Diffusion and concurrent solubility of self-adhering and new resin-matrix composites during water sorption/desorption
Yong-jie Wei1, Nick Silikas, Zhen-ting Zhang
1Department of Prosthodontics, School of Stomatology, Capital Medical University, Tiantan Xili No. 4, Chongwen District, Beijing 100050, PR China.
Objectives:
To investigate the kinetic process of water diffusion and mass change in new resin-matrix composites during water sorption/desorption cycles.
Methods:
Five new resin-matrix composites were investigated [Filtek(®) Silorane (FS), GC Gradia Direct Anterior (GDA), GC Gradia Direct Posterior (GDP), GC Kalore (GCK), Vertise(®) Flow (VF)]. Five disk-shaped specimens, per material (15.0±0.1) mm diameter by (2.0±0.1) mm, were prepared according to ISO 4049. Each disk was immersed separately in de-ionized water for 150 d and then reconditioned for 75 d; all at (37±1)°C. Mass was measured at different time intervals. Perspex disks were used as control. Data analysis was done by repeated measures ANOVA, one-way ANOVA and Tukey's post hoc test (p<0.05).
Results:
The water sorption (μg/mm³) after 150 d immersion ranged from 13.51 μg/mm³ (±0.40) for FS to 71.96 μg/mm³ (±0.90) for VF. The solubility ranged up to 16.95 μg/mm³ (±0.79) for VF. A significant mass reduction occurred in VF after the peak value [73.63 μg/mm³ (±0.31)] of water sorption was reached at 42 d. VF had the highest diffusion-coefficient for sorption: 5.23×10⁻⁹ cm²/s (±0.38) and desorption: 11.72×10⁻⁹ cm²/s (±0.16). Percentage sorption differences were significant for all materials (p<0.001), except between GCK and GDP. The early correlation between mass change and square root of time was linear.
Significance:
Each resin-matrix composite varied in sorption/desorption cycles which may affect clinical service. A concurrent solubility process occurred during sorption of the self-adhering composite VF. The silorane composite FS exhibited minimal sorption.
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