AIM: To re-examine a population after 20 years and evaluate changes in prevalence of endodontic treatment and apical periodontitis, as well as the technical quality of root fillings. METHODOLOGY: One hundred and fifteen out of an original 200 patients living in the northern part of Sweden were re-examined with a full mouth radiographic survey after 20 years. Frequencies of root canal treated teeth, apical periodontitis and quality parameters of root fillings were registered. RESULTS: The frequency of root canal treated teeth increased significantly (P