Final failures in fixed partial denture Richa.pptx

Final failures in fixed partial denture Richa.pptx

1. FAILURES IN TEETH SUPPORTED FIXED DENTAL PROSTHESIS Richa Roy 1

2. CONTENTS Introduction Classification of Failures Biological Failures Mechanical Failures Porcelain Fractures Esthetic failures Maintenance failures Repair of fracture porcelain units Summary & Conclusion References 2

3. INTRODUCTION . failures in fixed prosthodontic treatment can be frustrating and complex both in terms of diagnosis and treatment. . Failure of the restorations is a multifactorial problem which could be attributed to a combination of different reasons. they are varied and often complex in cause and effect. . When a problem occurs, the design and condition of the restoration and associated structures must be considered. . This, in turn, will determine whether the problem can be resolved by intraoral or extraoral adjustment or repair, or by replacement with new restoration . 3

4. The objectives of fixed prosthodontic treatment include: Preservation or improvement of related hard and soft tissue structures; Preservation or improvement of oral functions; Improvement or restoration of esthetics; Ensuring restoration retention, resistance, and stability; Providing restorations with mechanical or structural integrity; P reserving or improving patient comfort; and Designing restorations for maximum longevity. 4 Manappallil JJ. Classification system for conventional crown and fixed partial denture failures. The Journal of prosthetic dentistry. 2008 Apr 1;99(4):293-8.

5. CLASSIFICATION OF FAILURES 5

6. BERNARD G N SMITH 6

7. JOHN JOY MANAPPALLIL Class Description Class I Cause of failure is correctable without replacing restoration. Table I. Grading of failures based on severity J Prosthet Dent 2008;99:293-298 Class II Cause of failure is correctable without replacing restoration; however, supporting tooth structure or foundation requires repair or reconstruction . Class III Failure requiring restoration replacement only. Supporting tooth structure and/or foundation acceptable. 7

8. Class V Severe failure with loss of supporting tooth or inability to reconstruct using original tooth support . Fixed prosthodontic replacement remains possible through use of other or additional support for redesigned restoration. Class IV Failure requiring restoration replacement in addition to repair or reconstruction of supporting tooth structure and/or foundation. Class VI Severe failure with loss of supporting tooth or inability to reconstruct using original tooth support. Conventional fixed prosthodontic replacement is not possible . 8

9. JOHNSTON’ S CLASSIFICATION 9 Anusavice KJ. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal–ceramic fixed dental prostheses. Dental Materials. 2012 Jan 1;28(1):102-11.

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11. 11 Dykema R.W., Goodacre C.J. and Phillips R.W. “Johnston’s Modern Practice in Fixed Prosthodontics ”. Fourth Edn , W.B. Saunders Co. Philadelphia, London.

12. The four major diagnostic aids to making a dental diagnosis are :. DIAGNOSIS AND TREATMENT PLANNING 12 Contemporary fixed prosthodontics, Stephen F. Rosenstiel 3 rd edition

13. ABUTMENT TOOTH SELECTION D epends on the length of span of the restoration and the amount of stress that will be applied to the abutment . The strength of a tooth is directly proportional to the amount of periodontal ligament that attaches the tooth to bone. Minimal requirement for an abutment tooth is a 1:1 crown : root ratio. Contemporary fixed prosthodontics, Stephen F. Rosenstiel 3 rd edition 13

14. A simple guide in deciding whether to fabricate a fixed or a removable partial denture is ANTE’S RULE comes in to play. “In fixed bridges the combined pericemental area of the abutment teeth should be equal to or greater in pericemental area than the teeth to be replaced.” Contemporary fixed prosthodontics, Stephen F. Rosenstiel 3 rd edition 14

15. BIOLOGIC FAILURES 15

16. CAUSES: CARIES IATROGENIC Failure to detect Incomplete removal Misfit/Improper design of prosthesis PATIENT RELATED Systemic factors Xerostomia Drug induced Improper hygiene Diet 16 Amurdhavani BS, Ganapathy D. Failures in fixed partial denture. Drug Invention Today. 2020 Mar 1;13(3).

17. This is usually perceived by the patient as : Pain or sensitivity due to hot, cold or sweet foods Bad taste Bad breath Loose restoration Fractured teeth Discolored teeth 17 Amurdhavani BS, Ganapathy D. Failures in fixed partial denture. Drug Invention Today. 2020 Mar 1;13(3).

