Presence of third molar germs in orthodontic patients in Japan

• Published in: American journal of orthodontics and dentofacial orthopedics Vol. 119; no. 3; pp. 245 - 250
• Main Authors: Kajii, Takashi, Imai, Tohru, Kajii, Saori, Iida, Junichiro
• Format: Journal Article
• Language: English
• Published: United States Mosby, Inc 01.03.2001
• Subjects: Adolescent; Cephalometry; Chi-Square Distribution; Child; Female; Humans; Japan; Male; Malocclusion - classification; Malocclusion - diagnostic imaging; Malocclusion, Angle Class II - diagnostic imaging; Malocclusion, Angle Class II - pathology; Malocclusion, Angle Class III - diagnostic imaging; Malocclusion, Angle Class III - pathology; Mandible; Maxilla; Molar, Third - anatomy & histology; Molar, Third - diagnostic imaging; Orthodontics, Corrective; Radiography, Panoramic; Tooth Eruption; Tooth Germ - anatomy & histology; Tooth Germ - diagnostic imaging; Tooth, Impacted - diagnostic imaging
• ISSN: 0889-5406; 1097-6752
• DOI: 10.1067/mod.2001.111222

The purpose of this investigation was to evaluate the existence of third molar germs in orthodontic patients in Japan and to examine the relationship between the existence of third molars and sagittal maxillomandibular jaw relationships. The subjects comprised 306 patients from the orthodontic clinic of Hokkaido University Dental Hospital who were younger than 15 years. The subjects were divided into 2 groups: 1 group included 144 patients who were 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 results were obtained: (1) all 4 third molar germs were present in 77% of subjects, (2) mandibular third molars were present significantly more often than maxillary third molars, and (3) the percentage of skeletal Class III subjects who had all 4 third molars was lower than that of skeletal Class II subjects. The χ2 test was used to determine statistical significance in differences. (Am J Orthod Dentofacial Orthop 2001;119:245-50)