title: Clinical risk factors related to failures with zirconia-based restorations: an up to 9-year retrospective study.
abstract: OBJECTIVE
  The first objective of this study was to retrospectively evaluate zirconia-based restorations (ZBR). The second was to correlate failures with clinical parameters and to identify and to analyse chipping failures using fractographic analysis.
  
  
  METHODS
  147 ZBR (tooth- and implant-supported crowns and fixed partial dentures (FPDs)) were evaluated after a mean observation period of 41.5 ± 31.8 months. Accessorily, zirconia implant abutments (n=46) were also observed. The technical (USPHS criteria) and the biological outcomes of the ZBR were evaluated. Occlusal risk factors were examined: occlusal relationships, parafunctional habits, and the presence of occlusal nightguard. SEM fractographic analysis was performed using the intra-oral replica technique.
  
  
  RESULTS
  The survival rate of crowns and FPDs was 93.2%, the success rate was 81.63% and the 9-year Kaplan-Meier estimated success rate was 52.66%. The chipping rate was 15% and the framework fracture rate was 2.7%. Most fractographic analyses revealed that veneer fractures originated from occlusal surface roughness. Several parameters were shown to significantly influence veneer fracture: the absence of occlusal nightguard (p=0.0048), the presence of a ceramic restoration as an antagonist (p=0.013), the presence of parafunctional activity (p=0.018), and the presence of implants as support (p=0.026). The implant abutments success rate was 100%.
  
  
  CONCLUSIONS
  The results of the present study confirm that chipping is the first cause of ZBR failure. They also underline the importance of clinical parameters in regards to the explanation of this complex problem. This issue should be considered in future prospective clinical studies.
  
  
  CONCLUSIONS
  Practitioners can reduce chipping failures by taking into account several risk parameters, such as the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and the presence of implants as support. The use of an occlusal nightguard can also decrease failure rate.
authors.affiliation: Department of Fixed Prosthodontics, Institute of Dentistry, University of Liège Hospital (ULg, CHU, LIMARC), 45 Quai G. Kurth, Liège 4020, Belgium.
authors.forename: Vinciane
authors.initials: V
authors.lastname: Koenig
authors.forename: Alain J
authors.initials: AJ
authors.lastname: Vanheusden
authors.forename: Stéphane O
authors.initials: SO
authors.lastname: Le Goff
authors.forename: Amélie K
authors.initials: AK
authors.lastname: Mainjot
mesh_terms: D000328:Adult; D000368:Aged; D003442:Crowns; D000044:Dental Abutments; D003731:Dental Caries / Q000150:complications; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003769:Dental Occlusion, Traumatic / Q000150:complications; D003774:Dental Plaque Index; D017266:Dental Prosthesis; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear; D003801:Dental Veneers; D003830:Denture, Partial, Fixed; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000145:classification / Q000150:complications; D008422:Materials Testing; D008875:Middle Aged; D017090:Occlusal Splints; D010512:Periodontal Index; D012189:Retrospective Studies; D013499:Surface Properties; D016019:Survival Analysis; D019553:Tooth, Nonvital / Q000150:complications; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide
keywords: Chipping; Fixed dental prostheses; Fractography; Risk factors; Technical complications; Zirconia