RCT Comparing Molar Two- and Three-unit RBBs- Preliminary Findings

Abstract

Objectives: Resin-bonded bridges (RBBs) are a conservative prosthesis adhesively bonded to abutment teeth with minimal tooth preparation. Since its development in the 1970’s, RBB has had improved clinical success based on improved adhesive cements, biomechanical principles and the use of two-unit cantilevered (CL2) design. While the CL2 RBBs have been shown to be more successful than fixed-fixed design, they have not been recommended for molar-sized edentulous span due to Ante’s law. The aim of this study is to report the preliminary findings of a randomized controlled trial (RCT) comparing three-unit fixed-movable (FM3) and CL2 RBBs for molar-sized spans (8-10 mm). Methods: The protocol was registered with Clinicaltrial.gov (NCT02239718) and ethics approval obtained (UW 14-233). Patients with at least one missing molar and that fulfilled the inclusion/extrusion criteria were recruited and randomized (ratio 1:1) into CL2 (test) and FM3 (control) group. Patients were examined before and at 1, 6, 12 months after insertion of RBBs by independent assessors. Abutment teeth mobility and tightness of proximal contacts were recorded by periotest and digital gauge respectively. Patients satisfaction was recorded by visual analogue scale after insertion of RBBs. Results: Fifty-eight patients were enrolled and seventy-nine RBBs were inserted with forty-one CL2 and 38 FM3 RBBs. Thirty-seven patients attended at one-month review, 17 at 6-months and 4 at 12-months review. The vast majority these prostheses were provided by undergraduate dental students. One CL2 and one FM3 RBBs was debonded resulting in retention rate of 97.6 and 97.4%. Both RBBs were rebonded. The presence of proximal contacts inferred no abutment tooth drifted. Patients were generally satisfactory to both design. No adverse outcomes were reported. Conclusions: These preliminary findings show that CL2 RBBs can be successfully placed for molar spans with no observable drifting. Longer term and more comprehensive data will be collected.