Extrinsic Stains: Staining from outside of the teeth due to external factors like –

• Coffee, tea, wine, colas, colored foodstuffs
• Smoking and tobacco chewing
• Plaque and tartar deposition.

Intrinsic Stains: When there is discoloration of the inner surface (dentin) of the tooth due to any of the following reasons-

• Too much exposure to fluoride during early childhood.
• Use of tetracycline antibiotics by your mother during the second half of pregnancy or
• Use of tetracycline antibiotics in children who are 8 years old or younger.
• Trauma that affected a tooth at a young age may lead to internal bleeding and hence discolor the tooth.
• A rare genetic condition called dentinogenetic imperfect which causes gray, amber, or purple discolorations.
• Fluorosis Stains Genetic stains Staining due to trauma

Age-Related Stains: This is a combination of extrinsic and intrinsic factors.

• Dentin naturally yellows over time. The enamel that covers the teeth gets thinner with age, which allows the dentin to show through.
• Foods like tea, coffee, colored foodstuffs, tobacco, and smoking also can stain teeth as people get older.
• Finally, chips or other injuries can discolor a tooth, especially when the pulp has been damaged.