Q U I N T E S S E N C E I N T E R N AT I O N A L
PROSTHODONTICS
Aristidis A. Galiatsatos
Clinical evaluation of fractured metal-ceramic fixed dental prostheses repaired with indirect technique Aristidis A. Galiatsatos, DDS, Dr Dent1/Panagiotis A. Galiatsatos2 Objectives: Metal ceramic restorations continue to be widely used in dental practice, as they combine esthetics with superior mechanical properties. However, ceramic materials have the potential to fracture due to their brittle nature. The purpose of this study was to evaluate the clinical survival of fractured metal-ceramic restorations repaired with an indirect technique which uses a new “overlay” metal-ceramic crown that is luted to the existing restoration. Method and Materials: The study population consisted of 92 patients. Only patients with one or more fractured retainers of multipleunit metal-ceramic fixed partial dentures were involved in this study. In all cases there were a bulk fracture of the overlaying ceramic material and exposure of the underlying metal substructure. The remaining retainers of the fixed partial dentures were intact. The total number of fractured retainers was 106. All clinical procedures of the indirect repairs were carried out by a single investigator, according the previously published
technique. The patients were examined clinically at 1, 2, 4, 6, and 8 years after placement of the new restorations. The repaired restorations were examined for debonding, fracture rate, and esthetics. Patient acceptance was also recorded. Results: Of the 92 patients re-examined, all were satisfied with the function and the esthetic appearance of their restorations. None of the repaired restorations fractured after 8 years of service, and there were no gingival margin problems of significance. Four restorations debonded during the evaluation period. The overall survival rate was 96.2% after 8 years. Conclusion: Repair methodology and materials employed in this study resulted in satisfactory longevity for metal-ceramic dental prostheses. The success rate was 96.2% after 8 years. The retention rate was very good, patient satisfaction was very encouraging, and maintenance of the esthetics was good. (Quintessence Int 2015;46:229–236; doi: 10.3290/j.qi.a33179)
Key words: clinical longevity, fracture, indirect method, metal-ceramic fixed dental prosthesis, repair
Metal-ceramic restorations have been used for several decades by clinicians to provide esthetic and masticatory function. However, these restorations have the potential for fracture of the ceramic veneer, which poses serious cosmetic and clinical problems. The causes of 1
Assistant Professor, Department of Dental Technology, Faculty of Health and Caring Professions, Technological Educational Institution of Athens, Athens, Greece.
2
Undergraduate Student, Department of Dental Technology, Faculty of Health and Caring Professions, Technological Educational Institution of Athens, Athens, Greece.
Correspondence: Dr Aristidis A. Galiatsatos, 60 Str. Rogakou Str., 15125 Athens, Greece. Εmail: [email protected]
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such fractures are varied, and include impact and fatigue load, occlusal forces, incompatible thermal expansion coefficients between the ceramic and metal substructure, use of metal with low elastic modulus, seating force during trial insertion or cementation, improper design, micro defects within the material, and trauma.1-4 Fracture of the overlaying ceramic on a porcelainfused-to-metal fixed partial denture (FPD) can be a challenging problem. Ideally, replacing the broken prosthesis is the best treatment, but this may not be within the patient’s financial means. This becomes more costly with long-span prostheses. Moreover, it
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Table 1 Age (years)
Age and gender of patients Men (n)
Women (n)
Total
30–40
5
3
8
41–50
15
12
27
51–60
20
15
35
61–77
14
8
22
Total
54
38
92
Fig 1 Preoperative view of a patient with a fractured retainer (maxillary left canine) of an otherwise functional metal-ceramic restoration.
Table 2
Distribution of fractured retainers (FRs)
Arch location
Total FRs
Central incisors
Lateral incisors
Canines
First premolars
Second premolars
First molars
Second molars
Maxilla
60
9
7
18
10
5
8
3
Mandible
46
6
4
10
8
4
12
2
Total
106
15
11
28
18
9
20
5
may be desirable to repair the broken prosthesis, rather than removing it and possibly destroying restorations underneath or/and damaging the abutment teeth.1,2 Repairing ceramic-based restorations can increase the clinical longevity of failed restorations and offers both dentist and patient a cost-effective alternative to replacements, which could be the next best treatment that allows further function of the prosthesis until a more permanent solution can be rendered.1,2,5 Traditionally, repair techniques may be classified into two types: the direct method and the indirect method. Direct repairs include techniques that use light-polymerized composite resin applied directly to the fractured restoration,3,6-9 and indirect repairs include those that use ceramic prepared in the laboratory and bonded to the fractured restoration.10-14 The purpose of this study was to evaluate the survival of fractured metal-ceramic restorations repaired with an indirect technique.
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METHOD AND MATERIALS The study population consisted of 92 patients: 38 women and 54 men, ranging in age from 30 to 77 years (Table 1). Patient selection was accomplished according to pre-established criteria. Patients who exhibited bruxism, deep bite situation, severe inflammation, poor oral hygiene, or a high caries rate were ineligible for this study. Only patients with one or more fractured retainers of multiple-unit metal-ceramic FPDs were involved in this study. In all cases there were a bulk fracture of the overlaying ceramic material and exposure of the underlying metal substructure (Fig 1). The remaining retainers of the FPDs were intact. In addition, all the prostheses had a good aspect with satisfactory marginal adaptation around the abutments and good periodontal health. The total number of fractured retainers was 106 and the distribution is presented in Table 2. The majority of the repair cases were referred from private practices: 30 private practice dentists in Athens were asked to refer their patients who exhibited
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a Figs 2a and 2b
b The preparation is formed in the existing framework: (a) facial view, (b) palatal view.
