الفهرس 
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Abstract
Aim:This in vitro study was to evaluate and compare the effect of cigarette and waterpipe smoking on the color stability of three different recent tooth colored restorative materials. Methodology: A total number of sixty disc-shaped specimens(8 mm in diameter × 1 mm thickness) were made with nanohybrid resin composite, microhybrid resin composite and resin modified glass ionomer cements (RMGIC) (n=20). The specimens prepared in a rectangular glass mold contain individual cells with 10 internal holes against Mylar strip and pressed between two glass slaps. After light-curing for all three groups, all specimens were removed from the mold and hand polished using wet 600-grit silicon carbide abrasive paper. After that, baseline color was measured by CIEL *a*b* using spectrophotometer. All specimens stored in dark containers with deionized water at 37ºC ± 1ºC for 24 hours. All the groups divided into two subgroups, sub group1, specimens were subjected to cigarette smoking machine (n=10) and sub group2, specimens were subjected to waterpipe smoking machine (n=10). After exposed specimens to smoking machines, all specimens (n=60) color tests were detected by spectrophotometer. Results : The color change test in all three restorative materials showed that there was significance difference between cigarette smoke and waterpipe smoke(p≤ 0.001). After cigarette and waterpipe smoking, statistically significance differences were found between the three restorative materials (p≤ 0.001). Conclusion : Color stability of RMGIC and resin composites depend mainly on the composition of resin matrix and surface roughness. The composition of cigarette and waterpipe smoking has a deteriorating effect on resin matrix of composite materials in terms of color change.