Introduction:
Teeth agenesis is the most common teeth developmental anomaly. It mostly aff ects third molars (5-58%). The intensity of this agenesis can be various (from one to four teeth). Hypodontia of third molars can co-exist with other teeth number disturbances. The aim of this study was to fi nd relation between agenesis of third molars and agenesis of other teeth.

Material and Methods:
Medical documentation of 980 patients was analysed. The studied group were patients with absence of one or more third molars as confirmed radiografically. The second condition was to obtain stadium G of germs formation (by Demirijan) by the second lower molars. Patients possessing all four third molars create a control group. Prevalence and type of agenesis in the studied and control group were examined.

Results:
363 patients were qualified to thestudy, 296 in the control group and 67 in the studied one. The agenesis of 133 third molars were found (62 in the upper jaw and 71 in the lower one). The prevalence of other teeth agenesis in the studied group was 20.9% and concerns mainly the lower second premolars (19.4%), upper (17.9%) and upper lateral incisors (10.5%). The prevalence of other teeth agenesis in the control group was 8.8%.

Conclusions:
The most frequent form of agenesis was the absence of singular lower third molar. In the studied group prevalence of congenital lack of other teeth was higher than in the control group.