fractured retainers of multiple-unit metal-ceramic FPDs. Before treatment, all patients were asked to identify the situation that caused failure of the restoration. The clinical evaluation took place between January 2002 and December 2005. The follow-up examination stopped when all the patients had passed the 8-year follow-up time. All clinical procedures of the indirect repairs were carried out by a single investigator, according the previously published technique.14,15 The fractured abutment was evaluated clinically and radiographically to ensure adequate metal substructure to prepare the framework for an overlay metal-ceramic casting. All remaining facial and lingual ceramic was removed by use of a fine diamond rotary cutting instrument (38GS Uniprep C&B Set, Intesiv) under copious irrigation. Care was taken interproximally to avoid chipping the adjacent ceramic and the connector area of the original restoration. A chamfer finish line was created on the lingual aspect of the original crown, in the cervical area, and the metal along the facial chamfer was made thin or removed to simplify finishing and to prevent a cement line (Fig 2). The preparation was examined to verify that a 1.2 mm to 1.5 mm space along the buccal and incisal dimension was available. Adequate bulk was necessary for the metal casting, opaque material, and ceramic. In some cases, metal was removed in the incisal third of the coping to achieve the necessary reduction. The provisional restorations were fabricated using autopo-
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lymerizing acrylic resin (Jet, Lang Dental Manufacturing Company) and cemented with non-eugenol provisional cement (Temp Bond NE, Kerr). The provisional restoration was used to evaluate the preparation and to ensure adequate retention, absence of undercuts, and sufficient reduction for an esthetic result. Final impressions were made with a vinyl polysiloxane material (Panasil, Kettenbach). Care was taken to prevent entrapment of impression material around pontics and large embrasures that could cause distortion upon removal, using orthodontic wax as a block-out material (GUM Orthodontic Wax, Sunstar). An irreversible hydrocolloid impression (Blueprint cremix, Dentsply DeTray) of the opposite arch and a wax interocclusal record (Alminax, Whip Mix) was made in each case. All the “overlay” crowns were fabricated with sufficient thickness (0.2 mm to 0.3 mm) to ensure adequate strength and rigidity. Because a thin, rigid overlay crown was desired, the base metal alloy was used in all cases (Wiron 99, Bego). After application of a lowerfusing ceramic (Omega 900, VITA Zahnfabrik) to the crowns, the restorations were evaluated intraorally, and the occlusion was adjusted. All the new restorations were constructed by the same technician in accordance with the manufacturer’s recommendations within 1 week after the final impressions were made. The completed metal-ceramic crowns were luted using Panavia 21 (Kuraray). The patients were examined clinically at 1, 2, 4, 6, and 8 years after placement of the new restorations.
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Table 3
Results of the clinical investigation 1 year
2 years
4 years
6 years
8 years
Satisfied patients (esthetics, n)
92
92
92
92
92
Fractures (n)
0
0
0
0
0
Debonding (n)
1
2
4
4
4
Fig 3 The cemented "overlay" metal-ceramic crown in the mouth.
Such periodic tests were conducted with a mirror, a sharp probe, and intraoral radiographs and photographs. Patients were instructed to devote optimal care to their oral hygiene. None of the selected patients dropped out or were dismissed. The repaired restorations were examined for debonding, fracture rate, and esthetics. Patient acceptance was also recorded (Fig 3).
None of the repaired restorations fractured after 8 years of service, and there were no gingival marginal problems of significance. Four restorations debonded during the evaluation period. The first case occurred 1 year after the insertion of the restoration and the second case occurred 1.5 years after repair. The two other cases occurred at the beginning and at the end of the fourth year after repair respectively.
RESULTS From the statements of patients, it was found that 85% of the 106 failures happened during normal chewing function and 15% were due to accidents (car or motorcycle accident). Also, 75% of the failures were observed in posterior prostheses (including canine retainers), whereas 25% were in the anterior prostheses. The majority of the failures occurred at the labial, at the buccal, and in the incisal regions. The results for indirect repairs after 8 years of service are shown in Table 3. Of the 92 patients re-examined, all were satisfied with the function and the esthetic appearance of their restorations. All patients stated that the prosthesis did not cause any subjective symptoms such as headache, and their chewing ability was very good and satisfactory. Five patients avoided using their prostheses during chewing or biting on hard food, because they feared a new failure.
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DISCUSSION Metal-ceramic restorations continue to be widely used in dental practices, as they combine esthetics with superior mechanical properties. However, intraoral ceramic materials have the potential to fracture. The failures of these restorations are in fact a multifactorial problem which could be related to a combination of different reasons (Table 4).1-4 One of these reasons is the vast difference in modulus between the metal and ceramic material. Another reason is that the ceramic is inherently a brittle material. Once a crack initiates in the surface, it will propagate until the restorative material breaks away from the metal under-structure. In some cases, the reason for restoration fracture may be due to poor and inadequate laboratory techniques during fabrication of the restoration. There may be poor metal design of the coping or FDP substructure leaving unsupported ceramic or inadequate ceramic over the
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Table 4
Factors that contribute to the fracture of metal-ceramic restorations
Technical factors
Dentist-related factors
Patient-related factors
Inherent material properties
Surface treatment and design of the metal coping
Incorrect treatment planning
Trauma
Brittle material
Compatibility between the coefficient of thermal expansion of the metal and ceramic
Very long anteroposterior length of pontic span (up to three units)
Parafunction (bruxism, nail biting, chewing on pencils/ pens, sleep disturbances)
Dynamic and fatigue crack initiation and propagation
Ceramic build-up and firing technique
Adequacy and design of tooth preparation
Internal stresses
Thickness of ceramic material
Incorrect registration of occlusion and articulation
No mechanism for yielding
Thickness and elastic modulus of the metal substructure
Premature contacts
Silicate bonds in the glassy ceramic matrix are susceptible to hydrolysis by environmental moisture
Location of ceramic-metal finish lines
metal substructure. Metal may be incomplete or improperly prepared for bonding ceramic to the metal or the ceramic may be fired too many times during restoration fabrication, creating a weakened ceramic structure. These restorations can also fracture due to trauma, carelessness, hard substrates within food bitten on by the patient (eg, biting a pen or pencil or food having a hard foreign object), and parafunctional grinding habits. Failure resulting from ceramic fracture has been reported to range from 2.3% to 8%.16-19 Other studies indicate a higher prevalence of failures, ranging between 5% and 10% over 10 years of service.19,20 Intraoral ceramic repair has become a feasible, low-risk, and cost-effective alternative to removing and remaking fractured restorations. Repair of failed ceramic restorations typically involves the application of a composite resin to the fractured ceramic material. A combination of surface alterations of ceramic using acid etching or airborne-particle abrasion, in conjunction with chemical agents such as silane coupling agents, are used to promote adhesion to the fractured ceramic material. However, many such direct repairs are considered as temporary, because the bond strength decreases over time.6,19,21-23 The life time of such direct repairs is approximately 2 to 3 years.3,6,8,24,25 A more long-term solution to the problem of a fractured veneer of an otherwise functional restoration would be the indirect method. Indirect repair tech-
