Levels Of Matrix Metalloproteinases In Saliva During Orthodontic Tooth Movement

Purpose: To determine the levels of matrix metalloproteinases (MMPs) in response to orthodontic tooth movement, in order to clarify the relationship between the change of MMPs and distance of tooth retraction. Materials and methods: In total, 11 patients who needed tooth extraction and 11 patients who didn't before being subjected to fixed orthodontic appliance therapy were assigned into two groups: The extraction group and the nonextraction group. The saliva samples were collected from each patient at four indicated time points, including the first visit time (T1), time before fitting the orthodontic appliance (T2), one hour after (T3) and eight weeks after fitting the appliance (T4). Salivary MMPs concentration was determined using multiplexed bead immunoassay. Alginate impressions were taken at T1 and T4. Results: In the non-extraction group, the concentration of MMP-8 and MMP-9 were significantly increased at T3. In the extraction group, the concentration of MMP-8, MMP-9, and MMP-12 increased during the orthodontic tooth movement process, reaching a peak at T3. In particular, orthodontic tooth movement was positively associated with MMP-8, MMP-9, and MMP-12 levels in saliva at T3 in the extraction group. Conclusions: The result of our present study suggested that orthodontic force could modulate MMPs levels in saliva. MMP-8, MMP-9 and MMP-12 in saliva may represent novel indicators of the degree of orthodontic tooth movement.