Longevity of implant crowns and 2-unit cantilevered resin-bonded bridges

Objective: To compare "survival" and "success" of implant-supported crowns (ISC) and tooth-supported 2-unit cantilevered resin-bonded bridges (cRBB) in the rehabilitation of a bounded single tooth space (BSTS), after an observation period of ≥5 years.

Methods: A case-control study among subjects who received ISC or cRBB rehabilitation at a teaching hospital. The (i) survival (retention in mouth) and (ii) success (absence of complications requiring intervention) for the ISCs and cRBBs were compared (overall, supporting structures and that of the prostheses). Rates of survival and success were compared using log-rank statistics. Prevalence of survival and success (categories) were compared by chi-square/Fisher's exact test.

Results: Seventy eight subjects participated in this study (39 ISC and 39 cRBB cases). Both had a mean observation time exceeding 100 months, P > 0.05. ISCs and cRBBs had similar survival rates: overall (P = 0.96), supporting structures (P = 0.14) and prostheses (P = 0.44) There was a significant difference in the rate of overall success between ISCs and cRBBs (P = 0.03), specifically with respect to the success rate of the supporting structures (P = 0.03). There was also a significant difference in the prevalence of supporting structures categorized as a "success": ISCs (69.2%) and cRBBs (89.7%), P = 0.03. Biological complications of supporting structures were more common among ISCs (25.6%) compared with cRBBs (7.7%), P = 0.03.

Conclusion: Implant-supported crowns and cRBBs in the rehabilitation of a BSTS survive similarly after at least 5 years. However, cRBBs had a higher success rate and were more frequently categorized as successful than ISCs. Notably, there were fewer biological complications of cRBBs supporting structures than ISCs.