Effect of endodontic case difficulty on endodontic mishaps and the number of treatment visits: a clinical study

Root canal treatment, despite its high success rate, remains a challenging procedure due to anatomical complexities or procedural limitations, which may occasionally result in treatment failure. This study evaluated the influence of endodontic case difficulty, categorized by the American Association of Endodontists assessment form (low, moderate, high), on the incidence of endodontic mishaps and treatment visit requirements in postgraduate dental students.

This prospective clinical study analyzed 200 root canal treatments performed on 200 patients by a postgraduate dental student, classified according to the American Association of Endodontists Case Difficulty Assessment Form. Mishaps included over-instrumentation, working length loss, underfilling, overfilling, apical transportation, instrument fracture, and perforation. Statistical analyses, including independent t-test, one-way ANOVA, Spearman's correlation, and Chi-square tests (p < 0.050), were performed to evaluate the relationships among case difficulty, occurrence of mishaps, tooth type, and the influence of case difficulty on the number of treatment visits.

Of the cases, 48.5% were high difficulty, 31.5% moderate, and 20% low difficulty. Endodontic mishaps were significantly more frequent in molars compared to anterior and premolar teeth (p = 0.001). Case difficulty was significantly associated with mishaps such as underfilling, overfilling, and the need for additional visits (p < 0.050), while no significant relationship was observed for other mishap types (p > 0.050). Case difficulty showed significant positive correlations with both the number of mishaps (r = 0.344, p < 0.050) and the number of treatment visits (r = 0.433, p < 0.050).

This prospective clinical study demonstrated that the majority of procedural mishaps occurred in molar teeth and in high-difficulty cases. The American Association of Endodontists Case Difficulty Assessment Form proved useful in anticipating potential risks. Incorporating such structured case assessment tools may help clinicians reduce mishaps and enhance the success of root canal treatments.

The study protocol was registered in the ClinicalTrials.gov database with the identifier number NCT06640790 on 11 October 2024.