Discoloration.

Teeth can become discoloured due to 2 types of stains. They are internal stains and external stains. The external stains are acquired from the food we eat and our abusive habits like smoking, tobacco chewing, etc. External stains can be cleaned using ultrasonic waves and by bleaching. But if the stain is internal, it means that the tooth has lost its blood supply. In such cases the tooth will require a root canal treatment to mask the internal color of the tooth.