Introduction: Patients undergoing fixed appliance treatment are at greater risk for increases in salivary and plaque levels of Streptococcus mutans and an elevated risk of dental caries. The purpose of this study was to investigate if the commercially available orthodontic adhesive and cements would have antimicrobial properties. Methods: Six dental materials were evaluated for antimicrobial properties: a chemically cured composite with fluoride (Reliance), a light cured composite with fluoride (Reliance light bond), a chemically cured composite without fluoride (Monolok 2 RMC), a light cure composite without fluoride (alpha dent Lincolnwood), a glassionomer cement (Vivaglass CEM PL), and a polycarboxylate cement (Alpha-Dent). Streptococcus mutans strain was grown aerobically in brain heart infusion (BHI) broth containing 0.5% bacitracin at 37°C for 48 hrs. Under sterile conditions, these materials were placed onto plates of mitis salivarius agar and agar diffusion test (ADT) was performed. Results: the results indicated a visible zone of inhibition around the specimens which were measured and analyzed statistically by t and ANOVA tests. GIC (Vivaglass CEM PL), polycaboxylate cement and chemically activated composite containing fluoride (Reliance Orthodontic Products Inc). were significant at 5% level of confidence. GIC cement was the highest material exhibiting antimicrobial potency. Conclusion: The use of glass ionomer cement (Vivaglass CEM PL) for orthodontic bands cementation and a chemicallycured composite resin with fluoride (Reliance Orthodontic Prod Inc.) for bonding brackets reduced early activity of S. mutans bacterial strain. Also, fluoride content in the orthodontic adhesives and cements had an effect in reducing early activity of S. mutans.