Cantilever FPDs Have Lower Success Rates Than End Abutted FPDs After 10-Years of Follow-up

Abstract

Studies were located using a MEDLINE search strategy for English-language articles published from 1966 to 2004. A systematic review of 13 studies of cohort design (no randomized control trials were available) with the majority being retrospective. Seven hundred subjects with an age range of 26 to 84-years with a total of 816 FPDs with cantilever extensions were selected. The mean number of cantilever extensions varied from 1 to 6. Prostheses were of mixed design with 72% gold/acrylic structures. There are no data on the number of abutments compared with pontics or the overall length of the prostheses in this analysis Longitudinal follow-up of cantilever FPDs to failure or complication. All studies were required to have a mean minimum follow-up time of 5 years. Time to survival of the restorations, with secondary outcome measures of proportion of restoration successful at 10 years (success was defined as survival with no biological or mechanical complications) and time to biological (caries, loss of vitality and periodontal disease) and technical (loss of retention, abutment fracture, superstructure fracture) complication. The estimated aggregate proportion of cantilever FPDs surviving at 10 years was 81.8% (95% CI: 78.2-84.9%), with an annualized failure rate of 2 per 100 FPDs (95% CI: 1.63%-2.46%). Failure was not influenced by the number of cantilevered pontics or the material used for bridge construction in these data. The estimated aggregate proportion of cantilever FPDs successful (free of all complications) at 10 years was 63% (95% CI: 54.7%-70.2%). The estimated aggregate proportion with caries at one or more abutment teeth at 10 years was 9.1% (95% CI: 6.3%-13%). The estimated aggregate proportion with loss of vitality of one or more abutment teeth at 10 years was 32.6% (95% CI: 13.9%-64.9%). Rates of loss of vitality were much higher in the studies using extensive (12-unit FPDs supported by 2 cuspids) mandibular prostheses than those with shorter extensions. The estimated aggregate proportion with progression of periodontal disease leading to loss of the FPD at 10 years was 1% (95% CI: 0.3%-3%).The estimated aggregate proportion with loss of retention of the FPD at 10 years was 16.1% (95% CI: 8.8%-28.4%). Rates of loss of retention were much higher in the studies using extensive (12-unit FPDs supported by 2 cuspids) mandibular prostheses than those with shorter extensions. The estimated aggregate proportion with fracture of abutment teeth at 10 years was 2.4% (95% CI: 0.6%-9.8%). The estimated aggregate proportion with framework, veneer, or core fractures at 10 years was 5.9% (95% CI: 3.3%-10.4%). Estimated survival and success rates of cantilever FPDs were lower than previously reported rates for typical end-abutement supported FPDs; a 10-year failure rate of 18.2% had previously been reported for end-abutment supported FPDs for comparison.