Long-Term Follow-Up of a Patient with Ankylosis of a Primary Incisor Caused by Trauma: A Case Report

<b>Introduction and Clinical Significance:</b> Tooth ankylosis is a serious complication that can occur because of the replantation of an avulsed tooth. However, few reports have investigated the follow-up of replanted or ankylosed primary incisors because the replantation of primary teeth is not recommended in the guidelines of the International Association of Dental Traumatology. <b>Case Presentation:</b> A boy aged 4 years and 8 months was referred to hospital for further evaluation of the maxillary right primary central incisor. It had been avulsed and replanted 2 years earlier. The tooth was positioned higher than the central incisor on the left side, and a metallic percussion sound was noted, leading to a diagnosis of tooth ankylosis. Long-term follow-up revealed the progression of ankylosis, and the tooth was finally extracted. At the age of 7 years and 6 months, permanent tooth eruption was detected, and no pathological finding was observed. <b>Conclusions:</b> In this case, root resorption of the replanted primary incisor was observed with age, but tooth ankylosis progressed, and natural exfoliation was difficult. The authors extracted the primary incisor appropriately, which aided the eruption of a successor permanent tooth. This report suggests the importance of patients visiting the dentist regularly after trauma to primary teeth and appropriate treatment by dentists to erupt the permanent teeth.