Teeth whitening from the dentist is not a one-time process, but it should be repeated from time to time. The outer most layer of teeth is called enamel and if this part of the teeth gets discoloration or plaque, then they look grayish or bad, similarly this type of teeth cause inflammation and developed bad odor. Usually yellow color of teeth is due to using tobacco, taking tea or coffee, fizzy drinks and red wine. There are some other reasons are also there like nor proper caring or hygienic, while aging process also effect this.
