Occurrence of dental caries is an issue of prime concern in civic health. It is a multifactorial infection with pathological characteristics like salivary dysfunction, swelling of gums and degradation of periodontal tissues. Caries are caused primarily by Streptococcus mutans that forms oral biofilms and exhibits certain phenotypic characteristics like acidogenesis that is favorable for their growth. Clinical use of antibiotics for its control may cause hypersensitivity reactions, supra-infections and teeth staining with the organisms eventually also developing resistance to the same. Alternatively, development of green formulations that could effectively inhibit the development of caries could be an active area of research. In this study, synthesis and characterization of Melaleuca alternifolia oil in water formulation with a sorbitan ester and its ethoxylate have been attempted. Its mean particle diameter and zeta potential have been measured along with FTIR and AFM analysis. Its antibacterial activity and that of alumina nanoparticles at different concentrations has been assessed separately by broth microdilution method against an MTCC culture and clinical isolates of Streptococcus mutans. Minimum Inhibitory Concentration and Minimum Bactericidal Concentration for a range of concentrations have been recorded. Thereafter, a novel nanoparticle-incorporated emulsion has been formulated. Significant enhancement in bactericidal efficiency and decrease in biofilm formation has been observed with it. Additionally, the killing kinetics has been studied and the results clearly demonstrated a time-dependent killing pattern. It is inferred that this alumina nanoparticle incorporated tea tree oil formulation can be further explored as a pharmaceutical product for the treatment of dental caries. © 2020 Slovak University of Agriculture.