18. Early detection via probing of the margins of the prosthesis and tooth surfaces with sharp explorer. Radiographs are helpful in detection of caries inter proximally. Modern practice in fixed prosthdontics , Johnston, 4 th edition. Under extended margin 18

19. As per Schwartz et al, causes of unserviceability by frequency, of a fixed prosthesis include: Causes % Caries 36.8 Crowns uncemented 12.1 Excessive wear 11.3 Periodontal disease 7.4 Mobility of abutment 4.4 Lost veneer 3.7 Periapical involvment 3.3 19 Awareness of Hygiene Practices and Satisfaction Level among Patients Wearing Fixed Dental Prosthesis: A Cross-Sectional Survey. Journal of Clinical & Diagnostic Research. 2020 May 1;14(5).

20. MANAGEMENT Conventional operative procedures can be used to restore small carious lesions with out need to fabricate new prosthesis If the caries extends occlusally beyond the margins of the retainer then remove the F.P.D., explore the tooth and be guided in reconstruction by what remains . Over extension - correct extensions & restore the carious lesion. Open margins and under extended margins require the remaking of prosthesis . Modern practice in fixed prosthdontics , Johnston, 4 th edition. 20

21. Caries in the proximal surfaces may require removal of the prosthesis to obtain access to caries. If the lesion is small the tooth preparation can be extended to eliminate the caries and new prosthesis fabricated, if required. When larger lesions are present, they must be excavated and restored and the abutment preparation is extended to cover the filling and a new restoration is fabricated . Under extended margin 21 Modern practice in fixed prosthdontics , Johnston, 4 th edition.

22. CARIES OF ADJACENT TEETH Lack of proximal contact 22

23. Check the approximal contacts 23

24. ROOT CARIES Elderly , Gingival recession & pockets Xerostomia – Medication/radiation Marginal leakage Poor contact Modern practice in fixed prosthdontics , Johnston, 4 th edition. PRIMARY CAUSES 24

25. Extensive lesions ..encroach pulp.. endodontic treatment necessary or if it is not possible ..extracted. Marginal caries lesions generally begin at surface which progress inward.. Cause- incomplete removal of caries during a previous treatment or misfit of the casting that allows gross leakage to occur. 25 Modern practice in fixed prosthdontics , Johnston, 4 th edition.

26. PULP DEGENERATION This is usually perceived by patient as : 26

27. Modern practice in fixed prosthdontics , Johnston, 4 th edition. Whenever possible access made through retainer & endodontic treatment completed. Often Post & core may be necessary MANAGEMENT USE OF VARNISHES AND DENTIN BONDING AGENTS FORMS A BARRIER THAT PROTECTS THE PULP FROM CHEMICAL INJURIES. SIMILARLY EFFICIENT IRRIGATION MUST BE PROVIDED. 27

28. PERIODONTAL BREAKDOWN Modern practice in fixed prosthdontics , Johnston, 4 th edition. Causes Poor marginal adaptation and proximal contact Over contoured axial surfaces Excessively large connectors Large Pontic contacts on edentulous ridge. Prosthesis with rough surfaces Heavy occlusal forces Few abutment teeth Oversized food table 28

29. This is perceived by the patient as : Looseness of teeth or FPD Drifting of teeth Bleeding tissues Changes in color of gums Bad taste Bad breath Pain which is some times received by applying side ways pressure from opposing tooth . Abscess formation Poor esthetics 29

30. Aspects of the prosthesis that hinders with the effective plaque control or removal are: Poor marginal adaption Over contouring of the axial surfaces of the retainer. Excessively large connectors that restrict cervical embrasure space. Pontic that connects too large an area on the edentulous ridge. Prosthesis with rough surfaces that promotes plaque accumulation. 30 Dominiak M, Shuleva S, Silvestros S, Alcoforado G. A prospective observational study on perioperative use of antibacterial agents in implant surgery. Advances in Clinical and Experimental Medicine. 2020;29(3):355-63.

