Objectives: 1°) absorption and diffusion of water into resin-modified GIC and into conventional GIC, 2°) dissolution of ions in aqueous environment Methods: Two conventional GIC PR-Scell-HY (PR) (Shofu Inc. Kyoto, Japan) and Vivaglass-cem (VGC) (Vivadent Schaan Liechtenstein) and one resin-modified GIC: Vitremer-Luting Cement (VLC) (3M Dental Product Division, Minnesota, USA) were immersed at 37°C in water from 24h to 1000h. -Water diffusion. The specimens (13mm diameter and 3mm thickness), removed from water, were weighted at required time intervals to the nearest 0.1mg. -Hardness measurement were done with a Vickers microdurometer (Hauser 249A, Bienne, Switzerland) and samples with 13mm diameter and 3mm thickness. The indentations were made by application of a weight of 100g. - Dissolution kinetics: two discs (10mm diameter and 1mm thickness) were stoked in water in polyethylene bottles. Leached ions were analyzed by DPASV, Spectroscopy, Colorimetry and ICP. Results: 1) Penetration of water into hybrid GIC is D=2,56.10-11+/-10%m2s-1, into conventional GIC PR D=46.10-11+/-10%m2s-1 and into VGC D=50.10-11+/-10%m2s-1. After 24 h samples contain already 70%-80% of water. 2) Hardness values are lower in surface (S) than in the core (C) of samples. For t=1000h: PR (S)=9+/-2HV (C)=95+/-5HV VGC (S)=20+/-6HV (C)=50+/-4HV VLC (S)=15 +/-3HV (C)=29+/-2HV 3) During the first 10 days we observe for VGC and VLC a good linearity of the species eluted: F-, Na+, Ca2+, AL3+ as function of the square root of immersion time: the diffusion process controls the dissolution. With aging diffusion of ions is slower. Conclusion: HEMA controls properties. Hybrid cement absorbs less water, the hardness is steady from the surface to the core, the ion diffusion into the bulk is slower and results in a slower dissolution process. Build an interpenetrated polymer network offering a better resistance to moisture attack during the initial setting period.

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