Black Triangles Between Teeth: Causes and Fixes

By the team at Bollington Dental Practice, under the clinical direction of Dr Ellie Burrows, Principal Dentist. Updated October 2026.

Black triangles tend to be noticed in photographs first: small dark spaces just above or below where two front teeth touch, near the gum line. Some people see them appear gradually over the years. Others notice them suddenly, after their teeth have been straightened or after treatment for gum disease, which can feel unfair when they have done exactly what they were asked. They are very common, they usually have a clear explanation, and there is often something that can be done about them.

The short answer

Black triangles are spaces where the gum no longer fills the gap between two teeth just below the point where they touch. They usually come from gum recession, the shape of the teeth, or both, and they become more common with age. The first step is always making sure the gums are healthy, because gum disease is a common cause and needs treating before anything cosmetic. Once the gums are stable, small triangles can often be reduced with composite bonding, from £175 per tooth, and sometimes with clear aligners or veneers.

What causes black triangles

Gum recession and bone loss. The little point of gum between two teeth, called the papilla, is supported by the bone beneath it. When that bone is reduced, most often by gum disease, the gum shrinks back and leaves a space. Ageing, heavy-handed brushing and smoking can all contribute to recession. Our guide to receding gums covers the causes in more detail.

The shape of the teeth. Some teeth are much wider at the biting edge than at the gum, a triangular shape rather than a squarer one. Where two triangular teeth meet, they touch high up, near the edges, leaving a larger space below the contact point for the gum to fill. Even with perfectly healthy gums, that space may be too big for the papilla to fill completely.

After teeth are straightened. When crowded, overlapping teeth are lined up, triangular gaps that were hidden by the overlap can be revealed. This is a recognised effect of straightening rather than a sign of anything going wrong, and it can often be anticipated during planning and managed by reshaping the contact points between the teeth.

After gum disease treatment. Inflamed gums are swollen, and that swelling can fill spaces between the teeth. When gum disease is treated and the gums become healthy, they tighten and shrink back, and black triangles can appear. It is understandably disappointing, but it is a sign of healthier gums rather than of treatment failing.

Gaps and angles. Small gaps between teeth, or roots that angle away from each other, also leave more room than the gum can fill.

Treat the gums first

If black triangles have appeared alongside gums that bleed when you brush, look red or puffy, or have pulled back from the teeth, gum disease is the first thing to rule out. Covering triangles with bonding while gum disease is active would hide the problem rather than solve it, and the triangles would be likely to grow.

Treatment usually means thorough professional cleaning, improving the way you clean between your teeth at home, and regular reviews. Our hygiene treatments page explains what is involved. Hygiene appointments here need an examination with us within the last year, and cost £60 for 20 minutes or £89 for 30 minutes. Once the gums have been stable for a while, it is much clearer how large the triangles really are and what would help. If you smoke, stopping helps the gums heal and respond to treatment, and free support to stop is available through the NHS.

When to get urgent help. Call us the same day if you have a painful swelling on the gum, pus, a throbbing tooth, or a tooth that has suddenly become loose. We offer same-day slots where possible on 01625 574609, and out of hours NHS 111 can advise. If facial swelling is spreading towards your eye, or affects your breathing or swallowing, go to A&E or call 999.

Options for reducing black triangles

Composite bonding. Tooth-coloured composite is added to the sides of the teeth near the gum, changing their shape so they touch lower down and the space is filled. It usually needs little or no drilling and can often be done in one visit. The bonding has to be shaped carefully so it can still be cleaned, because a ledge that traps plaque would irritate the gum. Like all bonding, it can stain or chip and needs occasional polishing. It is from £175 per tooth here, and our composite bonding page explains the process.

Clear aligners with reshaping. Where the position or angle of the teeth is part of the cause, aligners can bring teeth together, and gently polishing the contact points narrower allows the teeth to meet lower down, giving the gum less space to fill. This is often used when straightening crowded teeth to reduce triangles before they appear. We provide ClearCorrect, from £2,499, and the ClearCorrect consultation is free for existing patients.

Veneers or crowns. Where several front teeth would also benefit from a change of colour or shape, veneers can be designed to close the spaces as part of the result. Composite veneers are from £225 per tooth and porcelain veneers from £650 per tooth. Where a tooth is already heavily filled, a crown, from £600, may be the more appropriate restoration.

Gum procedures. Surgical techniques that aim to rebuild the papilla exist, but their results are unpredictable, and they are not something we provide here. If needed, your dentist will explain whether this applies to you.

Accepting them. Small triangles that do not trap food or bother you need no treatment at all. Many people decide that keeping their gums healthy is all they want to do.

Living with black triangles

Food trapping. Spaces between teeth can catch food, which is annoying and, if left, feeds plaque. Cleaning between the teeth every day matters more, not less, when triangles are present.

Interdental brushes. The upside of a black triangle is that it is easy to clean with an interdental brush of the right size, which your hygienist can help you choose. Our guide to interdental brushes, water flossers and floss explains the options.

Gentle brushing. Brushing harder does not clean better and can make recession worse. A soft or medium brush, used gently twice a day with fluoride toothpaste, is enough. If exposed roots near the triangles feel sensitive, our sensitive teeth guide covers what helps.

Speech. Larger triangles between the upper front teeth can occasionally let air or a little saliva escape on certain sounds, which is one reason some people choose to have them closed even when appearance does not bother them.

Regular check-ups. Black triangles that are getting bigger are worth mentioning at your examination, because a change over time says more about gum health than the triangles themselves.

What it costs

For new patients, the starting point is an examination, £89 including X-rays, which includes a check of your gums. Hygiene appointments are £60 for 20 minutes or £89 for 30 minutes, and some people need more than one visit while their gums settle. After that, bonding is from £175 per tooth, composite veneers from £225 per tooth, porcelain veneers from £650 per tooth and ClearCorrect from £2,499. Closing black triangles for appearance is cosmetic treatment and is not generally available on the NHS, although treating gum disease itself is part of NHS care. If you want to keep your gums on track over the long term, our dental plan, from £15.95 a month, includes your annual examination and two hygiene visits a year.

Frequently asked questions

Can black triangles between teeth be fixed?

Often they can be reduced or closed, most commonly with composite bonding, and sometimes with clear aligners, veneers or a combination. The right option depends on the cause, so gum health is checked first. Very large triangles caused by significant bone loss are harder to close fully.

Will gums grow back to fill black triangles?

Lost gum does not usually grow back on its own. After gum disease treatment, a small amount of improvement can occur as the gums settle, but more often healthy gums tighten and the triangles become slightly more visible. Changing the shape or position of the teeth is the more predictable way to reduce them.

Why did black triangles appear after my teeth were straightened?

Crowded, overlapping teeth can hide triangular spaces, and lining them up reveals them. It is a recognised effect, more likely with triangular-shaped teeth or where the gums have receded. Reshaping the contact points between the teeth or adding composite bonding can often reduce them.

Are black triangles a sign of gum disease?

They can be, but not always. Gum disease is a common cause because it reduces the bone that supports the gum between teeth, but tooth shape, ageing and straightening also play a part. If your gums bleed, look swollen or have receded, have them checked before considering cosmetic treatment.

Noticed black triangles?

If dark spaces have appeared between your teeth, a check of your gums is the right place to start, and then we can talk through what would help. Call 01625 574609. New patient examinations are £89 including X-rays, bonding is from £175 per tooth, and every price is on our fees page.

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