Presence of third molar germs in orthodontic patients in Japan

The purpose of this investigation was to evaluate the existence of third mo lar germs in orthodontic patients in Japan and to examine the relationship between the existence of third molars and sagittal maxillomandibular jaw re lationships. The subjects comprised 306 patients from the orthodontic clini c of Hokkaido University Dental Hospital who were younger than 15 years. Th e subjects were divided into 2 groups: 1 group included 144 patients who we re born between 1966 and 1969 (60s group), and the other group included 162 patients who were born between 1980 and 1987 (80s group). Assessments were made from panoramic radiographs and lateral cephalograms. The following re sults were obtained: (1) all 4 third molar germs were present in 77% of sub jects, (2) mandibular third molars were present significantly more often th an maxillary third molars, and (3) the percentage of skeletal Class III sub jects who had all 4 third molars was lower than that of skeletal Class II s ubjects. The chi (2) test was used to determine statistical significance in differences.