Accelerated aging effects on color, microhardness and microstructure of ICON resin infiltration

Infiltration resins provide an ideal treatment alternative for white spot lesions on teeth. The icon infiltrant has been widely used as a dental material for a few years, but there are some studies on the in vitro accelerated aging process and the change of hardness and microstructure on this material. The innovation of this work is to aim at investigating characteristics associated with this infiltrant resin and comparing the Icon infiltrant with universal Filtek Z350 and flowable Filtek Z350 resins when exposed to artificial accelerated aging.

Materials were prepared as disc-shaped specimens sized to 12 mm × 2.2 mm and were aged through exposure to 150 kJ/m2 in an artificial accelerated aging machine. Two-time points, 24 h after aging and 96 h after aging, were selected for evaluation in the following trials. The morphology was observed using a scanning electron microscopy. The standard CIEL*a*b* color system was employed for color measurements. Microhardness of all specimens was analyzed by a Knoop indenter. Chemical components were examined by Fourier transform infrared spectroscopy.

Compared with universal Z350 and flowable Z350, the ICON infiltrant resin presented a uniform, slightly scratched surface before and after accelerated aging. The 24 h artificial accelerated aging of the three investigated materials resulted in acceptable color alterations, a ΔE* range of 2.52±0.63 for universal Z350, 2.43±0.59 for flowable Z350 and 3.31±0.32 for ICON. After 96 h aging, significant color changes were noted for universal Z350 (7.51±0.63) and ICON (4.70±0.69). The ICON infiltrant displayed reduced microhardness when compared to universal Z350 and flowable Z350. The absorption peaks of the chemical bonds were significantly altered after the accelerated aging process.

Composed in a triethylene glycol dimethacrylate (TEGDMA) monomer-based network, the color stability and microhardness of the infiltrant resin provided suitable material for treating white spot lesions (WSLs), yet presented susceptibility under accelerated aging. Thus, osmotic resin therapy has strict limitations to be most effective.