Grey discoloration near the base of your teeth usually comes from one of two broad problems: either the enamel in that area has worn thin enough to let the naturally darker layer underneath show through, or something has deposited pigment on or inside the tooth near the gumline. The gumline is where teeth take the most mechanical and chemical abuse, so it makes sense that color changes tend to show up there first. Figuring out which category your greyness falls into matters, because the causes range from harmless cosmetic staining to signs of a dying tooth that needs attention.
Thinning Enamel and the Dentin Underneath
Your teeth are not one uniform material. The outer shell, enamel, is translucent and whitish. Beneath it sits dentin, which is naturally yellow to grey. In young, healthy teeth, tiny structural features within the enamel scatter light and mask the color of that underlying dentin. As you age, or as enamel wears down from acid exposure and mechanical abrasion, those light-scattering structures shrink. The result is that dentin’s true color starts showing through more strongly, and the tooth looks darker.
Research on how tooth color changes with age found that specific microstructural features in enamel, particularly the gaps between crystal rods, decrease over time. When those gaps narrow, enamel stops diffusing light as effectively and instead lets the dentin color reflect outward more directly.1Journal of Hard Tissue Biology. Variation in the Color of Japanese Teeth and Structural Changes in Enamel Rod Sheath Associated with Age This is why older teeth often look greyer or more yellow even when they are perfectly healthy. The base of the tooth, right where it meets the gum, is especially vulnerable because enamel is thinnest there to begin with. Years of brushing, acidic drinks, and normal chewing concentrate their damage at that junction.
If your greyness is gradual, affects multiple teeth in the same zone, and has been creeping in over years, thinning enamel is the most likely explanation. It is not a disease. It is wear and tear. But it does make the teeth more sensitive and more prone to decay in that area, so it is worth mentioning to your dentist even if the color itself does not bother you.
Tartar Buildup and Chromogenic Bacteria
A very common and much simpler explanation for grey or dark discoloration at the gumline is calculus, the hardite deposit that forms when plaque mineralizes. Calculus tends to accumulate most heavily on the inner surfaces of the lower front teeth and the outer surfaces of the upper molars, right where salivary glands dump minerals into the mouth. Fresh calculus is yellowish or off-white, but as it ages and absorbs pigments from food, drink, and bacteria, it can turn grey, brown, or even black. Subgingival calculus, the kind that forms below the gumline, is typically darker from the start because it picks up blood pigments from inflamed gum tissue.
Separate from calculus, some people develop dark lines or bands along the gumline caused by chromogenic bacteria. These organisms produce pigmented compounds, and the dark material is a ferric compound, most likely ferric sulfide, formed when hydrogen sulfide from bacteria in the gum environment reacts with iron in saliva or gingival fluid.2Annals of Medical and Health Sciences Research. Occurrence of Black Chromogenic Stains and its Association with Oral Hygiene of Patients The resulting stains are typically black or dark grey, follow the contour of the gumline precisely, and are stubborn enough that regular brushing does not remove them. A professional cleaning will, but they tend to come back. Interestingly, people with these chromogenic stains often have lower rates of cavities, possibly because the same bacterial population that creates the stain outcompetes cavity-causing species. Still, the cosmetic effect is enough to send most people to the dental chair.
Trauma and Dying Teeth
If one tooth has turned grey and the others are fine, the most likely culprit is trauma. A bump, fall, or sports injury can damage the blood supply inside the tooth. When the pulp tissue dies, breakdown products from blood seep into the tiny tubules that run through the dentin. The chemical process involves hemoglobin and its derivatives infiltrating the dentin structure, which gives the tooth a grey, blue-grey, or brownish tint over time.3PubMed. Medico-legal aspects of postmortem pink teeth This color change can appear weeks or even months after the original injury, so people sometimes do not connect the two events.
Pulp necrosis after trauma is surprisingly common. A large retrospective study of injured permanent teeth found that pulp death occurred in about 27% of cases and was the most frequent complication across all types of dental injuries. Teeth with fully formed roots were more likely to lose their pulp than teeth still developing.4PubMed Central. A retrospective study of 889 injured permanent teeth This means that adults who take a hit to a front tooth face a real chance of that tooth eventually darkening. Children sometimes get lucky because their still-growing roots have better blood supply and can recover, but not always.
A grey tooth from trauma is not just a cosmetic issue. A dead pulp can harbor infection, leading to an abscess at the root tip. Even if it does not hurt, a dentist should evaluate a tooth that has changed color after an injury to determine whether root canal treatment is needed.
