Synthesis and evaluation of novel dental monomer with branched aromatic carboxylic acid group.

A new glycerol-based dimethacrylate monomer with an aromatic carboxylic acid, 2-((1,3-bis(methacryloyloxy)propan-2-yloxy)carbonyl)benzoic acid (BMPB), was synthesized, characterized, and proposed as a possible dental co-monomer for dentin adhesives. Dentin adhesives containing 2-hydroxyethyl methacrylate (HEMA) and 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (BisGMA) in addition to BMPB were formulated with water at 0, 5, 10, and 15 wt % to simulate wet, oral conditions, and photo-polymerized. Adhesives were characterized with regard to viscosity, real-time photopolymerization behavior, dynamic mechanical analysis, and microscale 3D internal morphologies and compared with HEMA/BisGMA controls. When formulated under wet conditions, the experimental adhesives showed lower viscosities (0.04-0.07 Pa s) as compared to the control (0.09-0.12 Pa s). The experimental adhesives showed higher glass transition temperature (146-157°C), degree of conversion (78-89%), and rubbery moduli (33-36 MPa), and improved water miscibility (no voids) as compared to the controls (123-135°C, 67-71%, 15-26 MPa, and voids, respectively). The enhanced properties of these adhesives suggest that BMPB with simple, straightforward synthesis is a promising photocurable co-monomer for dental restorative materials.