Periodontal therapy has dealt primarily with attempts at arresting progression of disease, however, more recent techniques have focused on regenerating the periodontal ligament having the capacity to regenerate the periodontium. The effect of chitosan, a carbohydrate biopolymer extracted from chitin, on periodontal ligament regeneration is of particular interest. The purpose of this study was to evaluate the effect of chitosan on the expression of extracellular matrix proteins in primary rat calvarial cells in vitro. In the control group, cells was cultured with BGJb media. In the experimental groups, cells were cultured with chitosan in concentration of 0.01, 0.1, 1.0 and 2.0 mg/ml. Then each group was characterized by examining alkaline phosphatase activity at 3 and 7 days, and the ability to produce mineralized nodules of rat calvarial cells at 14 and 21 days. Synthesis of type I collagen (COL-I), osteocalcin (OCN), bone sialoprotein (BSP) was evaluated by RT-PCR at 14 days.

The results were as follows:

1. Alkaline phosphatase activity was significantly higher in the concentration of chitosan 0.01mg/ml, 0.1mg/ml and 1.0mg/ml compared to control (p<0.05).

2. The percentage of mineralized bone nodule was more in the concentration of chitosan 0.1mg/ml and 1.0 mg/ml than the control.

3. At 14 day culture, the expression of OCN was increased by chitosan in concentration of 1.0 mg/ml and 2.0 mg/ml.

These results suggested that chitosan in concentration of 0.1 and 1.0 mg/ml stimulate the extracellular matrix of primary rat calvarial cells and may facilitate the formation of bone.