OBJECTIVETo observe the expression and distribution of matrix mentallproteinase-2 (MMP-2) in the periodontal tissues of diabetes mellitus (DM) rats during tooth movement, and to observe the affection of diabetes mellitus on the collagen metabolism.

METHODSEighty male Sprague-Dawley rats were used. Mesial force was applied to pull the maxillary first molar. Forty rats were rendered diabetic by injection of streptozotocin. In 3 weeks after the injection, rats were subjected to lateral tooth movement. The animals were sacrificed after 0, 3, 7, 14 and 21 days respectively. Two-step immunohistochemical method was applied to localize and examine the expression of MMP-2 in periodontal tissue of rats.

RESULTSMMP-2 immunohistochemical results indicated that the MMP-2 expression increased and was observed on both sides periodontium of movement tooth, osteoclast, cementoblast, osteocyte, fibroblast and osteoblast appeared positive. According to the immunohistochemistry image analysis, experiment group changes was less obvious than control group. Dynamic changes of OD occured, reaching the minimum on the 7th day and then increasing slowly. IOD increased steadily, up to the peak on the 7th day, and then decreased, which still remained a high level on the 21st day.

CONCLUSIONDM alveolar bone collagen metabolism increases. DM alveolar bone reactive potency decreases in orthodontic tooth movement, weak collagen metabolism. MMP-2's activity changes regularly, in close relation to bone remodeling, and plays an important role during the orthodontic tooth movement.