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niques include the fabrication of a pin onlay with a ceramic veneer cemented to the labial surface,26,27 fabrication of a pin-retained casting with a fused ceramic veneer,28 or fabrication of a new “overlay” metalceramic crown.14,15,29,30 This study evaluated for 8 years the clinical survival of fractured metal-ceramic restorations repaired with an indirect technique which uses a new “overlay” metal-ceramic crown that is luted to the existing restoration. This type of repair was selected because there were only broken retainers (no pontics) in all cases, and also there was a bulk fracture (> 50%) of the overlaying ceramic material. Direct repair with composite resin was not selected because the affected area was too large, so not much ceramic material remained to promote adhesion between metal and resin. Such adhesion, being practically mechanical, would not be feasible.1-3,31-33 The results of this clinical study suggest that when the indications and patients are selected appropriately, the overall outcome and clinical acceptance are satisfactory. In this study, the success rate was 96.2% after 8 years. Also, the results of this study revealed that the majority of the failures happened during normal chewing functions (85%) and that 75% of these failures were observed in posterior prostheses. Patient acceptance of the repaired restorations at 8 years was very encouraging. None of the patients complained and all were very satisfied with the function
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and the esthetic appearance of their restorations. This technique requires clinical and laboratory procedures, but is advantageous because of the esthetic ability of ceramic material to match the remaining ceramic units. The primary advantages of using composite for repair are less chair time, lower cost, and ease of application. On the other hand, disadvantages include low strength, and poor esthetic appearance due to lack of translucency or shade-matching to the remaining ceramic units. Wear and surface deterioration are also problems associated with direct repairs.10,34 Therefore, this indirect repair technique is superior and produces an esthetic result that is more satisfying and stable than that of composite resins. None of the repaired restorations fractured after 8 years of service and this finding supports the effectiveness of this procedure. In many instances, small fractures of the overlaying ceramic on a porcelain-fused-tometal FPD can be repaired with composite resin. However, the authors’ experience and many studies show that repairs with composite resin of large ceramic fractures associated with metal exposure will have a limited useful life.1-3,19,23-25 In an attempt to improve resistance to detachment, all the “overlay” metal-ceramic crowns were luted to the existing restorations with a modified resin cement (Panavia 21, Kuraray). This modified phosphate-monomer-containing resin cement has excellent chemical bonding properties between metals, a feature unobtainable with other materials, and does not require etching of the metal surfaces.3,35,36 Modified resin cements should be applied only on base alloys because they do not bond sufficiently to noble alloys.3,35,37 During the observation time, four of the restorations debonded. The explanation of this phenomenon could be related to the bonding agent. Degradation within the resin cement may be related to the breakdown of the filler-resin interface bond, which could contribute to resin cement failure.36,38 Many factors contribute to this phenomenon, such as the polymerization shrinkage of composite resin, the dissolution of the resin matrix of composite resins in oral fluids, and the loss of marginal integrity caused at baseline by
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polymerization shrinkage or by removal of cement flashes with blunt instruments.36,39,40 To improve the retention of the “overlay” crowns to the existing restorations, additional preparation of metal surfaces may be needed. The inner surface of the “overlay” crown and the intraoral metal surface to be bonded should be prepared by airborne-particle abrasion with alumina under rubber dam isolation, using an intraoral sandblaster (eg, MicroEtcher II, Danville Materials). Airborne-particle abrasion with 50 μm aluminum oxide particles at low air pressure will clean, roughen, enlarge, and activate the surface, resulting in better wetability and chemical accessibility.3,41,42 Also, for improved resistance to detachment, many authors have proposed additional surface preparation such as tin-plating, or chemical coating with various metal priming agents.12,43-45 For this repair technique, special attention should be given to the occlusion. The replacement crown, adequately adjusted and not suffering any kind of occlusal interference, will have a successful clinical performance. This is reinforced when the patient exhibits no parafunctional characteristics. While repairs can be durable, the patient needs to understand all the implications of treatment before committing to the repair of a fractured ceramic restoration, knowing that, in most circumstances, remaking the crown or FPD is the better choice. As part of the treatment planning process, the clinician should evaluate (if it is possible) the reason for the ceramic fracture, and if occlusion was a contributing factor, it may be necessary to evaluate and adjust the occlusion in all dynamic movements for success. A fractured metal-ceramic crown presents many variables, including the amount of ceramic material to be replaced, the location of the fracture (buccal or lingual), the surface of the metal coping, and the position of the tooth (anterior or posterior). Consideration of all of these factors is necessary to determine whether or not a repair will be successful. If the clinician decides to repair the broken restoration, the major factor for the choice of the type of repair method is the amount of the ceramic material that is missing. When a small por-
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tion of ceramic material is missing with or without exposed metal surface, the direct intraoral repair method can be used, with good results. The indirect repair method described is suitable for repairing restorations when a large bulk of ceramic material is fractured with a large exposed metal surface (> 50%), because it has encouraging clinical results and produces an esthetic result that is more satisfactory and stable than that of composites.
CONCLUSION Within the limitations of this clinical study, a long-term and successful solution to the problem of a fractured veneer of an otherwise functional metal-ceramic restoration would be the indirect method of repair using a new “overlay” metal-ceramic crown. The success rate was 96.2% after 8 years. The retention rate was good, patient satisfaction was encouraging, and there was good maintenance of the esthetics. The primary advantage of this technique is that it may be more predictable than the direct-repair method using composites, especially for situations in which a large portion of ceramic material is missing. An alternative to this method may be the use of zirconia allceramic crowns, because they have superior esthetics and good strength.
REFERENCES 1. Hickel R, Brüshaver K, Ilie N. Repair of restorations: Criteria for decision making and clinical recommendations. Dent Materials 2013;29:28–50. 2. Jagger DC, Wilson NHF. Defective dental restorations: To repair or not to repair? Part 2: All-ceramics and porcelain fused to metal systems. Dent Update 2011;38:150–158. 3. Kimmich M, Stappert GJ. Intraoral treatment of veneering porcelain chipping of fixed dental restorations. J Am Dent Assoc 2013;144:31–44. 4. Lamon J, Evans AG. Statistical analysis of bending strength for brittle solids: A multiaxial fracture problem. J Am Ceram Soc 1983;66:177–182. 5. Reston EG, Filho SC, Arossi G, Cogo RB, Rocha CS, Closs LQ. Repairing ceramic restorations: Final solution or alternative procedure? Oper Dent 2008;33: 461–466. 6. Özcan M. Evaluation of alternative intra-oral repair techniques for fractured ceramic-fused-to-metal restorations. J Oral Rehab 2003;30:194–203. 7. Dos Santos GJ, Fonseca RG, Adabo GL, Dos Santos AC. Shear bond strength of metal-ceramic repair systems. J Prosthet Dent 2006;96:165–173. 8. Özcan M, Van der Sleen JM, Kurunmäki H, Vallitu PK. Comparison of repair methods for ceramic-fused-to-metal crowns. J Prosthodont 2006;15:283–288.
