This study evaluated the effect of probiotic supplementation on gingival health in orthodontic patients. Participants undergoing fixed orthodontic treatment were randomly assigned to receive either a probiotic preparation containing Limosilactobacillus reuteri or no The primary objective was to assess changes in gingival inflammation using clinical periodontal indices(BOP). Secondary outcomes included plaque accumulation(PI) . The results of this study may help determine whether probiotic supplementation can support gingival health during orthodontic treatment