Mitotic index and chromosomal analyses for hydroxyapatite implantation in rabbits

Dentistry has searched for an ideal material to place in osseous defects for many years. Endogenous bone replacement has been the golden standard but involves additional surgery and may be available in limited quantities. Also, the exogenous bone replacement poses a risk of viral or bacterial transmission and the human body may even reject them. Therefore, before new biomaterials are approved for medical use, mutagenesis systems to exclude cytotoxic, mutagenic or carcinogenic properties are applied worldwide. The present preliminary study was carried out in five male New Zealand white rabbits (Oryctolagus cuniculus). Porous form of synthetic hydroxyapatite granules (500 mg), manufactured by School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Penang, was implanted in the femur of the rabbits. Blood samples were collected prior to implantation and one week after implantation. The blood was cultured in vitro and the cell division was arrested at metaphase using colcemid. This was followed by the hypotonic treatment and fixation. Then, the chromosomes were prepared and stained for analysis. The modal chromosome number of rabbit (Oryctolagus cuniculus) was found to be 2n=44. The mean mitotic index values prior to and after implantation were 3.30 ± 0.66 and 3.24 ± 0.27 per cent respectively. No gross chromosome aberrations, both numerical and structural were noticed either prior to or after implantation of the biomaterial. These findings indicate that the test substance, synthetic hydroxyapatite granules does not produce gross chromosome aberrations under the present test conditions in rabbits.