The prevalence of AP in root-filled and untreated teeth, and the frequency of root-filled teeth were comparable to those reported in previous similar studies carried out in European countries. The prevalence of root-filled teeth with AP was found to be higher compared to that demonstrated in other epidemiological studies.

The incidence of AP in root filled teeth was high. Many root fillings were technically unsatisfactory. Adequate root fillings and coronal restorations were associated with a lower incidence of AP; an adequate root filling had a more substantial impact on the outcome of treatment than the quality of the coronal restoration.

Type 2 diabetes mellitus is significantly associated with an increased prevalence of AP.

In this study population, smoking was significantly associated with a greater frequency of root canal treatment and with an increased prevalence of apical periodontitis.