Capability of new bone formation with a mixture of hydroxyapatite and beta‐tricalcium phosphate granules

Objectives The aim of this experimental study was to test a mixture of hydroxyapatite ( HA ) and beta‐tricalcium phosphate (beta‐ TCP ) granules inserted in cranial defects in rabbits, by the evaluation of the hard tissues volume, new bone formation, and residual graft after 4 and 8 weeks. Material and methods Two defects of 8 mm diameter were created at the calvarial bone of 24 J apanese white rabbits for a total of 48 defects. Four groups were created: defects filled with a mixture of HA and beta‐ TCP granules (test A ), defects filled with HA alone (test B), defects filled with beta‐ TCP (test C), and empty defects (control). Hard tissues volume (remaining graft + new bone) was evaluated by μ‐ CT and new bone ( NB ) and remaining graft ( RG ) percentages were evaluated by histomorphometry. The animals were sacrificed at 4 or 8 weeks postoperatively. Results The test groups A , B , and C showed a significant higher total volume compared with controls at 4 and 8 weeks ( P  <   0.05). Regarding the percentages of NB and RG at 4 and 8 weeks, no significant differences were detected ( P  > 0.05). When comparing 4 and 8 weeks, test group A showed a significant increase in new bone formation. At both 4 and 8 weeks, no group showed significant differences in NB ( P  > 0.05). At 8 weeks, test group B had more RG than test group A . Conclusions The novel mixture could maintain the volume of the grafted area compared with that with intervention, and in a similar way compared with HA .