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 < 0.05) from 13.9% at the first investigation to 17.7% after 20 years. There was also a statistically significant increase (P < 0.05) in teeth with apical periodontitis from 3.3% to 6.8%. Apical periodontitis both in connection with root canal treated teeth and teeth without endodontic treatment, had increased during the follow‐up period. Even though the quality of the root fillings had improved, there was no corresponding improvement of the apical status in teeth with root fillings.

Conclusions  There is still a great need for endodontic treatment in the Swedish population, and no improvement in apical health was found during this 20‐year follow up.