Sixty-six patients with mandibular fractures under the age of 15 years were examined concerning number of tooth follicles involved in fractures and their prognosis thereof. One hundred and twenty six teeth were involved in the fractures. Most teeth were canines. This may be due to that a canine follicle occupies a larger area in the mandible and remains longer than other follicles.
In thirty-eight follicles followed up after fractures, sixteen showed abnormalities of tooth formation (abnormal angulat, ion of roots, protuberance on root surfaces, interruption of tooth formation) and disturbance of eruption. These abnormalities were found in corresponding to growing tips of tooth germs (basal area) which were involved in fracture lines. Disturbances of eruption was observed only in an infected case. It was, therefore, suggested that traumatic injuries and infections affecting toothforming tissues were major causes of such abnormalities.
