1, food
In our daily diet, we inevitably eat colored food. Except for light-colored foods such as tofu and eggs, most other colorful foods are the causes of yellowing teeth. There are many kinds of bacteria on the tooth surface, and they secrete a lot of sticky substances on the tooth surface. The intake of tobacco (smoking or chewing tobacco), tea, coffee, cola, red wine and colored food will leave pigments on our teeth. These pigments are adsorbed on these sticky substances, which gradually make the tooth surface yellow or black. As time goes on, these substances will gradually penetrate from the surface of the teeth to the inside of the teeth, forming internal stains and slowly discoloring the inside of the teeth. This kind of tooth is called exogenous colored tooth. In other words, as long as teeth have "close contact" with color in life, they may be dyed and turned yellow!
2. Drugs and water quality
When teeth are developing, especially children under 8 years old, taking tetracycline drugs can easily lead to tooth discoloration into tetracycline teeth. In some areas, especially in some mountainous areas, because of the high fluorine content in water, drinking too much fluorine will make teeth yellow, instead of 1~2 teeth, which are full of rhubarb teeth and become dental fluorosis. These colored teeth are called endogenous colored teeth. These "sick" teeth, with dark pigments buried deep in the teeth, can't be touched by daily brushing. Only through special whitening methods can teeth be "thoroughly remoulded".
3. Hygienic habits
Some people don't pay attention to oral hygiene, and they don't have the habit of brushing their teeth correctly in the morning and evening, so that a layer of "bad marks" such as food residue, soft dirt, tartar, tobacco stains and tea stains are accumulated on the surface of their teeth. These yellow teeth are not caused by the yellowing of the teeth themselves, but by careless oral hygiene.
4, age yellow teeth
What we can never resist is natural aging. With the growth of age, our teeth are hard to resist the vicissitudes of life, and the color is gradually dim and yellow. Years leave wrinkles on the skin, which will also make teeth not as white as before.