extrinsic tooth staining
Discoloration originating from outside the tooth. Extrinsic stains include tobacco, red wine, tea, chlorhexidine mouthwash, and some metallic deposits encountered as occupational hazards. Extrinsic staining is usually successfully removed with mild abrasive toothpaste, or professionally, using an abrasive prophylactic paste. Compare intrinsic tooth staining.
Sulieman M. An overview of tooth discoloration: extrinsic, intrinsic and internalized stains. Dent Update 2005;32(8):463–4, 466–8, 471.