Effect of Diabetes Mellitus on Survival and Complication Rates of Tooth-Supported Fixed Dental Prostheses (FDPs): Long-Term Clinical Evaluation

Background/Objectives: Diabetes mellitus (DM) can adversely affect oral health by compromising immune function and promoting chronic inflammation. This effect can significantly impact the outcomes of fixed dental prostheses (FDPs). This study aimed to evaluate the rates of complications in FDPs in diabetes patients. Methods: The study investigated various clinical factors, including technical complications and biological complications. The investigation included diabetic patients (test group) and non-diabetic patients (control group), who were evaluated during their follow-up visits. Clinical and radiographic assessments were performed to determine the cumulative survival rate, and life table survival analyses of FDPs in the presence of complications were performed. Results: This study evaluated 1125 FDPs (66.1% in women), with 27.1% in diabetics, over a mean of 9.3 ± 7.7 years. The overall complication rates analysis, using the Mann–Whitney U test, showed a significant difference between diabetic and non-diabetic patients (p = 0.002). Diabetic patients had higher biological complications (58.4% vs. 51.1%, p = 0.03) and more technical complications (7.5% vs. 6.1%, p = 0.382). Poor oral hygiene strongly correlated with failure (72.1% vs. 12.9%, p < 0.001). Survival analysis revealed a decline in FDP survival probability to 0.23 for diabetics and 0.33 for non-diabetics at 15 years (p = 0.012). Conclusions: DM may reduce the durability of fixed dental prostheses, with diabetic patients showing noticeably higher rates of technical and biological complications compared to non-diabetics.