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AIMS The aim of the present study was to investigate the effect of probiotic (Bacillus Subtilis) supplementation on bone remodelling induced by mechanical loading. METHODS C57BL/6 mice were divided in two groups: (1) Probiotic and (2) Vehicle (water). The probiotic (1.5×108CFU/mL) was administered orally for 14 days, starting two days before the induction of orthodontic tooth movement (OTM). OTM was determined by histomorphometric analysis by comparing the right to the left side of the maxilla. The number of osteoclasts was determined by counting TRAP-positive cells. Osteoblasts were counted on Masson's trichrome-stained slides. RESULTS OTM was similar between groups (with and without probiotic supplementation) (p=0.46). The number of TRAP-positive cells increased (p<0.01) on the experimental side (where the spring coil was installed) in comparison to the control side in both groups. However, the number of osteoclasts decreased (p˂0.01) in the probiotic group, in comparison to the vehicle group. There was an increase in the number of osteoblasts (p˂0.05) in both the Vehicle and Probiotic groups on the side under OTM, independent of probiotic supplementation. CONCLUSION Oral Supplementation with a probiotic influenced the number of osteoclasts adjacent to the tooth root during orthodontic movement in mice.