Effect of Low Intensity Laser Therapy (LILT) on MMP-9 expression in gingival crevicular fluid and rate of orthodontic tooth movement in patients undergoing canine retraction: A randomized controlled trial

Introduction > Low Intensity Laser Therapy (LILT) has been shown to increase the rate of tooth movement. Since its use in orthodontics as a method of acceleration there has been a variety of views regarding its mode of action. MMP-9 is a known bone resorption factor studied in Bone remodelling. The aim of this study was to know the effect of LILT on rate of tooth movement and expression of MMP-9 in GCF. Materials and methods > Ten patients (3 males and 7 females) who required maxillary first premolar extraction for routine orthodontic treatment were recruited. The individual canine retraction was studied, and the side of the experimental canine was randomly selected. The laser regimen was followed on the 1st, 3rd, 5th, 7th, 14th and then 15th days consecutively. GCF was collected at baseline, 14th day, 3 months and at the end of canine retraction on experimental side and MMP-9 was estimated quantitatively using a standard ELISA kit. Results > The average increase in rate of tooth movement on experimental side at 3 months was 44% and MMP-9 concentration was also high. At the end of canine retraction (4.5 months) in the experimental group the average rate increase was 38% with MMP-9 concentrations similar in both the experimental and control group. Conclusions > LILT increases the rate of tooth movement. LILT also has an effect of bio-stimulation as depicted by rise in MMP-9 concentrations in GCF. However, this bio-stimulatory effect is restricted to the initial part of the tooth movement.