Factors Affecting Root Canal Treatment Case Difficulty, Practitioner Rating of Difficulty and Treatment Complications Among General Dentists and Endodontists: A Prospective Cohort Study From National Dental Practice-Based Research Network PREDICT Project.

Aim: Successful root canal treatment (RCT) is necessary for managing pulpal and periapical disease. The technical quality of RCT affects its outcome. Recognising complicating factors can be important to optimising outcomes. The aims of this study were to compare the practitioner reported case difficulty before and after completion of RCT; and to determine whether any case difficulty items were associated with complications encountered while performing the RCT.

Methodology: One hundred and four general dentists (GDs) and 49 endodontists enrolled 1860 patients needing RCT, April to September 2017. Both before RCT and upon its completion, practitioners used a 10-point scale to rate the RCT's case difficulty (Difficulty Rating [DR]). Then they used a modified Case Difficulty Assessment Form (CDAF) to record the items for difficulty using the form's list of 10 provided choices. We related practitioners' pre-RCT CDAF items to their DR ratings and to the procedural complications that they subsequently experienced during this RCT. General estimating equations (GEE) were used to assess the significance of differences in proportions between GDs and endodontists. Non-parametric tests were used to analyse compositive variables.

Results: Data of 1,698 patients were available for CDAF analyses. The mean CDAF was higher for endodontists than GDs (p < 0.001). Pre- and post-RCT DRs were significantly correlated (r = 0.79, p < 0.001), as were pre-RCT DR and the number of reported CDAF difficulties (r = 0.57, p < 0.001). Overall, practitioners encountered complications in treating 16% of patients. The complications were length of obturation > 2 mm from radiographic apex or beyond apex, canals not negotiable within 2 mm of apex, instrument separation, inadvertent filing/file placement past root apex, and perforation. Several CDAF items were independently predictive of complications. Despite the higher CDAF in teeth treated by endodontists, complications were less frequent among endodontists compared to GDs (13% vs. 19%, p < 0.001).

Conclusions: Pre-RCT assessments predicted intra-operative difficulties and outcomes. Our work underscores the need for targeted assessment tools and specialised training to improve RCT, especially in complex cases treated by GDs.