Photopolymerizable phosphate acrylates as comonomers in dental adhesives with or without triclosan monomer units

Phosphate diacrylates (CO-DAP, TMP-DAP) based on castor oil or trimethylolpropane were synthesized and evaluated in dental adhesive formulations in comparison with 3-acryloyloxy-2-hydroxypropyl methacrylate phosphate (AMP-P). In an attempt to promote antibacterial activity, another photopolymerizable monomer (TCS-UMA) containing 5-chloro-2-(2,4-dichlorophenoxy)phenol moiety (triclosan) was prepared and incorporated in adhesive resins. Each of these monomers had a molecular structure confirmed by spectral methods. The photopolymerization rates for monomers (0.063-0.088 s(-1)) were lower than those determined in the monomer combinations (0.116-0.158 s(-1)) incorporating phosphate diacrylate (11 wt.%), BisGMA (33 wt.%), TEGDMA (10 wt.%), UDMA (10 wt.%) and HEMA (15 wt.%), the degree of conversion varying between 63.4 and 74.5%. The formed copolymers showed high values for water sorption (18.65-57.02 mu g/mm(3)) and water solubility (3.51-13.38 mu g/mm(3)), and the contact angle was dependent on the presence of CO-DAP (theta(F1): 66.67 degrees), TMP-DAP (theta(F2): 55.05 degrees) or AMP-P (theta(F3): 52.90 degrees) in the photocrosslinked specimens compared to the sample without phosphate monomer (theta(F4): 82.14 degrees). The scanning electron microscopy image of the dentin-resin composite interface after applying our F1 formulation (pH: 4.1) and its light-curing for 20 s supports the evidence of the formation of the hybrid layer with the tooth structure created by self-etching approach, with no gaps or cracks in the adhesive. A comparative analysis of the adhesion achieved with commercial adhesive systems (Single Bond Universal, C-Bond) rather indicates similarities than differences between them. The addition of triclosan methacrylate (1 wt.%) into the formulation inhibited the bacterial growth of the Streptococcus mutans and Escherichia coli in the direct contact area due to the covalently linked antibacterial monomer. (C) 2013 Elsevier B.V. All rights reserved.