The isolated human PDL cells and gingival fibroblasts were prepared and cultured. The fourth or sixth subpassage cells were used in this experiments. control group, ascorbic acid and β-glycerophosphate treated group, ascorbic acid, β-glycerophosphate and 100nM Dex treated group, ascorbic acid, β-glycerophosphate, and 5µM Dex treated group were made for study.

The results were as follows:

Cellular morphological change of PDL cells according to time was investigated.

At first, the cells exhibited confluent monolayer of spindle or polygonal appearance. The multilayer of cells were seen after 7 days of treatment. After 14 days, the cells lost polarity and were densely packed.

The mineralized nodule formation was seen at 21 days in the only Dex treated PDL cell groups. In the gingival fibroblast groups and no Dex treated PDL cell groups, the mineralized nodule was not seen. The mineralized nodule formation of 5µM Dex treated group was higher than 100 nM Dex treated group.

Alkaline phosphatase(ALP) activity was higher in the Dex treated PDL cell groups of 14 and 21 days than 0 and 7 days.

MGP was expressed in the control and all experimental groups and the expression was constant at 0, 7, 14, 21 day.

The above results confirm that Dex is affected to differentiation of the PDL cells to osteoblastic or cementoblastic cells and has dose-dependent effect for mineralization. And, MGP is expressed in the PDL cells and is not affected to mineralization of PDL cells.