Fifteen-year survival of resin-bonded vs full-coverage fixed dental prostheses

Abstract

Purpose

We clarified cumulative survival and event-free rates of resin-bonded fixed dental prostheses (RBFDPs) and compared them to those of fixed dental prostheses (FDPs) to refine risk factors for non-survival/event and use of tooth extraction after the period of non-survival/event.

Methods

Study subjects were selected among all patients who consecutively attended the Fixed Prosthodontic Clinic of Okayama University Hospital. Eligible patients were those who received 3-unit metal-framed 2-retainer (wing–wing) RBFDPs or conventional full-coverage FDPs (RBFDPs/FDPs: 129/177 prostheses). Data were analyzed by Kaplan–Meier analysis with the log-rank test, Mann–Whitney test, chi-square test, and Cox proportional hazards analysis.

Results

The 15-year cumulative survival rates were 66.5% for the RBFDP group and 61.6% for the FDP group, which were not significantly different (p = 0.59). The 15-year cumulative event-free rates were 53.4% for the RBFDP group and 59.2% for the FDP group, which were not significantly different (p = 0.52). No significant risk factors related to non-survival and event-free of RBFDPs/FDPs were identified in the analysis model using treatment method, sex, age, number of remaining teeth, and treatment site as explanatory variables. The number of cases in which RBFDPs/FDPs resulted in non-survival due to abutment tooth extraction was significantly lower in RBFDPs (p < 0.01). Further, the abutment tooth as a non-vital tooth was identified as a risk factor for RBFDPs/FDPs resulting in non-survival due to abutment tooth extraction.

Conclusions

The present study is the first to indicate RBFDP as a prosthetic treatment option which should be selected for patients with slight or no abutment tooth decay.

Introduction

Fixed dental prostheses (FDPs), which restore form, function, and esthetics by connecting and fixing to remaining teeth as an abutment tooth, is a flawed functional restoration method frequently used in dental treatment. Because conventional full-coverage FDPs, which cover the entire abutment tooth, require the undercut of the abutment tooth to be removed, the amount of tooth removed increases and there is a risk of causing complications in some cases such as pulp extirpation of the abutment tooth. Conversely, because resin-bonded FDPs (RBFDPs), in which cutting of the abutment tooth is limited in the enamel, can minimize cutting of the abutment tooth, RBFDPs may be a less invasive treatment than conventional FDPs. The history of RBFDPs is thought to have originated with the so-called Rochette bridge [1]. Early Rochette bridges had high failure rates; a study by Creugers et al. [2] on non-perforated cast-metal resin-bonded bridges inserted in 1983–1984 reported a survival rate of only 28% in the posterior regions after 7.5 years. Since then, RBFDPs have evolved including developments in framework design (e.g., Maryland bridge) and adhesive procedure (e.g., metal surface treatment and resin cement system), all of which have improved clinical success rates [3]. Moreover, the degree of patient satisfaction with RBFDPs appeared to be high and did not seem to be influenced by the occurrence of failure [4], [5], [6], [7], [8].

The clinical success rate of RBFDPs varies. The latest report declared that the survival rates of metal-frame RBFDPs after 5, 10, and 15 years were 86%, 42%, and 15% with repair, respectively, whereas 69%, 32%, and 14% of the prostheses survived without repair, respectively [9]. Conversely, the estimated cumulative survival rate of RBFDPs was 95% after 5 years, 88% after 10 years, and 66% after 20 years [10]. Concerning FDPs, the 15-year cumulative survival rate of 3-unit porcelain-fused FDPs was 90% [11]. There are some reports regarding the respective prognostic evaluations for RBFDPs or conventional full-coverage FDPs; however, there are no reports comparing the cumulative survival and success rates of both RBFDPs and full-coverage FDPs using the same population and study design. In addition, no reports have considered the risk factors related to the occurrence of non-survival cases and events in detail, such as persistent tooth number. Moreover, there are also no reports regarding the presence of occurrence of abutment tooth extraction or decision-making on prosthodontic treatment at the time of re-treatment in the event of non-survival in subject RBFDPs and full-coverage FDPs, although it is said that RBFDP failure is often less catastrophic than FDP failure [12].

Therefore, the purposes of this study included clarifying (1) the cumulative survival and event-free rates of 3-unit metal-framed 2-retainer (wing-wing) RBFDPs and comparing them to those of full-coverage FDPs; (2) the risk factors related to the occurrence of non-survival/event in each FDP; and (3) the circumstances in which abutment tooth extraction occurred for each FDP as well as decisions made regarding prosthodontic treatment at the time of re-treatment.