Aim: To develop a novel aesthetic resin composite using a nitrogen-doped titanium dioxide (N-TiO2) filler that possesses photocatalytic antimicrobial properties against cariogenic bacteria. Setting: Biomaterials and oral microbiology laboratories, Bristol Dental School. Design: In-vitro study to produce an aesthetic composite resin, with long-term antimicrobial properties under visible light. This was done by incorporating a N-TiO2 filler within the resin. Methods: N-TiO2 powder was manufactured by heating commercial TiO2 with urea. Free radical release from the N-TiO2 powder under visible light irradiation was analysed using spectrophotometry. The N-TiO2 powder was incorporated into dental resin and the photocatalytic activity assessed using a dye under both visible light and dark conditions. Using XTT assay to measure the cellular metabolic activity, the antibacterial properties of the N-TiO2 within the resin discs were tested against cariogenic bacteria. Results: Doping nitrogen into TiO2 resulted in a band gap shift towards the visible light spectrum, which enabled the compound to release reactive oxygen species when exposed to visible light. When incorporated into dental resin, the N-TiO2 still demonstrated sustained release of reactive oxygen species, maintaining its photocatalytic activity and showing an antibacterial effect towards Streptococcus mutans under visible light conditions. Conclusions: N-TiO2 filled resin showed great promise as a potential aesthetic resin-based adhesive for orthodontic bonding.