Introduction: The most important goal of orthodontic treatment is to improve esthetics in the dentofacial region. Demineralization around orthodontic brackets is a discouraging sequela during and after orthodontic treatment. In order to overcome this phenomena, TiO2-NPs was added to orthodontic adhesives to assess its antibacterial effect. Materials and Methods: Twenty healthy albino rats were randomly divided into two groups. A small increment of commercial unmodified composite was placed on the lower central incisor of rats for study group. A small increment of composite containing TiO2-NPs was placed on the lower central incisor of rats for study group. For antibacterial test, a swab was taken every week to for counting S. mutans and total bacterial count in both groups. Results: Results showed significant reduction in bacterial counting for S. mutans and total bacterial count in study group more than that of control group. Conclusion: TiO2-NPs is a promising antibacterial agent and may play a major role in preventing WSLs which developed during orthodontic treatment. INTRODUCTION Orthodontic appliances can affect the self-cleaning ability of teeth, alter the oral micro flora and increase the levels of acidogenic bacteria. These bacterial byproducts causes demineralization and formation of WSLs which formed around fixed orthodontic attachments. These can cause caries thereby leading to poor esthetics and patient dissatisfaction. Due to antibacterial capabilities of certain NPs, these have been incorporated in orthodontic adhesives to control the oral biofilm and reduce the demineralization around the brackets. Since certain NPs have antibacterial activity directly on bacteria and indirect by providing smooth surface both inhibit bacterial growth and plaque accumulation, so in the current study we are going to evaluate the antibacterial effect of the composite containing TiO2-NPs.