What kind of teeth called black tooth?

There are many reasons for the black teeth, one tooth out black: Some people have long-term consumption of tea, coffee, cola and other habits, in fact, deep color of black food generally makes teeth turn yellow. Betel nut chewing, smoking can lead to teeth black. Second, the internal teeth black: such as tetracycline antibiotics, these drugs will affect the dental tissue, so the permanent tooth discoloration. The third is tooth decay. The fourth reason is that black teeth aging. Teeth black to our lives and work are more or less brought a certain extent, solve this problem, teeth whitening technique can greatly improve this phenomenon.
Advantages:
1, the results are obvious: faster whitening effect, more pronounced;
2, fast: just one treatment, treatment is only 30 minutes, you can achieve the whitening effect;
3, security: low-temperature cold, hydrophilic drugs and no contact of the whitening process of the gum, to completely avoid the operation of nerve stimulation on the tooth, the teeth will not cause any damage.