Porcelains and composites used to restore teeth can change in color over time from exposure to foods, saliva, sunlight, tobacco, and poor oral hygiene.  The objective was to measure the stain resistance of commercial dental composites and porcelains used for inlays, onlays, and crowns.  Polished test samples were aged at 37^oC for 4 weeks in several stain solutions; color in L*-a*-b* coordinates was measured on a spectrophotometer before and after aging.  The change in color, dE,  during aging was calculated as dE=sqrt(dL*²+da*²+db*²); the data were analyzed via one-way ANOVA and compared with Tukey's T-test (p<0.05).  The test solutions were:  deionized water (DIW); professional dental bleaching gel (BLE); cola soda (COLA); ketchup/mustard blend(KM); coffee/tea/juice blend(CTG). The test samples were: Vita™ Mark II (VM2) porcelain; 3M™ ESPE™ Paradigm™ MZ100 Block for CEREC^® (MZ100) composite;  Ivoclar™ ProCAD™  (PCAD) porcelain;  Kulzer™ Artglass™ (AG);  Kerr™ Belleglass™ (BG). 

	DIW	BLE	COLA	KM	CTG
VM2	2.2±0.3	3.1±1.3	6.9±3.9	4.1±0.6	12.5±1.4
MZ100	2.3±0.1	2.3±0.2	7.3±4.3	17.7±2.3	14.6±1.7
PCAD	1.1±0.2	3.2±0.9	7.8±2.5	2.9±1.1	9.2±2.2
AG	0.2±0.1	3.5±0.1	5.3±2.9	66±0.5	14±6.9
BG	2.5±0.1	5.7±0.5	9.4±0.5	66.2±2.6	16.4±7

For CTG and COLA stains, all groups were statistically equivalent; for KM stain, the VM2, MZ100, and PCAD groups were statistically lower than AG and BG; for BLE stain, BG was greater than all other groups.  For DIW,  all groups are statistically equal or lower than 3, the accepted threshold of detectability to the human eye.   rprusin@mmm.com