Long Term Survival Rate of Teeth Requiring Multiple Treatment Procedure

Methods: 245 teeth in 87 patients were clinically and radiographically evaluated. The patients were contacted by phone. All the teeth had received crown lengthening surgery (CLS) by a single periodontist. Root canal therapy and prosthehetic procedures were rendered either by specialists or experienced general dentists. Aside from lost teeth, the criteria for a hopeless tooth was defined and applied at the time of examination. Survival rate was determined using the Kaplan-Meier estimator. Clinical indices including pocket depth (PD), bleeding points index, C/R ratio, position of the restoration margin relative to the gingival margin (RM-GM), and presence of intra-canal post were compared between different survived groups (<3, 3-5, 5-10, and >10 years) using one-way Analysis of Variance (ANOVA). Potential predictors of failure were determined using the Cox regression model.

Results: The mean±SD of 3, 5, 10 and 13-year survival rates were 98±1%, 96±1.6%, 83.1±4.5%, and 51.9±14.5%, respectively. The mean PD (P<0.013), as well as C/R ratio in the mesial (P=0.003) and distal (P=0.007) surfaces were significantly higher in the >10 year survived teeth. BPI and RM-GM showed no significant differences among the groups. C/R ratio and sub-gingival placement of restoration margins appeared to be the major determinants of tooth loss.

Conclusions: The long-term survival rate for compromised teeth that have undergone combined endodontic, periodontic, and prosthodontics therapies, was 83-98%.