ROLE OF OCCLUSION IN FIELD OF PERIODONTOLOGY

DENTAL

1. Occlusal analysis, diagnosis and management in the practice of periodontics and implantology Dhandapani Arunachalam MDS

2. 1. Is there a relationship between excess occlusal forces and the progress of periodontal disease ? 2. How can I diagnose excessive occlusal force and when does a regular occlusal force become excessive ? 3. If diagnosed when should treatment be initiated and what should be accomplished ? Pertinent questions

3. Only in limited circumstances does occlusal force contribute to periodontal disease progression. POINT COUNTERPOINT Is there an association between occlusion and periodontal destruction? Yes— occlusal forces can contribute to periodontal destruction.

4. Evolution of the concept – The last 100 years !

5. What is the role of occlusion in the pathogenesis of periodontal disease? Karyoli 1901- Beobachtungen uber Pyorrhea alveolaris : Ost Ung vierteljhcsr Zanheilk Stillman PR 1917 – The management of pyorrhea. Dent.Cosmos 1917 , 59:405-414 Stillman PR 1926 – What is traumatic occlusion and how can it be diagnosed and corrected . JADA 1926, 12; 1330-1338

6. Stones HH 1938 : An experimental investigation into the association of traumatic occlusion to periodontal disease. Proc Royal Soc of Medicine ( Odontol Sec ) 1938 :31, 479- 495 HK Box 1935 : Experimental traumatic occlusion in sheep , Oral Health : 1935 : 25, 9 -15 Occlusal trauma as a contributing factor in periodontal disease

7. “Teeth undergoing excessive occlusal stress seem to have more periodontal destruction than teeth not experiencing occlusal stress” “Excessive occlusal stress is the cause of periodontal disease…. to treat periodontal disease successfully, the clinician must control occlusal forces” By the 1930’s most practitioners felt that: Excessive occlusal forces were a causative factor in periodontal disease Occlusal adjustment is an essential part of periodontal therapy Occlusal discrepancies should be prophylactically treated to prevent periodontal diseases

8. Occlusal forces need to be controlled to prevent and treat periodontal disease. The Dominant theme of the 30’s

9. What is occlusal trauma ? Occlusal trauma : Injury resulting in tissue changes within the attachment apparatus as a result of occlusal forces Primary Occlusal Trauma : Injury resulting in tissue changes from excessive occlusal forces applied to a tooth or teeth with normal support Secondary Occlusal Trauma : Injury resulting in tissue change from excessive occlusal forces applied to a tooth or teeth with reduced support . It occurs in association with bone loss, attachment loss and normal / excessive occlusal forces

10. Primary Occlusal Trauma Secondary Occlusal Trauma

11. What is traumatic occlusion ? The excessive occlusal force, traumatogenic occlusion is the etiologic factor causing the injury

12. Orban B, Weinmann J 1933 : Signs of traumatic occlusion in average human jaws. J Dent Res 1933,13:216 Gingival inflammation extending into the bone tissues is the cause of periodontal destruction !

13. Gingival inflammation extending into the bone tissues is the cause of periodontal destruction ! There is no relationship between occlusal forces and periodontal destruction !

14. Then why are there different forms of periodontal destruction ?

15. Weinmann J Progress of gingival inflammation into the supporting structure of the teeth. J Periodontol 1941;12:71-6. Human autopsy material “ an inflammatory process that began at the gingival attachment and spread into the surrounding bone, following the course of blood vessels”

16. ‘Altered pathways of destruction’

17. ‘Change in the orientation of the periodontal and gingival fibers which occurred in the presence of excessive occlusal forces allowing gingival inflammation to extend along the periodontal ligament – the cause of vertical bony defects ’

18. Glickman I, Smulow JB . Alterations in the pathway of gingival inflammation into the underlying tissues induced by excessive occlusal forces. J Periodontol 1962;33:7-13. Glickman I, Smulow J. The combined effects of inflammation and trauma from occlusion in eriodontitis . Int Dent J 1969;19(3):393-407 “in teeth undergoing occlusal trauma, the inflammation progressed in a different manner than that in teeth that were not undergoing occlusal trauma - an “altered pathway of destruction.” “Combined effects of occlusal trauma and inflammation as “co-destructive factors” in periodontal disease” . Multiple Risk Factors affecting the progression and severity of the disease process.

