[Osteopontin mRNA expression in remodeling alveolar bone incident to tooth movement--visualized by in situ hybridization].

The purpose of this study was to investigate the osteopontin mRNA expression in the alveolar bone incident to the physiologic and experimental tooth movement. The upper jaws of female rats (7 weeks old) which were submitted to experimental molar tooth movement and control specimens were decalcified and sliced into paraffin sections. Osteopontin mRNA expression and tartrate-resistant acid phosphatase (TRACPase) activity were examined in the alveolar bone by use of in situ hybridization techniques and enzyme histochemistry, respectively. In the control specimens high levels of osteopontin mRNA expression was observed in the osteocytes and lining cells close to the osteoclasts which were detected by TRACPase staining in the distal areas of the tooth sockets. In the mesial tooth socket areas however, low levels of osteopontin mRNA expression was observed. In the experimental specimens high levels of osteopontin mRNA expression of both the osteoblasts and osteocytes was observed in the mesial areas of tooth sockets in response to the experimental tooth movement. These results indicated that osteopontin gene expression is related to the alveolar bone remodeling as far as the bone resorption incident to the physiologic tooth movement and that this expression level significantly increased in response to a certain mechanical stress incident to the experimental tooth movement.