[The effects of dexamethasone and expansion stress on the osteoblasts in mouse calvarial suture in vitro, with special reference to incorporation of 3H-thymidine and 3H-proline].

Behavior of sutures in response to expansion stress are thought to be in parallel with the response of bone to orthodontic tooth movement. To investigate this relation between psychologic stress and osteoblasts during orthodontic tooth movement, the effects of expansion stress and 10(-7) M dexamethasone on sutural osteoblasts of mouse calvaria were examined in vitro. The model consists of a tensile force applied to the mouse sagittal suture. Expansion stress induced the formation of osteoid in the sutural areas, and incorporation of 3H-thymidine and 3H-proline in sutural osteoblasts were found to be stimulated by expansion stress. Furthermore, labelling index of 3H-thymidine in the osteoblasts was also found to be stimulated. On the other hand, dexamethasone inhibited the incorporation, labelling index and matrix formation. Moreover, these induced stimulations in expansion stress were inhibited by 10(-7) M dexamethasone treatment. As described above, dexamethasone, which is a synthetic glucocorticoid, inhibited the incorporation of 3H-thymidine and 3H-proline, the labelling index of 3H-thymidine, and the matrix formation in sutural osteoblasts that were stimulated by expansion stress. Therefore, also during orthodontic tooth movement, increased secretion of glucocorticoid that is stimulated by psychologic stress may inhibit the proliferation, cell differentiation, and matrix formation of osteoblasts in periodontal ligaments.