19. Glickman’s Co-Destructive Model for the role of occlusion in periodontal disease -1968 Excessive Occlusal forces Plaque and Local factors Gingival inflammation Horizontal Bone loss Vertical Bone Loss Normal Occlusal forces Standard Pattern of Bone Destruction Altered Pattern of Bone Destruction

20. Waerhaug J The angular bone defect and its relationship to trauma from occlusion and downgrowth of subgingival plaque. J Clin Periodontol 1979;6(2):61-82. Waerhaug J The infrabony pocket and its relationship to trauma from occlusion and subgingival plaque. J Periodontol 1979;50(7):355-65. No differences in disease progression could be detected between teeth that were undergoing occlusal trauma and teeth that were not All inflammation and bone loss were associated with the presence of bacterial plaque. Bacterial plaque always was present in close proximity to the site of periodontal destruction. Occlusal trauma played no part in periodontal destruction and plaque-related inflammation was the only cause of periodontal disease

21. Jens Waerhaug 1976 The plaque front is in close approximation to the epithelial attachment level and closely follows the morphology of the bone defect Relationship of plaque levels between adjacent teeth follow the apico – coronal bone levels Vertical bone defects distributed equally between traumatized and non traumatized teeth No relationship between excessive occlusal force and underlying bone defect No relationship between excessive occlusal forces and underlying vertical defets Bone loss always associated with the downgrowth of plaque

22. Lindhe J, Svanberg G . Influence of trauma from occlusion on the progression of experimental periodontitis in the beagle dog. J Clin Periodontol 1974;1(1 ):3-14. Lindhe J, Ericsson I . The influence of trauma from occlusion on reduced but healthy periodontal tissues in dogs. J Clin Periodontol 1976;3(2):110-22 . Lindhe J, Ericsson I . The effect of elimination of jiggling forces on periodontally exposed teeth in the dog. J Periodontol 1982;53(9):562-7. Ericsson I, Lindhe J . Effect of longstanding jiggling on experimental marginal periodontitis in the beagle dog. J Clin Periodontol1982;9(6):497-503.

23. Jan Lindhe Ingvar Ericsson Ericsson I , Lindhe J 1977 : Lack of effect of trauma from occlusion on the recurrence of experimental periodontitis . J Periodontol 1977: 4: 115-127

24. Eastman Dental Center , Rochester NY Polson A, Kennedy J, Zander H . Trauma and progression of marginal periodontitis in squirrel monkeys, Part I: co-destructive factors of periodontitis and thermally-produced injury. J Periodontal Res 1974;9(2):100-7. Polson A . Trauma and progression of marginal periodontitis in squirrel monkeys, Part II: co-destructive factors of periodontitis and mechanically-produced injury. J Periodontal Res 1974;9(2):108-13 . Polson A, Meitner S, Zander H . Trauma and progression of marginal periodontitis in squirrel monkeys, Part III: adaptation of interproximal alveolar bone to repetitive injury. J Periodontal Res 1976;11(5):279-89. Polson A, Meitner S, Zander H . Trauma and progression of marginal periodontitis in squirrel monkeys, Part IV: reversibility of bone loss due to trauma alone and trauma superimposed upon periodontitis. J Periodontal Res 1976;11(5):290-8. Polson A, Zander H . Effect of periodontal trauma upon intrabony pockets. J Periodontol 1983;54(10):586-91.

25. Polson AM, Meitner SW, Zander HA 1974 -1979 Trauma and progression of marginal periodontitis in squirrel monkeys I, II , III and IV . J Periodont Res

26. Within both animal models,researchers found that if oral hygiene was maintained and inflammation controlled, occlusal trauma resulted in increased mobility and loss of bone density, but no loss of attachment, during the length of the study. In no case in which inflammation was controlled was there any attachment loss or pocket formation. If the occlusal forces were removed, there was a return to pretreatment stability and bone volume. In animals in which plaque was allowed to accumulate and gingival inflammation was present, there was greater loss of bone volume and increased mobility, but still no attachment loss. Only in cases in which the bone support of beagle dogs was surgically decreased, inflammation was allowed to develop and occlusal stress was applied was there any evidence of attachment loss. The conclusion of both research groups was that without inflammation, occlusal trauma does not cause irreversible bone loss or loss of attachment Results

27. Important Conclusion : Occlusal forces thus do not initiate periodontal disease and so no prophylactic occlusal adjustment is necessary to prevent periodontitis N o one believes that excessive occlusal force initiates periodontitis , H owever, neither does anyone believe that occlusal force is incapableof causing periodontal injury.

