1. Exogenous coloring: Tooth coloring caused by foods containing pigments in daily diet, such as cola, tea and soy sauce.

2. Endogenous coloring: mild to moderate tetracycline teeth, dental fluorosis, discolored teeth caused by other factors, hereditary jaundice, etc.

3, aging discoloration: with the growth of age, teeth will slowly wear, so there will be yellowing.

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