Practice-Based Longitudinal Study of Multifactorial Risk Assessment for Periodontal Condition and Survival of Remaining Teeth in Patients with Removable Partial Dentures

Purpose: This retrospective cohort study examined factors affecting the periodontal condition and survival of remaining teeth 5 years after removable partial denture (RPD) placement using multivariate analyses. Materials and Methods: Of 231 patients who received RPDs at Tohoku University Hospital, 108 patients who had agreed to undergo a 5-year follow-up were examined. The outcomes of RPD treatment were assigned to one of three categories: successful (n = 58), remake (n = 36), and failure (n = 14). A total of 80 patients in the successful and remake groups were included in this study. The parameters analyzed to evaluate the periodontal condition were probing depth, Miller index of tooth mobility, and bone resorption level. Criterion variables were the outcome of each periodontal condition, deterioration, and tooth loss. Independent variables were sex, age, smoking habit, number of periodic maintenance appointments, location of RPD, number of abutment teeth, denture base material, design, and existence of a denture in the opposite jaw. Bivariate analyses were performed using chi-square test, and multivariate regression analysis was used to assess significance. Results: Sex and frequency of maintenance care were independently associated with deterioration of the periodontal condition. Sex and existence of a denture in the opposite jaw were independently associated with tooth loss. Conclusion: The findings suggest that periodic maintenance care and condition of the opposite jaw are essential for maintaining the condition of the remaining teeth.