first of all, we should identify the reason for discoloration and has to identify whether the cause is intrinsic or extrinsic. later the treatment may be planned accordingly. if stains are just because calculus, a simple scaling and polishing of the teeth would be fine. for more details, go through my article on teeth whitening.

Discoloured teeth may be due to internal stains fluorosis, need veneers cosmetic treatment or Troma need rct with caps, If the stains or from out side,like tartar, smoking stains,needs cleaning and polishing can consult me or nearby dentist