Clinical comparison of metal ceramic resin-bonded fixed dental prostheses with a conventional and a mixed retainer design

Statement of problem Little is known about the clinical performance of fixed dental prostheses that rigidly connect adhesive retainers and crowns. Purpose The purpose of this retrospective analysis was to assess and compare the clinical performance of resin-bonded fixed dental prostheses with a conventional and a mixed retainer design. Material and methods Included as participants were all patients of the hospital since 2004 with regular clinical follow-up who were treated with 3-unit or 4-unit metal ceramic resin-bonded fixed dental prostheses with a conventional 2-adhesive retainer design (conventional group) or with a mixed type combining an adhesive retainer with a crown or a partial crown retainer (mixed group). The analysis included 84 participants with a total of 57 (64%) prostheses in the conventional group and 32 (36%) prostheses in the mixed group. Treatment and data collection were standardized. Cumulative survival without failure (defined as a restoration in need of replacement), chipping, and debonding were estimated by the Kaplan-Meier method and compared for the groups (log-rank test) (α=.05). Results During a mean observation period of 4.1 years (SD, 2.5 years; minimum, 0.4 years; maximum, 9.4 years), 12 complications occurred in 10 restorations. Defects of the ceramic veneer (n=6) were observed most frequently. The estimated 5-year failure-free survival rate was 97.4% (standard error, .025) in the conventional group and 95% (standard error, .049) in the mixed group (log-rank, P =.32). The 5-year cumulative survival rate without chipping was 90.7% (standard error, .064) for the conventional group and 93.8% (standard error, .061) for the mixed group (log-rank, P =.44). The 5-year cumulative survival rate without debonding was 95.1% (standard error, .034) for the conventional group and 91.5% (standard error, .058) for the mixed group (log-rank, P =.54). Conclusions Limited by a small sample size and a short follow-up period, the findings of this retrospective analysis indicate that the clinical performance, in terms of survival and the incidence of complications, is comparable for conventional resin-bonded fixed dental prostheses and those that rigidly connect an adhesive wing and a partial or complete crown. Acceptable 5-year survival and complication rates imply that the medium-term prognosis for resin-bonded restorations with a retentive preparation design is comparable with that for conventional fixed dental prostheses.