Staining on the tooth is a common symptom of dental health issues. It can appear as yellow, brown, or gray spots on the surface of the tooth. It can develop over time due to poor oral hygiene, drinking coffee, tea, or other beverages, or smoking. It can also be caused by certain medications, aging, or trauma. The severity of the stain can vary, from light discoloration to deep discoloration. Treatment options depend on the type and severity of the stain, and may include professional teeth whitening, dental bonding, or veneers.