A multicentered clinical study on posterior resin-bonded bridges: the 'Manchester trial'.

This study was designed to investigate and identify factors relevant to the success and failure of posterior resin-bonded bridges (PRBBs) related to the patient, technique, operator and bridge design. It was a long-term controlled clinical trial and formed part of a multicentered study on PRBBs. Data are presented 2.5 years from the start of the study. Following a strict protocol for case selection, 54 posterior, resin-bonded, fixed-fixed, three unit bridges were placed in 45 patients. Twenty-four patients with 27 PRBBs attended for 2.5-year recall. Treatment variables were limited to one of two operators and either a conventional tooth preparation or a more extensive modified preparation was performed. The allocation of treatment modalities was performed using a computer program to balance patient variables such as age, gender, location of bridge, restoration of abutment teeth. All bridges were produced in one laboratory, treated to produce a silicate-coating bond and placed using Microfill Pontic C (Kulzer, Wehrheim, Germany). Data relating to the patients, the open spaces, bridge preparation, bridge placement and subsequent annual evaluation were recorded. The survival of PRBBs in the maxilla was 77% and in the mandible 47%.