Black Triangles After Braces UK

What are black triangles?

Black triangles, clinically called open gingival embrasures, are the dark triangular spaces visible between teeth at the base of the contact point — the area where teeth touch — near the gum line. In a dentition with ideal gum health and tooth proportions, the gum tissue called the interdental papilla fills this space completely. When the papilla is absent or receded, or when the contact point between teeth is higher up the tooth than the gum can reach, a visible dark space is left. The term 'black triangle' refers simply to the shadow created by the empty space — there is nothing wrong with the tooth surface itself. They are not a sign that your teeth have been damaged by orthodontic treatment.

Why do black triangles appear after braces?

There are several reasons why black triangles become visible after orthodontic treatment, and understanding them helps clarify that orthodontics usually reveals rather than creates the underlying condition. The most common explanation is that crowded teeth were touching and overlapping before treatment — concealing the spaces that were present all along. As orthodontic treatment aligns the teeth, the contact points move to their correct positions and the triangular spaces beneath them become visible for the first time. Tooth shape is another major factor: teeth that are triangular or tapered in cross-section — widest at the biting edge and narrower at the neck — have higher contact points, leaving more space beneath them than rectangular teeth. Pre-existing gum recession or periodontal bone loss means the interdental papilla is shorter than it should be, making it unable to fill the embrasure space even when teeth are correctly aligned. Age is relevant too — gum tissue naturally becomes thinner and less resilient with time, so adults are more likely to notice black triangles than younger patients. Finally, the way teeth are moved during orthodontic treatment can influence contact point position, particularly if teeth are intruded or the angulation of roots is changed.

Who is at higher risk?

Adults undergoing orthodontic treatment are at significantly higher risk of noticing black triangles after treatment compared with adolescents. This is partly because adult teeth are more likely to have some history of periodontal disease or gum recession, even if mild and asymptomatic. Patients with triangular or tapered incisor shapes are at higher risk regardless of age. Patients who have had periodontal treatment, bone loss, or who have generalised gingival recession are more likely to develop open embrasures after alignment. Those with a Bolton discrepancy — where the relative size of upper and lower teeth is mismatched — may also have persistent spacing or poor contact point positions that increase the risk. A thorough orthodontic assessment, including discussion of tooth shape and any existing gum issues, should ideally identify high-risk patients before treatment begins.

Prevention during orthodontic planning

The best time to address the risk of black triangles is before treatment starts. Orthodontists experienced with adult cases should identify triangular tooth shapes and pre-existing gum changes during the initial assessment and discuss realistic expectations with the patient. Interproximal reduction (IPR) — the controlled removal of a thin layer of enamel from the sides of teeth using fine strips or discs — is one of the most effective preventive tools. By reshaping triangular teeth to be slightly more rectangular, IPR can lower the contact point toward the gum line, reducing or eliminating the embrasure space. Accurate root angulation during treatment also helps: teeth whose roots are correctly paralleled have contact points lower on the crown. In high-risk cases, the orthodontist may discuss what residual spacing is expected after treatment and plan for cosmetic finishing procedures accordingly.

Treatment options for existing black triangles

If black triangles are present after orthodontic treatment has been completed, several options are available depending on the size and number of spaces. Composite bonding is the most widely used solution — a tooth-coloured resin material is applied to the sides of the adjacent teeth to widen them and reduce the visible space. It is quick, minimally invasive, reversible, and typically costs between £100 and £300 per tooth at private practices in the UK. The Bioclear technique uses a specific composite method with anatomically shaped matrices designed to create a better seal at the base of the contact point, and is particularly effective for larger black triangles. Further targeted IPR combined with orthodontic space closure can sometimes reduce the spaces if treatment is still active or there is scope for further aligner refinement. Pink porcelain or pink composite can be used to fill embrasure spaces where they are very large — mimicking gum tissue — but this is less commonly used because it looks artificial at close range. Periodontal papilla reconstruction procedures exist but carry unpredictable results and are not widely used in the UK for post-orthodontic black triangles. For very small spaces, patients sometimes adapt and find the spaces less noticeable than they expected once they have lived with the result for a few months.

Will black triangles go away on their own?

Small black triangles that appeared at the end of orthodontic treatment sometimes reduce over the following months as the gum tissue adapts and the papilla partially regrows — particularly in younger patients where the tissue is more resilient. However, this is not predictable and should not be relied upon as the primary management plan. Larger spaces, or spaces in patients with any pre-existing gum recession, are unlikely to close spontaneously. If you notice black triangles forming during treatment, mention them to your orthodontist early — there may be scope to adjust tooth movement or add IPR before the end of active treatment.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.