28. HUMAN STUDIES Yuodelis RA, Mann WV Jr . The prevalence of and possible role of nonworking contacts in periodontal disease. Periodontics 1965;3(5):219-23. Shefter GJ, McFall WT Jr . Occlusal relations and periodontal status in human adults. J Periodontol 1984;55(6):368-74. Pihlstrom B, Anderson K, Aeppli D, Schaffer E. Association between signs of trauma from occlusion and periodontitis . J Periodontol1986;57(1):1-6. Jin L, Cao C. Clinical diagnosis of trauma from occlusion and its relation with severity of periodontitis . J Clin Periodontol 1992;19(2):92-7 Mixed results Teeth with nonworking contacts showed greater CAL and PPD. Periodontal charting and study models used , no direct patient examinations. Studies were epidemiologic in nature and looked at a general population rather than patients with periodontal disease.

29. Burgett F, Ramfjord S, Nissle R, Morrison E, Charbeneau T, Caffesse R. A randomized trial of occlusal adjustment in the treatment of periodontitis patients. J Clin Periodontol 1992;19(6):381-7. Effect of treating the occlusion on healing outcomes after periodontal treatment. In this trial, one-half of the patients received occlusal adjustment by means of selective grinding before undergoing surgical and non-surgical periodontal therapy. The other one-half did not receive occlusal adjustment. Group that received occlusal adjustment showed statistically significant improvements in attachment levels, when compared with patients who did not receive occlusal adjustment. This well-controlled study demonstrated that in a group of patients with existing periodontal disease, there was improved healing if occlusal trauma was minimized by occlusal adjustment.

30. 1996 World Workshop in Periodontics Gher M. Non-surgical pocket therapy: dental occlusion. Ann Periodontol1996;1(1):567-80. Current data indicates that there is inadequate information to determine whether a relationship exists between occlusion and the progression of periodontal disease.

31. 1999 Consensus Report on Periodontal Disease Classification Excessive occlusal forces alone do not initiate plaque-induced gingival disease or loss of connective tissue associated with periodontitis . Table of Contents Preface Jack G. Caton, Jr. Occlusal Trauma: Effect and Impact on the Periodontium William W. Hallmon Consensus Report: Occlusal Trauma

32. Retrospective and Observational research human studies in a private practice setting Nunn M, Harrel SK . The effect of occlusal discrepancies on periodontitis , part I: relationship of initial occlusal discrepancies to initial clinical parameters. J Periodontol 2001;72(4):485-94. Harrel SK, Nunn M . The effect of occlusal discrepancies on treated and untreated periodontitis , part II: relationship of occlusal treatment to the progression of periodontal disease. J Periodontol 2001;72(4):495-505 . Harrel S, Nunn M . Longitudinal comparison of the periodontal status of patients with moderate to severe periodontal disease receiving no treatment, non-surgical treatment, and surgical treatment utilizing individual sites for analysis. J Periodontol 2001;72(11):1509-19 .

33. Nunn M, Harrel SK . The effect of occlusal discrepancies on periodontitis,part I: relationship of initial occlusal discrepancies to initial clinical parameters. J Periodontol 2001;72(4):485-94.

34. In evaluating the initial data of all patients within the study, we found that teeth with an occlusal discrepancy had pocket depths approximately 1 mm deeper than those of teeth with no occlusal discrepancy. This difference was highly statistically significant (P ≤ .0001) and was true regardless of age, sex, smoking status or other risk factors Nunn M, Harrel SK “Our studies demonstrate very strong statistical evidence that occlusal discrepancies are a significant risk factor in the progression of periodontal disease”

35. Harrel SK, Nunn ME 2001 : The effect of occlusal discrepencies in treated and untreated periodontitis – II – Relationship of occlusal treatment to the progression of periodontal disease J Periodontol 2001 72, 495-505 Untreated Group (n=30) Partially treated Group (n=18) Fully treated Group (n=41) Individual teeth as experimental unit Progression of periodontal disease or improvement followed for every tooth

