Evaluation of the relationship between factors affecting the success of root canal treated molar teeth and apical periodontitis: a retrospective study

In this study, we aimed to evaluate the quality of root canal treatment, the prevalence of apical periodontitis (AP), and the impact of treatment quality on periapical status in endodontically treated maxillary and mandibular molars in a Turkish population using cone beam computed tomography (CBCT). CBCT images of 396 endodontically treated maxillary and mandibular first and second molars from 282 patients (aged 18–50 years) were analyzed in axial, sagittal, and coronal sections. The quality of endodontic treatment, including canal filling length, homogeneity, coronal restoration, and complications, as well as periapical status, such as lesion size, relationship to the root, and site of bone destruction, were assessed using the Periapical and Endodontic Status Scale (PESS). Statistical analyses were performed using the Mann-Whitney U, Kruskal-Wallis H, Yates correction, Fisher-Freeman-Halton, and Pearson Chi-square tests. Apical periodontitis was detected in 57.6% of the examined teeth. The quality of endodontic treatment was significantly associated with the presence, size, root relationship, and location of periapical lesions (p<0.05). Apical periodontitis was more frequent when the filling material was positioned more than 2 mm short of the radiographic apex (51.1%), root canal filling homogeneity was inadequate (77.5%), coronal restoration was insufficient (39.2%), root perforation was present (7.5%), or missed canals were identified (43.2%). Lesions wider than 5 mm were more commonly observed in cases of short root canal fillings. Additionally, inadequate canal filling homogeneity and insufficient coronal restorations were associated with wider lesions as well as increased occurrence of cortical bone destruction and furcation lesions (p<0.05). In contrast, lesions in cases of root perforation and missed canals were generally smaller than 3 mm, localized to a single root, and confined to the root area. This study underscores the critical role of high-quality endodontic treatment in minimizing the prevalence and severity of apical periodontitis and highlights its influence on lesion size, root relationships, and the extent of bone destruction. Key Words: Cone Beam Computed Tomography, Apical Periodontitis, Periapical Lesion, Failure in Root Canal Treatment, Retreatment