Occlusal schemes in CD_Dr Shuchi Jain.pptx

Prosthodontics, Crown and Bridge and Implantology

1. Occlusal SCHEMES in Complete Denture DR SHUCHI JAIN MDS 1 ST YEAR DEPARTMENT OF PROSTHODONTICS

2. Table Of Contents Introduction Definitions Difference between natural and artificial occlusion Requirements of complete denture occlusion Concept of occlusion Occlusal schemes in complete denture Conclusion References 2

3. Introduction Occlusion – It is a term that describes the contact relationship of upper and lower teeth. Occlusion in complete dentures must be developed to function efficiently and with the least amount of trauma to the supporting tissues. It is important to plan an occlusal scheme before the selection and arrangement of artificial teeth. 3

4. Definition 4 Definitions

5. Definition 5 Definitions

6. Difference between Natural & Artificial teeth 6

7. Requirements of complete denture occlusion 7

8. Requirements for Incising Units 8

9. Requirements for Working Occlusal Units 9

10. Requirements for Balancing Occlusal Units 10

11. CONCEPTS OF COMPLETE DENTURE OCCLUSION 11

12. Static Concept The static relations in occlusion include centric occlusion, protrusive occlusion, and right and left lateral occlusion. These relations must be balanced with the simultaneous contacts of all the teeth on both sides of the arch at their first contact. 12

13. Dynamic Concept The dynamic concept of occlusion is primarily concerned with opening and closing movements involved in mastication. Jaw movements and tooth contacts are made, as the teeth of one jaw glide over the teeth of the opposing jaw. 13

14. Occlusal Schemes in Complete Denture Unlike natural teeth, artificial teeth act as a single unit. Hence there should be a minimum of three contact points/tripod contact (usually one anterior and two posterior) for the even distribution of forces and stabilization of the denture at any position of the mandible. 14

15. 15 Occlusal schemes categorized for complete dentures are:

16. Balanced Occlusion 16 Balanced Occlusion is the bilateral, simultaneous, anterior, and posterior occlusal contact of teeth in centric and eccentric positions.

17. 17 Balanced occlusion in complete dentures is unique, as it does not occur with natural teeth. If it occurs in natural teeth, it is considered premature contact on the nonworking side and is considered to be pathologic. Usually, anatomic teeth are used in balanced occlusion. Non-anatomical teeth can be used with balancing ramps .

18. 18 All the teeth of the working side (central incisor to the second molar) should glide evenly against the opposing teeth. No single tooth should produce any interference or disocclusion of the other teeth. There should be contacts on the balancing side, but they should not interfere with the smooth gliding movements of the working side. There should be simultaneous contact during protrusion. Characteristic requirements of balanced occlusion:

19. 19 Balanced occlusion is one of the most important factors that affects denture stability and retention . Sheppard stated, “ Enter bolus, Exit balance ”. According to this statement, the balancing contact is absent when food enters the oral cavity. This makes us think that balanced occlusion has no function during mastication; hence, it is not essential in a complete denture, but this is not true. IMPORTANCE OF BALANCED OCCLUSION :

20. 20 On an average, a normal individual makes masticatory tooth contact only for 10 minutes in one full day compared to 4 hours of total tooth contact during other functions. So, for these 4 hours of tooth contact, balanced occlusion is important to maintain the stability of the denture.

21. TYPES OF BALANCED OCCLUSION 21

22. Unilateral balanced occlusion 22 Unilateral balanced occlusion involves the contact of the teeth together as a group simultaneously as they glide on one side uninterruptedly. This occlusion is not followed in complete denture preparations and is more pertained to fixed partial dentures .

23. Unilateral balanced occlusion 23

24. Bilateral balanced occlusion 24 Bilateral balance is the posterior contact on both sides of the mandible during centric and eccentric movements of the jaw. It helps maintain stability, and retention and provides better masticatory function. This occlusion can be protrusive or lateral balance. The more the contacts, the more assured the balance.

25. Protrusive balanced occlusion 25 Protrusive balanced occlusion is present when the mandible moves in a forward direction with simultaneous and smooth occlusal contacts anteriorly and posteriorly. It is a three-point contact, two posterior and one anterior. It is absent in natural dentition.

26. Lateral balanced occlusion 26 Lateral balanced occlusion presents minimal simultaneous three-point contact during a lateral moment of the mandible. It is absent in normal dentition. The teeth should be arranged such that there is simultaneous tooth contact in the balancing & working sides .

