Aim:Bis-GMA has been most commonly used in dental resin composites over 40 years. Concerns have arisen with respect to the presence of the estrogen analogue, Bis-phenol A from Bis-GMA materials. Therefore, the development of new monomers is important to eliminate this concern. The aim of this study was to investigate the degree of conversion, polymerization exotherm, water sorption and ageing effects on surface hardness of a fluorinated urethane dimethacrylate (FUDMA) monomer.

Materials and Methods: Two resins were investigated. The first a 50:50wt% FUDMA and TEGDMA, the second 50:50wt% bis-GMA and TEGDMA. One wt% camphorquinone and dimethylaminoethyl methacrylate was the photoinitiator. The degree of photopolymerization (after 20 sec exposure) and exotherm were measured via near IR. Water sorption and solubility were measured by placing 1x5x18 mm specimens in de-ionised water for 28 days. Surface hardness was measured using Vickers hardness by application of a 0.49 N load, 10 s dwell time on dry and wet samples (n=3).

Results: Degree of conversion of the FUDMA resin was 93% compared with 78% for bis-GMA. A much higher exotherm peak temperature of 48°C for FUDMA compared with 29°C for bis-GMA was recorded. The peak exotherm occurred at 8 sec for FUDMA compared with 17S for bisGMA indicating a more rapid polymerisation. For surface hardness, FUDMA was significantly harder for both dry and water stored specimens. In the case of water sorption, FUDMA showed greater sorption of water (4.37%) compared with bis-GMA (3.56%), and FUDMA was less soluble.

Conclusion: Based on the outcomes of this study, it was determined that FUDMA shows good potential as an alternative resin matrix monomer that is Bis-phenol-A-free. The only issue of concern is the exotherm during polymerization, however, this can be modified by altering the amount of photoinitiator, ratio of FUDMA: TEGDMA and inclusion of filler particles. This needs further investigation.