title: Quality of reporting of clinical studies to assess and compare performance of implant-supported restorations.
abstract: OBJECTIVE
  The objective of this analysis was to assess and compare the 5- and 10-year survival of different types of tooth-supported and implant-supported fixed dental prostheses (FDPs) and single crowns (SCs), and to describe the incidence of biological and technical complications with emphasis on quality of reporting.
  
  
  METHODS
  The analysis was based on six systematic review identifying prospective and retrospective cohort studies and case-series on FDPs and SCs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Failure and complication rates were analysed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions.
  
  
  RESULTS
  Meta-analyses of the included studies indicated that the 5-year survival rates ranged from 89.2% to 95.5% for different types of restorations. Investigating the relative failure rates using implant-supported SCs as reference, conventional and cantilever tooth-supported FDPs and resin-bonded prosthesis (RBPs) showed higher failure rates. Moreover, for RBPs, this difference reached statistical significance (p = 0.018). Analysing the studies with 10 years follow-up time, the survival ranged from 65% to 89.4%. After a 10-year observation period, the lowest annual failure rates were seen for implant-supported SCs (1.12%), conventional tooth-supported FDPs (1.14%) and implant-supported FDPs (1.43%). Cantilever tooth-supported FDPs, combined tooth-implant-supported FDPs and RBPs had significantly (p < 0.001) higher annual failure rates of 2.20%, 2.51% and 4.31%, respectively. According to presently recommended standards for reporting cohort studies (STROBE Statement), it was evident that the included studies did not fulfil the present standards to a great extent. Information on study design, methods of selecting study participants, percentage and reason for participants lost to follow-up was often not reported. Furthermore, the included studies rarely discussed possible limitations and potential sources of bias. Moreover, funding sources were generally not reported.
  
  
  CONCLUSIONS
  Based on the present analysis treatment planning in a mutilated dentition in need of oral reconstructions should base on the results of the systematic reviews performed. In this context, the choice of reconstructions on teeth with end abutments, of reconstructions on implants (both FDPs and SCs) should be given first priority, while combined tooth-implant-supported reconstructions, cantilever reconstructions on teeth and RBPs represent options of second priority. Future studies on performance of implant-supported restorations should be prospective in design and should follow the present recommendation for reporting cohort studies (The STROBE statement).
authors.affiliation: Faculty of Odontology, University of Iceland, Reykjavik, Iceland. bep@hi.is
authors.forename: Bjarni E
authors.initials: BE
authors.lastname: Pjetursson
authors.forename: Marcel
authors.initials: M
authors.lastname: Zwahlen
authors.forename: Niklaus P
authors.initials: NP
authors.lastname: Lang
mesh_terms: D003442:Crowns; D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003830:Denture, Partial, Fixed; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D012107:Research Design / Q000592:standards*; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants