Risk Factors for Tooth Extraction after Fixed Prosthesis Treatment in Patients with Cerebral Palsy

Abstract

In our previous studies on fixed prostheses in patients with cerebral palsy, we found that the survival rate of the fixed partial denture was lower than that of a single crown, however, this survival rate includes the risks of debonding, removal, and tooth extraction, and may differ from the risk of tooth extraction alone, which is an irreversible failure. In this study, we investigated the tooth extraction risk factors for the abutment teeth of a fixed prosthesis. The study examined 268 abutment teeth of 35 patients with cerebral palsy who visited the Special Dental Comprehensive Treatment Department from 1984 to 2017 and in whom a fixed prosthesis was set. The data (sex, age, number of teeth, tooth type, type of prosthesis, anesthesia, disease, etc.) were collected and shared frailty analysis was performed using a mixed effect model with patient ID as random effect. The significance level was 5%. During the observation period, 22 of the 268 abutment teeth were extracted. The 10-year survival rate of the abutment teeth was 92.1% and the 20-year survival rate was 78.1%. As a result of shared frailty analysis, the survival rate of abutment teeth in a single crown was lower than that of a fixed partial denture, and the hazard ration of the fixed partial denture was 0.35, using the single crown as a reference. When we set a fixed prosthesis for patients with cerebral palsy, the fixed partial denture was often detached or removed, while the single crown was considered to be more likely to eventually lead to tooth extraction. Patients with cerebral palsy have their peculiar mandibular activity, which tends to cause a high stress load on their teeth. When a single crown is used, the occlusal force is not distributed and root fracture is likely to occur.

These results showed that selecting a fixed partial denture for prostheses in CP patients is useful for preserving the teeth.