Complete Denture Occlusion

1. Complete Denture Occlusion Rola M. Shadid, BDS, MSc

2. Occlusion the static relationship between the incising or masticating surfaces of the maxillary and mandibular teeth, or tooth analogs Articulation the contact relationship between the occlusal surfaces of teeth during function

3. Centric occlusion • Eccentric occlusion * Protrusive occlusion Lateral occlusion

4. Working side the side toward which the mandible moves in a lateral excursion Non working (balancing) side that side of the mandible that moves toward the median line in a lateral excursion.

5. Occlusal Schemes For CD • Balanced articulation • Nonbalanced articulation (linear or monoplane articulation) • Lingualized articulation • Functionally generated occlusal scheme

6. Balanced Occlusion/Articulation • Bilateral simultaneous contact betw. anterior & posterior teeth during all centric and eccentric positions • There should be no interferences during movement from centric position to eccentric positions • The movements should be in harmony with TMJ & neuromuscular control

7. Advantages of Balanced Occlusion • To improve stability & retention • To decrease soreness & resorption of residual ridge • To improve oral comfort of the patient

8. Mechanics Of Balanced Occlusion Christensen’s phenomenon*

10. How Could You Achieve Balanced Occlusion In CD?

11. Factors That Affect Occlusal Balance

12. Factors Affecting Balanced Occlusion (Hanau’s Quint) * 1. Condylar Guidance 2.  Incisal Guidance 3.  Plane of occlusion • Cuspal inclination • Compensating curve.

13. Condylar Guidance* Mandibular guidance generated by the condyle and articular disc traversing the contour of the glenoid fossae The posterior determinent of mandibular movement

14. Condylar Guidance Angle The angle formed by an imaginary horizontal line at the superior head of the condyle and the path that the condyle will pass through during function Varies from individual to individual because of anatomical differences

15. Incisal Guidance * It’s the influence of the contacting surfaces of the mandibular & maxillary anterior teeth on mandibular movement

16. Incisal Guidance Angle The angle formed by the intersection of the plane of occlusion and a line within the sagittal plane determined by the incisal edges of the maxillary and mandibular central incisors when the teeth are in maximum intercuspation

17. Incisal Guidance Angle This angle varies directly with the vertical overbite and inversely with the horizontal overjet This angle is set to 10˚ in CD and not exceeding 20˚

18. Incisal Guidance ↓Incisal Guidance Angle by ↑horizontal overlap

19. Incisal Guidance • For CD, the incisal guidance should be as shallow as esthetics and phonetics will permit when arrangement of anterior teeth to reduce protrusive displacing forces

20. Incisal Guidance ↓ Incisal Guidance Angle by either:* ↑ horizontal overlap ↓ vertical overlap

21. If Increased Incisal Guidance Angle For CD? During protrusion: Upper denture drops at the back Lower denture slides backward

22. Plane Of Occlusion Its inclination can be altered slightly * It is not as important as other factors

23. Cusp Height & Angulation* It is the smooth gliding of the cusp tips along the cusp inclines of the opposing teeth to provide balanced articulation

24. Cusp Height & Angulation • Anatomic teeth are easier to balance than nonanatomic teeth • Cuspal inclines should not be too steep as it can increase lateral forces • It is possible to decrease cuspal height by using compensating curves

25. Compensating Curves Artificial curves introduced into complete denture occlusion to achieve balanced occlusion Are among the most important determinents of occlusal balance

26. Compensating Curves The anteroposterior curving (in the median plane) and the mediolateral curving (in the frontal plane) within the alignment of the occluding surfaces and incisal edges of artificial teeth that is used to develop balanced occlusion

27. The Curvatures In Natural Dentition Curve of Spee An arc of a circle 65mm to 70mm radius that touches the tips of all the mandibular teeth when the skull is viewed laterally; when continued it touches the anterior surface of the condyles

28. The Curvatures In Natural Dentition Curve Of Monson A proposed ideal curve of occlusion in which each cusp and incisal edge touches or conforms to a segment of the surface of a sphere 4 inches (102mm) in radius with its centre in the region of the glabella.

29. Compensating Curves Anteroposterior curve * Mediolateral curve ¤

30. Compensating Curves • The steepness of the curve necessary to achieve balance is the result of guiding influence of angle of condylar guidance and angle of incisal guidance • It is functionally and mechanically advantageous to keep compensating curve as modest as possible → This is accomplished by setting as shallow an incisal guidance as phonetics, esthetics permit

31. Theilmann’s Formula IGxCG = CHxOPxCC

32. According To The Formula • To achieve balanced occlusion: For high condylar guidance we need to have high compensating curve, occlusal plane and cuspal height. • To achieve balanced occlusion: For high incisal guidance we need to have high compensating curve, occlusal plane and cuspal height.

33. According To The Formula To achieve balanced occlusion, the steeper the condylar guidance, the greater the cusp height toward the posterior or the steeper the compensating curves

34. According To The Formula To achieve balanced occlusion, the steeper the compensating curves, the less the cusp height toward the posterior

37. Question Q) Suppose that the incisal guidance is set and the condylar guidance is steeper than your chosen 20 degree teeth. To obtain balanced occlusion in your complete denture, what should you do? • steepen the compensating curves in both sagittal and frontal planes • steepen the compensating curves in only sagittal but not frontal plane • decrease the inclination of occlusal plane • decrease the steepness of compensating curves in both sagittal and frontal planes • steepen the condylar guidance • none of the above

38. Occlusal Schemes For CD

39. Philosophies of Denture Occlusion • Many philosophies of arranging denture occlusion • Nodefinitivescientific studies prove one occlusal scheme clearly superior

40. Occlusal Schemes • Balanced articulation • Nonbalanced articulation (linear or monoplane articulation) • Lingualized articulation • Functionally generated occlusal scheme

41. Lingualized Occlusion Max. lingual cusps contact central fossae/marginal ridge ~ 1mm space between buccal cusps

42. Lingualized Occlusion • Lingualized occlusion is a type of bilaterally balanced occlusal schemes * • Anatomic teeth are used in the maxilla opposing a flat-cusped, or shallow cusped mandibular tooth.

43. Lingualized Occlusion • Forces directed toward lingual side • Maxillary lingual cusps articulate with the mandibular central fossae • Elimination of contacts on the buccal cuspsin both centric and eccentric • The aim is to provide greater masticating efficiency and the elimination of lateral interferences

44. Lingualized Occlusion • Maxillary anatomic (33°) • Mandibular Teeth • Steep Condylar Guidance • Shallow cusped (Anatoline) • Shallow Condylar Guidance • Non-anatomic (Portrait 0°) Lingualized (lingual contact)

45. Lingualized Occlusion Verify centric No max. buccal cusp contacts in: • Centric • Lateral excursions

46. Contraindications Of Balanced Occlusion & Lingualized Occlusion Extreme cases of the following: Difficulty in obtaining repeatable centric record (incoordination, jaw malrelations) Severe ridge resorption (lateral forces displace the denture) may more easily be handled with a monoplane scheme

47. Monoplane Articulation (Neutrocentric Concept) • Cuspless teeth (0°) on a flat plane with 1.5-2.0 mm overjet • No cusp to fossa relationship • No anterior contacts in centric position

48. Monoplane Articulation • Eliminate cusps • lateral forces reduced • improves stability • Simplifies tooth arrangement

49. Monoplane Articulation • No overbite (would cause tilting) • Overjet of 2 mm is used to create an illusion of overbite

50. Monoplane Articulation • Excursions - may or may not contact on balancing sides • Depends on condylar inclination and other aspects of the tooth arrangement