When a person ages, the enamel layer of his teeth gets thinner with brushing and the more the yellowish dentin shows through.
Trauma or mouth and/or tooth injury can also change the color of one’s teeth because it reacts to an injury by laying down more dentin instead of the enamel.
Another major cause of teeth discolorations is medication. The darkening of the teeth can also be a side effect of certain antihistamines, antipsychotics, and high blood pressure medications.
In fact, young kids who have been treated with antibiotics like tetracycline and doxycycline when their teeth are forming, eventually suffer from teeth discoloration when they grow up. It has also been proven that chemotherapy and head and neck radiation can also cause teeth discoloration.
In terms of side effects of teeth whitening, some people may actually experience tooth sensitivity especially when the peroxide in the whitener gets past the enamel and goes straight to the dentin and irritates the tooth’s nerves. However, it is often temporary so users can opt to delay the treatment if it persist.
People should also bear in mind that overuse of teeth whitening products can also damage the enamel of the teeth or their gums and that is another reason why dentist’ supervision of the process should always be considered.