Purpose: The purpose of this study was to explore possible associations between prosthodontic, occlusal, endodontic, and periodontal factors and the endodontic status of endodontically treated teeth. Materials and Methods: Forty-six patients who had received endodontic treatment followed by a fixed restoration for at least one of their teeth were recalled and examined clinically and radiographically according to a predetermined set of evaluation criteria. A total of 89 teeth were included, and data obtained included assessments of the coronal restoration and post and core, occlusal contact relationships, a number of endodontic parameters, and periodontal status of the study teeth. For the latter assessment, 54 contralateral teeth were available for purposes of comparison. Teeth were grouped into those with and without periapical radiolucencies, and differences between the groups, with respect to all parameters, were analyzed by logistic regression. Results: Three factors were significantly associated with the presence of radiolucency: confirmed occlusal contact, by virtue of the tooth being either involved in group function or the only contact in working-side and protrusive movements, and endodontic filling and crown margins of poor quality. None of the other independent variables showed significant associations with the dependent variable of periapical radiographic appearance. Contralateral teeth had better periodontal conditions than restored study teeth. Conclusion: The finding that a good-quality endodontic filling and crown margin improve endodontic outcome corroborates many other similar reports; however, with occlusal contact shown to be associated with failing endodontic treatment, the range of factors that may influence endodontic outcome appears to have widened.