[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.