Date of Award

Spring 2018

Document Type


Degree Name

Master of Science (MS)



First Advisor

Bhagavatula, Pradeep

Second Advisor

Hashimoto, Lance

Third Advisor

Ibrahim, Mohamed


Objective: To study the factors effecting the survival of teeth with non-surgical root canal therapy (NS-RCT) and to compare the transitions between failure states for teeth treated with NS-RCT based on initial provider type. Methods: Insurance claims were analyzed for 438,487 initial NS-RCT procedures to determine the effect of provider type, patient age, tooth position, presence of post/core, and crown at 90 days on tooth survival. Kaplan Meier survival estimates were evaluated for 1, 3, 5, and 10 years and adjusted hazard ratios (aHR’s) were calculated. A multi-state model with six transitions was created using the ‘mstate’ R package. Results: Overall survival was 98.2% at 1 year, 94.4% at 3 years, 90.8% at 5 years, and 82.8% at 10 years. Ten-year survival rates were 84.5% and 81.9% for teeth treated by endodontists and other providers, respectively. In the multiple regression analysis, significant differences in survival were found comparing NS-RCT provider (other provider vs. endodontist, aHR 1.31 [1.27, 1.35]) and tooth location (molar vs. anterior, aHR 1.26 [1.21, 1.31]). Increasing age at NS-RCT was significantly associated with a greater hazard of extraction. Placement of core/post and crown within 90 days were each significantly associated with a reduced hazard of extraction (aHR = 0.74 [0.72, 0.76] and aHR = 0.53 [0.51, 0.54]). Most teeth treated by NS-RCT had no subsequent treatment interventions. Teeth that were retreated were more likely to be extracted than teeth that did not have such an intervention. Teeth were more likely to be extracted than retreated. If a tooth had a non-surgical retreatment and subsequently a surgical retreatment, then it was more likely that the surgical intervention occurred during the first year of treatment. Conclusion: Survival rates of NSRCT treated teeth are higher among teeth treated by endodontists, when a crown was placed within 90-days of NSRCT and among younger patients. NS-RCT failures are most likely to result in tooth extraction. When retreatment is performed, it is more likely to be non-surgical and retreatment in any form increases the likelihood for future extraction. NS-RCTs initially performed by non-endodontists also have a greater chance for non-surgical retreatment or extraction.