Background and aim: The application of fixed orthodontic appliances could be eventuated different imposition, For example: Develop the favorable condition to accumulation of streptococcus mutans (ms) and after that, enamel demineralization and an increased number of carious lesions, Predominantly in sits adjacent to brackets. This research has been designed and executed with the aim of surveying the dimension of effectiveness of the Listerine and Oral-B and Ortho-kin on the dimension of gathering of streptococcus mutans, which exist in plaque around the orthodontic brackets and in saliva and dimension of dental plaque.Material and Methods: Study with design of Double-Blind Randomized Cross over Clinical Trial on 25 orthodontic patients, who are classified to 6 groups, has been done. The dimension of streptococcus mutans in plaque and saliva with the side specific modified strip mutans technique and the dimension of PI has been measured before and after of using mouth rinse.Between using every mouth rinse with next mouth rinse has been considered a period of 3 weeks (washout) the data according to Wilcoxon and Kruskal Wallis statistics tests, have been judged.Results: The research has been done on 25 patients whose average ages were 19±6/3. They were 5 men and 20 women. The dimension of gathering of streptococcus mutans in every teeth based on mouth rinse, showed that the effect of Ortho-kin was better than Oral-B and Listerine (P<0/09). Also, according to kind of mouth rinse (percent of increase, percent of without changing and decrease), the changes of streptococcus mutans in person’s saliva, were in 3 similar groups, and there were not meaningful statistical differences (P<0/4). The dimension of changes in person's Bacterial plaque, based on kind of mouth rinse, showed that the effect of Ortho-kin was better than Oral-B and Listerine, too (P< 0/001).Conclusion: Ortho-kin in decreasing of streptococcus mutans and PI, was done better than Listerine and Oral-B. it is because of had Chlorhexidine.