Alveolar Ridge Preservation Prior To Implant Placement With Surgical Grade Calcium Sulfate Hemihydrate And Platelet-rich Plasma: A Pilot Study In Canine Model

Objects: To evaluate the combination of the surgical grade calcium sulfate hemihydrate (SGCS) and platelet-rich plasma (PRP) for alveolar ridge preservation prior to implant placement and investigate the effects of PRP in this combination.Materials and Methods: Four enlarged extraction sockets, with two on the each side, were created in the mandibles of five mongrel dogs by extracting the second and third premolars and the first molars and removing the intra-alveolar septa and interradicular septa. One of the mesial sockets were placed SGCS/PRP (SGCS/PRP-M group) or left unfilled on the other side as a control. Another SGCS/PRP (SGCS/PRP-D group) and SGCS (SGCS group) were placed respectively into the two distal sockets. CT scans were conducted 1 day and 8 weeks after the operation to detect the change of the ridge height. Bone scintigraphy was performed 2, 4, and 6 weeks after the surgery to investigate the variance of the bone metabolism activity. One dog (Group 1) was sacrificed after 8 weeks for histological and histomorphmetric studies. Meanwhile, The other four dogs (Group2) were subject to the second surgery to receive 48 mini-implants with 3 mini-implants in each of the interdental edentulous ridge. They were then sacrificed 3 months later for histological and histomorphmetric studies.Results: The addition of PRP to the SGCS facilitated the manipulation of the graft. Less ridge resorption (P=0.001) was observed in the SGCS/PRP-M group (1.39±0.38mm) compared with the unfilled group (2.77±0.30mm). However, no statistical difference (P=0.544) was found between the SGCS/ PRP-D (1.26±0.27mm) and the SGCS group (1.32±0.34mm). Concerning to average count/pixel ratio, the SGCS/PRP-M group showed higher values at 2, 4, and 6 weeks than the unfilled group, but the SGCS/PRP-D group achieved higher values than the SGSC group only at 2 weeks postextraction. The histological observation showed that complete SGCS resorption and similar bone maturity were achieved in group 1. Meanwhile, in group 1, the Bone Area/Tissue Area (B.Ar/T.Ar)was respectively 51.88% in the SGCS/PRP-M group, 42.32% in the unfilled group, 61.19% in the SGCS/PRP-D group, and 52.61% in the SGCS group. In group 2, the significantly larger percentage of bone-to-implant contact (BIC) (P=0.024) was noted in the SGCS/PRP-M group (56.84±5.17%) than the unfilled group (41.48+4.47%), but no statistically significant difference (P=0.979) was detected between the SGCS/PRP-D (50.03±4.18%) and the SGCS groups (49.97+6.62%).Conclusion:1 SGCS/PRP reduced the resorption of the alveolar ridge, promoted the wound healing and bone formation in the extraction sockets.2 The addition of PRP to SGCS resulted in the enhancement of wound healing at the early phase.