Effect of Apical Micro-Intervention on Pulp Vitality and Periodontal Regeneration Following Tooth Autotransplantation: A Clinical Outcome Study

OBJECTIVE: To explore the effects of different root apex preparation methods on pulp revascularization and periodontal regeneration after autologous tooth transplantation. METHODS: Using 64 anterior teeth from 6 male Beagle dogs, we compared natural socket preservation (retaining periodontal ligament/PDL) versus artificial socket preparation, with subgroups receiving: (1) circumferential 2 mm apex PDL removal (Cpr), (2) 3 mm apical resection+iRoot BP retrofilling (ArrN/ArrA), (3) apical foramen enlargement >1 mm (Afe), (4) immediate root canal treatment (RCTN/RCTA), or (5) no treatment (ControlA/ControlN). Contralateral autotransplantation of teeth was performed, followed by 6 months of clinical and radiographic monitoring prior to micro-CT and histological analysis. RESULTS: The natural socket group showed superior outcomes, with significantly lower probing depths (P < .05) and better survival rates. Radiographic and Micro-CT revealed severe root resorption in Controls and ArrN groups, while ArrA/Cpr groups exhibited reduced apical radiolucency. Notably, high-density intracanal deposits in ArrN/ArrA suggested pulp regeneration, whereas Afe specimens displayed osteoid-like pulp deposits. Histologically, Controls developed discontinuous PDL (Periodontal ligament), extensive resorption and fibrous tissue thickening, while treated teeth maintained better periodontal integrity. These findings demonstrate that PDL preservation combined with apical sealing (particularly ArrN/ArrA protocols) significantly enhances transplantation success by: (1) maintaining apical vascularity, (2) preventing inflammatory resorption through hermetic sealing, and (3) facilitating stem cell recruitment. CONCLUSION: In tooth autotransplantation, maximal preservation of periodontal ligament cells within the recipient socket helps reduce postoperative root resorption and periodontal inflammation. Sealing the donor tooth apex, whether by intraoperative apical resection-retrofilling or postoperative root canal treatment, effectively controls apical inflammation and improves the success rate of transplantation.