Overeruption without root exposure of third molars and periodontal health in the mandible.

Bone formation is seen around the third molar even when the tooth is exposed to the oral environment due to overeruption. To determine if overeruption of the third molar with or without root exposure is related to the status of the exposure of other teeth in the mandible, using orthopantomographs, 424 third molars were studied in 371 patients who were over 41 years of age. The rate of overeruption and root exposure in third molars was measured, and its relationship to the number of teeth lost and the rate of root exposure in other teeth in the mandible was analyzed. Tooth loss in the group of third molars with overeruption without root exposure was greater than in that without overeruption or root exposure in men, whereas the relationship was not seen in women. We found that root exposures of other teeth in the group of third molars with overeruption without root exposure were significantly smaller than in those with root exposure in both genders. Third molars with overeruption without root exposure, in which bone formation was easy to observe for radiographic diagnosis, were correlated with periodontal health in the mandible, suggesting a component of precision determination for predicting resistance to periodontitis.