title: Survival of direct resin restorations in posterior teeth within a 19-year period (1996-2015): A meta-analysis of prospective studies.
abstract: OBJECTIVE
  The aim of this study is to analyze the survival of posterior composite restorations published within the last 19 years (1996-2015).
  
  
  METHODS
  In this study only prospective, clinical trials with specification of the failure rate according to Class I/II composite fillings were included. Studies were analyzed according to the observation period (all studies vs. short-term vs. long-term studies). Retrospective studies and/or open laminate studies, tunnel restorations and Class V restorations were excluded. The following variables possibly influencing the failure rate were extracted from the studies: observation period, recall rate, average age of patients, number of patients, ratio of Class I/II fillings, number of restorations, ratio of premolars/molars, operator, method of isolation, bonding generation and filler size.
  
  
  RESULTS
  A total of 88 studies were included for statistical analysis. The observation period of the studies varied between 1 and 17 years, while most of the studies did not last longer than 5 years. Fracture of the restorations, secondary caries and marginal gap are the main causes for failure in the first 5 years (in descending order), while fracture and secondary caries are similarly distributed in long-term studies. Variables of investigation differed greatly in significance according to the respective observation period. The observation period, the recall rate, the ratio of Class I/II fillings and the number of restorations and patients had a significant influence on the overall failure rate when including all studies (short- and long-term). A linear correlation between the observation period and the failure rate was observed. In long-term studies these variables were not significant any longer. No significant difference in the failure rates between the materials per study was observed. The most common commercial composites investigated were: Tetric Ceram, Surefil, Filtek Supreme (incl. XT), Filtek Z250. The mean annual failure rate was 1.46% (±1.74%) for short-term studies and 1.97% (±1.53) for long-term studies. There is still a big need for clinical studies lasting longer than 5 years, as failure rates of composite restorations in posterior teeth increases with longer observation periods.
  
  
  CONCLUSIONS
  A decreasing failure rate with an increasing recall rate as observed in our study suggests a patient selection in regard to availability and dental awareness. Internationally standardized evaluation criteria are mandatory in order to allow comparisons of the outcomes of clinical studies.
authors.affiliation: Division of Oral Surgery, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria; Competence Center for Dental Materials, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Beck
authors.affiliation: Division of Oral Surgery, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria; Karl Donath Laboratory for Hard Tissue and Biomaterial Research, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Lettner
authors.affiliation: Center for Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Graf
authors.affiliation: Division of Conservative Dentistry and Periodontology, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria; Competence Center for Dental Materials, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Bitriol
authors.affiliation: Division of Conservative Dentistry and Periodontology, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria.
authors.forename: N
authors.initials: N
authors.lastname: Dumitrescu
authors.affiliation: Center for Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Vienna, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Bauer
authors.affiliation: Division of Conservative Dentistry and Periodontology, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria; Competence Center for Dental Materials, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Moritz
authors.affiliation: Division of Conservative Dentistry and Periodontology, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria; Competence Center for Dental Materials, University Clinic of Dentistry Vienna, Medical University of Vienna, Austria. Electronic address: andreas.schedle@meduniwien.ac.at.
authors.forename: A
authors.initials: A
authors.lastname: Schedle
mesh_terms: D002986:Clinical Trials as Topic; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D006801:Humans; D011446:Prospective Studies; D012307:Risk Factors
keywords: Clinical trials; Longevity; Posterior resin composites; Review