Periodontal healing by periodontal ligament fiber with or without cells: A preclinical study of the decellularized periodontal ligament in a tooth replantation model

Background: The periodontal ligament (PDL) comprises cells embedded in the extracellular matrix (ECM) and is required for periodontal healing upon tooth transplantation. However, the extent to which the ECM contributes to periodontal regeneration remains unknown. This study aimed to evaluate effects of separate PDL matrix without cells on periodontal healing. Methods: Mandibular premolars extracted from six beagle dogs, were 1) left untreated, 2) decellularized, or 3) surface planed. Cytologic, histologic, scanning electron microscopy, and transmission electron microscopy analyses confirmed that detergents could be used to decellularize the PDL. An additional circumferential osteotomy was performed to replant dental roots into extraction sockets. Radiography and histology were used to evaluate periodontal regeneration 8 weeks later, with the data adjusted for multiple testing. Results: In pristine extraction sites, total root resorption (P = 0.034), recovered PDL space (P = 0.012), and new cementum (P = 0.004) were greater in untreated teeth than in roots that underwent surface planing. There were no significant changes when comparing untreated teeth with teeth having a decellularized PDL (P = 0.081, P = 0.170, and P = 1.000, respectively), and decellularized teeth showed significant increase of new cementum compared to surface planed teeth (P = 0.048). In the defect area, only the recovered PDL space (P = 0.034) was greater in untreated teeth when comparing with denuded roots. Conclusion: These results suggest that in addition to untreated PDL, decellularized PDL also partially supports reattachment (particularly cementogenesis) in pristine extraction sites but not in defect areas.