Abstract
The development of dental adhesive resins with long-lasting antibacterial properties is a possible solution to overcome the problem of secondary caries in modern adhesive dentistry. OBJECTIVES: (i) Synthesis and characterization of nitrogen-doped titanium dioxide nanoparticles (N_TiO(2)), (ii) topographical, compositional and wettability characterization of thin-films (unaltered and experimental) and, (iii) antibacterial efficacy of N_TiO(2)-containing dental adhesives against Streptococcus mutans biofilms. MATERIALS AND METHODS: Nanoparticles were synthesized and characterized using different techniques. Specimens (diameter = 12 mm, thickness ≅ 15 μm) of OptiBond Solo Plus (Kerr Corp., USA) and experimental adhesives [50, 67 and 80% (v/v)] were fabricated, photopolymerized (1000 mW/cm(2), 1 min) and UV-sterilized (254 nm, 800,000 μJ/cm(2)) for microscopy, spectroscopy, wettability and antibacterial testing. Wettability was assessed with a contact angle goniometer by dispensing water droplets (2 μL) onto four random locations of each specimen (16 drops/group). Drop profiles were recorded (1 min, 25 frames/s, 37 °C) and contact angles were calculated at time = 0 s (θ(INITIAL)) and time = 59 s (θ(FINAL)). Antibacterial testing was performed by growing S. mutans (UA159-ldh, JM10) biofilms for either 3 or 24 h (anaerobic conditions, 37 °C) with or without continuous light irradiation (410 ± 10 nm, 3 h = 38.75 J/cm(2), 24 h = 310.07 J/cm(2)) against the surfaces of sterile specimens. RESULTS: N_TiO(2) was successfully prepared using solvothermal methods. Doped-nanoparticles displayed higher light absorption levels when compared to undoped titania. Experimental adhesives demonstrated superior antibacterial efficacy in dark conditions. CONCLUSIONS: The findings presented herein suggest that N_TiO(2) is a feasible antibacterial agent against cariogenic biofilms.