Medications That Stain From the Inside
Tetracycline antibiotics are notorious for causing permanent tooth discoloration when given to children whose teeth are still forming. The drug binds to calcium and gets incorporated directly into the tooth structure during mineralization. The resulting stain ranges from yellow to grey to brown, depending on the dose, the specific tetracycline variant, and how much of it was given relative to body weight.5PubMed. Tetracycline and other tetracycline-derivative staining of the teeth and oral cavity Because the pigment is locked inside the tooth itself, it does not brush off and it does not respond well to surface whitening treatments.
Tetracycline staining often appears as horizontal bands across the teeth, and the grey variant can look particularly striking on the lower portions of teeth where enamel is thinner and the dentin color shows through more readily. This type of staining is much less common than it used to be, because doctors now avoid prescribing tetracyclines to pregnant women and children under eight. But adults who were born before that guideline became standard, or who received the drugs in countries with different prescribing practices, still live with the results.
Other medications can also affect tooth color. Certain antihistamines, antipsychotics, and blood pressure drugs have been associated with discoloration, though usually less dramatically than tetracycline. If your grey teeth appeared during or after a course of medication, bring it up with both your doctor and your dentist.
Mouthwash and Chemical Staining
If you have been using a chlorhexidine mouthwash, the culprit for your grey-brown gumline staining may be sitting on your bathroom counter. Chlorhexidine is an effective antiseptic prescribed for gum disease, but it has a well-documented side effect of staining teeth and oral tissues. The mechanism is complex: the chlorhexidine molecule breaks down and deposits on tooth surfaces, triggers chemical reactions with food compounds that produce brown pigments, and promotes the formation of pigmented metal sulfides by interacting with proteins in the film that naturally coats your teeth.6PubMed Central. Comparative Effects of Kemphor and Chlorhexidine Mouthwashes on Tooth Staining and Gingivitis: A Randomized Controlled Crossover Clinical Trial The staining is worst near the gumline, where the mouthwash pools, and in people who drink tea, coffee, or red wine alongside their chlorhexidine use.
The good news is that chlorhexidine staining is extrinsic, meaning it sits on the surface rather than inside the tooth. A dental cleaning removes most or all of it. If you need to keep using the mouthwash for medical reasons, your dentist may suggest rinsing at a different time than you eat or drink pigmented beverages, or switching to a lower concentration.
Dental Restorations and Amalgam Shadow
Old silver amalgam fillings contain metals that corrode over time and leach dark pigments into the surrounding tooth structure. If you have a filled tooth that looks grey, particularly near the base, the metallic byproducts from the filling may have seeped into the dentin. This is sometimes called an “amalgam tattoo” when the discoloration spreads into the gum tissue itself. The grey appearance can be quite uniform and is often mistaken for a shadow or stain, but it is actually metal compounds embedded in the tooth.
Even non-metallic restorations can contribute to greying. When a tooth has had extensive work, the remaining natural tooth structure is thinner, and whatever is underneath, whether it is a metal post, a dark core buildup material, or residual staining from a previous filling, can show through the enamel. Treating highly discolored teeth from intrinsic staining poses a challenge for cosmetic dentistry because conventional crowns or highly opaque porcelain veneers carry drawbacks. Techniques that progressively lighten stained teeth using layered approaches allow for more natural-looking results in conservative veneer procedures.7PubMed Central. Using a modified subopaquing technique to treat highly discolored dentition
Genetic and Developmental Conditions
In rare cases, grey teeth are present from childhood and affect most or all of the teeth rather than just the gumline area. One such condition is dentinogenesis imperfecta, a genetic disorder in which the dentin forms abnormally. Teeth with this condition can appear opalescent grey, yellowish-brown, or translucent, and they tend to wear down much faster than normal teeth. A clinical study of children with osteogenesis imperfecta, a connective tissue disorder that frequently co-occurs with dentinogenesis imperfecta, found that affected teeth showed severe structural changes in the dentin organized into distinct abnormal layers, with the discoloration described as yellow-brown or opalescent grey.8PubMed Central. Dentinogenesis imperfecta in children with osteogenesis imperfecta: a clinical and ultrastructural study
Dental fluorosis is another developmental condition that can produce discoloration, though it more commonly causes white spots or brown staining rather than grey. Fluorosis happens when children ingest too much fluoride during tooth development, and the severity depends on the dose and timing. For people with fluorosis who want cosmetic improvement, treatments like resin infiltration or combinations of bleaching and resin infiltration have shown better esthetic results than microabrasion alone.9Wiley Online Library. Interventions for dental fluorosis: A systematic review
Internal root resorption is yet another, rarer cause. In this condition, the body’s own cells start dissolving the tooth from the inside, usually triggered by chronic inflammation in the pulp. The affected tooth may develop a pinkish or greyish spot as the internal structure breaks down and the thinning walls become more translucent. Root canal treatment remains the standard approach because it removes the inflamed tissue driving the resorption.10PubMed Central. Management of internal root resorption on permanent teeth
What You Can Do About Grey Teeth
Treatment depends entirely on the cause. External stains from tartar, chromogenic bacteria, chlorhexidine, or food pigments respond well to professional cleaning and polishing. Your dentist or hygienist can remove these deposits in a routine visit, and the teeth often look dramatically better immediately afterward. Staying on top of six-month cleanings prevents most external staining from building up to noticeable levels.
