Clinical and histological observations of continuously formed bilateral mandibular deciduous central incisor roots...

We encountered a rare case of continuously forming bilateral mandibular deciduous central incisor roots after traumatic coronal destruction. The patient, 3 year 3 month old boy, had sustained an external injury which had caused the crowns of hist bilateral deciduous central incisors to fall out when he was 12 months old. Oral examination revealed two small, hard tissues resembling tooth structures on the alveolar ridge in the area of the lost mandibular central incisors. X-ray examination revealed them to be deciduous central incisor roots. We observed the extracted roots histologically and found that the lesion of the crown fracture and pulpal exposure on these roots was completely covered by newly formed irregular dentin and cementoid tissues. In this case, the causes of the continuous root formation were considered to be that the pulp tissues of traumatized teeth were able survive, so the injured lesion was quickly healed and covered with gingival tissue. The vital pulp produced the reparative hard tissue, sealing the site of pulpal exposure and continuing root formation after the trauma.