31. Under contoured areas - reconstruction of the F.P.D . Over contoured areas - reshaped and repolished Improper clearance – reconstruction of F.P.D. Oversized pontic - F.P.D. must be removed, the tissue allowed to reorganize and the F.P.D. reconstructed. A removable irritant - the area should be cleaned. Severe periodontal breakdown can produce extensive bone loss results in the loss of abutment teeth and attached prosthesis . Less severe breakdown can be treated without fear of loss of teeth but treatment involves surgery . Which might require new prosthesis fabrication due to altered soft tissue configuration. MANAGEMENT Modern practice in fixed prosthdontics , Johnston, 4 th edition. 31

32. In case of long span F.P.D ., the F.P.D. must be removed and remade with multiple terminal abutments . If not possible then the prepared abutment teeth should be recontoured for the support and retention of a removable prosthesis. For oversized occlusal table , an attempt may be made to narrow the distance between the cusp tips by reducing the bucco -lingual measurement often at the expense of lingual cusp. Maintenance of proper oral hygiene. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 32

33. Occlusal problems Modern practice in fixed prosthdontics , Johnston, 4 th edition. Causes Centric and eccentric interferences Unequal occlusal forces Habits like bruxism , clenching Clinical features: Wear facets Mobility Tenderness on percussion Open contacts Perforation and cusp fracture PDL space widening 33

34. Occlusal discrepancies can be perceived by the patient as : General discomfort with the bite. Sore teeth Loose teeth or FPD . Sensitive teeth. Tired or sore muscles. 34

35. Interfering centric or eccentric occlusion contacts can cause tooth mobility overtime. If it is detected early occlusal adjustment with out permanent damage can be done . When left unattended can also cause irreversible pulp damage requiring endodontic treatment . Use of an occlusal splint where required Slightly flatter occlusal table MANAGEMENT Contemporary fixed prosthodontics, Stephen F. Rosenstiel 3 rd ed 35

36. Tooth perforation Modern practice in fixed prosthdontics , Johnston, 4 th edition. Root canal treatment Pinhole and pin placement Preparation of post space 36

37. Contemporary fixed prosthodontics, Stephen F. Rosenstiel 3 rd ed MANAGEMENT Extend the preparation to cover the defect Surgically inaccessible, may ultimately lead to extraction of the tooth periodontal surgery , smoothening Place a restoration into perforated area Endodontic treatment 37

38. Sub pontic inflammation It is perceived by the patient as : Pain, swelling Bad breath Bad taste Bleeding gums Poor esthetics 38

39. Is an ectopic growth of bone occurring on the edentulous ridge beneath a fixed partial denture. P ossible etiologies of SOH such as functional stresses and chronic irritation by the prosthetic treatments as well as genetic predisposition . SOH does not usually require treatment or a biopsy . It is a slow-growing and benign proliferation of the alveolar bone which regresses on its own after removing the cause Sub- pontic osseous hyperplasia 39

40. Aydin , U., Yildirim , D., & Bozdemir , E. (2013). Subpontic osseous hyperplasia: Three case reports and literature review.  European journal of dentistry ,  7 (3), 363–367. https://doi.org/10.4103/1305-7456.115424 40

41. MECHANICAL FAILURES 41 Porcelain Jacket Crown Failures

42. The patient may sense general looseness or sensitivity to temperature or sweets . R ecurring bad taste or odour which must be differentiated from similar symptoms caused by poor oral hygiene or periodontal problems. Recall appointments should include attempts to un seat existing prosthesis by lifting the retainers up and down ( occlusocervically ) while they are held between fingers and curved explorer placed under the connector . LOSS OF RETENTION Modern practice in fixed prosthdontics , Johnston, 4 th edition. 42

43. If loose the occlusal motion causes fluids to be drawn under the casting and when casting is reseated with cervical force the fluid is expressed generally producing bubbles as the air and saliva are simultaneously displaced. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 43

44. CAUSES FOR RETENTION FAILURE Contemporary fixed prosthodontics, Stephen F. Rosenstiel 3 rd edition 44

45. A. Excessive taper : Theoretically , the more nearly parallel the opposing walls of the preparation are, the greater should be the retention . Tooth preparation taper should be kept minimal because of its adverse effect on retention . Recommendations for optimal axial wall taper of tooth preparations for cast restorations ranged from 10 to 12 degrees , insuring the absence of undercuts. Journal of Clinical and Diagnostic Research. 2011 October, Vol-5(5): 1128-1133 Bernard G.N., Smith. Planning and making crown and bridges, 3rd edition, 1981 St. Louis Mosby, p. 184. 45

46. B. Short clinical crown : G reater the surface area of the preparation the greater is its retention. A short, over-tapered or short clinical crown would be without retention as there would be many paths of removal . T he length must be great enough to interfere with the arc of the casting pivoting about a point on the margin on the opposite side of the restoration . A shorter wall cannot afford this resistance . The walls of short preparations should have as little taper as possible. Journal of Clinical and Diagnostic Research. 2011 October, Vol-5(5): 1128-1133 Bernard G.N., Smith. Planning and making crown and bridges, 3rd edition, 1981 St. Louis Mosby, p. 184. 46

47. In case of excessive taper: Incorporation of proximal grooves. Additional retentive grooves (should be along with the path of insertion). Additional pins In case of short crowns: Crown lengthening procedure Modification of supra-gingival margin to sub-gingival margin Additional retentive grooves and proximal box Incorporation of pins Addition of extra abutments 47 Journal of Clinical and Diagnostic Research. 2011 October, Vol-5(5): 1128-1133 Bernard G.N., Smith. Planning and making crown and bridges, 3rd edition, 1981 St. Louis Mosby, p. 184.