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9. Raposo LHA, Neiva NA, Silva GR, et al. Ceramic restoration repair: report of two cases. J Appl Oral Sci 2009;17:140–144. 10. Fahmy NZ, Mohsen CA. Assessment of an indirect metal ceramic repair system. J Prosthodont 2010;19:25–32. 11. Al-Moaleem MM, Al-Qahtani NM. A combination of intra and extra oral technique for repairing a multi-unit metal ceramic fixed partial denture. Int J Dent Clinics 2012;4:84–86. 12. Wood M, Litkowski LJ, Thompson VP, Church T. Repair of porcelain/metal restoration with resin bonded overcasting. J Esthet Dent 1992;4:110–113. 13. Ben-Ur Z, Patael H, Gorfil C. Overcasting to repair a fractured porcelain fixed partial denture. Quintessence Int 1993;24:809–811. 14. Galiatsatos AA. An indirect repair technique for fractured metal-ceramic restorations: A clinical report. J Prosthet Dent 2005;93:321–323. 15. Galiatsatos AA. Overlay metal-ceramic crown for fractured restoration. Dent Abstr 2005;50:349–350. 16. Goodacre CJ, Bernal G, Rungcharassaeng K, Kan JYK. Clinical complications in fixed prosthodontics. J Prosthet Dent 2003;90:31–41. 17. Libby G, Arcuri MR, Lavelle WE, Hebl L. Longevity of fixed partial dentures. J Prosthet Dent 1997;78:127–131. 18. Strub JR, Stiffler S, Scharer P. Causes of failure following oral rehabilitation: biologic versus technical factors. Quintessence Int 1988;19:215–222. 19. Özcan M, Niedermeier W. Clinical study of the reasons for and location of failures of metal-ceramic restorations and survival of repairs. Int J Prosthodont 2002;15:299–302. 20. Coornaert J, Adriaens P, de Boever J. Long term clinical study of porcelain fused to gold restorations. J Prosthet Dent 1984;51:338–342. 21. Saygili G, Sahmali S, Demirel F. Colour stability of porcelain repair materials with accelerated ageing. J Oral Rehab 2006;33:387–392. 22. Kumbuloglu O, User A, Toksavul S, Vallittu PK. Intra-oral adhesive systems for ceramic repairs: a comparison. Acta Odontol Scand 2003;61:268–272. 23. Liobell A, Nicholls Jl, Kois JC, Dary CH. Fatigue life of porcelain repair systems. Int J Prosthodont 1992;5:205–213. 24. Özcan M. Longevity of repaired composite and metal-ceramic restorations: 3.5 year clinical study. J Dent Res 2006;85:76. 25. Kato H, Matsumara H, Tanaka T, et al. Bond strength and durability of porcelain bonding systems. J Prosthet Dent 1997;78:511–517. 26. Miller TH, Thayer KE. Intraoral repair of fixed partial dentures. J Prosthet Dent 1971;25:382–388. 27. Johnson JF, Dykema RW, Cunningham DM. The use and construction of gold crowns with a fused porcelain veneer: a progress report. J Prosthet Dent 1956;6:811–821. 28. Bakland LK. Replacing porcelain veneers in the mouth. Quintessence Int 1972;3:45–49. 29. Bruggers H, Jeansonne EE, Grush L. Repair technique for fractured anterior facings. J Am Dent Assoc 1979;98:947–948. 30. Dent RJ. Repair of porcelain-fused-to-metal restorations. J Prosthet Dent 1979;41:661–664. 31. Hirschfeld Z, Rehany A. Esthetic repair of porcelain in a complete mouth reconstruction: a case report. Quintessence Int 1991;22:945–947. 32. Yanikoglou N. The repair methods for fractured metal-porcelain restorations: a review of the literature. Eur J Prosthodont Restor Dent 2004;12:161–165. 33. Ahmad I. Salvaging fractured porcelain crowns with a direct composite repair technique. Pract Proced Aesthet Dent 2002;14:233–236. 34. Creugers NH, Snoek PA, Kayser AF. An experimental porcelain repair system evaluated under controlled clinical conditions. J Prosthet Dent 1992;68:724–727. 35. Tjan AHL, Tjan L. Seating and retention of complete crowns with a new adhesive resin cement. J Prosthet Dent 1992;67:478–488. 36. Blatz MB, Sadan A, Kern M. Resin-ceramic bonding: a review of the literature. J Prosthet Dent 2003;89:268–274. 37. Antoniadou M, Kern M, Strub JR. Effect of a new metal primer on the bond strength between a resin cement and two high-noble alloys. J Prosthet Dent 2000;84:554–560.
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38. Walker MP, Spencer P, Eick JD. Effect of simulated resin-bonded fixed partial denture clinical conditions on resin cement mechanical properties. J Oral Rehabil 2003;30:837–846. 39. Galiatsatos AA, Bergou D. Six-year clinical evaluation of ceramic inlays and onlays. Quintessence Int 2008;39:407–412. 40. Meng X, Yoshida K, Atsuta M. Influence of ceramic thickness on mechanical properties and polymer structure of dual-cured resin luting agents. Dent Mater 2008;24:594–599. 41. Petridis H, Garefis P, Hirayama H, Kafantaris NM, Koidis P. Bonding indirect resin composites to metal: part 1. Comparison of shear bond strengths between different metal-resin bonding systems and a metal-ceramic system. Int J Prosthodont 2003;16:635–639.
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42. Petridis H, Garefis P, Hirayama H, Kafantaris NM, Koidis P. Bonding indirect resin composites to metal: part 2. Effect of alloy surface treatment on elemental composition of alloy and bond strength. Int J Prosthodont 2004;17:77–82. 43. Fonseca RG, de Almeida JG, Haneda IG, Adabo GL. Effect of metal primers on bond strength of resin cements to base metals. J Prosthet Dent 2009;101: 262–268. 44. Haneda IG, Fonseca RG, de Almeida JG, Cruz CA, Adabo GL. Shear bond strength of metal-ceramic repair systems. Gen Dent 2009;57:644–651. 45. Tanoue N, Ogata T, Koizumi H, Matsumura H. Repair of an anterior fixed partial denture with resin-bonded overcasting and a dual functional metal priming agent: a clinical report. Int Chin J Dent 2006;6:17–20.
