The study is based on the orthopantomographic evaluation of the formation and the development of the permanent third molar (n = 938 patients with known age between 15 and 25 years). We used a modified method according to Gleiser and Hunt (1955) with 3 stages of crown formation and 7 stages of root formation. The correlation between age and the formation of the third molar is not very close. There is a deviation of +/- 4 years (97% statistical safety). The root is completed at the age of about 23 years (upper jaw: 23 years in males and females, mandible: males 23.2 years, females 23.6 years). There is a slight sexual dimorphism with an accelerated development of the third molar in males. The dentition of the molars runs parallel on both sides of the jaw. Only a small proportion (14%) of all persons has completely formed roots at the age of 21. Retination of the third molars (produced by the second molar and by the ascending branch of the mandible) causes a delay of its development.