48. Hasanzade M, Aminikhah M, Afrashtehfar KI, Alikhasi M. Marginal and internal adaptation of single crowns and fixed dental prostheses by using digital and conventional workflows: A systematic review and meta-analysis. The Journal of Prosthetic Dentistry. 2020 Sep 12. C. Misfit : The measurement of misfit at different locations and geometrically related to each other and defined as : 48

49. Causes for misfit : Expansion of the metal substructure Improper burnout temperature Distortion of the margins (towards the tooth surface) Distortion of the metal substructure Metal bubbles in occlusal or marginal regions Inadequate vacuum during investing Improper brush technique No surfactant Excessive oxide layer formation in inner side of the retainer (due to contaminated metal or repeated firing of porcelain). Too tight contact points 49

50. Misalignment : In case of the FPD , it is more difficult to differentiate whether the FPD is not seating because of a faulty fit, or the alignment of the retainers relative to each other is incorrect. In case of misalignment, the FPD will have some ‘spring’ in it and tend to seat further on pressure due to the abutment teeth moving slightly, whereas in the case of a defective fit, the resistance felt will be solid. 50

51. Causes for misalignment Abutment displacement due to improper temporization. Distortion of wax pattern while sprueing and investing. Casting defects. Distortion of metal frameworks in porcelain firing. Porcelain flow inside the retainers. Misalignment of soldering points . 51

52. Cement selection Expired cements In correct manipulation of cement Too thin mix Setting of the cement prior to cementation Inadequate isolation Incomplete removal of temporary cement Inadequate amount of cement Saliva or cotton Contamination 52 D. Improper cementation procedures

53. When retainer comes loose the prosthesis must be removed so that the abutment teeth can be evaluated, both clinically as well as radiologically . If the restoration can be dislodged from other prepared teeth with out damage and if no caries is present it is possible to re-cement the restoration . Improper cementation procedure may have caused the problem. 53

54. Connector failure A connector between an abutment and a pontic or between two pontics can fracture under occlusal forces . Connector fracture will cause excessive forces on the surviving abutment as the prosthesis will act as a cantilever bridge Connectors mainly fracture due to metal weakening caused by casting porosity or due to too small joint area 54

55. Detection of Connector F ailure Wedges are placed beneath the connector to separate the fixed partial component to conform diagnosis 55

56. Occasionally an inlay like dove tailed preparation can be developed in the metal to span the fracture site and casting and can be cemented to stabilize the prosthesis . If this is not possible the pontic should be removed by cutting through intact connectors A temporary removable partial denture can be placed to maintain the space between teeth.  Modern practice in fixed prosthdontics , Johnston, 4 th edition. 56

57. Extend the connector area lingually and proximally as close to the occlusal and labial surface as possible. Extend the connectors as far as possible towards the labial/ buccal and occlusal /cervical aspect without overly compromising the aesthetic The connector area must be sufficiently large to provide adequate strength and stability. 57

58. Influence of Radius of Curvature at Gingival Embrasure in Connector Area on Stress Distribution of Three-Unit Posterior Fixed Partial Denture 58 SaranBabu , Kalamalla A et al. “Influence of Radius of Curvature at Gingival Embrasure in Connector Area on Stress Distribution of Three-Unit Posterior.”  Journal of International Society of Preventive & Community Dentistry  vol. 9,4 338-348. 6 Aug. 2019

59. Occlusal Wear It is caused due to : Insufficient thickness of restorative material Inadequate control of occlusion Highly abrasive diet Poor abrasion resistance of the restorative material Habits Modern practice in fixed prosthdontics , Johnston, 4 th edition. 59

60. Perforation allows leakage and caries to occur which ultimately leads to prosthesis failure . In case of cast restorations, perforation when detected early and is very small, a goldfoil or amalgam restoration can be placed that gives excellent marginal seal.. If metal is extremely thin a new prosthesis should be fabricated. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 60