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PROSTHODONTICS
Aristidis A. Galiatsatos
Clinical evaluation of fractured metal-ceramic fixed dental prostheses repaired with indirect technique Aristidis A. Galiatsatos, DDS, Dr Dent1/Panagiotis A. Galiatsatos2 Objectives: Metal ceramic restorations continue to be widely used in dental practice, as they combine esthetics with superior mechanical properties. However, ceramic materials have the potential to fracture due to their brittle nature. The purpose of this study was to evaluate the clinical survival of fractured metal-ceramic restorations repaired with an indirect technique which uses a new “overlay” metal-ceramic crown that is luted to the existing restoration. Method and Materials: The study population consisted of 92 patients. Only patients with one or more fractured retainers of multipleunit metal-ceramic fixed partial dentures were involved in this study. In all cases there were a bulk fracture of the overlaying ceramic material and exposure of the underlying metal substructure. The remaining retainers of the fixed partial dentures were intact. The total number of fractured retainers was 106. All clinical procedures of the indirect repairs were carried out by a single investigator, according the previously published
technique. The patients were examined clinically at 1, 2, 4, 6, and 8 years after placement of the new restorations. The repaired restorations were examined for debonding, fracture rate, and esthetics. Patient acceptance was also recorded. Results: Of the 92 patients re-examined, all were satisfied with the function and the esthetic appearance of their restorations. None of the repaired restorations fractured after 8 years of service, and there were no gingival margin problems of significance. Four restorations debonded during the evaluation period. The overall survival rate was 96.2% after 8 years. Conclusion: Repair methodology and materials employed in this study resulted in satisfactory longevity for metal-ceramic dental prostheses. The success rate was 96.2% after 8 years. The retention rate was very good, patient satisfaction was very encouraging, and maintenance of the esthetics was good. (Quintessence Int 2015;46:229–236; doi: 10.3290/j.qi.a33179)
Key words: clinical longevity, fracture, indirect method, metal-ceramic fixed dental prosthesis, repair
Metal-ceramic restorations have been used for several decades by clinicians to provide esthetic and masticatory function. However, these restorations have the potential for fracture of the ceramic veneer, which poses serious cosmetic and clinical problems. The causes of 1
Assistant Professor, Department of Dental Technology, Faculty of Health and Caring Professions, Technological Educational Institution of Athens, Athens, Greece.
2
Undergraduate Student, Department of Dental Technology, Faculty of Health and Caring Professions, Technological Educational Institution of Athens, Athens, Greece.
Correspondence: Dr Aristidis A. Galiatsatos, 60 Str. Rogakou Str., 15125 Athens, Greece. Εmail: [email protected]
VOLUME 46 • NUMBER 3 • MARCH 2015
such fractures are varied, and include impact and fatigue load, occlusal forces, incompatible thermal expansion coefficients between the ceramic and metal substructure, use of metal with low elastic modulus, seating force during trial insertion or cementation, improper design, micro defects within the material, and trauma.1-4 Fracture of the overlaying ceramic on a porcelainfused-to-metal fixed partial denture (FPD) can be a challenging problem. Ideally, replacing the broken prosthesis is the best treatment, but this may not be within the patient’s financial means. This becomes more costly with long-span prostheses. Moreover, it
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Table 1 Age (years)
Age and gender of patients Men (n)
Women (n)
Total
30–40
5
3
8
41–50
15
12
27
51–60
20
15
35
61–77
14
8
22
Total
54
38
92
Fig 1 Preoperative view of a patient with a fractured retainer (maxillary left canine) of an otherwise functional metal-ceramic restoration.
Table 2
Distribution of fractured retainers (FRs)
Arch location
Total FRs
Central incisors
Lateral incisors
Canines
First premolars
Second premolars
First molars
Second molars
Maxilla
60
9
7
18
10
5
8
3
Mandible
46
6
4
10
8
4
12
2
Total
106
15
11
28
18
9
20
5
may be desirable to repair the broken prosthesis, rather than removing it and possibly destroying restorations underneath or/and damaging the abutment teeth.1,2 Repairing ceramic-based restorations can increase the clinical longevity of failed restorations and offers both dentist and patient a cost-effective alternative to replacements, which could be the next best treatment that allows further function of the prosthesis until a more permanent solution can be rendered.1,2,5 Traditionally, repair techniques may be classified into two types: the direct method and the indirect method. Direct repairs include techniques that use light-polymerized composite resin applied directly to the fractured restoration,3,6-9 and indirect repairs include those that use ceramic prepared in the laboratory and bonded to the fractured restoration.10-14 The purpose of this study was to evaluate the survival of fractured metal-ceramic restorations repaired with an indirect technique.
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METHOD AND MATERIALS The study population consisted of 92 patients: 38 women and 54 men, ranging in age from 30 to 77 years (Table 1). Patient selection was accomplished according to pre-established criteria. Patients who exhibited bruxism, deep bite situation, severe inflammation, poor oral hygiene, or a high caries rate were ineligible for this study. Only patients with one or more fractured retainers of multiple-unit metal-ceramic FPDs were involved in this study. In all cases there were a bulk fracture of the overlaying ceramic material and exposure of the underlying metal substructure (Fig 1). The remaining retainers of the FPDs were intact. In addition, all the prostheses had a good aspect with satisfactory marginal adaptation around the abutments and good periodontal health. The total number of fractured retainers was 106 and the distribution is presented in Table 2. The majority of the repair cases were referred from private practices: 30 private practice dentists in Athens were asked to refer their patients who exhibited
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a Figs 2a and 2b
b The preparation is formed in the existing framework: (a) facial view, (b) palatal view.
