Water sorption characteristics of restorative dental composites immersed in acidic drinks

To determine the diffusion coefficient, water sorption and solubility of various types of restorative dental composites and to evaluate the effect of acidic media (orange juice and coke) on their characteristics.

Resin composite specimens (Filtek™ Z350, Spectrum(®) TPH(®)3 and Durafill(®) VS) were prepared in a stainless steel mold of 1mm thickness and 10mm diameter (n=5) and light-cured. All samples were dried at 37°C, immersed in media (distilled water, orange and coke) at 37°C and weighed at suitable time intervals (15, 35, 155, 320, 785, etc.min) until 40 days of immersion and then were dried again for 40 days. Diffusion coefficient (m(2)s(-1)) was determined according to Fick's second law while water sorption and solubility (μg/mm(3)) were calculated based on BS EN ISO 4049:2000. Data of water sorption and solubility were analyzed with One-Way ANOVA and post hoc Scheffe test at p=0.05.

The experimental data obtained were obeyed and nearly fitted to the diffusion theoretical data plot. The highest values of diffusion coefficients were presented by Durafill(®) VS (32.23-45.25×10(-13)m(2)s(-1)). Diffusion coefficients of Filtek™ Z350 and Spectrum(®) TPH(®)3 were the highest when immersed in coke media followed by distilled water and orange juice. The water sorption of most composites was significantly increased after immersion in coke and orange (p<0.05). Meanwhile only Spectrum(®) TPH(®)3 showed an increase in solubility when immersed in coke media. Z350 presented the highest water sorption after immersion in distilled water and coke (16.13 and 18.22μg/mm(3)) while Durafill(®) VS presented the highest solubility (7.20-9.27μg/mm(3)).

The exposure of restorative dental composites to acidic drinks can cause an increase in diffusion coefficient, water sorption and solubility parameters which may accelerate the degradation process and thus reduce the life span of composite restoration.