Development of an Animal Model for Coronectomy

Abstract

Purpose: This study aimed to develop an animal model suitable for coronectomy research. Materials and Methods: Eighteen Sprague-Dawley rats were divided into six groups: incisor control (InC), incisor flap (InF), incisor non-flap (InNF), molar control (MC), molar flap (MF), and molar non-flap (MNF). Coronectomy was not performed in the control groups (InC and MC). In the incisor (In) groups, coronectomy was performed on the mandibular incisors, with flap elevation in the InF group and without flap elevation in the InNF group. In the molar (M) groups, coronectomy was performed on the maxillary first molar, with flap elevation in the MF group and without flap elevation in the MNF group. The incisor groups were sacrificed on day 7, and the molar groups on days 7 and 14. Clinical healing, tooth movement, and histological and immunohistochemical analyses were performed. Results: InF and InNF groups showed tooth eruption similar to or the same as that before coronectomy, whereas the MF and MNF groups' roots moved slowly. In InF and InNF groups, the pulp at the maturation zone was mineralized, but apical pulp vitality was maintained. MF and MNF groups showed bacterial infection and inflammation on day 7, with mineralization on day 14; however, apical pulp vitality was maintained. The MF group showed varied healing patterns, whereas the MNF group had consistent results across individuals. Conclusion: Both incisors and molars are meaningful models for coronectomy. However, for consistent experimental results, coronectomy without flap elevation on the maxillary first molar is recommended.