Tooth discolouration or tooth staining can be due to extrinsic or intrinsic reasons.
Extrinsic stains happen because of our food, acidic beverages, habits like smoking,
chronic use of some mouthwashes, prolonged use of some medicines, dry mouth etc.
Intrinsic stains, discolour the tooth from within and can be due to dental fluorosis,
developmental reasons from birth, loss of vitality of tooth after accidents/trauma.