Influence of Span Length on Long-Term Complications of Tooth-Supported Fixed Dental Prostheses

This retrospective study evaluated the long-term clinical performance and complication rates of tooth-supported fixed dental prostheses (FDPs) of different span lengths and assessed the influence of design, span length, material type and location on complication rate.

A total of 199 FDPs placed in 199 patients (mean age: 50.3 ± 12.9 years) were examined clinically and radiographically at a mean follow-up of 9.0 ± 6.3 years. Biological complications (secondary caries, loss of tooth vitality) and technical complications (loss of retention, framework or veneer fracture) were recorded. Biological and technical complications were summarized descriptively. Kaplan-Meier, life-table and univariate and multivariable Cox proportional hazards analyses were performed.

The mean observation period was 9.0 ± 6.3 years. At least one complication was detected in 170 FDPs (85.4%); biological complications were detected in 133 (66.8%) and technical complications in 40 (20.1%). Crude total complication frequencies differed by design (p = 0.002), whereas span length was not associated with complication frequency. In the adjusted Cox model, metal-ceramic restorations had a lower hazard of complication detection than full-ceramic restorations (hazard ratio [HR] = 0.400; 95% confidence interval [CI], 0.253 to 0.634; p < 0.001). Cantilever FDPs also showed a lower adjusted hazard than conventional FDPs (HR = 0.578; 95% CI, 0.337 to 0.989; p = 0.046); other adjusted associations were not statistically significant.

Biological complications were more frequent than technical complications in this follow-up cohort. The findings support structured long-term maintenance, but comparisons by design and material should be interpreted cautiously because complication onset was approximated by the follow-up examination, historical resolved complications were not systematically captured, and several subgroups were small.