Influence of additives on the properties of Bis-GMA/Bis-GMA analog comonomers and corresponding copolymers

Objectives The purpose of this study was to evaluate the effect of two additives: propionaldehyde (aldehyde) and 2,3-butanedione (diketone) on the properties of Bis-GMA diluted with TEGDMA and the synthesized Bis-GMA analogs, propoxylated Bis-GMA (CH3Bis-GMA) and propoxylated fluorinated Bis-GMA (CF3Bis-GMA). Methods Nine experimental comonomers were prepared combining Bis-GMA and TEGDMA, CH3Bis-GMA, CF3Bis-GMA, with aldehyde (32 mol%) and diketone (32 mol%). Photopolymerization was effected by using Camphorquinone (0.2 wt%) and N,N-dimethyl-p-toluidine (0.2 wt%). Experimental comonomer viscosity (Brookfield viscometer), polymerization shrinkage (gravimetrically), degree of conversion (FT-IR) and contact angles (contact angle goniometer) were determined. Comonomer and copolymer Tgs (DSC and Fox equation) were also evaluated. Data were analyzed by one-way ANOVA and Tukey test (α = 0.05). Results Bis-GMA/CH3Bis-GMA and Bis-GMA/CF3Bis-GMA with additives exhibited lower viscosities (p < 0.01). Inclusion of additives into the comonomer systems did not produce significant increase in polymerization shrinkage (p > 0.05). A significant increase in degree of conversion was shown for Bis-GMA/TEGDMA and Bis-GMA/CH3Bis-GMA with additives (p < 0.01). Additives reduced contact angle and comonomer Tg values, whereas the corresponding copolymers with additives showed an increase in Tg. Significance Use of novel comonomer systems with the addition of aldehyde and diketone functional groups would improve dental resin composite properties.