BACKGROUND: Culturing odontoblasts with nano-hydroxyapatite can more intuitively reflect the biocompatibility of hydroxyapatite as dental pulp capping materials. However, odontoblasts are difficult to culture in vitro.
OBJECTIVE: To observe the effect of nano-hydroxyapatite and calcium hydroxide on the cell activity of mouse odontoblasts.
METHODS: Tooth germ of the first mandibular molar was took in fetal mice; mouse dental papilla cells were primary cultured using tissue block culture method. Cells with the cellular morphology of odontoblast-like shape were selected for the observation under inverted microscope. RT-PCR was used to detect the dentin sialophosphoprotein expression in order to identify the odontoblasts. Passage 4 odontoblasts in log-phase were cultured in the media containing 100 mg/L nano-hydroxyapatite and  100 mg/L calcium hydroxide respectively for 1, 3, 5 and 7 days. Blank control group was set up.
RESULTS AND CONCLUSION: CCK-8 results showed that cells in the nano-hydroxyapatite group grew well on 1, 3, 5 and     7 days after culture. Cell activity in the calcium hydroxide group was lower than that in the blank control group on 3, 5 and 7 days after culture (P < 0.01). Alkaline phosphatase test results showed that nano-hydroxyapatite and calcium hydroxide had no obvious effect on the activity of alkaline phosphatase. These findings indicate that nano-hydroxyapatite has no effect on the activity of the odontoblasts, while calcium hydroxide has an inhibition effect on the activity of the odontoblasts.