fractured retainers of multiple-unit metal-ceramic FPDs. Before treatment, all patients were asked to identify the situation that caused failure of the restoration. The clinical evaluation took place between January 2002 and December 2005. The follow-up examination stopped when all the patients had passed the 8-year follow-up time. All clinical procedures of the indirect repairs were carried out by a single investigator, according the previously published technique.14,15 The fractured abutment was evaluated clinically and radiographically to ensure adequate metal substructure to prepare the framework for an overlay metal-ceramic casting. All remaining facial and lingual ceramic was removed by use of a fine diamond rotary cutting instrument (38GS Uniprep C&B Set, Intesiv) under copious irrigation. Care was taken interproximally to avoid chipping the adjacent ceramic and the connector area of the original restoration. A chamfer finish line was created on the lingual aspect of the original crown, in the cervical area, and the metal along the facial chamfer was made thin or removed to simplify finishing and to prevent a cement line (Fig 2). The preparation was examined to verify that a 1.2 mm to 1.5 mm space along the buccal and incisal dimension was available. Adequate bulk was necessary for the metal casting, opaque material, and ceramic. In some cases, metal was removed in the incisal third of the coping to achieve the necessary reduction. The provisional restorations were fabricated using autopo-
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lymerizing acrylic resin (Jet, Lang Dental Manufacturing Company) and cemented with non-eugenol provisional cement (Temp Bond NE, Kerr). The provisional restoration was used to evaluate the preparation and to ensure adequate retention, absence of undercuts, and sufficient reduction for an esthetic result. Final impressions were made with a vinyl polysiloxane material (Panasil, Kettenbach). Care was taken to prevent entrapment of impression material around pontics and large embrasures that could cause distortion upon removal, using orthodontic wax as a block-out material (GUM Orthodontic Wax, Sunstar). An irreversible hydrocolloid impression (Blueprint cremix, Dentsply DeTray) of the opposite arch and a wax interocclusal record (Alminax, Whip Mix) was made in each case. All the “overlay” crowns were fabricated with sufficient thickness (0.2 mm to 0.3 mm) to ensure adequate strength and rigidity. Because a thin, rigid overlay crown was desired, the base metal alloy was used in all cases (Wiron 99, Bego). After application of a lowerfusing ceramic (Omega 900, VITA Zahnfabrik) to the crowns, the restorations were evaluated intraorally, and the occlusion was adjusted. All the new restorations were constructed by the same technician in accordance with the manufacturer’s recommendations within 1 week after the final impressions were made. The completed metal-ceramic crowns were luted using Panavia 21 (Kuraray). The patients were examined clinically at 1, 2, 4, 6, and 8 years after placement of the new restorations.
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Table 3
Results of the clinical investigation 1 year
2 years
4 years
6 years
8 years
Satisfied patients (esthetics, n)
92
92
92
92
92
Fractures (n)
0
0
0
0
0
Debonding (n)
1
2
4
4
4
Fig 3 The cemented "overlay" metal-ceramic crown in the mouth.
Such periodic tests were conducted with a mirror, a sharp probe, and intraoral radiographs and photographs. Patients were instructed to devote optimal care to their oral hygiene. None of the selected patients dropped out or were dismissed. The repaired restorations were examined for debonding, fracture rate, and esthetics. Patient acceptance was also recorded (Fig 3).
None of the repaired restorations fractured after 8 years of service, and there were no gingival marginal problems of significance. Four restorations debonded during the evaluation period. The first case occurred 1 year after the insertion of the restoration and the second case occurred 1.5 years after repair. The two other cases occurred at the beginning and at the end of the fourth year after repair respectively.
RESULTS From the statements of patients, it was found that 85% of the 106 failures happened during normal chewing function and 15% were due to accidents (car or motorcycle accident). Also, 75% of the failures were observed in posterior prostheses (including canine retainers), whereas 25% were in the anterior prostheses. The majority of the failures occurred at the labial, at the buccal, and in the incisal regions. The results for indirect repairs after 8 years of service are shown in Table 3. Of the 92 patients re-examined, all were satisfied with the function and the esthetic appearance of their restorations. All patients stated that the prosthesis did not cause any subjective symptoms such as headache, and their chewing ability was very good and satisfactory. Five patients avoided using their prostheses during chewing or biting on hard food, because they feared a new failure.
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DISCUSSION Metal-ceramic restorations continue to be widely used in dental practices, as they combine esthetics with superior mechanical properties. However, intraoral ceramic materials have the potential to fracture. The failures of these restorations are in fact a multifactorial problem which could be related to a combination of different reasons (Table 4).1-4 One of these reasons is the vast difference in modulus between the metal and ceramic material. Another reason is that the ceramic is inherently a brittle material. Once a crack initiates in the surface, it will propagate until the restorative material breaks away from the metal under-structure. In some cases, the reason for restoration fracture may be due to poor and inadequate laboratory techniques during fabrication of the restoration. There may be poor metal design of the coping or FDP substructure leaving unsupported ceramic or inadequate ceramic over the
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Table 4
Factors that contribute to the fracture of metal-ceramic restorations
Technical factors
Dentist-related factors
Patient-related factors
Inherent material properties
Surface treatment and design of the metal coping
Incorrect treatment planning
Trauma
Brittle material
Compatibility between the coefficient of thermal expansion of the metal and ceramic
Very long anteroposterior length of pontic span (up to three units)
Parafunction (bruxism, nail biting, chewing on pencils/ pens, sleep disturbances)
Dynamic and fatigue crack initiation and propagation
Ceramic build-up and firing technique
Adequacy and design of tooth preparation
Internal stresses
Thickness of ceramic material
Incorrect registration of occlusion and articulation
No mechanism for yielding
Thickness and elastic modulus of the metal substructure
Premature contacts
Silicate bonds in the glassy ceramic matrix are susceptible to hydrolysis by environmental moisture
Location of ceramic-metal finish lines
metal substructure. Metal may be incomplete or improperly prepared for bonding ceramic to the metal or the ceramic may be fired too many times during restoration fabrication, creating a weakened ceramic structure. These restorations can also fracture due to trauma, carelessness, hard substrates within food bitten on by the patient (eg, biting a pen or pencil or food having a hard foreign object), and parafunctional grinding habits. Failure resulting from ceramic fracture has been reported to range from 2.3% to 8%.16-19 Other studies indicate a higher prevalence of failures, ranging between 5% and 10% over 10 years of service.19,20 Intraoral ceramic repair has become a feasible, low-risk, and cost-effective alternative to removing and remaking fractured restorations. Repair of failed ceramic restorations typically involves the application of a composite resin to the fractured ceramic material. A combination of surface alterations of ceramic using acid etching or airborne-particle abrasion, in conjunction with chemical agents such as silane coupling agents, are used to promote adhesion to the fractured ceramic material. However, many such direct repairs are considered as temporary, because the bond strength decreases over time.6,19,21-23 The life time of such direct repairs is approximately 2 to 3 years.3,6,8,24,25 A more long-term solution to the problem of a fractured veneer of an otherwise functional restoration would be the indirect method. Indirect repair tech-
