Treatment of the delayed eruption of the segmented permanent successors

"Objectives:" The peak incidence of traumatic injury to primary dentition is observed in children aged 1-3 years, when the permanent successors are formed. A permanent tooth germ traumatized at the pre-eruption stage frequently suffers various consequences. We experienced a very rare case that a permanent successor was segmented by the traumatic injury to primary dentition. A 9-year-old boy visited the Clinic of Pediatric Dentistry of Showa University Dental Hospital with the delayed eruption of mandibular right lateral incisor and canine. He had traumatized mandibular fracture when he was 2 years old. X-ray examinations appeared the segmented 1/3 crown of the lateral incisor was located separately from the body on the germ of first premolar. The pulp chamber of lateral incisor was closed, while the root was almost matured. The canine was odontoma-like. There was no report to deal with the delayed eruption of the segmented permanent successors. The objective of this study was to develop the novel treatment for the delayed eruption of a segmented permanent successor. "Methods:" Under general anesthesia, the crown segment was surgically removed. The morphology of crowns of lateral incisor was restored and the fragile canine was reinforced using glass ionomer cement followed by bonding a ligature wire and orthodontic buttons for traction. After the flap was closed, modified lingual arch was fixed to the dentition connecting a ligature wire for traction. "Results:" The lateral incisor and canine successfully erupted after 1 year. Even if a tooth was segmented, we could guide to erupt it when it was discovered and treated early. Both incisor and canine were restored with resin composites after eruption and have been functioning well. "Conclusion:" Since the traumatic injury to the primary dentition affects the permanent successor, we at least have to monitor the development and eruption of the succeeding permanent incisor.