
• Contact
• Normal buccal overjet

• Anterior Teeth
• AP 2-3 mm Hor OJ
• Vertical 2-4 mm Ver OB,
• 50
• Transverse Midlines aligned

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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

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My first patient in the clinic!
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Biologic Variation of Occlusion
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I. Morphologic Variation Brunelle JA et al.
Prevalence and distribution of selected occlusal
characteristics in the US Population, 1988-1991,
J Dent Res 199675706-713.

• Third National Health and Nutrition Examination
  Survey (NHANES III)
• Age 8-11 18-50 y/o
• n 11,000
• Hx of ortho tx 20
• Crowding Children 48-58 Adults 57-67

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A. Sagittal Plane(Children and Youths)

• Angle I Normal 30
• Angle I Malocclusion 55
• Angle II Malocclusion 15
• Angle III Malocclusion 1

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B. Horizontal Plane (Transverse)

• Posterior Crossbite 9.1

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High Mandibular Plane Angle

• Tall lower face
• Smile maxillary teeth and gingival visible
• Lips postured to seal
• Anterior open bite tendency

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Low Mandibular Plane Angle

• Short lower face
• Smile Minimal maxillary tooth visibility
• Lower lip everted
• Deep bite tendency

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C. Vertical Plane

• Open Bite ( 0 mm) lt 3
• Vertical Deep Bite (gt5 mm) 16

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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

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II. Functional Occlusal Variation
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A. CR/IP (CO) Slide

• Slide Prevalence gt90
• Horizontal Component Usually 0.5-1.0 mm
• Lateral Component 25
• (Rieder CE J Prosthet Dent 39324-329, 1978
  n323)

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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 197942335-342.

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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
  197717191-200)

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Skeletal Variation of Occlusion
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Skeletal Effect

• Canine Guidance tend to have mandibular plane
  angle lt 24o
• Group Function tend to have a mandibular plane
  angle gt 24o
• (DiPietro GJ J Prosthet Dent 38452-458, 1977
  n112)

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2. Nonworking Side Contacts

• Nonworking contacts identified in gt 60 of a
  sample (Ingervall B, Archs Oral Biol 17191-200,
  1977)

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2. Nonworking Side Contacts

• Nonworking interferences (contact only on the
  nonworking side) identified in 8 of a study
  sample (Ingervall B, Archs Oral Biol 17191-200,
  1977)

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C. Intercuspal Position Contacts Ideal

• Size small circular areas
• 1 mm diameter
• Location cusp tips to flat fossae marginal
  ridges or balanced inclines.
• Number n26 or 66

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C. IP Contact Biological Variation (Riise C
Ericsson SG J Oral Rehabil 10473-480, 1983.)

• Size large irregular areas
• Location on cuspal inclines
• Number average of 2 contacts/ molar, 1 contact/
  premolar and lt1 contact/ anterior tooth

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Homo sapiens exhibit greater occlusal variation
than any other primate
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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.

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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.

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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

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Occlusal Adjustment A Method
Goal All centric cusps contacting and every
posterior tooth pair holding shimstock.
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Thank you!