Hypoplasia in crown of primary mandibular left lateral incisor identified in infant Japanese girl

A girl aged 0 years 11 months was referred to our clinic by a local pediatrician for examination of a missing tooth crown of a primary mandibular left lateral incisor. Our intraoral examination showed that seven primary incisors had emerged into the oral cavity, while no tooth crown was noted in the region of the primary mandibular left lateral incisor. A calcified structure was identified close to the gingival margin, which had a bone-like appearance and color, with no inflammation seen in the gingiva around the structure. Furthermore, the pulp space could be seen through the layer of hard tissue located close to the gingival region. A periapical radiograph taken at the first visit demonstrated a root-like structure with dentin and pulp, whereas enamel was not detected. The structure was speculated to be the root of the primary mandibular left lateral incisor, which was in the developmental stage. As there were no abnormal signs or symptoms, we decided to perform periodical examinations at 3-month intervals. Periapical radiographs taken at 1Y0M and 1Y7M showed root formation with no unusual conditions observed around the affected tooth.