61. Tooth fracture Coronal tooth fracture can result in considerable loss of tooth structure or it can be minor with little damage . Small coronal tooth fracture often leaves the restoration adequately retained with only formation of a small defect which can be restored. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 61

62. Abutment tooth fractures under full coverage retainers usually occur horizontally at the level of the finish line leaving behind little or no coronal tooth structure . This requires removal of prosthesis, endodontic treatment a post and core with a new prosthesis . Single restorations can be salvaged if finish line with a little coronal tooth structure remain intact after fracture . A post and core can be fabricated to fit both the restoration with the prepared tooth. 62

63. Fracture around full crowns :– horizontally at level of finish line – Endo, post & core, new prosthesis If finish line is intact – Retrofit technique Modern practice in fixed prosthdontics , Johnston, 4 th edition. 63

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65. Root fracture They are often located well below the alveolar bone crest so it generally undergoes extraction and alternate treatment plan suggested. In some cases fracture terminates at or just below the alveolar bone. Perform periodontal surgery remove adequate bone to expose the fracture site and evaluate if it can be encompassed by a new prosthesis. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 65

66. These fractures are mainly caused due to: Trauma During endodontic treatment Forceful sewing of a post. Attempt to fully seat a improperly fitting cast post and core. Short screw tapered with poorly fitting posts are conducive to root fracture as is excessive thinning of the root. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 66

67. Porcelain fracture Porcelain fracture’s occur with both metal ceramic and all ceramic restoration Majority of metal ceramic fracture owe to design characteristics of the metal frame work, problems related to occlusion. All ceramic restoration fractures mainly due to faulty tooth preparation or presence of heavy occlusal forces. 67

68. Metal ceramic failure 68

69. Frame work design 69

70. The presence of heavy occlusal forces or habits such as clenching or bruxism can cause fracture . Centric or eccentric occlusal interferences can also place forces on porcelain, capable of causing fracture. OCCLUSION 70

71. Modern practice in fixed prosthdontics , Johnston, 4 th edition. Improper handling of alloy metal contamination B ubbles at the interface of metal and ceramic- creating stress and possibly cracks Excessive oxide formation on alloy cause separation of the porcelain from the metal Metal handling procedures 71

72. A tooth preparation with slight undercut can cause binding of the prosthesis as it is seated which could initiate a crack in the porcelain . The fracture may not be apparent during try in that could go unnoticed until premature post insertion failure occurs. An impression that is slightly distorted can cause same problem. Modern practice in fixed prosthdontics , Johnston, 4 th edition. Preparation, impression and insertion 72

73. ALL CERAMIC FAILURES The quality of tooth preparation with the magnitude of the occlusal forces present are the predominant factors that determine clinical success or failure. Presence of heavy occlusal forces during clenching or bruxism has also been reported harmful. T he tooth preparation must be designed to support the restoration since no metal is present to provide support. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 73

74. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 74

75. Vertical fracture: Sharp areas of the prepared tooth such as line angles or incisal edge produce high stress in the restoration that can cause these fractures . When tapered finish line is used, restoration contacts the tooth on a sloping surface resulting in forces that attempt to expand the restoration which are not well resisted by porcelain, leading to vertical fracture. 75

76. Facial cervical fracture: It occurs in a semilunar form mainly due to short tooth preparation. The incisocervical length of the preparation should be 2/3 to 3/4 th that of final restoration. When preparation is short forces applied at incisal edge attempt to tip the restoration facially and cause cervical porcelain fracture. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 76

77. Lingual fracture : 77

78. All-ceramic or metal-ceramic tooth-supported fixed dental prostheses. A systematic review of the survival and complication rates 78 After an observation period of 3 years , the lowest failure rate were observed for metal-ceramic FDPs (5.6%) compared with a failure rates of 9.6% for densely sintered zirconia ceramic FDPs, 10.9% for reinforced glass ceramic FDPs and 13.8% for glass-infiltrated alumina FDPs Pjetursson , B. E., Sailer , I., Makarov , N. A., Zwahlen , M., & Thoma , D. S. (2015).  All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A

79. Two approaches to porcelain repair are possible . If a larger area of porcelain has been lost- a porcelain facing may be constructed, and placed using a resin based luting material . If a lesser amount of porcelain is lost - application of composite restorative material . Repair of fractured porcelain units 79

