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Occlusion basics


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Occlusion basics

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. OCCLUSION • ANGLE defined occlusion as the normal relation of the occlusal inclined planes of the teeth when the jaws are closed. • SHAW defined dental occlusion as the static,closed contacting position of the upper teeth to the lower teeth
  3. 3. TERMINOLOGY • NORMAL OCCLUSION-in orthodontics is ANGLES CLASS 1 OCCLUSION The mesiobuccal cusp of the maxillary 1st molar should occlude in the mesiobuccal groove of the mandibular 1st molar. If this molar relationship existed and the teeth were arranged on a smoothly curving line of occlusion normal occlusion would result
  4. 4. • THE LINE OF OCCLUSION-is a smooth curve passing through the central fossa of each upper molar and across the cingulum of the upper canine and incisor teeth. • The same line runs along the buccal cusps and incisal edges of the lower teeth,thus specifying occlusal as well as interarch relationships once the molar relation is established.
  5. 5. IDEAL OCCLUSION • Is a preconceived theoretical concept of occlusal,structural and functional relationships that includes idealized principles and characteristics that an ideal occlusion should have.
  6. 6. PHYSIOLOGIC OCCLUSION • This refers to an occlusion that deviates in one or more ways from ideal yet is well adapted to that particular environment,is esthetic and shows no pathologic manifestations or dysfunction.
  7. 7. BALANCED OCCLUSION • An occlusion in which balanced and equal contacts are maintained throughout the entire arch during all excursions of the mandible. • There is simultaneous contact of maxillary and mandibular teeth on the right and left ,in anterior and posterior occlusal areas when the jaws are either in centric or eccentric occlusion.
  8. 8. FUNCTIONAL OCCLUSION • It is defined as an arrangement of teeth which will provide the highest efficiency during all the excursive movements of the mandible which are necessary during function.
  9. 9. THERAPEUTIC OCCLUSION • A n occlusion that has been modified by appropriate therapeutic modalities in order to change a non physiologic occlusion to one that is at least physiologic if not ideal.
  10. 10. TRAUMATIC OCCLUSION Is an abnormal occlusal stress which is capable of producing or has produced an injury to the periodontium.
  11. 11. TRAUMA FROM OCCLUSION • It is defined as periodontal tissue injury caused by occlusal forces through abnormal tissue contacts.
  12. 12. TYPES OF CUSPS • CENTRIC HOLDING CUSPS • The facial cusps of mandibular and palatal cusps of maxillary posterior teeth are called the centric holding cusps.They occlude into the central fossa and marginal ridges of opposing teeth.They are also called the STAMP CUSPS.
  13. 13. • NON SUPPORTING CUSPS • The maxillary buccal and mandibular lingual cusps are called non supporting cusps.They contact and guide the mandible during lateral excursions and shear food during mastication.Hence they are called SHEARING OR GUIDING CUSPS.
  14. 14. CLASSIFICATION OF 0CCLUSION • BASED ON MANDIBULAR POSITION • CENRIC OCCLUSION-Is that position of the mandibular condyle when the teeth are in maximum intercuspation.It is also called INTERCUSPAL POSITION OR CONVENIENCE OCCLUSION.
  15. 15. • ECCENTRIC OCCLUSION • It is defined as the occlusion other than centric occlusion.It refers to contact of teeth that occurs during movement of the mandible. • It includes:LATERAL OCCLUSION RIGHT AND LEFT LATERAL OCCLUSION
  16. 16. • It is defined as the contact between opposing teeth(canines and posterior teeth)when the mandible is moved right or left of the midsaggital plane.The contacts occur on the sides towards which the mandible moves. • PROTRUDED OCCLUSION:Defined as the occlusion of the teeth when the mandible is protruded.The position of the mandible is anterior to centric relation.Ideally the six anterior teeth contact along the lingual inclines of the max. ant. teeth while the posteriors disocclude.
  17. 17. • RETRUSIVE OCCLUSION Occlusion of the teeth when the mandible is retruded.It is the position of the mandible posterior to centric relation.
  18. 18. BASED ON THE RELATIONSHIP OF THE 1ST MOLAR • NEUTRO-OCCLUSION/CLASS1 • The anteroposterior relationshipof the maxillary and mandibular molars is correct,with the mesiobuccal cusp of the maxillary 1st molar occluding in the mesiobuccal groove of the mandibular ist molar.
  19. 19. • DISTO OCCLUSION/CLASS2 • The lower dental arch is in a distal or posterior relation to the upper dental arch,as reflected by the 1st permanent molar relationship.The mesiobuccal groove of the mandibular 1st molar contacts the distobuccal cusp of the maxillary 1st molar or it may be farther posterior.
