Development of third molar in the Czech population.

The third molar development was studied on the basis of 1700 panoramic radiographs analysis of randomly selected individuals in the age ranging between 5-21 years inclusive. Each age group consisted of 100 probands--50 boys and 50 girls. The characteristics of the third molar development were following: time of dental follicle formation--dynamics of development--the most frequent stages of third molar development in individual age groups-- intraindividual differences and symmetry of development--incidence of 1-4 third molars agenesis--relation between the third molar development and the dental age--differences in the third molar development between individuals with all four third molars present and individuals with 1-3 third molars agenesis--ntersexual differences. On the basis of our analysis of seven stages of development, differences of this process between males and females and the changes in dynamics of development characterizing upper and lower jaw were described. The incidence of the third molar agenesis was statistically significant, being more frequent in boys (24.2%) than in girls (17.6%). The study showed, that when the third molar is not present at the age of thirteen, it could be taken in the Czech population as agenesis. Correlation between developmental stage of third molars and dental age was ascertained. With the exception of the agenesis, no other statistically significant intersexual differences were found.