Evaluation of Various Properties of Novel Urethane-based Resin Composites

Objectives: Esterases have shown to negatively impact resin composites. The aim was to synthesize novel urethane-based oligomers and use them to develop novel urethane-based resin composites without compromising chemical, mechanical and physical properties relative to traditional Bis-GMA resin composites.
Methods: Two novel urethane-based methacrylate monomers (M1 and M2) were synthesized, mixed with a diluent (triethylene glycol dimethacrylate-TEGDMA) at different weight-ratios (25/75, 55/25 and 75/25). Camphorquinone and ethyl-4-N,N dimethylaminobenzoate initiators and silanated barium borosilicate filler (70%) were used. Two resin composite controls [Bisphenol A glycidyl methacrylate (Bis-GMA) and urethane dimethacrylate (UDMA)] at 55/45 weight-ratio were also formulated. The degree of conversion (DC) of the composites was measured (n=3/group) at different curing times (20, 40 and 60 seconds). Furthermore, flexural strength (FS), diametral tensile strength (DTS), compressive strength (CS) and Knoop hardness (KH) were evaluated (n=5/group). One-way ANOVA was used for comparisons. Pair-wise group comparisons were made using Fisher’s Protected Least Differences method (α=0.05).
Results: The DC for each resin composite at 55/45 weight-ratio was not significantly different between the curing times. DC of M1/TEGDMA at 55/45 and 75/25 weight-ratio was not significantly different from Bis-GMA/TEGDMA control. FS of M1/TEGDMA and M2/TEGDMA at 55/45 and 75/25 ratios met the ISO 4049 requirement, and were not significantly different from the controls at 40 seconds curing time. FS, DTS and KH of M1/TEGDMA at 55/45 and 75/25 weight-ratios were not significantly different from Bis-GMA/TEGDMA at 20 seconds curing time. Additionally, CS of M1/TEGDMA at 55/45 weight-ratio was not significantly different from UDMA/TEGDMA control, whereas flexural modulus of M1/TEGDMA at 55/45 and 75/25 ratios was significantly higher than both controls.
Conclusions: A M1/TEGDMA novel urethane-based resin composite at 55/45 and 75/25 weight-ratios showed comparable DC, FS, DTS and KH to the model traditional Bis-GMA resin composite. Additionally, further investigation is warranted relative to degradation resistance.