Unsightly tooth stains can cause great embarrassment and keep people from smiling. Usually, as age progresses, the teeth tend to become yellow, which is normal. However, certain factors can cause changes as well. There are two types of tooth stains: extrinsic stains or surface stains and intrinsic stains when the interior sections of the tooth have darkened. Coffee, tea, soda, red wine, curries, turmeric or even soy sauce can cause extrinsic tooth stains when consumed over a long period of time.Bad oral hygiene and smoking too can greatly discolour teeth. Intrinsic stains can be caused by certain drugs, some mouthwashes, dental fluorosis, large silver fillings or trauma too can cause discoloration which is the result of a dead nerve. Depending upon the cause of the discoloration, your dentist may advise a treatment which can vary from changing oral habits, ultrasonic cleaning, teeth whitening, tooth coloured fillings or porcelain veneers.