27. 27 Different concepts for obtaining balanced occlusion:

28. 1. Gysi’s concept 28 In 1914, he proposed the first concept of balancing occlusion. He suggested arranging 33 anatomic teeth that could be used under various movements of the articulator to enhance the stability of the denture.   (a) Gysi's concept: In centric occlusion (b) Gysi's concept: In right lateral position

29. 2. French’s concept 29 Mandibular posterior teeth – occlusal surface reduced to increase the stability of denture. Maxillary posterior teeth – slight lingual occlusal inclines.

30. 3. SEAR’S CONCEPT 30 He proposed balanced occlusion for non-anatomical teeth using posterior balancing ramps or an occlusal plane which curves antero-posteriorly and laterally.

31. 4. PLEASURE CONCEPT 31 Pleasure introduced a pleasure curve or the posterior lateral curve to align and arrange posterior teeth to increase the stability of the denture.

32. 5. Frush’s concept 32 He advised arranging teeth in a one-dimensional contact relationship , which should be reshaped during try-in to obtain balanced occlusion.

33. 6. HANAU’S QUINT 33

34. 1. Condylar guidance 34 Definition: Condylar guidance can be defined as, “Mandibular guidance generated by the condyle and articular disc traversing the contour of the glenoid fossa.”

35. 35 A shallow condylar guidance → Less posterior tooth separation in protrusion → Requires teeth with shorter cusps and flatter fossa to achieve balanced occlusion. A steep condylar guidance → More posterior tooth separation → Requires longer cusps with deeper fossa.

36. 36 If a lesser compensating curve is substituted for a steep condylar guidance it would result in a steep incisal guidance resulting in loss of molar balancing contacts. This is the only factor obtained from the patient and is not under the dentist’s control. The condylar path should be determined on the patient and set on the instrument so that the patient’s temporomandibular joint is in harmony with the occlusion as programmed on the articulator.

37. 2. Incisal Guidance 37 It is defined as, “The influence of the contacting surfaces of the mandibular and maxillary anterior teeth during mandibular movements.” It is established during try-in.

38. 38 Steep incisal guidance → Requires steep cusps, a steep occlusal plane, or a steep compensating curve to effect an occlusal balance. A steep inclined plane is detrimental to the stability and equilibrium of the denture base. Hence for complete dentures, the incisal guidance should be as flat as esthetics and phonetics permit.

39. 39 When the arrangement of the anterior teeth necessitates a vertical overlap, a compensating horizontal overlap should be set to prevent dominant incisal guidance (anterior interference) from upsetting the occlusal balance on the posterior teeth.

40. 3. Plane of Occlusion 40 It is defined as, “An imaginary surface which is related anatomically to the cranium and which theoretically touches the incisal edges of the incisors and the tips of the occluding surfaces of the posterior teeth.” –GPT 10

41. 41 It is established anteriorly by the height of the lower cuspid and posteriorly by the height of the retromolar pad. It is also related to the ala-tragus line, or Camper’s line. Its position can be altered only slightly without creating serious functional problems.

42. 4. Compensating Curve 42 Compensating curve is defined as, “The anteroposterior and lateral curvatures in the alignment of the occluding surfaces and incisal edges of artificial teeth which are used to develop balanced occlusion.” –GPT

43. 43 Anteroposterior curve – run in an anteroposterior direction and help obtain protrusive balance. Mediolateral curve – runs in a lateral direction from one side of the arch to the other and helps obtain lateral balance.

44. Anteroposterior curve ( curve of spee ) 44 The anatomic curve established by the occlusal alignment of the teeth, as projected onto the median plane, beginning with the cusp tip of the mandibular canine and following the buccal cusp tips of the premolar and molar teeth, continuing through the anterior border of the mandibular ramus, ending with the anterior-most portion of the mandibular condyle. First described by Ferdinand Graf Spee, a German anatomist, in 1890. - GPT10

45. 45 This curve assists in obtaining protrusive balance . Without this curve, it would be necessary to tilt the entire occlusal plane at an angle and raise it distally, to obtain balance. This will destabilize the upper denture and cause damage to the rugae area, increasing bone resorption in this area.

46. Mediolateral curves 46 Curve of Wilson: This is a curve that is convex downwards. Wilson adopted this curve in setting the artificial teeth in balanced occlusion for complete dentures. It is used to arrange the molars . It is named after George Wilson who described it in 1911.

