Metal‐free materials for fixed prosthodontic restorations

Background Fixed prosthodontic treatment (crowns, fixed dental prostheses (FDPs), complete arch prostheses) involves the use of several different materials to replace missing tooth structure. Traditionally full metal or metal frameworks veneered with ceramic (metal‐ceramic (MC)) have been used. In recent years several different metal‐free systems have become available to clinicians and patients. In general, metal‐free restorations should allow practitioners to better reproduce natural tooth colour, avoiding shortcomings of MC restorations. The comparative in service clinical performance of fixed prosthodontic treatments of different materials is unclear. Objectives To assess the effects of metal‐free materials for prosthodontic restorations compared to metal‐ceramic or other conventional all‐metal materials. Search methods Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (searched 3 May 2017), Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 4) in the Cochrane Library (searched 3 May 2017), MEDLINE Ovid (1946 to 3 May 2017), and Embase Ovid (1980 to 3 May 2017). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials (searched 3 May 2017). No restrictions were placed on the language or date of publication when searching the electronic databases. Selection criteria Randomised controlled trials (RCTs) in which the clinical performance of metal‐free fixed prosthodontic restorations was compared with metal‐ceramic (MC) or other conventional restorations in adult patients requiring prosthodontic treatment. RCTs in which the clinical performance of different kinds of metal‐free systems were compared among themselves were also considered. Data collection and analysis We used standard methodological procedures expected by Cochrane. Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted independently and in duplicate. Trial authors were contacted for missing information. Available results for the outcomes of interest of the systematic review of the studies included were tabulated as they could not be included in a formal meta‐analysis. Main results Nine trials involving a total of 448 participants were included. We judged two trials to be at unclear risk of bias and seven to be at