A green tooth is almost always a sign that something has changed inside or on the surface of the tooth — and the shade is a clue to the cause. Green discolouration can come from staining bacteria on the enamel, from bleeding inside a tooth after an injury, from pigment laid down while the tooth was still forming, or from a metal restoration showing through thin enamel. Only one of those causes is harmless, so a green tooth is worth having looked at rather than waiting to see whether the colour fades.
The most common cause of a green or greenish-black line along the gumline, particularly in children, is chromogenic bacteria. These organisms produce a pigment as they grow in plaque, and the stain sits on the outside of the enamel rather than inside the tooth. It resists brushing because it is bound into the plaque film, but a hygienist can usually polish it off completely in one visit. Because it comes back if plaque is allowed to build up again, regular preventive care and cleanings are the real fix.
If a tooth is knocked hard enough, blood vessels inside the pulp can rupture. Blood products seep into the dentine and the tooth darkens from the inside out — often pink or grey at first, then yellow-brown, grey-green or almost black as the pigment breaks down over weeks and months. A tooth that changes colour after a knock has usually lost its blood supply, and it needs to be assessed even if it does not hurt. Treatment is normally root canal therapy, after which the tooth can be lightened internally or covered with a crown.
Green teeth in babies and young children are sometimes caused by severe jaundice in the newborn period. When bilirubin levels run very high while enamel and dentine are still being built, the pigment is incorporated into the tooth itself and the tooth erupts green. Certain antibiotics taken during tooth development, and some inherited conditions affecting enamel, produce similar built-in discolouration. Because the colour is part of the tooth structure, polishing and whitening will not shift it — these teeth are managed cosmetically once the child is old enough, usually with composite bonding and later with porcelain veneers.
An old amalgam filling, a metal post, or the metal core under a porcelain-fused-to-metal crown can cast a grey-green shadow through enamel that has thinned with age. Nothing is wrong with the tooth itself; the colour is the restoration underneath. Replacing the old work with a tooth-coloured filling or an all-ceramic restoration removes the shadow for good.
Chlorhexidine mouthrinse, iron supplements, some herbal teas and heavily pigmented foods can all leave a green-tinged film on enamel, especially in the grooves and along the gumline. This kind of stain is superficial. It responds to a professional clean and, where the underlying tooth shade is also dull, to professional whitening.
Not usually, but two situations should be seen quickly. The first is a tooth that changed colour after a blow or fall, because that points to a dying pulp. The second is discolouration with swelling, a bad taste, a spot on the gum, or pain on biting — those are signs of infection. If either applies, book emergency dental care rather than waiting for a routine appointment. A green line along the gumline of an otherwise comfortable tooth is not urgent, but it should be cleaned off and the cause identified.
Working out why a tooth is green takes very little time in the chair. Stain that sits on the surface can be scratched away with an instrument, so if the colour lifts, the cause is external. If the colour is inside the tooth, an X-ray shows whether the pulp chamber has changed and whether there is infection at the root tip, and a simple vitality test shows whether the nerve is still alive. That distinction decides everything that follows: external stains are polished away, internal discolouration needs the tooth treated before the colour is addressed.
Surface stain caused by plaque bacteria may fade slightly with thorough brushing and flossing, but it rarely clears completely because the pigment is bound into the plaque layer and sits in areas a brush does not reach. Whitening toothpastes and whitening strips are designed to lighten the natural shade of a tooth; they do not remove bacterial pigment and they do nothing at all for discolouration coming from inside a tooth. Abrasive home remedies such as baking soda scrubs or acidic rinses can thin enamel, which makes an underlying grey-green shadow more obvious rather than less. A professional clean is both faster and safer.
Not every green tooth is a problem. This post began as a guessing game about a patient of ours whose tooth turned green — and the answer was that he asked for it that way. Rio Waittier guessed correctly: the patient is a tattoo artist, green is his favourite colour, he needed a crown, and he asked whether we could make it green. We could, so we did. The tooth is perfectly healthy and free of any problems. Rio, when you want your teeth whitened, your 50% discount is waiting. Congratulations and great guessing!
Any tooth that has changed colour deserves a look, and the earlier the cause is identified the simpler the fix usually is. Dr. Darren Chu has treated discoloured teeth in Anaheim Hills for years, from a child’s stained gumline to a single dark front tooth after an old injury. Contact our Anaheim Hills office to arrange an examination, or read more about the cosmetic options available once a tooth has been treated.
