Effect of a ceramic and a non-ceramic hydroxyapatite on cell growth and procollagen synthesis of cultured human gingival fibroblasts

Background: Ceramic hydroxyapatites and non-ceramic hydroxyapatites have be en used extensively as alloplastic materials for bone reconstruction. Howev er, different forms of hydroxyapatite induce different types of tissue resp onse. Methods: Human gingival fibroblasts (FMM1 cells) were used to analyze ceram ic and non-ceramic hydroxyapatite biocompatibility. The cells were grown on surfaces covered either by collagen (control group), collagen plus ceramic hydroxyapatite, or collagen plus non-ceramic hydroxyapatite. Scanning elec tron microscopy, growth and cell viability curves, and procollagen immunopr ecipitation were obtained. For the growth and viability curves, 10(4) cells were seeded on 60 mm dishes. Cells from each group were counted, in tripli cate, at 1, 3, 4, 5, and 6 days after seeding using the Trypan blue dye exc lusion assay. Results: The cells grew in close contact with both types of hydroxyapatite particles. No differences were found in the amount of procollagen synthesis among any experimental group. The cultures treated with ceramic hydroxyapa tite had a growth delay for the first 5 days. There was no difference in ce ll viability between the control group and the non-ceramic hydroxyapatite g roup. However, cultures treated with ceramic hydroxyapatite showed signific antly fewer viability percentages than the other groups. Conclusions: Hydroxyapatite supports cell growth and fibroblast metabolism including collagen production, and hence is biocompatible. Cell viability a nd structural studies showed that non-ceramic hydroxyapatite has relevant p hysical and biological properties as an implant material.