Abstract: Objectiv To evaluate the influence of microscopy on plaque controlof orthodontic patients with fixed appliance.Methods 86 patients undergoing fixed orthodontic treatment were randomly divided into two groups:groupⅠwere guided with traditional plaque control pathway,group Ⅱ were treated with chair side guidance,microscope observation and traditional plaque control pathway.The oral health status of each patient was evaluated during a treatment period of more than 6 months.Results 1 month,3 months and 6 months after orthodontic treatment,the gingival index (GI) of group Ⅰ was 1.157±0.202,1.254±0.357,1.427±0.297,whilethat of group Ⅱ was1.015±0.236,1.107±0.216,1.152±0.052,and significant difference was observed between the two groups; the plaque index of group Ⅰwas 1．21±0.33,1.67±0.37,1.79±0.25,while that of group Ⅱ was 1.10±0.25,1.01±0.32,0.92±0.39,and there was also significant difference.When the treatment finished,incidence rate of gingivitis in group Ⅰwas 32.55%，and that in groupⅡwas 13.95%.Conclusions The combination of microscope observationand traditionalplaque control pathway showsobvious advantage in reducing plaque accumulation compared with traditional plaque control pathway.It is an effective way for fixed orthodontic patients to maintain oral health.

Key words: fixed orthodontic appliances, microscope, plaque control