Objective: To investigate the quality of root canal fillings and coronal restorations in relation to periapical status in a Greek population. Method and Materials: A total of 320 patients who required full-mouth radiographic examination were included. The quality of root canal fillings and the periapical status, as well as the quality of coronal restorations, were assessed by radiographic criteria. Results were analyzed using random effects logistic regression models. Results: Root canals with adequate filling length had a lower incidence of apical periodontitis than root canals with inadequate filling length (51.7% versus 63.4%, P = .002). Root-filled canals with adequate coronal restorations showed a lower incidence of apical periodontitis than those with inadequate restorations (47.3% versus 67.4%, P .001). When both root filling and coronal restoration were assessed, the incidence of apical periodontitis ranged from 39.2% to 67.6%. Conclusion: Quality of root canal treatment, as well as quality of coronal restoration, are strongly associated with the incidence of apical periodontitis. Keywords: apical periodontitis, coronal restoration, epidemiologic study, Greek population, radiographic criteria, root canal filling