<ORGINAL ARTICLE>Roentgenographic Observation of Lower Wisdom Teeth

P(論文)To estimate the state of lower wisdom teeth eruption, we observed orthopantomografic films of 642 students (age 20～29, 567 males, 75 females) and analysed the 1028 lower wisdom teeth there (898 male, 130 female) for the following 5 items 1. The direction of wisdom teeth to the occlusal plane. 2. The position of the highest portion of the wisdom teeth relative to the second molar cervical line. 3. The distance between the lowest part of a wisdom tooth and the mandibular canal. 4. The number of wisdom teeth roots. 5. The eruption space between the ramus and distal side of the second molar and the mesiodistal diameter of the wisdom tooth crown. The following results were obtained: 1. 72 2% of wisdom teeth showed a mesioangular tendency. 2. 87.5% of wisdom teeth erupted above the second molar cervical line. 3. In 53 4% of the cases, the lowest part of the wisdom tooth was separate from the mandibular canal. 4. 75 1% of wisdom teeth had two roots and 17.3% had one. 5. In 57 4% of the cases, the eruption space was narrower than the wisdom tooth diameter. The results suggest that the narrow eruption space may cause the mesioangular tendency of the wisdom teeth, and that the extent of the mesioangular tendency is larger than in past surveys.departmental bulletin pape