RESUMO
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 (CH(3)Bis-GMA) and propoxylated fluorinated Bis-GMA (CF(3)Bis-GMA). METHODS: Nine experimental comonomers were prepared combining Bis-GMA and TEGDMA, CH(3)Bis-GMA, CF(3)Bis-GMA, with aldehyde (32mol%) and diketone (32mol%). Photopolymerization was effected by using Camphorquinone (0.2wt%) and N,N-dimethyl-p-toluidine (0.2wt%). Experimental comonomer viscosity (Brookfield viscometer), polymerization shrinkage (gravimetrically), degree of conversion (FT-IR) and contact angles (contact angle goniometer) were determined. Comonomer and copolymer T(g)s (DSC and Fox equation) were also evaluated. Data were analyzed by one-way ANOVA and Tukey test (alpha=0.05). RESULTS: Bis-GMA/CH(3)Bis-GMA and Bis-GMA/CF(3)Bis-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/CH(3)Bis-GMA with additives (p<0.01). Additives reduced contact angle and comonomer T(g) values, whereas the corresponding copolymers with additives showed an increase in T(g). SIGNIFICANCE: Use of novel comonomer systems with the addition of aldehyde and diketone functional groups would improve dental resin composite properties.