Abstract
The purpose of this study is to as certain whether the upper and lower third molars can contribute to the occurrence or aggravation of crowding. The sample of this study consisted of 187 subjects (103 males and 84 females) aged 20–30 years, then the sample was divided into two main groups and three subgroups. The groups consisted of crowded and normal subjects. The subgroups consisted of persons who had maxillary or mandibular third molars that were either impacted, erupted into function or agenesis.The results showed that the crowded group revealed a higher percentage of im-pacted third molar and a smaller percen-tage of erupted third molar particularly in the mandible and a smaller percentage of third molar agenesis than the normal group.The females had more impacted third molar in the upper and lower jaws for both crowded and normal groups. The percen-tage of third molar agenesis in the males was higher in the upper jaw and smaller in the lower jaw than the females.In normal group, no significant differ-ence was found between upper and lower jaws except in females where the uni-lateral third molar agenesis was greater in the lower jaw. In crowded group, the low-er jaw revealed a higher percentage of impacted third molar for all subjects and a smaller percentage of erupted third molar for females and a smaller third molar age-nesis for the males as compared with upper jaw.
