Effect of RHPDGF-BB and RhBMP-2 on Osseointegration of Titanium Implants at Periimplant Bone Defects Grafted with Hydroxyapatite: Micro-Ct and Histologic Analysis

ABSTRACT

PURPOSE: Platelet derived growth factor(PDGF)-BB and bone morphogenetic protein(BMP)-2 are wellknown representative growth factors. The purposes of this study were to investigate the effect of rhPDGFBB and rhBMP-2 on osseointegration of titanium implants at periimplant bone defects grafted withhydroxyapatite and to evaluate the feasibility of imaging bone structures around screw-type titanium implant with micro-CT.MATERIALS AND METHODS: The first molar and all premolars in the mandible region of four beagle dogs were extracted. Following a healing period of 4 months, three 8x8x6mm-sized bony defects were formed and screw-type titanium implants were placed with hydroxyapatite(HA) block and growth factors;Control group, PDGF group and BMP group. Two months post-implantation, the mandible was harvested. Bone volume(BV), bone-to-implanct contact(BIC) and bone mineral density(BMD) were analyzed with micro-CT and histology.RESULTS: According to micro-CT analysis, BV and BMD measures of PDGF and BMP group were significantly higher than control group(BV; PDGF group p falling dots 0.011, BMP group p falling dots 0.006 /BMD; PDGF groupp falling dots 0.020, BMP group p falling dots 0.011) and BIC measures of BMP group were significantly higher than PDGF group(p falling dots 0.015). In histologic evaluation, BIC measures of BMP group was significantly higher than PDGF group(p falling dots 0.048). The values of BV in histologic sections were higher than in micro-CT images and the values of BIC in micro-CT images were higher than in histologic sections.CONCLUSION: The findings of this experimental study indicates that the use of rhPDGF-BB and rhBMP-2 can increase new bone formation in a large bony defect around titanium implant, and rhBMP-2 is more effective than rhPDGF-BB. Micro-CT can be considered useful for assessment as a rapid and nondestructivemethod for 3-dimensional measurement of bone healing around implants. Further study is necessary, however, to remove metal artifacts around titanium implant and to standardize the method.