For teeth darkened by trauma or a dead nerve, internal bleaching is an option once root canal treatment has been completed. The procedure, sometimes called the “walking bleach” technique, involves placing a bleaching paste made of sodium perborate and water or a low-concentration hydrogen peroxide solution inside the pulp chamber and sealing it in for several days.11PubMed. Review of the current status of tooth whitening with the walking bleach technique An analysis of over 250 internally bleached teeth found that the color improvement was rated good in about 87% of cases and acceptable in the remaining 13%, though darker teeth, especially black ones, needed more rounds of treatment than grey or light yellow teeth.12PubMed. Internal bleaching of teeth: an analysis of 255 teeth Grey teeth actually respond more easily to internal bleaching than teeth that have turned very dark.
Tetracycline staining and severe intrinsic discoloration are harder to treat because the pigment is embedded in the tooth structure itself. Standard over-the-counter whitening strips make little difference. Professional options include extended courses of high-concentration bleaching, porcelain veneers, or in severe cases, crowns. The layered veneer approach mentioned earlier allows dentists to gradually mask dark staining without removing excessive tooth structure, which is a meaningful advantage for patients who want to preserve as much natural tooth as possible.
For enamel thinning, prevention is more practical than reversal. Fluoride treatments, remineralizing toothpastes, and avoiding acidic drinks can slow further erosion. Once enamel is gone, it does not grow back, so protecting what remains is the priority. Bonding or veneers can restore the appearance if the greying bothers you cosmetically.
When Grey Teeth Affect More Than Your Smile
It is easy to dismiss tooth color as purely cosmetic, but discoloration carries a real psychological weight for many people. A study of adolescents with discolored front teeth found that about two-thirds reported the discoloration prevented them from freely answering questions in class, half said it kept them from smiling openly, and 40% said it interfered with social interaction.13PubMed Central. Psychosocial aspect of anterior tooth discoloration among adolescents in igbo-ora, southwestern Nigeria Those are substantial effects on daily life, and they help explain why people seek treatment for discoloration even when the tooth is otherwise healthy.
Research on bleaching outcomes confirms that the benefits extend beyond the mirror. A year-long follow-up study found that improvements in psychosocial well-being and self-perception after whitening treatment were maintained at the twelve-month mark, regardless of whether a low or high concentration bleaching gel was used.14PubMed Central. The change of teeth color, whiteness variations and its psychosocial and self-perception effects when using low vs. high concentration bleaching gels: a one-year follow-up In other words, the psychological boost from addressing discolored teeth is real and lasting, which makes it a perfectly reasonable reason to seek treatment even if there is no underlying health concern.
How to Tell the Difference at Home
You probably cannot diagnose the exact cause of grey teeth on your own, but a few clues help narrow it down before you see a dentist. If the greyness scrapes off or feels rough and gritty when you run your tongue along the gumline, you are likely dealing with tartar or external staining. If it is smooth and seems to be part of the tooth itself, the cause is more likely intrinsic, whether from enamel thinning, trauma, medications, or a restoration underneath.
Location matters too. Greyness that follows the gumline on multiple teeth in a thin band points toward external staining or enamel wear. A single tooth that has turned uniformly grey suggests trauma or a dying nerve. Grey-brown banding that crosses multiple teeth in horizontal lines, especially if it has been there since childhood, suggests tetracycline exposure. And greyness clustered around an old filling is most likely amalgam corrosion.
Timing offers another clue. Discoloration that appeared suddenly, over days or weeks, is more urgent than color changes that have crept in over years. A rapidly greying tooth could indicate an acute pulp problem or internal resorption, both of which benefit from prompt treatment. Gradual changes are more consistent with wear, aging, or slow external staining, all of which are less urgent but still worth bringing up at your next dental visit. Whatever the cause, grey teeth at the gumline are common enough that your dentist will have seen them many times and can usually identify the source with a quick visual exam and an X-ray.