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OCCLUSION IN ORTHODONTICS
Veerasathpurush Allareddy, BDS MBA MHA MMSc PhD
Department of Developmental Biology
Boston Children’s Hospital
Harvard School of Dental Medicine
04/23/2013
OUTLINE
• History
• Terminology
• Occlusion – definition
• Angle’s Classification
• Andrew’s Six Keys to Occlusion
• Clinical Scenarios
History
• Dr. Edward H. Angle
• First dental specialty: Orthodontics
Terminology
Orientations
Buccal
Lingual
Mesial Distal
Overjet
Overbite
OB
Curve of Wilson
Transverse Occlusal Deviations
Midline Deviation
Midline Deviation
Midline Deviation
Functional Shift
Curve of Spee
Curve of spee is 3.5 mm
OCCLUSION
DEFINITION
“The relationship of the mandibular and maxillary teeth as they are brought into functional contact”
COMPLEXITY OF OCCLUSION
• Teeth (morphology and angulation)
• Masticatory muscles
• Skeletal structures
• Temporomandibular joints
• Functional jaw movements
ANGLE’S CLASSIFICATION
Mesiobuccal cusp of maxillary first molar rests on the buccal groove of the mandibular first molar
CLASS II
Class II Division I Class II Division II
CANINE CLASSIFICATION
CANINE CLASSIFICATION
A. Class I - Maxillary canine fits in the embrasure between the mandibular canine and first premolar
B. Class II - Maxillary canine occludes mesial to Class I
C. Class III - Maxillary canine occludes distal to Class I
ANDREW’S SIX KEYS OF NORMAL
OCCLUSION
SIX KEYS OF NORMAL OCCLUSION
• Molar interarch relationship
• Mesiodistal crown angulation
• Labiolingual crown inclination
• Rotations
• Tight contacts
• Occlusal plane (curve of spee)
MOLAR INTERARCH RELATIONSHIP • Mesiobuccal cusp of maxillary first molar occludes in
the buccal groove of mandibular first molar
• Mesiolingual cusps of the maxillary first molar occludes in the central fossa of the mandibular first molar
• Distal marginal ridge of the maxillary first molar occludes with the mesial marginal ridge of the mandibular second molar
MOLAR INTERARCH RELATIONSHIP
MOLAR INTERARCH RELATIONSHIP
YES
MESIODISTAL CROWN ANGULATION
Gingival part of the long axis of the crown must be distal to the occlusal part of the axis
LABIOLINGUAL CROWN INCLINATION BETWEEN MAXILLARY AND MANDIBULAR INCISORS
LABIOLINGUAL CROWN INCLINATION OF POSTERIOR TEETH
NO ROTATIONS
TIGHT CONTACTS – NO SPACING
CURVE OF SPEE
A. Excessive
B. Normal
C. Reverse
REFERENCES Casko J et al. "Objective grading system for dental casts and panoramic radiograph," The American Journal of Orthodontics and
Dentofacial Orthopedics, 114:590-599, 1998.
Cangialosi TJ. “The ABO discrepancy index: A measure of case complexity.” American Journal of Orthodontics and Dentofacial Orthopedics, 125(3):270-278, Mar 2004.
Riolo et al. "ABO Resident Clinical Outcomes Study: Case Complexity as Measured by the Discrepancy Index.” American Journal of Orthodontics and Dentofacial Orthopedics, pp. 161-163, Feb 2005.
Andrews LF. "The Six Keys to Normal Occlusion." American Journal of Orthodontics, 62:296-309, 1972.
Proffit WR et al. “Contemporary Orthdontics”. Fourth edition. Mosby.
English JD et al. “Mosby’s Orthodontic Review”. Mosby.
Rakosi T et al. “Color Atlas of Dental Medicine - Orthodontic Diagnosis”. Thieme.
CLINICAL SCENARIOS