Objective: To evaluate the effect of chlorhexidine-thymol varnish alone, its combination with chlorhexidine-fluo - ride containing dentifrice and fluoride varnish on oral hygiene and caries prevention in orthodontic patients. Study design: Sixty patients, aged 12-18, with orthodontic fixed appliances were randomly assigned into three groups as follows: Group 1 (n=20): 1% chlorhexidine and 1% thymol varnish (Cervitec ® Plus); Group 2 (n=20): Cervitec ® Plus+ 0.2% chlorhexidine and 0.2% sodium fluoride (900 ppm fluoride) (Cervitec ® Gel)); and Group 3 (n=20): 0.1% fluoride varnish (Fluor Protector ® ). Mutans streptococci (MS), lactobacilli (LB) levels, buffering capacity (BC), visible plaque index (VPI), and gingival bleeding index (GBI) scores were evaluated at four stages: T 0 , before orthodontic bonding; T 1 , one week after orthodontic bonding; T 2 , one week; and T 3 , four weeks after the first application, respectively. Inter and intra group comparisons were made by the Kruskal-Wallis, Mann- Whitney U, Friedman and Wilcoxon Signed-Rank tests with Bonferroni step-down correction ( P< 0.017). Results: Significantly lower MS and LB levels were found in Group 2 than Group 1 (T 2 ) and 3 (T 2 , T 3 ) ( P< 0.017). Groups 1-2 (T 2 ) showed significantly higher BC ( P< 0.017) and lower VPI and GBI ( P< 0.017) scores compared with Group 3. Decreased MS levels at T 2 ( P< 0.017) and T 3 ( P> 0.017) were found in Group1-2 compared with T 0 . Significantly lower LB levels were recorded in Group 2 at T 2 compared with T0 ( P< 0.017) while no significant differences were seen in Group 1 and 3 ( P> 0.017). Conclusions: Addition of Cervitec ® Plus+Cervitec ® Gel combination to the standard oral hygiene regimen may be beneficial for orthodontic patients for maintaining oral health by reducing bacterial colonisation and gingivitis.