Volumetric dimensional changes of dental light-cured dimethacrylate resins after sorption of water or ethanol

Objectives This study evaluated the influence of water and ethanol sorption on the volumetric dimensional changes of resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D3MA. Methods The resin specimens (15 mm diameter × 1 mm height) were immersed in water or ethanol 37 ± 1 °C for 30 days. Volumetric changes of specimens were obtained via accurate mass measurements using Archimedes principle. The specimens were reconditioned by dry storage in an oven at 37 ± 1 °C until constant mass was obtained and then immersed in water or ethanol for 30 days. The volumetric changes of specimens were determined and compared to those obtained from the first sorption. Results Resins showed similar volume increase during the first and second sorptions of water or ethanol. The volume increase due to water absorption is in the following order: poly-TEGDMA > poly-Bis-GMA > poly-UDMA > poly-Bis-EMA > poly-D3MA. On the contrary, the order in ethanol is poly-Bis-GMA > poly-UDMA > poly-TEGDMA > poly-Bis-EMA ≈ poly-D3MA. The volume increase was found to depend linearly on the amount of water or ethanol absorbed. Significance In the choice of monomers for preparation of composite resin matrix the volume increase in the resin after immersion in water or ethanol must be taken into account. Resins of Bis-EMA and D3MA showed the lowest values.