how come come peoples teeth are so white it looks as white as toothpaste?

I have had my teeth prossesionaly whitened, they are whiter but not GLOWING white. How come some peoples are so white? Is it because they are veeners or capped
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Let me say one thing about this...No one has glowing white teeth naturally. Be in a position where you have to have a bridge made to replace a tooth that had been damaged beyond repair, and when the dentist goes to match it to your teeth, when you look at the color spectrum, and all of them are some shade of pale gray , ivory or yellow. Caps are the same, as are dentures. If you want to have "glowing white teeth", many would say that you would probably have to stop eating...the consumption of soda ( especially cola), coffee,tea, berries, etc. all have staining properties on your teeth that becomes permanent after time, Smoking does this too...and much of what you see on celebs is the effect of having photos retouched. It is not natural, and whitening too much by chemical process can damage the enamel of your teeth.The excessively white teeth thing just came about in the past 10 years...
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