36. Results

37. Conclusions

38. General Conclusions Teeth with occlusal discrepancies had deeper probing depths Teeth with occlusal discrepancies had poorer prognosis Teeth with occlusal discrepancies had increase in probing depths with time Teeth with occlusal discrepancies had worsening prognosis with time Teeth receiving occlusal adjustment shows slowing of the progression of disease Thus occlusal discrepancies are a significant risk factor in the progression of periodontal destruction and treatment of occlusal discrepancies slows down periodontal destruction

39. So, how can we detect occlusal trauma clinically ? Occlusal trauma : Injury resulting in tissue changes within the attachment apparatus as a result of occlusal forces Since occlusal trauma is defined and diagnosed on the basis of histological changes it is impossible to diagnose occlusal trauma without a block section biopsy

40. 1. Is there a relationship between excess occlusal forces and the progress of periodontal disease ? 2. How can I clinically diagnose excessive occlusal force and when does a regular occlusal force become excessive ? 3. If diagnosed when should treatment be initiated and what should be accomplished ? Pertinent questions

41. Clinical indicators of occlusal trauma Fremitus Progressive mobility Occlusal discrepancies Wear facets in the presence of other indicators Tooth migration Tooth fractures Thermal sensitivity These clinical findings are extremely difficult to correlate with occlusal contacts. You cant arrive at a diagnosis only at an assumption

42. Centric Relation Centric Slide Acquired Centric ‘The relationship of the cusps is the most important factor in the transmission of forces to the periodontal supporting structures and any role it may play in the progression of disease or outcome of treatment ‘ Contact relationships of teeth

43. What is abfraction ? Is there a role for occlusion in its development ? Abfraction is the pathological loss of hard tooth substance by biomechanical loading forces Abrasion usually accompanied by marginal tissue recession and associated with a few teeth JS Rees : The role of cuspal flexure in the development of abfraction lesions – an FEM study Eur Jour of Oral Sci 1998 , 106: 1028-1032

44. Is there a role of occlusal loading in the genesis of NCCL’s Abfractions increase in size and depth with age – Levitch and Bader 1994 65% of affected individuals confirm parafunction – Berdnt 1991 96% evidence occlusal discrepancy – Barnes 1976 Affected individuals are six times likely to have group function rather than canine guidance in laterotrusion – Rees 1998 Conclusion Periodontal plastic procedures if envisaged should take into account control of any untoward habits and untoward occlusal loading to yield a better clinical outcome

45. Of what value is mobility assessment to management of periodontitis ?

46. Fleszar TJ, Knowles JW, Morrisson C, Brugett FG, Nissle RR, Ramfjord SP – Tooth mobility and periodontal therapy _ J Clin Periodontol 1980:7:495-505 8 year follow up study Patients receive scaling, OHI, Occlusal Adjustment Periodontal surgery Baseline , 3 month maintenance and annual PPD, CAL and Tooth mobility assessed Result: Teeth associated with mobility did not respond as positively as firm teeth becoming more pronounced with the second year though these could be effectively treated and maintained

47. Sheet anchor of mobility assessment Progressive mobility is to be addressed by controlling inflammation, occlusal adjustment, stabilizing appliances or splinting. The long term objective is to maintain heath, function, stability and comfort for the patients natural dentition or implants Association of mobile teeth with greater attachment loss, bone loss and increase in probing depth – Harrel 2001 Mobility and furcation have a compounding effect on the risk of greater attachment loss – Hom Lay Wang 1994

48. Cortellini P etal . The papilla preservation flap in the regenerative treatment of deep infrabony defects : clinical outcomes and postoperative morbidity J Periodontol 2000: 72: 1707-1712 Result : When tooth mobility was evaluated as a covariate, baseline tooth mobility was associated with a reduced anticipated gain in clinical attachment. Conclusion : Clinicians might consider reducing tooth mobility before starting regenerative procedures to facilitate therapeutic success

