Color stability of new-generation indirect resins for prosthodontic application

Statement of problem. Several new-generation indirect resins are being advo cated for full contour restoration of teeth. Previous indirect resin system s have failed in this application, due in part to color instability. Purpose. This study evaluated and characterized the color stability of vari ous new-generation indirect resins (ceramic-polymers) when subjected to acc elerated aging. Material and methods. Four new-generation indirect resin systems, 1 direct resin system, and 1 dental porcelain control were subjected to accelerated aging for a period of 300 hours. Initial specimen color parameters were det ermined in the Commission International de l'Eclairage Lab (CIELAB) color o rder system with a colorimeter. Color changes (Delta E) were calculated bet ween baseline color measurements and measurements made after 150 and 300 ho urs of accelerated aging. Color difference data were subjected to a 1-way a nalysis of variance to examine the interaction between material and time in terval of aging. Where significant interactions occurred, a least-squared m eans test was performed to identify differences in the color stability betw een the materials (P less than or equal to.05). Results. After 300 hours of accelerated aging, color changes of the indirec t resins ranged between 0.62 and 3.40 Delta E units. Two of the products te sted demonstrated color stability that was not significantly different from the porcelain control. Conclusion. All the indirect resins tested demonstrated color stability at or below a quantitative level that would be considered clinically acceptabl e. Color changes of ceramic-polymers occurred because of changes in chroma, rather than alterations in lightness.