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Occlusion part(iii) /certified fixed orthodontic courses by Indian dental academy
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Occlusion part(iii) /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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  • 1. OCCLUSION (PART III) INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • 2. Contents     Introduction Posterior controlling factors Anterior controlling factors Understanding the controlling factors www.indiandentalacademy.com
  • 3. Vertical determinants of occlusal morphology (on cusp height) Horizontal determinants of occlusal morphology (on ridge and groove direction) Summary References www.indiandentalacademy.com
  • 4. Introduction   The occlusal anatomy of the teeth must function in harmony with the structures controlling the movement patterns of the mandible. To maintain harmony of the occlusal condition, the posterior teeth must pass close to but must not contact their opposing teeth during mandibular movement www.indiandentalacademy.com
  • 5. Posterior controlling factors www.indiandentalacademy.com
  • 6. The angle at which the condyle moves away from horizontal reference plane is referred to as the condylar guidance angle. Two TMJ’s factors –posterior controlling Fixed factors www.indiandentalacademy.com
  • 7. Anterior controlling factors Vertical overlap and horizontal overlap Variable factor (altered by dental procedures) www.indiandentalacademy.com
  • 8. Understanding the controlling factors If the criteria for optimum functional occlusion has to be fulfilled, the morphologic characteristics of each posterior tooth must be in harmony with those of its opposing tooth or teeth during all eccentric mandibular movements. The relationship of a posterior tooth to the controlling factors influences the precise movement of that tooth. www.indiandentalacademy.com
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  • 12. Therefore, the significance of the anterior and condylar guidances lies in how they influence posterior tooth shape. www.indiandentalacademy.com
  • 13. Occlusal surface of the posterior teeth can be affected in 2 manners 1. Height 2. Width  Factors that influence the heights of cusps and depths of fossae are the vertical determinants of the occlusal morphology  Factors that influence the direction of ridges and grooves on the occlusal surfaces are considered the horizontal determinants of the occlusal morphology www.indiandentalacademy.com
  • 14. Vertical determinants of occlusal morphology (on cusp height) a) Effect of condylar guidance b) Effect of anterior guidance c) Effect of plane of occlusion d) Effect of curve of Spee e) Effect of mandibular lateral translation movement www.indiandentalacademy.com
  • 15. a) Effect of condylar guidance www.indiandentalacademy.com
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  • 17. b) Effect of anterior guidance It is a function of the relationship between the maxillary & mandibular anterior teeth. Anterior guidance = Overjet X overbite www.indiandentalacademy.com
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  • 19. c) Effect of plane of occlusion It is an imaginary line extending from cusp tip of mandibular canine to distobuccal cusp of lower second molar Relationship of this plane to the angle of articular eminence influences the steepness of the cusps. www.indiandentalacademy.com
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  • 22. As the plane of occlusion becomes more nearly parallel to the angle of the articular eminence, the posterior cusps must be made shorter. www.indiandentalacademy.com
  • 23. d) Effect of curve of Spee 3 components affecting the cusp height are: a) Length of the radius of the curve b) Degree of curvature of the curve of Spee c) Orientation of curve of Spee www.indiandentalacademy.com
  • 24. Length of the radius of the curve www.indiandentalacademy.com
  • 25. Degree of curvature of the curve of Spee www.indiandentalacademy.com
  • 26. Orientation of curve of Spee www.indiandentalacademy.com
  • 27. e) Effect of mandibular lateral translation movement Bennett movement- A bodily side shift of the mandible that occurs during lateral movements. www.indiandentalacademy.com
  • 28. The degree of medial movement of orbiting condyle depends on two factors : a. Morphology of medial wall of the fossa. b. Inner horizontal portion of the Temporomandibular ligament (which attaches to the lateral pole of the rotating condyle) www.indiandentalacademy.com
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  • 30. Lateral translation movement has 3 attributes 1. Amount 2. Direction 3. Timing  Amount and Timing are dependent on medial wall of fossa and TM ligament.  Direction depends on the direction taken by the rotating condyle. www.indiandentalacademy.com
