Radiographic Evaluation of the Association Between Coronal Restoration Type and the Presence of Periapical Lesions in Root Canal–Treated Teeth

Background: This study evaluated the association between coronal restoration type and periapical lesions in root canal–treated teeth. Methods: Digital periapical radiographs (2021-2025) of 233 root canal-treated teeth from 157 patients were evaluated. Restoration type and periapical status were independently assessed by 2 calibrated endodontists, while root canal treatment (RCT) and restoration quality were classified by consensus using predefined radiographic criteria. Chi-square tests and logistic regression adjusted for tooth group and jaw location were repeated after excluding unacceptable RCT, then unacceptable restorations, and using the second observer’s ratings. Results: Periapical lesions were present in 121 teeth (51.9%): 72.0% without restoration, 50.0% with direct, and 46.9% with indirect restorations (P = .099). Adjusted odds of periapical lesion were lower for direct (odds ratio [OR] = 0.402, 95% CI: 0.159-1.017) and indirect restorations (OR = 0.343, 95% CI: 0.112-1.050) than for no restoration, without reaching significance. Root canal treatment was unacceptable in 30 teeth and restoration in 6. After excluding unacceptable RCT (n = 203), the gradient persisted (70.0%, 45.8%, and 42.9%; P = .107), and further excluding unacceptable restorations (n = 198) yielded virtually identical results. The second observer’s ratings showed the same pattern (P = .058). Conclusion: Teeth classified as having no coronal restoration showed the highest lesion prevalence. This pattern remained similar after accounting for radiographically detectable endodontic and restorative quality and was consistent across observers. However, the overall association did not reach statistical significance, and preoperative periapical status was unavailable, warranting cautious interpretation.