47. 47 2. Reverse curve or anti-Monson curve: A curve of occlusion that is convex upwards. This is usually used to arrange the first premolars .

48. 48 3. Curve of Monson: The curve of occlusion in which each cusp and incisal edge touches or conforms to a segment of the surface of a sphere 8 inches in diameter with its center in the region of the glabella. First described by George S. Monson, a US dentist. In three dimensions, this curve is a combination of the ‘ curve of Spee and the curve of Wilson ’.

49. 49 4. Pleasure curve: In excessive wear of the teeth, the obliteration of the cusps and formation of either flat or cupped-out occlusal surfaces, associated with the reversal of the occlusal plane of the premolar, first and second molar teeth (the third molars being generally unaffected), whereby the occlusal surfaces of the mandibular teeth slope facially instead of lingually and those of the maxillary teeth incline lingually. - (GPT10)

50. 50 This is a combination of Monson and anti-Monson curves . Hence, it is not a single curve but a combination of curves. It was used for arranging nonanatomic teeth in balanced occlusion. Premolars and the first molars → Reverse curve → To prevent buccal tipping and seat the denture. Second molars → Conventional Monson’s curve → To provide eccentric lateral balance.

51. 5. Cuspal height 51 Cusp angle is defined as “The angle made by the average slope of a cusp with the cusp plane measured mesiodistally or buccolingually.” –GPT 10

52. 52 The mesiodistal cusp heights that inter-digitate lock the occlusion so that repositioning of the teeth due to settling of the base cannot take place. To prevent this problem, it is advocated that all mesiodistal cusp heights be eliminated, hence only the buccolingual inclines are considered determinants of balanced occlusion in anatomic-type teeth.

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54. Thielmanns' formula 54 This also describes the interrelationship of the 5 factors affecting balanced occlusion: Balanced Occlusion (C) = Condylar Guidance Incisal Guidance   Occlusal Plane Cuspal Inclination Compensating Curve  

55. 7. TRaPOZZANO'S CONCEPT 55 Trapozzano reviewed Hanau's five factors and decided that only three factors were concerned with balanced occlusion. He eliminated the plane of orientation and compensating curve inclination.

56. 8. BOUCHER’S CONCEPT 56 PT Carl O Boucher analyzed Trapazzano's work and stated his concepts and ideas as follows:- There are three fixed factors of balanced occlusion : the occlusal plane’s orientation, the incisal guidance, and the condylar guidance. The angulation of certain cuspal inclines is more important than the height of the cusps. Boucher felt that the compensatory curve is important since it helps increase the effective height of the cusps without changing the form.

57. 9. LOTT’S CONCEPT 57 He stated the laws as follows: The greater the angle of the condyle path, the greater the posterior separation. The greater the angle of the overbite (vertical overlap), the greater the separation between the anterior region and the posterior region regardless of the angle of the condylar path. The greater the separation of the posterior teeth, the greater, or higher, must be the compensation curve.

58. 58 Posterior separation compensation curve to balance the occlusion requires the introduction of the plane of orientation. The greater the separation of the teeth, the greater must be the posterior teeth.

59. 10. BERNARD LEVIN'S CONCEPT 59 Bernard Levin's concept of the laws of articulation is quite similar to Lott's, but he eliminated the plane of orientation because he believed it was not very useful practically . He also stated that the plane of occlusion can be altered by 1-2mm to increase the stability of the denture.

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62. 62 Advantages Disadvantages Seat the dentures in a stable position during mastication, swallowing, and even during bruxing activity. Difficult to achieve in mouths with Class Il cases (increased vertical incisor overlap). Maintain retention and stability of the denture and the health of the oral tissues. May tend to encourage lateral and protrusive grinding habits. Cross-arch balance. A semi-adjustable or fully adjustable articulator is required. Balanced Occlusion

63. Monoplane occlusion 63 Jones advocated monoplane articulation in 1972. This concept uses a nonanatomic occlusal scheme with a few specific modifications (balancing ramps). The amount of horizontal overlap is determined by the jaw relationships. The maxillary posterior teeth are arranged first, and the occlusal plane must fulfill certain requirements.

64. 64 The occlusal plane should evenly divide the space between the upper and lower ridges. The occlusal plane should be parallel to the mean denture base foundation. Finally, the plane should fall at the junction of the upper and middle thirds of the retromolar pads.

