Effect of platelet-derived growth factor-BB on root resorption after reimplantation of partially denuded tooth in dog

– The prognosis for a reimplanted tooth depends largely on the condition of the root. Platelet‐derived growth factor (PDGF)‐BB has been shown to regenerate periodontal tissue in animal and human clinical studies. However, information regarding the effect of PDGF‐BB on tooth reimplantation is limited. The objective of this study was to investigate the effect of PDGF‐BB on root resorption after reimplantation of a partially denuded tooth in dog. A total of 15 healthy female beagle dogs were used. Mandibular third and fourth premolars were endodontically treated and then extracted as atraumatically as possible. The coronal portion of each root was carefully scaled and planed. The roots on the right side of the mandible were treated with PDGF‐BB and reimplanted, while the roots on the left side served as controls. After 2, 4, or 8 weeks, specimens were collected and processed for histopathological examination. By the 4th week after reimplantation, new periodontal ligament (PDL)‐like tissue had formed around the PDGF‐BB‐treated root surfaces and new bone. By the 8th week, healing of the PDGF‐BB‐treated roots was characterized by newly formed PDL with inserting attachment formation. In contrast, control roots showed multiple areas of replacement resorption. Immunohistochemical staining of proliferating cell nuclear antigen (PCNA) performed at 2 weeks after reimplantation showed that the number of PCNA‐positive cells in the connective tissue area was statistically significantly greater in the PDGF‐BB‐treated group than in the control group (P