Defect healing with various bone substitutes

Biphasic calcium phosphates (BCPs), mixture of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) are synthetic bone substitutes, which are increasingly used in adjunctive implant and periodontal surgery. The aim of this study was to evaluate the rate and amount of bone regeneration in defects filled with three different BCPs in relation to deproteinized bovine bone mineral (DBBM).

Ten New Zealand rabbits were used in the experiment. Four defects of 6 mm in diameter were prepared in each rabbit, and they were filled with different biomaterials: BCP with HA/β-TCP ratio of 60/40 (BCPG1), ratio of 10/90 (BCPG2), a BCP with polylactide incorporated (moldable BCP) and DBBM. Group A (n = 5) rabbits were sacrificed after 3 months, and group B (n = 5) were sacrificed 6 months after surgery. Histological and histomorphometric analyses were performed. Mean percentages of mineralized new bone (%MNB), bone marrow (%BM), residual grafting material (%RG) and soft tissue (%ST) were calculated for each bone substitute.

Percentages of MNB in defects filled with the four bone substitutes were comparable after 3 months and 6 months. Amount of MNB regenerated for moldable BCP and DBBM after 6 months were significantly higher than after 3 months (P < 0.05), whereas those for BCPG1 and BCPG2 did not show significant change. Percentage RG was significantly higher in moldable BCP compared with BCPG1 (P < 0.05) after 3 months.

After 3 months, the granules-form synthetic materials performed better than DBBM in terms of bone regeneration. The grafting materials performed similarly after 6 months of healing. Addition of polylactide in moldable BCP may slow down osteogenesis in grafted defects.