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  • 32. Effect of amount of lateral translation movement on cusp height Greater the amount of lateral translation movement, shorter is the posterior cusp www.indiandentalacademy.com
  • 33. Effect of the direction of lateral translation movement on cusp height Determined by the morphology and ligamentous attachments of the TMJ undergoing rotation. The movement occurs within a 60 degree cone whose apex is located at the axis of rotation. www.indiandentalacademy.com
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  • 35. Effect of timing of lateral translation movement on cusp height Dependent on the medial wall of fossa and TM ligament. Immediate side shift – when the lateral translation movement occurs early Progressive side shift – if movement occurs in conjunction with an eccentric movement www.indiandentalacademy.com
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  • 37. Horizontal determinants of occlusal morphology Influences the direction of ridges and grooves on the occlusal surfaces Each centric cusp tip generates both laterotrusive and mediotrusive pathways across its opposing tooth Each pathway represents a portion of the arc formed by the cusp rotating around the rotating condyle www.indiandentalacademy.com
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  • 39. Horizontal determinants of occlusal morphology (on ridge and groove direction) a) Effect of distance from rotating condyle b) Effect of distance from mid-Sagittal plane c) Effect of distance from rotating condyle and from mid-Sagittal plane d) Effect of mandibular lateral translation movement e) Effect of inter-condylar distance www.indiandentalacademy.com
  • 40. a)Effect of distance from rotating condyle Greater the distance – wider the angle www.indiandentalacademy.com
  • 41. b) Effect of distance from midSagittal plane More the distance – wider the angle www.indiandentalacademy.com
  • 42. c) Effect of distance from rotating condyle and from mid-Sagittal plane  The combination of the two positional relationships is what determines the exact pathways of the centric cusp tips  Because of the curvature of the dental arch; as the distance of tooth from rotating condyle increases – distance from midsagittal plane decreases, but distance from rotating condyles increases FASTER than decrease in distance from midsagittal plane. www.indiandentalacademy.com
  • 43. Therefore, the teeth toward the anterior region (e.g. premolars) have larger angles than posterior teeth (e.g. molars). www.indiandentalacademy.com
  • 44. d) Effect of mandibular lateral translation movement  influences the directions of ridges and grooves Movement depends on 2 factors: 1. Amount 2. Direction www.indiandentalacademy.com
  • 45. Effect of amount of lateral translation movement on ridge and groove direction www.indiandentalacademy.com
  • 46. Effect of direction of lateral translation movement on ridge and groove direction www.indiandentalacademy.com
  • 47. e) Effect of inter-condylar distance  As inter condylar distance increases – distance between the condyle and the tooth increases – wider angles (in a given arch configuration)  As inter condylar distance increases – the tooth is placed nearer the mid-sagittal plane relative to the rotating condylemidsagittal plane distance – decrease in the angle generated www.indiandentalacademy.com
  • 48. Increase in inter-condylar distance – decrease in angle between mediotrusive and laterotrusive pathways www.indiandentalacademy.com
  • 49. Summary Vertical determinants of occlusal morphology (on cusp height and fossa depth) Horizontal determinants of occlusal morphology (on ridge and groove direction) www.indiandentalacademy.com
  • 50. Factor Condition Effect Condylar guidance Steeper Taller Anterior guidance More overbite More Overjet Taller Shorter Plane of occlusion More parallel Shorter Curve of Spee More acute Shorter Lateral translation Greater movement Shorter More superior Shorter Greater immediate shift Shorter www.indiandentalacademy.com
  • 51. Factor Condition Effect Distance from rotating condyle Greater Wider the angle Distance from midsagittal plane Greater Wider the angle Lateral translation Greater Wider the angle Intercondylar distance Greater Smaller the angle www.indiandentalacademy.com
  • 52. References  Occlusion series in BDJ, 2001;191:6- 7  Okeson JP. Management of Temporomandibular Disorders and Occlusion, ed. 4th, 1998; Mosby  Ash MM and Ramfjord S. Occlusion, ed. 4th, 1966; WB Saunders Company, Michigan www.indiandentalacademy.com
  • 53. Santos JD. Occlusion Principles and Concepts, ed. 2nd, 1999; Ishiyaku EuroAmerica, Inc. U.S.A.  Shillingburg HT. Fundamentals of Fixed Prosthodontics, ed.3rd, 1997;Quintessence www.indiandentalacademy.com
  • 54. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com