Delayed eruption of mandibular primary central incisors in a child with severe lingual inclination and their spontaneous movement to appropriate positions

We previously reported a quite uncommon case of delayed eruption of primary mandibular bilateral incisors with severe lingual inclination identified in a Japanese girl aged 2 years 8 months. An intraoral examination demonstrated the tooth crown morphology of the primary mandibular incisors in the lingual submucosal area, while radiographic examinations of the affected teeth revealed what appeared to be a standard root morphology and the permanent successors located close to the affected teeth. We decided to perform periodical examinations at least until the roots of the permanent successors were sufficiently formed and here report recent findings in this case. At 2Y10M, the edge of the tooth crown of the primary mandibular left central incisor had emerged into the oral cavity and one-third of the tooth crown was identified at 2Y11M. Thereafter, the tooth crown of the primary mandibular right central incisor was identified under the mucosa at 3Y1M. A periapical radiograph taken at 3Y7M demonstrated formation of the permanent successors under development. At 3Y10M, nearly the entire part of the tooth crowns of both affected teeth had emerged and then they started to move gradually in a labial direction. At 4Y2M, the crowns of the affected were nearly within the dental arch, while periapical radiograph images showed straight roots for the affected teeth and the developing permanent successors. We intend to continue to perform periodical examinations to follow the development of the permanent successors until eruption.