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niques include the fabrication of a pin onlay with a ceramic veneer cemented to the labial surface,26,27 fabrication of a pin-retained casting with a fused ceramic veneer,28 or fabrication of a new “overlay” metalceramic crown.14,15,29,30 This study evaluated for 8 years the clinical survival of fractured metal-ceramic restorations repaired with an indirect technique which uses a new “overlay” metal-ceramic crown that is luted to the existing restoration. This type of repair was selected because there were only broken retainers (no pontics) in all cases, and also there was a bulk fracture (> 50%) of the overlaying ceramic material. Direct repair with composite resin was not selected because the affected area was too large, so not much ceramic material remained to promote adhesion between metal and resin. Such adhesion, being practically mechanical, would not be feasible.1-3,31-33 The results of this clinical study suggest that when the indications and patients are selected appropriately, the overall outcome and clinical acceptance are satisfactory. In this study, the success rate was 96.2% after 8 years. Also, the results of this study revealed that the majority of the failures happened during normal chewing functions (85%) and that 75% of these failures were observed in posterior prostheses. Patient acceptance of the repaired restorations at 8 years was very encouraging. None of the patients complained and all were very satisfied with the function
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and the esthetic appearance of their restorations. This technique requires clinical and laboratory procedures, but is advantageous because of the esthetic ability of ceramic material to match the remaining ceramic units. The primary advantages of using composite for repair are less chair time, lower cost, and ease of application. On the other hand, disadvantages include low strength, and poor esthetic appearance due to lack of translucency or shade-matching to the remaining ceramic units. Wear and surface deterioration are also problems associated with direct repairs.10,34 Therefore, this indirect repair technique is superior and produces an esthetic result that is more satisfying and stable than that of composite resins. None of the repaired restorations fractured after 8 years of service and this finding supports the effectiveness of this procedure. In many instances, small fractures of the overlaying ceramic on a porcelain-fused-tometal FPD can be repaired with composite resin. However, the authors’ experience and many studies show that repairs with composite resin of large ceramic fractures associated with metal exposure will have a limited useful life.1-3,19,23-25 In an attempt to improve resistance to detachment, all the “overlay” metal-ceramic crowns were luted to the existing restorations with a modified resin cement (Panavia 21, Kuraray). This modified phosphate-monomer-containing resin cement has excellent chemical bonding properties between metals, a feature unobtainable with other materials, and does not require etching of the metal surfaces.3,35,36 Modified resin cements should be applied only on base alloys because they do not bond sufficiently to noble alloys.3,35,37 During the observation time, four of the restorations debonded. The explanation of this phenomenon could be related to the bonding agent. Degradation within the resin cement may be related to the breakdown of the filler-resin interface bond, which could contribute to resin cement failure.36,38 Many factors contribute to this phenomenon, such as the polymerization shrinkage of composite resin, the dissolution of the resin matrix of composite resins in oral fluids, and the loss of marginal integrity caused at baseline by
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polymerization shrinkage or by removal of cement flashes with blunt instruments.36,39,40 To improve the retention of the “overlay” crowns to the existing restorations, additional preparation of metal surfaces may be needed. The inner surface of the “overlay” crown and the intraoral metal surface to be bonded should be prepared by airborne-particle abrasion with alumina under rubber dam isolation, using an intraoral sandblaster (eg, MicroEtcher II, Danville Materials). Airborne-particle abrasion with 50 μm aluminum oxide particles at low air pressure will clean, roughen, enlarge, and activate the surface, resulting in better wetability and chemical accessibility.3,41,42 Also, for improved resistance to detachment, many authors have proposed additional surface preparation such as tin-plating, or chemical coating with various metal priming agents.12,43-45 For this repair technique, special attention should be given to the occlusion. The replacement crown, adequately adjusted and not suffering any kind of occlusal interference, will have a successful clinical performance. This is reinforced when the patient exhibits no parafunctional characteristics. While repairs can be durable, the patient needs to understand all the implications of treatment before committing to the repair of a fractured ceramic restoration, knowing that, in most circumstances, remaking the crown or FPD is the better choice. As part of the treatment planning process, the clinician should evaluate (if it is possible) the reason for the ceramic fracture, and if occlusion was a contributing factor, it may be necessary to evaluate and adjust the occlusion in all dynamic movements for success. A fractured metal-ceramic crown presents many variables, including the amount of ceramic material to be replaced, the location of the fracture (buccal or lingual), the surface of the metal coping, and the position of the tooth (anterior or posterior). Consideration of all of these factors is necessary to determine whether or not a repair will be successful. If the clinician decides to repair the broken restoration, the major factor for the choice of the type of repair method is the amount of the ceramic material that is missing. When a small por-
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tion of ceramic material is missing with or without exposed metal surface, the direct intraoral repair method can be used, with good results. The indirect repair method described is suitable for repairing restorations when a large bulk of ceramic material is fractured with a large exposed metal surface (> 50%), because it has encouraging clinical results and produces an esthetic result that is more satisfactory and stable than that of composites.
CONCLUSION Within the limitations of this clinical study, a long-term and successful solution to the problem of a fractured veneer of an otherwise functional metal-ceramic restoration would be the indirect method of repair using a new “overlay” metal-ceramic crown. The success rate was 96.2% after 8 years. The retention rate was good, patient satisfaction was encouraging, and there was good maintenance of the esthetics. The primary advantage of this technique is that it may be more predictable than the direct-repair method using composites, especially for situations in which a large portion of ceramic material is missing. An alternative to this method may be the use of zirconia allceramic crowns, because they have superior esthetics and good strength.
REFERENCES 1. Hickel R, Brüshaver K, Ilie N. Repair of restorations: Criteria for decision making and clinical recommendations. Dent Materials 2013;29:28–50. 2. Jagger DC, Wilson NHF. Defective dental restorations: To repair or not to repair? Part 2: All-ceramics and porcelain fused to metal systems. Dent Update 2011;38:150–158. 3. Kimmich M, Stappert GJ. Intraoral treatment of veneering porcelain chipping of fixed dental restorations. J Am Dent Assoc 2013;144:31–44. 4. Lamon J, Evans AG. Statistical analysis of bending strength for brittle solids: A multiaxial fracture problem. J Am Ceram Soc 1983;66:177–182. 5. Reston EG, Filho SC, Arossi G, Cogo RB, Rocha CS, Closs LQ. Repairing ceramic restorations: Final solution or alternative procedure? Oper Dent 2008;33: 461–466. 6. Özcan M. Evaluation of alternative intra-oral repair techniques for fractured ceramic-fused-to-metal restorations. J Oral Rehab 2003;30:194–203. 7. Dos Santos GJ, Fonseca RG, Adabo GL, Dos Santos AC. Shear bond strength of metal-ceramic repair systems. J Prosthet Dent 2006;96:165–173. 8. Özcan M, Van der Sleen JM, Kurunmäki H, Vallitu PK. Comparison of repair methods for ceramic-fused-to-metal crowns. J Prosthodont 2006;15:283–288.
