The aim of this study was to investigate the effect of periodontal status at the time of nonsurgical root canal treatment (NSRCT) on the survival rate of endodontically treated teeth (ETT).Methods
In this retrospective investigation, molars that received NSRCT in an advanced specialty education program in endodontics from 2009 through 2017 were initially recruited. After the application of inclusion and exclusion criteria, 315 teeth were included in the study. Inclusion criteria were ETT with an acceptable quality of NSRCT; ETT that received an adequate crown within 3 months after NSRCT; and ETT with complete periodontal charting before NSRCT including pocket depths, clinical attachment loss, and bone loss. The periodontal status of all included teeth was assessed based on American Academy of Periodontology guidelines. All included ETT were divided into 3 groups as follows: healthy group, mild periodontitis, and moderate periodontitis. The survival rate of ETT was analyzed using univariate Kaplan-Meier and log-rank tests for differences between groups (P < .05). A Cox regression model was used to assess the effect of independent variables on the survival rate.Results
Teeth that were diagnosed with mild periodontitis were almost 2 times more likely to be extracted compared with ETT diagnosed with normal periodontium at the time of NSRCT (odds ratio [OR] = 1.9, P < .05). This increased risk of tooth loss was 3.1 (OR = 3.1, P < .05) for ETT diagnosed with moderate periodontitis. Smokers were twice as likely to have tooth loss compared with nonsmokers (OR = 2.2, P < .05).Conclusions
Patients' periodontal health, being 1 of the prognostic determinants of the outcome of NSRCT, requires attention before and subsequent to NSRCT. This may improve the survival of ETT and help patients maintain their natural dentition.