For a multiplicity of factors, your teeth might turn from white to not-so-white over time:
Tobacco Use- Tar and nicotine, two substances contained in tobacco, cause permanent stains. Tar is a black substance by nature. Until it comes into contact with oxygen, nicotine is colorless. Then it transforms into a yellowish material that stains the surface.
Food and Drink- Coffee, tea, and red wine are some of the most common stains. What is it that they all share in common? Chromogens are intense color pigments that adhere to the white, outside surface of your tooth known as enamel.
Trauma- If you’ve been hit in the mouth, your teeth may change color as a result of the damage, which causes it to lay down more dentin, a darker layer beneath the enamel.
Medications- Certain antihistamines, antipsychotics, and high blood pressure drugs might cause tooth darkening as a side effect. Antibiotics like tetracycline and doxycycline can cause discolouration of adult teeth in young children who are exposed to them when their teeth are growing . Chemotherapy and radiation to the head and neck can cause discolored teeth.