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[Proliferation of myofibroblast in periodental tension side during orthodontic tooth movement of beagle dogs].

OBJECTIVE
To examine the proliferation of myofibroblast in periodental tension side of beagle dog during experimental tooth movement in orthodontics.


METHODS
By the fixed orthodontic appliance, the five beagles were treated with 100 g forces that moved medially the maxillary first premolar, and the treatment lasted for four weeks. Using transmission electron microscope and immunohistochemistry, the proliferation of myofibroblast and expression of alpha-smooth muscle actin (alpha-SMA) were evaluated at week 1, 2, 3, 4 or 8 respectively after the orthodontic treatment.


RESULTS
During the total of four weeks, the expression of a-SMA increased in week 1 and reached the maximum in week 2; in week 4, the expression of alpha-SMA went back to normal level. Transmission electron microscopy showed that the myofibroblast contained the dense body appearing in cytoplasm.


CONCLUSION
The myofibroblast exists in periodontium and is concerned with the orthodontic tooth movement.