White teeth are not factors include external environment and the tooth itself on two factors. External factors are mainly long-term smoking, drinking tea, eating drinking and easy staining caused by foods such as cola, etc. In addition, contact with iron, sulfur and other substances easily become brown teeth, exposure to copper, nickel, chrome teeth will appear green calm.
Tooth itself main factors:
(1), dental pulp death will be grayed out;
(2), tooth development of certain medications cause discoloration of the teeth, such as tetracycline; tooth development when excessive intake of certain substances will tooth discoloration, such as dental fluorosis;
(3), with age, the teeth will be slightly discolored;
Of course, whether it is the cause of tooth discoloration that the use of modern medical means are treatable.