Design, formulation, and evaluation of isocyanatoacrylate copolymer dental adhesives

Experiments have recently been completed to explore the development of isocyanatoacrylate copolymers as new dental adhesives. A main goal of this work was to test the utility of solubility parameter differences between the candidate adhesives and etched dentin as a predictor of relative bond strength. All candidate adhesive mixtures contained 2-isocyanatoethyl methacrylate (IEM), a selected amount of tri-n-butylborane oxide (TBBO) initiator, and one of 13 methacrylate comonomers. Reactivity ratios were computed for comonomer pairs as indicators of relative reactivity. The concentration of TBBO was optimized for each comonomer mixture to obtain working times of 2–6 min and setting times of 6–10 min. The solubility parameter difference Δδ (J/cm3)1/2 was calculated for each test mixture with respect to an etched dentin substrate, as an approximation of wetting ability. Using standard techniques for shear bond strength evaluation, mean shear bond strength values ranging between 7–15.5 MPa were obtained for comonomer adhesives in bonding Z-100 composite to treated dentin. Shear bond strength values showed a good correlation (r = −0.612, P ≤ 0.05) with solubility parameter differences. This study illustrates the usefulness of reactivity ratios and solubility parameters in the design and development of effective dentin bonding agents. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 48: 496–503, 1999