Color Stability of a Composite Containing Hydroxyapatite, Fluorine, and Silver Fillers After Artificial Aging

This work concerns composite materials containing hydroxyapatite, fluorine, and nanosilver fillers. These composites are intended for the reconstruction of lost hard tooth tissues. The aim of the work was to evaluate the color stability of a flow composite containing hydroxyapatite, fluorine, and silver fillers after artificial thermal, chemical, and a combination of thermal and chemical aging processes. The samples were prepared from a commercial flow-type composite material (Arkona Flow Art, Niemcy, Poland) color A2 VITA (Vita Classical, Vita Zahnfabrick, Bad Sackingen, Germany) original and a modified composite material containing a filler additive of 2 wt.% hydroxyapatite powder containing fluorine (calcium fluoride) and nanosilver (n = 15). An Optishade (Style Italiano, Italy) colorimeter was used to measure color against a black background. Samples were submitted to thermal aging (T) using thermocycling equipment; to chemical aging (C) by immersion on artificial saliva at pH7, 37 °C; and to constant agitation or thermal–chemical aging using a combination of the previous two methods. The modified composite showed reduced color differences compared to the original composite. The results also show that thermal aging has a stronger influence on ΔE increase than chemical and combined aging, but only for the modified composite. Cumulative aging processes had an influence below the acceptability threshold for the modified composite.