80. Repair of porcelain facing : 80

81. Repair by placement of composite 81

82. 82

83. Esthetic failure Ceramic restoration more often fails esthetically than biologically or mechanically. One of the main reason is unacceptable color match. This could be the result of the inability to match patients natural teeth with porcelain colour . “ Metamerism ” is an ever present problem that contributes to poor color matching. Modern practice in fixed prosthdontics , Johnston, 4 th edition. 83

84. Insufficient tooth reduction or failure to properly apply and fire the porcelain may have created a restoration that does not match the shade guide or the surrounding teeth. Esthetic failures can also occur because of incorrect form or a frame work design that display metal. In addition natural teeth under go color changes that do not occur in porcelain 84

85. ESTHETIC FAILURES IN FIXED PARTIAL DENTURES-A SYSTEMATIC REVIEW Poor color match is the most frequent reason for the remake of tooth supported fixed restorations . Failure to identify patient expectations regarding esthetics Improper shade selection Metal exposure in connector, cervical and incisal regions Failure to produce incisal and proximal translucency Improper contouring Journal of Int Dent Med Res 2018; 3: (3), pp. 146-153 ) 85

86. Failure to harmonize contralateral tooth morphology Color Contour Position Angulation Discoloration of facing or supporting natural tooth 86 Journal of Int Dent Med Res 2018; 3: (3), pp. 146-153 )

87. causes Failure to transfer the shade to dental laboratory Excessive metal thickness at incisal and cervical region Thick opaque layer application Surface blistering ("chalky" appearance) Over glazing Metal exposure in connector, cervical and incisal regions Dark space in cervical third due to improper pontic selection ( Anteriors ) Failure to produce incisal and proximal translucency Improper contouring 87

88. Post Cementation Instructions RECALL APPOINTMENTS HOME CARE MAINTENANCE FAILURES 88

89. CONCLUSION Failures most often occur because of violation of principles either collectively or individually. The renewal process is both costly and time consuming and therefore remains a clinical problem. Failures in the anterior region pose an aesthetic problem while in the posterior, chewing function is also affected. The published literature reveals that reasons for failures cover a wide spectrum from iatrogenic factors and laboratory mistakes to patients setbacks, which with careful planning and use of novel materials and techniques, can be overcome. 89

90. References Modern practice in fixed prosthdontics , Johnston, 4 th edition. Contemporary fixed prosthodontics, Stephen F. Rosenstiel 3 rd edition Dykema R.W., Goodacre C.J. and Phillips R.W. “Johnston’s Modern Practice in Fixed Prosthodontics”. Fourth Edn , W.B. Saunders Co. Philadelphia, London. Brown M.H. “Causes and prevention of fixed prosthodontic failures”. J. Prosthet . Dent. 1993 ; 30: 617-622. Barreto M.T. “Failures in ceramometal fixed restoration”. J. Prosthet . Dent. 1994 ; 51: 186-189. Mutlu Ozcan , Wilhelm Niedermeier “Clinical study on the reasons for and location of failures of metal-ceramic restorations and survival of repairs”. Int. J. Prosthodont . 2012 ; 15: 299-302 . Association CD. Quality evaluation for dental care: guidelines for the assessment of clinical quality and professional performance. Los Angeles; Anusavice KJ, Kakar K, Ferree N. Which mechanical and physical testing methods are relevant for predicting the clinical performance of ceramic-based dental prostheses? Clin Oral Implants Res 2007;18(Suppl. 3):218–31. Kelly JR. Clinically relevant approach to failure testing of all-ceramic restorations. J Prosthet Dent 1999;81:652–61 90

91. Burke E.J.T. and Grey N.J.A. “Repair of fractured porcelain units: alternative approaches”. Br. Dent. J. 1994; 176: 251-256. Chung K.H. and Hwang Y.C. “Bonding strengths of porcelain repair systems with various surface treatments”. J. Prosthet . Dent. 1997; 78: 267-273. Walten J.N., Gardner F.M. and Agar J.R. “A survey of crown and fixed partial denture failures: Length of service and reasons for replacement”. J. Prosthet . Dent. 1996; 56: 416-421 . Sailer I, Pjetursson BE, Zwahlen M, Hammerle CH. A systematic review of the survival and complication rates of all-ceramic and metal–ceramic reconstructions after an period of at least 3 years. Clin Oral Implants Res 2007;18(Suppl. 3): 86–96. Heintze SD, Rousson V. Survival of zirconia - and metal-supported fixed dental prostheses: a systematic review. Int J Prosthodont 2010;23:493–502. 91

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