Clinical and radiographic factors associated with failure of endodontically treated teeth: A cross-sectional study

Abstract Introduction: Despite high reported success rates for endodontic treatment, failures remain a common clinical challenge. Identifying the contributing factors to such failures is critical to improving long-term treatment outcomes. This study aimed to determine the clinical and radiographic causes of failure in endodontically treated teeth and analyze their association with tooth type, quality of obturation, coronal restoration status, and other procedural factors. Materials and Methods: This cross-sectional study included 117 patients presenting with 145 failed endodontically treated teeth. After obtaining ethical clearance and informed consent, each case was assessed using clinical examination and standardized periapical radiographs. Data regarding tooth type, gender, quality of root canal obturation, coronal restoration, and reasons for failure were recorded. Descriptive statistics were used to analyze the distribution and frequency of failure-related variables. Results: Endodontic factors alone accounted for 40.68% of failures, followed by combined endodontic and restorative factors (31.03%) and restorative factors alone (28.27%). Maxillary molars were the most frequently affected teeth (47.58%). The most common radiographic defect was underfilled canals (41.37%), followed by poorly filled (24.82%) and missed canals (22.06%). Regarding coronal restorations, 22.06% of failed teeth had no restoration, while 24.82% had full-coverage crowns. Among extracted teeth, 48.27% failed due to restorative reasons. Overall, 80% of teeth were referred for retreatment, and 20% were extracted. Conclusion: The majority of failures were associated with technical deficiencies, primarily related to inadequate obturation (endodontic factors) and coronal restoration quality, highlighting the importance of strict adherence to clinical protocols.