Aim: To investigate and compare the prevalence of root canal fillings, apical periodontitis and endodontic treatment needs in a German subpopulation in 1994 and 2004, respectively. Methodology: Two hundred panoramic radiographs taken from 1994 and 2004, respectively, were evaluated using the Periapical Probability Index (PRI). The technical quality of the root canal fillings in terms of length and homogeneity was estimated. Minimum and maximum endodontic treatment needs were calculated. Statistical analysis was performed using the chi-square and Fisher exact test at P 0.05. Results: There was a total of 4660 teeth without root canal fillings for radiographs taken in 1994 and 4244 teeth for those in 2004. In teeth without root canal fillings in 1994, the frequency of PRI 4 was 1.0% and PRI 5 was 1.2%. In 2004, PRI 4 was 1.1% and PRI 5 was 2.4%. The difference was not significant (P > 0.05). A total of 168 teeth (3.4%) in 1994 and 217 (4.8%) in 2004 were root canal filled and the difference was significant (P 0.05). The frequency of PRI scores 4 and 5 for the root canal-filled teeth was 8.5% and 26.1% for 1994, and 6.9% and 31.8% in 2004, respectively. The difference was not significant (P > 0.05). The percentage of short root canal fillings was 52.7% in 1994, and 50.8% in 2004. In 1994, 48.6% of the root canal fillings were scored as inhomogeneous, and in 2004 the percentage was 40.6%. There were no significant differences concerning the radiographic quality of root canal fillings (P > 0.05). Endodontic treatment need was calculated as 3.7% of all teeth in 1994, and 4.6% in 2004. Retreatment need was calculated as 49.7% of root canal-filled teeth for 1994 and 54.5% of root canal-filled teeth for 2004. Conclusion: The prevalence of apical periodontitis in root canal-filled teeth and the need for retreatment increased over the observation period. There were no significant improvements in the technical quality of endodontic treatment from 1994 to 2004. Keywords: apical periodontitis, endodontic epidemiology, root canal treatment, treatment needs