In vitro color stability of double-layer veneers after accelerated aging

Statement of problem. porcelain laminates made from thin alumina shells ven eered with feldspathic porcelain could he a promising alternative to conven tional veneers. Long-term shade stability is critical for esthetics. Purpose. This study compared changes in CIE L*a*b* color coordinates of sim ulated veneers made from aluminum oxide core material veneered with feldspa thic porcelain after 300 hours of accelerated photothermal aging (weatherin g). Material and methods. Fifteen aluminum oxide disks (Procera) were divided i nto 3 groups. Each of the 5 disks was veneered with All-Ceram porcelain of the Vita shades A1 and B4, respectively. Five disks remained unfinished as controls. The disks were bonded to composite substrates simulating stained teeth. The color of the specimens was measured with a colorimeter. All spec imens were subjected to 300 hours of accelerated aging under light exposure and thermocycling. Color measurements were repeated, and the data were sta tistically evaluated with multiple paired t tests. Results. Color changes in the test groups involved an increase in lightness and a decrease in chroma. The calculated total color differences were not statistically significant compared with a level of 3 DeltaE units. Conclusion. This simulation of double-layer veneers appears to demonstrate acceptable color stability for this type of restoration. Clinical research is necessary to substantiate these in vitro findings.