Limited Evidence that Cantilevers Are Associated With Slightly Lower Survival Rates of Implant-Supported Fixed Partial Dentures

Abstract

Systematic review conclusion. Implant-supported fixed partial dentures (FPDs) with cantilevers have a higher incidence of technical complications and lower five-year survival rates compared with those for FPDs without cantilevers.Critical summary assessment. The authors included only three studies (totaling 175 patients) of limited methodological quality, which weakened their conclusions.Evidence quality rating. Limited. Systematic review conclusion. Implant-supported fixed partial dentures (FPDs) with cantilevers have a higher incidence of technical complications and lower five-year survival rates compared with those for FPDs without cantilevers. Critical summary assessment. The authors included only three studies (totaling 175 patients) of limited methodological quality, which weakened their conclusions. Evidence quality rating. Limited. In partially dentate patients who require implant-supported fixed partial dentures (FPDs), do FPDs with cantilevers exhibit different survival rates, associated complications or both compared with FPDs without cantilevers? The authors searched one electronic database for systematic reviews and clinical studies that compared the survival rates and associated complications (technical and biological) of implant-supported FPDs with and without cantilevers. Search criteria specified English-language studies published up to November 2008 that involved a follow-up period of at least five years. The authors did not contact the authors of some of the excluded studies to obtain missing information. The authors identified a total of 103 articles from their initial search. Two independent reviewers chose 11 of these articles for full-text review. They identified an additional article from a hand search of the literature. After conducting a full-text review of the 12 articles, the reviewers selected a total of three studies composed of 175 patients (a total of 216 FPDs). The five-year weighted mean survival rate of the implant-supported FPDs with cantilevers was 91.9 percent, whereas the weighted mean survival rate of the FPDs without cantilevers was 95.8 percent. Implant fracture was the main cause of failure for the FPDs with cantilevers. The weighted mean rate of technical complications was 20.3 percent for the FPDs with cantilevers and 9.7 percent for the FPDs without cantilevers. Porcelain fractures and bridge-screw loosening were the most common complications. The authors did not report any statistically significant differences between the two groups with regard to peri-implant bone-level change. Both prosthetic designs demonstrated high five-year survival rates, but FPDs with cantilevers experienced a higher incidence of minor technical complications. Regarding bone level around the implants (a potential biological complication), the cantilever design did not demonstrate any statistically significant differences from the non-cantilever design.