Comparative evaluation of three calcium phosphate synthetic block bone graft materials for bone regeneration in rabbit calvaria

Abstract

Various synthetic materials that maintain space and allow bone ingrowth have been developed for use in implant dentistry and periodontal treatments. Among various alloplastic bone substitutes, calcium phosphate ceramics have been investigated extensively because their mineral chemistry resembles that of human bone. In this work, we evaluated the bone formation of three calcium phosphate synthetic block-type bone grafts in rabbit calvarial defects. Four 8-mm-diameter defects were created in each of ten young adult New Zealand white rabbits. Each of three of the defects was randomly filled with one of three fabricated synthetic block-type bone graft materials: hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP). BCP is a mixture of HA and β-TCP at a ratio of 7:3. The fourth defect, a sham-surgery control, was filled with blood clots. The specimens were harvested at 4 and 8 weeks postsurgery for histologic and histomorphometric evaluation. Our results indicate that the amount of newly formed bone and bone density were increased more for the BCP block bone substitute than for the other two types. Furthermore, the histologic and histometric findings revealed that the space-maintaining ability was significantly better for all three calcium phosphate block bone graft materials than for the control group at both 4 and 8 weeks. However, measurement of the absorption of each particle revealed a significant decrease in the residual particles for β-TCP, while there were only small decreases for HA and BCP