49. 1. Is there a relationship between excess occlusal forces and the progress of periodontal disease ? 2. How can I diagnose excessive occlusal force and when does a regular occlusal force become excessive ? 3. If diagnosed when should treatment be initiated and what should be accomplished ? Pertinent questions

50. Role of Splinting Result : No difference between splinted and non splinted teeth receiving osseous surgery Mobility returns to baseline levels in 6 months Conclusion : Based on available data it is prudent to reduce baseline mobility as an part of periodontal therapy Galler C et al . The effect of splinting on tooth mobility .2. After osseous surgery J Clin Periodontol 1979:317-333

51. Reversible approaches with a bight guard Selective occlusal grinding Orthodontic therapy Treatment Approaches

52. Modalities of reducing Night Guard Orthodontics Reduction of the interferences Splinting of mobile teeth Occlusal treatment should be performed where indicated as a routine part fo periodontal therapy

53. Under what clinical conditions is occlusal adjustment indicated ? Current Evidence: Centric slides contribute to the progression of periodontal destruction Mobility negatively affects the outcome of periodontal therapy How much each of these contributes together or separately to periodontal destruction is unknown and not guessable Thus when periodontal destruction is evident, occlusal treatment to reduce occlusal interferences and decrease tooth mobilty is indicated as a routine measure

54. Foz AM, Artese HP, Horliana AC, Pannuti CM, Romito GA . Occlusal adjustment associated with periodontal therapy-A systematic review.   J Dent. December 2012, Vol. 40:12, pp. 1025-1035 "Although the four studies evaluated in this review had demonstrated a possible improvement in periodontal parameters when occlusal adjustment is associated with periodontal therapy, there are still conflicts between them....Methodological issues suggest the need for new trials of a higher quality.” “It is important to note, however, that no adverse effects have been linked to occlusal adjustment, which means that although its benefits are not proved, it is also not detrimental”.

55. The Timeline Stillman PR 1917 Occlusal forces need to be controlled to prevent and treat periodontal disease. Orban B, Weinmann J 1933 : Gingival inflammation extending into the bone tissues is the cause of periodontal destruction ! Glickman I, Smulow 1968 Co-Destructive Model for the role of occlusion Waerhaug J 1978 Plaque-related inflammation was the only cause of periodontal disease Lindhe J 1977 Without inflammation, occlusal trauma does not cause irreversible bone loss World Workshop 1996 inadequate information to determine whether a relationship exists Nunn M, Harrel SK 2001 Very important adjunct to comprehensive care Foz AM, Artese HP 2012 Possible improvement in periodontal parameters with occlusal adjustment but data conflicting

56. Conclusions - Periodontics The need for adjustment should be based on a definite diagnosis of a traumatic lesion rather than the location of some occlusal interferences which may be of no significance.” Occlusal discrepancies are a significant risk factor in the progression of periodontal destruction and treatment of occlusal discrepancies slows down periodontal destruction The approach best supported by the available evidence , and it is the best way to ensure that treatment of occlusal trauma is directed toward the specific instances in which occlusal trauma truly exists.

57. The treatment of occlusal discrepancies should be considered as an integral part of the overall treatment of periodontal disease and should be included in the comprehensive treatment plan. However,since not every tooth with an occlusal discrepancy is suffering from occlusal trauma — not every occlusal discrepancy in a patient with periodontitis needs adjustment. Summary View occlusal therpay as a mechanism of reducing risk factors in the multifactorial etiology of periodontal disease – perform it always !

58. Occlusal considerations in Implants The fundamental, inherent difference between the tooth and implant is that while an endosseous implant is in direct contact with the bone a natural tooth is suspended by PDL Mean value of displacement upon axial loading of tooth: 25-100µm Range of motion of osseointegrated dental implants : 3-5µm Sekine et al. 1986; Schulte 1995

59. Characteristic Tooth Implant Connection PDL Osseointegration Proprioception Mechanoreceptors Osseoperception Tactile Sensitivity High Low Axial Mobility 25-100 µm 3-5 µm Movement Phases Primary non-linear Secondary elastic One phase –Linear and elastic Movement Patterns Primary immediate Secondary gradual Gradual Fulcrum to lateral forces Apical third of root Crestal bone Load bearing Shock absorbing function Stress concentration Signs of overloading PDL thickening , mobility, fremitus , wear facets, pain Screw loosening, fracture Loading Characteristics : Tooth vs Implant

