The aim of this study was to determine the frequency of endodontic treatment in an adult Ukrainian population in relation to the age and its distribution depending on the type of the teeth. Materials and methods: A total of 435 digital panoramic radiographs of adults (aged 18 to 72 years) were examined. A tooth was qualified as root filled (endodontically treated), if radiopaque root-filling material was determined in the pulp chamber and/or in the root canals. Pearson's chi-squared test (χ2) and Spearman's rank correlation were applied for data analysis. Results: It was revealed that 82.5% of patients had previously received endodontic treatment of the teeth. The overall percentage of root filled teeth in adult dentition is 12.08%. The analysis of the rate of endodontically treated teeth in different age groups identified an increasing of treated teeth with age - from 5.2% in the youngest cohort (18-19 years old) to 24.9% in the oldest cohorts. It was revealed that 822 teeth (14.2%) on maxilla and 569 (9.9%) on the mandible were endodontically treated. Most often root filled teeth were first mandibular molars (39.3%), first maxillary molars (26.7%) and second maxillary premolars (20.4%). Much lower rate of endodontic treatment were considered in lower mandibular incisors and canines (0.7%, 0.9% and 1.5% respectively). Conclusions: A total of 82.5% examined adults had one or more endodontically treated teeth in this study. The obtained results prove the necessity of prevention of carieswith special emphasis on the first maxillary and mandibular molars, and maxillary second premolars, which have significantly higher frequency of root canal treatment in comparison to other teeth groups.