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9. Raposo LHA, Neiva NA, Silva GR, et al. Ceramic restoration repair: report of two cases. J Appl Oral Sci 2009;17:140–144. 10. Fahmy NZ, Mohsen CA. Assessment of an indirect metal ceramic repair system. J Prosthodont 2010;19:25–32. 11. Al-Moaleem MM, Al-Qahtani NM. A combination of intra and extra oral technique for repairing a multi-unit metal ceramic fixed partial denture. Int J Dent Clinics 2012;4:84–86. 12. Wood M, Litkowski LJ, Thompson VP, Church T. Repair of porcelain/metal restoration with resin bonded overcasting. J Esthet Dent 1992;4:110–113. 13. Ben-Ur Z, Patael H, Gorfil C. Overcasting to repair a fractured porcelain fixed partial denture. Quintessence Int 1993;24:809–811. 14. Galiatsatos AA. An indirect repair technique for fractured metal-ceramic restorations: A clinical report. J Prosthet Dent 2005;93:321–323. 15. Galiatsatos AA. Overlay metal-ceramic crown for fractured restoration. Dent Abstr 2005;50:349–350. 16. Goodacre CJ, Bernal G, Rungcharassaeng K, Kan JYK. Clinical complications in fixed prosthodontics. J Prosthet Dent 2003;90:31–41. 17. Libby G, Arcuri MR, Lavelle WE, Hebl L. Longevity of fixed partial dentures. J Prosthet Dent 1997;78:127–131. 18. Strub JR, Stiffler S, Scharer P. Causes of failure following oral rehabilitation: biologic versus technical factors. Quintessence Int 1988;19:215–222. 19. Özcan M, Niedermeier W. Clinical study of the reasons for and location of failures of metal-ceramic restorations and survival of repairs. Int J Prosthodont 2002;15:299–302. 20. Coornaert J, Adriaens P, de Boever J. Long term clinical study of porcelain fused to gold restorations. J Prosthet Dent 1984;51:338–342. 21. Saygili G, Sahmali S, Demirel F. Colour stability of porcelain repair materials with accelerated ageing. J Oral Rehab 2006;33:387–392. 22. Kumbuloglu O, User A, Toksavul S, Vallittu PK. Intra-oral adhesive systems for ceramic repairs: a comparison. Acta Odontol Scand 2003;61:268–272. 23. Liobell A, Nicholls Jl, Kois JC, Dary CH. Fatigue life of porcelain repair systems. Int J Prosthodont 1992;5:205–213. 24. Özcan M. Longevity of repaired composite and metal-ceramic restorations: 3.5 year clinical study. J Dent Res 2006;85:76. 25. Kato H, Matsumara H, Tanaka T, et al. Bond strength and durability of porcelain bonding systems. J Prosthet Dent 1997;78:511–517. 26. Miller TH, Thayer KE. Intraoral repair of fixed partial dentures. J Prosthet Dent 1971;25:382–388. 27. Johnson JF, Dykema RW, Cunningham DM. The use and construction of gold crowns with a fused porcelain veneer: a progress report. J Prosthet Dent 1956;6:811–821. 28. Bakland LK. Replacing porcelain veneers in the mouth. Quintessence Int 1972;3:45–49. 29. Bruggers H, Jeansonne EE, Grush L. Repair technique for fractured anterior facings. J Am Dent Assoc 1979;98:947–948. 30. Dent RJ. Repair of porcelain-fused-to-metal restorations. J Prosthet Dent 1979;41:661–664. 31. Hirschfeld Z, Rehany A. Esthetic repair of porcelain in a complete mouth reconstruction: a case report. Quintessence Int 1991;22:945–947. 32. Yanikoglou N. The repair methods for fractured metal-porcelain restorations: a review of the literature. Eur J Prosthodont Restor Dent 2004;12:161–165. 33. Ahmad I. Salvaging fractured porcelain crowns with a direct composite repair technique. Pract Proced Aesthet Dent 2002;14:233–236. 34. Creugers NH, Snoek PA, Kayser AF. An experimental porcelain repair system evaluated under controlled clinical conditions. J Prosthet Dent 1992;68:724–727. 35. Tjan AHL, Tjan L. Seating and retention of complete crowns with a new adhesive resin cement. J Prosthet Dent 1992;67:478–488. 36. Blatz MB, Sadan A, Kern M. Resin-ceramic bonding: a review of the literature. J Prosthet Dent 2003;89:268–274. 37. Antoniadou M, Kern M, Strub JR. Effect of a new metal primer on the bond strength between a resin cement and two high-noble alloys. J Prosthet Dent 2000;84:554–560.
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38. Walker MP, Spencer P, Eick JD. Effect of simulated resin-bonded fixed partial denture clinical conditions on resin cement mechanical properties. J Oral Rehabil 2003;30:837–846. 39. Galiatsatos AA, Bergou D. Six-year clinical evaluation of ceramic inlays and onlays. Quintessence Int 2008;39:407–412. 40. Meng X, Yoshida K, Atsuta M. Influence of ceramic thickness on mechanical properties and polymer structure of dual-cured resin luting agents. Dent Mater 2008;24:594–599. 41. Petridis H, Garefis P, Hirayama H, Kafantaris NM, Koidis P. Bonding indirect resin composites to metal: part 1. Comparison of shear bond strengths between different metal-resin bonding systems and a metal-ceramic system. Int J Prosthodont 2003;16:635–639.
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42. Petridis H, Garefis P, Hirayama H, Kafantaris NM, Koidis P. Bonding indirect resin composites to metal: part 2. Effect of alloy surface treatment on elemental composition of alloy and bond strength. Int J Prosthodont 2004;17:77–82. 43. Fonseca RG, de Almeida JG, Haneda IG, Adabo GL. Effect of metal primers on bond strength of resin cements to base metals. J Prosthet Dent 2009;101: 262–268. 44. Haneda IG, Fonseca RG, de Almeida JG, Cruz CA, Adabo GL. Shear bond strength of metal-ceramic repair systems. Gen Dent 2009;57:644–651. 45. Tanoue N, Ogata T, Koizumi H, Matsumura H. Repair of an anterior fixed partial denture with resin-bonded overcasting and a dual functional metal priming agent: a clinical report. Int Chin J Dent 2006;6:17–20.
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