60. Additional factors that can cause overloading Large cantilevers especially distally Parafunctional activity Improper occlusal designs Combination of poor bone quality and overload Underengineered prosthesis Loss of osseointegration and excessive marginal bone loss from excessive lateral load provided with premature occlusal contacts in animal studies ( Isidor 1996, 1997; Miyata et al.2000). Contradictory to the findings from the above studies, some studies have demonstrated that overloading did not increase marginal bone loss ( Asikainen et al. 1997; Hurzeler et al. 1998). Occlusal overload may act as one of the factors causing marginal bone loss and implant failure.

61. Types and principles of implant occlusion Balanced Occlusion - Pameijer 1983 Group function - Santos 1985 Mutually protected occlusion - Hobo et al.1989 All of the concepts may have maximum intercuspation (MIP) during habitual and/or centric occlusion

62. Bilateral balanced occlusion has all teeth contacting during all excursions In group-function occlusion , posterior teeth contact on the working side during lateral movements, without balancing side contacts . Mutually protected occlusion has posterior teeth protection in habitual and/ or centric occlusion via posterior contacts in MIP while light contacts on anterior teeth and anterior guidance during all excursions. These occlusal concepts have been successfully adopted with modifications for implant-supported prostheses ( Adell et al. 1981; Chapman 1989; Hobo et al. 1989; Naert et al. 1992; Lundgren & Laurell 1994; Wismeijer et al. 1995; Mericske -Stern et al. 2000).

63. Many philosophies of occlusion No definitive scientific studies to prove: -one type of tooth form -one type of occlusal scheme -clear preference by patients -one more efficient than the other

64. Implant protective occlusion – Carl Misch & Martha Bidez Medially positioned – Lingualized occlusion Timing of contacts Influence of contact area Mutually protected articulation Crown – Implant body angle and occlusal load Cusp angle of crowns Cantilever distance Crown height Crown contour Protection of the weakest component Occlusal materials

65. The rationale for an implant protective occlusion Poor occlusal schemes Increase the magnitude of loads Increases mechanical stress and strain at bone crest Increased complications of prosthesis and bone support

66. Implant-protected occlusion has been proposed strictly for implant prostheses ( Misch & Bidez 1994 ). Key features Providing load sharing occlusal contacts Modifications of the occlusal table and anatomy Correction of load direction Increasing of implant surface areas Reductionof occlusal contacts in unfavorable biomechanics. Occlusal morphology guiding occlusal force to the apical direction Utilization of cross-bite occlusion Narrowed occlusal table Reduced cusp inclination Reduced length of cantilever in mesio -distal andbucco -lingual dimension

67. Basic principles of implant occlusion B ilateral stability in centric (habitual ) occlusion E venly distributed occlusal contacts and force N o interferences between retruded position and centric (habitual ) position W ide freedom in centric (habitual) occlusion Anterior guidance whenever possible Smooth,even , lateral excursive movements withoutworking /non-working interferences

68. Weinberg (1998) recommended continuous 1.5mm flat fossa area for wide freedom in centric in the prosthesis based on his clinical experience. In addition, Gibbs et al. (1981) found that anterior or canine guidance decreased chewing force compared with posterior guidance . Quirynen et al. (1992) reported that lack of anterior contacts in an implant-supported cross-arch bridge created excessive marginal bone loss in posterior implants Occlusal schemes may be less crucial factors of implant overloading than the number and position of occlusal contacts on implant prostheses . ( Hobkirk & Brouziotou-Davas (1996) More Ideas

69. Typically 30–40 % reduction of occlusal table in a molar region has been suggested, but any dimension larger than the implant diameter can create cantilever effects and eventual bending moments in single implant prosthesis ( Misch 1993; Rangertet al. 1997) Misch ( 1999) described that a narrow occlusal table also improves oral hygiene and reduces risks of porcelain fracture . The utilization of cross-bite occlusion can avoid the buccal cantilever and increase the axial loading ( Misch 1993; Weinberg 1998 ). In order to prevent the potential overloading on implants from the positional changes, re-evaluation and periodic occlusal adjustments are imperative ( Dario 1995 ; Rangert et al. 1997; Misch 1999) Even more Ideas

