[Observation of alveolar bone remodeling accompanied with tooth movement by in situ hybridization--expression of type I collagen and bone sialoprotein mRNAs].

The purpose of this study was to investigate expression of type I collagen and bone sialoprotein (BSP) mRNAs in the alveolar bone accompanied with tooth movement. The right side of the upper jaw of the rat was used for orthodontic tooth movement, and the left side was used for physiological tooth movement. After the proper number of days of movement, histological specimens were decalcified and sliced into paraffin sections. The expression of mRNAs was examined by the in situ hybridization method. In the samples of physiological tooth movement, a high level of expression in both mRNAs was observed in osteoblasts along the mineralization front and adjacent osteocytes in the interradicular septum (IRS). In contrast, a low level of mRNA expression was observed on the opposite side of the IRS. In the specimens of experimental tooth movement, a high level of expression was detected in the osteoblasts on the tension side of IRS, but negligible reaction in those on the compression side. These results suggest that BSP gene expression as well as that of collagen are related not only to mineralization in physiological bone remodeling but also to the process by activated osteoblasts induced by orthodontic force. In addition, response to the artificial force was observed in osteocytes in IRS.