Staining on teeth can be Extrinsic (due to external factors) for eg. Tobacco chewing, smoking, excessive tea intake etc.
Or can be Intrinsic (due to internal factors) for eg. Developmental anomalies, Inadequate mineralization, Fluorosis, or due to some medications.
Teeth whitening and Dental laminates or Esthetic Crowns are some of the frequently used treatment options.
Next Steps
Visit a dentist for a proper diagnosis and appropriate treatment.
Health Tips
Do not brush aggressively, sometimes the brown spots can be easily confused with the dentin layer of your teeth.Brushing aggressively will lead further abrasion and eroding of your tooth surface.