title: A systematic review of the performance of ceramic and metal implant abutments supporting fixed implant reconstructions.
abstract: OBJECTIVE
  The objective of this systematic review was to assess the 5-year survival rates and incidences of complications associated with ceramic abutments and to compare them with those of metal abutments.
  
  
  METHODS
  An electronic Medline search complemented by manual searching was conducted to identify randomized-controlled clinical trials, and prospective and retrospective studies providing information on ceramic and metal abutments with a mean follow-up time of at least 3 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by three reviewers. Failure rates were analyzed using standard and random-effects Poisson regression models to obtain summary estimates of 5-year survival proportions.
  
  
  RESULTS
  Twenty-nine clinical and 22 laboratory studies were selected from an initial yield of 7136 titles and data were extracted. The estimated 5-year survival rate of ceramic abutments was 99.1% [95% confidence interval (CI): 93.8-99.9%] and 97.4% (95% CI: 96-98.3%) for metal abutments. The estimated cumulative incidence of technical complications after 5 years was 6.9% (95% CI: 3.5-13.4%) for ceramic abutments and 15.9% (95% CI: 11.6-21.5%) for metal abutments. Abutment screw loosening was the most frequent technical problem, occurring at an estimated cumulative incidence after 5 years of 5.1% (95% CI: 3.3-7.7%). All-ceramic crowns supported by ceramic abutments exhibited similar annual fracture rates as metal-ceramic crowns supported by metal abutments. The cumulative incidence of biological complications after 5 years was estimated at 5.2% (95% CI: 0.4-52%) for ceramic and 7.7% (95% CI: 4.7-12.5%) for metal abutments. Esthetic complications tended to be more frequent at metal abutments. A meta-analysis of the laboratory data was impossible due to the non-standardized test methods of the studies included.
  
  
  CONCLUSIONS
  The 5-year survival rates estimated from annual failure rates appeared to be similar for ceramic and metal abutments. The information included in this review did not provide evidence for differences of the technical and biological outcomes of ceramic and metal abutments. However, the information for ceramic abutments was limited in the number of studies and abutments analyzed as well as the accrued follow-up time. Standardized methods for the analysis of abutment strength are needed.
authors: Clinic for Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland. irena.sailer@zzmk.uzh.ch
authors: Irena
authors: I
authors: Sailer
authors: Alexander
authors: A
authors: Philipp
authors: Anja
authors: A
authors: Zembic
authors: Bjarni E
authors: BE
authors: Pjetursson
authors: Christoph H F
authors: CH
authors: Hämmerle
authors: Marcel
authors: M
authors: Zwahlen
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology; D000818:Animals; D003442:Crowns; D000044:Dental Abutments / Q000009:adverse effects; D003776:Dental Porcelain; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003830:Denture, Partial, Fixed; D005889:Gingival Recession / Q000209:etiology; D006047:Gold Alloys; D006801:Humans; D016019:Survival Analysis; D014025:Titanium
chemical_list: D006047:Gold Alloys; D003776:Dental Porcelain; D014025:Titanium