Photopolymerization and properties of fluorene‐based dimethacrylate monomer used as a root canal sealer

The methacrylate resin‐based sealers have attracted wide attention with easy handling, superior aesthetic qualities, good mechanical properties, and excellent adhesive ability with dentin. 2,2‐bis[4‐(2′‐hydroxy‐3′‐methacryloyloxypropoxy)phenyl]‐propane (Bis‐GMA) is the main component of a new developing commercial root canal sealer “Epiphany,” which is one of the methacrylate resin‐based sealers. To further reduce polymerization volume shrinkage of bis‐GMA, 9,9′‐bis[4‐(2′‐hydroxy‐3′‐methacryloyloxypropoxy)‐phenyl]fluorene (HMPF) with higher molecular weight and larger molecular volume was selected to replace bis‐GMA as one of the components of the root canal sealer in this study. Photopolymerization behavior of a mixture of HMPF and triethylene glycol dimethacrylate (TEGDMA) was investigated by FTIR spectroscopy. Degree of conversion, volume shrinkage, and water sorption of various HMPF/TEGDMA formulations were measured and compared with a 50:50 bis‐GMA/TEGDMA formulation. The results illustrated that, with increasing content of HMPF in HMPF/TEGDMA system, the double bond conversion of the cured resin increased and volume shrinkage decreased. Its water sorption increased with increasing content of HMPF when the content was less than 50% and decreased with an increase in HMPF when the content was more than 50%. Compared with bis‐GMA/TEGDMA system, HMPF/TEGDMA had lower double bond conversion, lower polymerization shrinkage, and higher water sorption. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:108–116, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/adv.20125