Why teeth discolor
Tooth discoloration can be external staining or internal damage. Learn causes and treatment options.
Medically reviewed by Dr. Jose — June 8, 2026
Tooth discoloration is either external (surface staining) or internal (damage within the tooth).
External causes
- Food/drinks — coffee, tea, red wine, dark sauces
- Smoking/tobacco — yellows teeth
- Poor oral hygiene — plaque and tartar buildup
Internal causes
- Trauma/injury — can darken or gray a tooth
- Decay — brown or black spots
- Root death — tooth turns gray
- Certain medications — antibiotics like tetracycline
- Fluorosis — excess fluoride during tooth development
Treatment
- Professional cleaning — removes surface stains
- Whitening — for external discoloration
- Bonding or veneer — covers discolored tooth
- Crown — for severely discolored tooth
- Root canal — if a single tooth is gray (possibly a dead nerve)
Prevention
- Limit staining foods/drinks — or rinse mouth after consuming
- Don’t smoke
- Brush and floss daily
- Regular dental cleanings
A single discolored tooth, especially if it’s gray, warrants a dentist visit to rule out nerve damage.
Frequently asked questions
Why is one tooth turning gray?
A single gray tooth often indicates past trauma or a dying nerve inside. See a dentist—it may need a root canal or other treatment.
Can discolored teeth be whitened?
External stains can often be whitened. Internal discoloration may require bonding, veneers, or crowns. Ask your dentist.