CONCEPTS OF OCCLISION(Dr.ARAVIND)
- 2. Dr. ARAVIND H Senior Lecturer DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS BASIC CONCEPTS OF OCCLUSION
- 3. INTRODUCTION The term occlusion has both STATIC and DYNAMIC aspects: STATIC: Form, alignment and articulation of teeth within and between the arches, and relationship of teeth to their supporting structures. DYNAMIC: Function of the stomatognathic system as a whole, comprising of teeth, supporting structures, TMJ, neuromuscular and nutritive systems.
- 4. SOME TERMINOLOGIES IDEAL OCCLUSION: It is a preconceived theoretical concept of occlusal structures and functional relationships that include idealized principles and characteristics that an occlusion should have. PHYSIOLOGIC OCCLUSION: deviates from ideal and yet remains well adapted to that particular environment. BALANCED OCCLUSION: balanced and equal contacts are maintained throughout the entire arch during all excursions of mandible. FUNCTIONAL OCCLUSION: that which provides the highest efficiency during all excursive movements TRAUMATIC OCCLUSION: Abnormal occlusion that is capable of producing injury to the periodontium
- 5. TYPES OF CUSPS CENTRIC HOLDING CUSPS: • Buccal cusps of mandibular posterior teeth • Palatal cusp of maxillary posterior teeth • Occlude into the central fossae and marginal ridges of opposing teeth • Also known as stamp cusps NON SUPPORTING CUSPS: • The maxillary buccal and mandibular lingual cusps • Contact and guide mandible during lateral excursions and mastication
- 6. ARRANGEMENT OF TEETH IN HUMANS Human dentition exhibit two type of tooth arrangement while in occlusion. They are: CUSP- FOSSA OCCLUSION • Stamp cusp of one tooth occludes with a single fossa of an opponent • Upper stamp cusps fit into all except the mesial fossa of the lower teeth • Lower stamp cusps fit into all upper fossa except the distal ones of bicuspids CUSP EMBRASURE OCCLUSION In this type 0f arrangement, each tooth occlude with two opposing teeth
- 7. IMAGINARY CURVES CURVE OF SPEE • It relates to the anteroposterior curvature of the occlusal surface, beginning at the tip of the lower cuspid & following the cusp tip" of the bicuspids & molars continuing as an arc through the condyle. • The curve, when extended, forms a circle of about 4inch in diameter CURVE OF WILSON It is a mediolateral curve that contacts the buccal & lingual cusp tips of the mandibular buccal teeth. It result, from inward inclination of the lower posterior tooth. CURVE OF MONSON Obtained by extending the curve of Spee and Wilson to all the cusps and incisal edges.
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- 9. CENTRIC RELATION & CENTRIC OCCLUSION • CENTRIC RELATION is the relation of the mandible to the maxilla when en the mandibular condyle are in the most superior and retruded position in the glenoid fossa with the articular disc properly interposed. • Centric relation is also called ligamentous position Or terminal hinge position. At centric relation, both the condyles are simultaneously seated most superiorly in the glenoid fossa. • CENTRIC OCCLUSION is that position of the condyle when the teeth are in maximal intercuspation. • Research show that centric occlusion is found to be 1-2mm ahead of centric relation in majority of the population.
- 10. CENTRIC CONTA CTS • They are areas of teeth that contact the opposing teeth. Classified as: POSTERIOR CENTRIC CONTACTS • Consists of facial and lingual ranges of contacts. • In Facial range of posterior contacts, mandibular facial cusp tips contact central fossa and mesial marginal ridge of opposing teeth. • Lingual range involves maxillary lingual cusp tips contacting central fossa and distal marginal ridges of opposing mandibular teeth. ANTERIOR CENTRIC CONTACTS • They are in line with the facial range of posterior centric contacts.
- 11. ECCENTRIC OCCLUSION Refers to the contact of teeth that occurs during movement of mandible. Classified into two types: FUNCTIONAL OCCLUSION • Tooth contacts occur in the segment of the arch toward which the mandible moves. Further divided into two types: • 1) LATERAL FUNCTIONAL OCCLUSION: tooth contacts that occur on canines and posteriors on the side toward which mandible moves. • A) Canine guided • B) Grouped lateral • 2) PROTRUSIVE FUNCTIONAL OCCLUSION NON FUNCTIONAL OCCLUSION Tooth contacts that occur in the segment away from which the mandible moves.
- 12. DISCLUSION • It is used to describe dis-occlusion or seperation of non functional posterior teeth during eccentric movements. • Brought about by condylar and incisal guidance CONDYLAR GUIDANCE • IN case of protrusive movements, both condyles translates downwards along the slope of articular eminence leading to disocclusion of posteriors. • In case of lateral movements, condyle on the working side rotates on its axis while condyle on the non working side translates forward, leading to disocclusion of non working side. INCISAL GUIDANCE • Leads to mandibular incisors sliding down from the area of centric contacts towards the incisal edges of maxillary anteriors, thus leading to posterior disocclusion.
- 13. ANDREWS SIX KEYS TO NORMAL OCCLUSION Andrew, during the 1970s put forward six keys to normal occlusion after studying 120 patient models. • MOLAR INTERARCH RELATIONSHIP • MESIOLINGUAL CROWN ANGULATION • LABIOLINGUAL CROWN INCLINATION • ABSENCE OF ROTATION • TIGHT CONTACTS • CURVE OF SPEE
- 14. CONCLUSION • By understanding various concepts of occlusion, we will be able to formulate an ideal treatment plan for an individual that could bring forward a final outcome where there is not derangement of jaw movement, better cuspal and incisal relationship and improved esthetics.