Objectives: Determine the survival time of root-canal-treated (RCT) permanent teeth in National Dental Practice-Based Research Network (PBRN; www.NationalDentalPBRN.org) practices using electronic dental record (EDR) data, and investigate any differences by patient age, gender, placement of crown post-RCT, tooth type, and Network regions.
Methods: Ninety-nine Network general dentistry practices that used Dentrix or EagleSoft EDR shared de-identified data of patients who received RCT on permanent teeth through October 31, 2015. We calculated survival time as the number of years of post-RCT observation or extraction of the tooth, whichever came first. We retrieved patient age, gender, and insurance of patients, date of RCT, tooth type, placement of crown post-RCT and the date and type of subsequent restorative procedures performed on the same tooth. The last dental visit was considered the censoring date. Survival time was calculated by Kaplan Meier statistics and a Cox proportional hazards model was performed to assess the influence of selected variables (p<0.05).
Results: 71,258 permanent teeth (46,700 patients) received RCT with 47% performed on molar teeth, 33% on bicuspids, and 20% on anterior teeth. The observation period ranged from 0 days-25 years; median survival time was 10.3 years (inter-quartile range: 9.88 -10.7 years). There were no statistically significant differences in survival time by age group (18-44 years, 45-64 years, 65 years and older). However, the Cox model detected significant differences by patient gender, tooth type, placement of crown post-RCT, presence or absence of insurance, and Network regions.
Conclusions: Although the results indicated a higher survival time compared to a previous dental PBRN study that reported a mean survival of 7.3 years, it is still lower than reported in studies of populations with dental insurance. Future research is needed to investigate the differences observed in the survival times based on practitioner characteristics and practice locations in the six different Network regions.