65. Advantages of monoplane occlusion 65 Easy to arrange. Lesser resorption of the residual ridges. Increase adaptability to Class II and Class III situations. Reduced horizontal forces impact. Improve patient comfort due to no locking of the inclines.

66. disadvantages of monoplane occlusion 66 Less esthetic. Reported as less efficient in chewing tests. If condylar guidance is steep the denture becomes unstable.

67. lingualized occlusion 67 Lingualized occlusion can be defined as, the form of denture occlusion where the maxillary lingual cusps articulate with the mandibular occlusal surfaces in centric working and non-working mandibular positions. The concept was introduced by Alfred Gysi in 1927. S.H. Payne (1941): 'cusp-to-fossa occlusion’. Pound: 'lingualized occlusion’.

68. INDICATION of lingualized occlusion 68 When a patient places high priority on esthetics but oral conditions indicate a non-anatomic occlusal scheme such as: Severe alveolar resorption Class II jaw relationship Displaceable supporting tissues When a complete denture opposes a removable partial denture. When a more favourable stress distribution is desired in patients with parafunctional habits.

69. ADVANTAGES OF LINGUALIZED OCCLUSION 69 It is a simple technique requiring less precise records than fully balanced occlusion. Most of the advantages attributed to both anatomic & non-anatomic forms are retained. More natural appearance of upper premolars. Good penetration of food bolus is possible. This may reduce the lateral chewing component. Better masticatory efficiency than monoplane occlusion.

70. 70 Vertical forces are centralized on mandibular teeth & it provides an area of closure, allowing easier accommodation to unpredictable basal seat changes. With lingualized occlusion, additional stability is imparted to the denture during parafunctional movements when balanced occlusion is used. Can be used in Class II, and Class III & cross-bite situations.

71. Disadvantages of LINGUALIZED OCCLUSION 71 The constant wearing of the maxillary lingual cusp or mandibular fossa rapidly results in buccal and lingual contact of equal intensity results in the depletion of centralization of forces on the mandibular posterior teeth and increases the potential lateral displacement. Difficulty in teeth arrangement. Cant be used in flat ridges.

72. Neutrocentric occlusion 72 Neutrocentric occlusion is at the far right of the occlusal spectrum and the exact opposite of the anatomic occlusion, which was developed by De van. De Van coined the term Neutrocentric to embody the two key objectives of his occlusal scheme: The neutralization of inclines. The centralization of forces.

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75. 75 Advantages Disadvantages Simple technique and requires less precise records. The least esthetic as there is no incisal overlap and no posterior cusps. Reduced lateral destructive forces. The flat nature of teeth results in impaired mastication. Teeth arranged are easier to adjust. It is indicated in class II (retrognathic), class III (Prognathic), and crossbite cases.

76. conclusion Many occlusal schemes have been proposed over the years. Most schemes when correctly used give satisfactory results. The result is satisfactory if the patient gets better function, esthetics & comfort without any adverse changes in the denture foundation. 76

77. references 77 De Van MM. The concept of neutrocentric occlusion as related to denture stability. J Am Dent Assoc. 1954;48:165–169. Boucher CO. Prosthodontic Treatment for Edentulous Patients. 9th ed. Delhi: CBS Publishers; 1990. p. 119. Rahn AO, Heartwell CM. Textbook of Complete Dentures. 5th ed. Philadelphia: Lea and Febiger ; 1993. Winkler S. Essentials of Complete Denture Prosthodontics. 2nd ed. Delhi: AITBs Publishers; 2000. Schuyler CH. The function and importance of incisal guidance in oral rehabilitation. ˜the œJournal of Prosthetic Dentistry/˜the œJournal of Prosthetic Dentistry. 2001 Sep 1;86(3):219–32.

78. references 78 Zarb Bolender: Prosthodontic treatment for edentulous patients. 12 th ed, 2004. Concepts of occlusion in prosthodontics: A literature review, part I (jpd-10.4103/0972-4052.165172)2015. Bhatnagar P, Gupta I, Trivedi A, Kusum CK, Saxena D, Kaur J. Occlusal schemes in complete denture patients:  A review. Zenodo (CERN European Organization for Nuclear Research). 2022 Apr 15. The Glossary of Prosthodontic Terms: Tenth Edition. J Prosthet Dent. 2023 May;117(5S):e1-e105.

79. Thank you 79