  20. 20. • It is further subdivided into: • DIV1:Bilateral distal retrusion with a narrow maxillary arch and protruding maxillary incisors.Increased overjet. • DIV2:Bilateral distal retrusion with a normal or square shaped maxillary arch,retruded maxillary centrals,labially malposed maxillary laterals and an excessive overbite.
  21. 21. • MESIO-OCCLUSION/CLASS-3 • The mandibular 1st molar is mesial to the maxillary 1st molar and the mandibular incisors are in anterior crossbite.
  22. 22. BASED ON THE ORGANIZATION OF OCCLUSION • A) CANINE GUIDED OR PROTECTED OCCLUSION • During lateral mandibular movements,the opposing upper and lower canines of the working side contact thereby causing disclusion of all posterior teeth on the working and balancing sides.This is because the mandible moves away from centric occlusion.
  23. 23. MUTUALLY PROTECTED OCCLUSION Occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in maximum intercuspation. Also,the anterior teeth disengage the posterior teeth in all mandibular excursive movements.
  24. 24. GROUP FUNCTION OCCLUSION • Is defined as the multiple contact relationship between maxillary and mandibular teeth,in lateral movements of the working side,where by simultaneous contacts of several teeth is achieved and they act as a group to distribute forces.
  25. 25. BASED ON PATTERN OF OCCLUSION • A)CUSP TO EMBRASURE/MARGINAL RIDGE • Development of occlusion can result in fitting of one stamp cusp into a fossa and the fitting of another cusp of the same tooth into the embrasure area of two opposing teeth. • This is TOOTH-TO- • TWO-TEETH • relation occlusion.
  26. 26. • B)CUSP-FOSSA OCCLUSION • In this type of occlusion,the stamp cusp of one tooth occludes in a single fossa of a single opponent. • This is a tooth to one tooth relation. • Has advantages over the cusp-embrasure arrangement: • A)Forces are directed more towards the long axis.
  27. 27. • B)Arrangement leads to greater stability of the arch,decreasing the tendency towards tooth movement. • C)The chances of food impaction in the embrasure is less.
  28. 28. IMAGINARY CURVES • A)CURVE OF SPEE-BY VON SPEE • It refers to the anteroposterior curvature of the occlusal surface,beginning at the tip of the lower cuspid and following cusp tip of bicuspids and molars continuing as an arc through the condyle. • If the curvature were extended,it would form a circle about • 4inches in dia.
  29. 29. • B)CURVE OF WILSON- • It is a curve that contacts the buccal and lingual cusp tips of mandibular posterior teeth. • It is mediolateral on each side of the arch • It results from the inward inclination of the lower posterior teeth.
  30. 30. CURVE OF MONSON It is obtained by the extension of the curve of spee and the curve of wilson to all cusps and incisal edges.
  31. 31. CENTRIC RELATION • Is the relation of the mandible to the maxilla when the mandibular condyles are in the most superior and retruded position in their glenoid fossa with the articular disc properly interposed. • Also called LIGAMENTOUS OR TERMINAL HINGE POSITION. • Is a bone to bone relation.
  32. 32. ANDREWS KEYS OF OCCLUSION • A)MOLAR INTERARCH RELATIONSHIP • The mesiobuccal cusp of the upper first molar should occlude in the groove between the mesial and the medial buccal cusp of the lower first molar. • The mesiolingual cusp of the upper 1st molar should occlude in the central fossa of the lower 1st molar
  33. 33. • The crown of the upper first molar must be angulated so that the distal marginal ridge occludes with mesial marginal ridge of the lower second molar.
  34. 34. • MESIO DISTAL CROWN ANGULATION • The 2nd key makes use of a line that passes along the long axis of the crown through the most prominent part in the centre of the labial or buccal surface.This is called the long axis of the crown. • The gingival part of the long axis of the crown must be distal to the occlusal part of the line.
  35. 35. • LABIOLINGUAL CROWN INCLINATION • Determined from the mesial or the distal view. • If the gingival area of the crown is more lingually placed than the occlusal area,it is referred to as POSITIVE CROWN INCLINATION.The maxillary incisors exhibit this inclination.
  36. 36. • Incase the gingival area of the crown is more labialy or buccally placed than the occlusal area it is referred to as NEGATIVE CROWN INCLINATION. • Mandibular incisors exhibit mild –ve inclination. • Maxillary and mandibular posteriors exhibit the same.
  37. 37. • CURVE OF SPEE-Should not be exceeding 1.5mm. •ABSENCE OF ROTATION •TIGHT CONTACTS
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