Evaluation of the effects of biphasic calcium phosphate and growth factors on bone regeneration in one-wall defects around implant : an experimental study in mongrel dogs

Abstract

Evaluation of the effects of biphasic calcium phosphate and growth factors on bone regeneration in one-wall defects around implant: an experimental study in mongrel dogsYoung Woo SON, DDS, MSThe Graduate SchoolYonsei UniversityDepartment of Prosthodontics(Directed by Prof. Hong Seok Moon, DDS, MS, Ph.D)Objectives. The aim of this study was to evaluate the effect of Biphasic Calcium Phosphate(Osteon II), Bone Morphogenic Protein-2 (BMP-2) and Fibroblast Growth Factor-2 (FGF-2) when simultaneously placed with SLA surface implant on surgically created one wall critical bone defectMaterials & Methods. In vitro wound-healing assay was used to evaluate the effect of BMP-2, FGF-2 and Osteon II, which were treated to the scrape-wounded cultures. Thecell migration toward the scratched area wasevaluated at 0, 12, 24 and 48 h. For animal study,one-wall critical bone defects(5x5x8 mm) were created in 6 male mongrel dogs. A total of 8 implants were placed for each mongrel dog, having 4 implantsat both sides of mandible. At each side, one control (No graft) and three type grafts (OsteonII, OsteonII+BMP-2, OsteonII+FGF-2) were done within defect area.Total 48 titanium implants were placed. Bone to implant contact (BIC), the inter-thread bone volume, the length of bone loss, and defect area volume (unfilled area, new bone area, remained bone graft area) were investigated using micro-computed tomographic evaluation and histomorphometric analysis at 4 and 8 weeks.Results. In vitro study,Osteon II did not greatly influencethemigration of MC3T3-E1 cells, but BMP inhibited the migration of MC3T3-E1 cells regardless of BMP concentration and FGF facilitatedthe migration of MC3T3-E1 cells regardless of FGF concentration. In animal study,the bone volume value of control (no graft) group in micro CT evaluation was significantly lowerthan other grafted groups (Osteon II, Osteon

II+BMP, Osteon II + FGF)at both 4 weeks and 8 weeks. The new bone formation volume in Osteon II + BMP groups wassignificantly better than that ofotherexperimental groups.Osteon II + BMP graft could enhance the BICin the critical defect site around the implant both at 4 weeks and 8 weeks. However, Osteon II + FGF graft could enhance the BIC only at 4 weeks as compared with Osteon II group.90% of grafts materials had disappeared in the critical defectsat 4 weeks and there was no significant difference in remained bone graft percentage between 4 weeks and 8 weeks groups.Conclusions. Bone graft materials may have a role to play in critical bone defect reconstruction and BMP mayenhance new bone formation.Osteon II acted as a good scaffold for new bone formation during whole healing period and BMP playeda critical role of enhancing BIC around implant during whole oseeointegration period, while FGF had contributed to enhance BIC at initial period, but the effect of FGF graft faded over time. Keywords: biphasic calcium phosphate,bone morphogenic protein-2,fibroblast growth factor-2,woundhealing assay,critical bone defect,BIC, bone graft, new bone formation, dental implant