70. Occlusion on full-arch fixed prostheses Bilateral balanced occlusion with opposing complete denture Group function occlusion or mutually protected occlusion with shallow anterior guidance when opposing natural dentition No working and balancing contact on cantilever Infraocclusion in cantilever segment (100 mm) Freedom in centric (1–1.5mm) Chapman 1989; Quirynen et al.1992 ; Lundgren & Laurell 1994

71. Occlusion on overdentures Bilateral balanced occlusion using lingulized occlusion Monoplane occlusion on a severely resorbed ridge Lang & Razzoog 1992 ; Wismeijer et al. 1995; Mericske -Stern et al. 2000).

72. Occlusion on posterior fixed prostheses Anterior guidance with natural dentition Group function occlusion with compromised canines Centered contacts, narrow occlusal tables, flat cusps , minimized cantilever Cross bite posterior occlusion when necessary Natural tooth connection with rigid attachment when compromised support During lateral excursions, working and non-working interferences should be avoided in posterior restorations (Lundgren & Laurell 1994 ). Moreover, reduced inclination of cusps, centrally oriented contacts with a 1– 1.5mmflat area, a narrowed occlusal table, and elimination of cantilevers have been proposed as key factors to control bend overload in posterior restorations ( Weinberg 1998 ; Curtis et al. 2000 ).

73. Narrowing the bucco -lingual width of the occlusal surface by 30% and chewing soft food significantly reduced bending moments on the posterior three-unit fixed prosthesis ( Morneburg & Pro¨schel 2003). The study also suggested that soft diet and reduction of the buccolingual , occlusal surface need to be considered in unfavorable loading conditions, such as immediate loading, initial healing phase, and/or poor bone quality. Occlusion on posterior fixed prostheses

74. Wennerberg & Jemt (1999) described that additional implants in the maxilla could provide tripodism to reduce overloading and clinical complications . Also, axial positioning and reduced distance between posterior implants are important factors to decrease overloading (Belser et al. 2000 ). The utilization of cross-bite occlusion with palatally placed posterior maxillary implants can reduce the buccal cantilever and improve the axial loading ( Misch 1993; Weinberg 1998). If the number, position, and axis of implants are questionable, natural tooth connection with a rigid attachment can be considered to provide additional support to implants ( Rangert et al. 1991; Belser et al. 2000; Naert et al. 2001). Occlusion on posterior fixed prostheses

75. Occlusion on single implant prosthesis Anterior or lateral guidance with natural dentition Light contact at heavy bite and no contact at light bite Centered contacts (1–1.5mm flat area) No offset contacts Increased proximal contact The occlusion in a single implant should be designed to minimize occlusal force onto the implant and to maximize force distribution to adjacent natural teeth ( Misch 1993; Lundgren&Laurell 1994; Engelman 1996 ). In addition, working and non-working contacts should be avoided in a single restoration ( Engelman 1996 ). Light contacts at heavy bite and no contact at light bite in MIP are considered a reasonable approach to distribute the occlusal force on teeth and implants (Lundgren & Laurell 1994 )

76. Increased proximal contacts in the posterior region may provide additional stability of restorations ( Misch 1999). Two implants for a single molar have been utilized and demonstrated less screw loosening and higher success rates ( Balshi et al. 1996 ). Occlusion on single implant prosthesis

77. Poor quality of bone/Grafted bone Longer healing time Progressive loading by staging diet and Occlusal contacts/materials

78. Increase support area Bone quality • Extended healing time • Progressive loading Bone quantity • Implant number • Implant diameter • Implant length • Implant surface Occlusal morphology • Flat central fossa • ↓ Cusp inclination • ↓ Occlusal table • Along implant axis • Centered contacts Improve Force direction Reduce force magnification Occlusal contacts • Position • Distribution Types of Prosthesis • Cantilever length ↓ • Cross bite • Splinting Implant position Basic Tenets

79. What then is the golden rule of implant occlusion ?

80. The golden rule is that , there is no golden rule George Bernard Shaw , 1903

81. Summary No definitive studies to show one type of occlusion is the best Follow established clinical principles Assess each case and adapt to the clinical situation And Continue to read the literature Currently, there is no evidence-based , implant-specific concept of occlusion

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