If you’ve started to notice small triangular gaps opening up between your teeth — especially near the gumline at the front — you’ve probably wondered what they are and whether anything can be done. These are commonly called “black triangles,” and they’re a frequent question at our clinic, particularly from people who’ve recently finished braces or Invisalign, and from adults noticing changes with age.
Black triangles between teeth are more common than most people realise. They affect a significant proportion of adults, and the number increases with age. Despite how common they are, many people feel self-conscious about them, especially when they appear unexpectedly after orthodontic treatment.
Here’s a plain-English guide to what causes them and the options for closing them.
What is a black triangle?
A black triangle is the small dark gap that can appear between two teeth, below the point where they touch and above the gum. It happens when the gum tissue between the teeth doesn’t completely fill that space, so the gap looks like a little dark triangle. The clinical name is an open gingival embrasure.
The gum tissue that normally fills this space is called the interdental papilla, a small, pointed projection of gum that sits between each pair of teeth. When this papilla is full and healthy, it closes the space completely and you won’t notice any gap. When it recedes, shrinks, or never fully develops, the triangle becomes visible.
They’re usually a cosmetic concern rather than a sign of a dental health problem — but they can trap food, and many people simply don’t like how they look when they smile. In some cases, the gaps can also make it harder to keep the area clean, which is worth monitoring even if the appearance doesn’t bother you.
Why do black triangles appear?
There are a few common reasons:
After braces or Invisalign
This is one we’re asked about often. When teeth are crowded or overlapping, they can hide the space between their roots. As orthodontic treatment (like braces and Invisalign) moves them into a neat line, that previously hidden space is revealed — and a black triangle can appear where the crowding used to be. It doesn’t mean the orthodontic treatment went wrong; it’s simply the shape of the teeth and gums becoming visible once the teeth are aligned.
This is one of the most common reasons we see patients asking about gaps between teeth after braces or a black triangle after Invisalign. The orthodontic work itself is successful — the teeth are straight, but the gum tissue, which doesn’t move the way teeth do, can’t always fill a space it was never occupying. It’s particularly common when there was significant crowding beforehand, or when the contact point between two teeth sits high up rather than close to the gumline.
If you’ve finished Invisalign or braces and noticed a triangle appearing, it’s worth having it assessed sooner rather than later. Early treatment is generally simpler.
Gum recession and age
Gums naturally tend to recede over time, and faster if there’s gum disease or from very aggressive brushing. As the gum pulls back, the tissue that once filled the gap between teeth retreats with it, opening a triangle.
Gum recession gaps are particularly common in adults over 40, and the front lower teeth are often the first place they’re noticed. The thinness of the gum tissue in this area, combined with years of brushing, eating, and normal wear, means the interdental papilla can gradually lose volume. If you’re also experiencing sensitivity along the gumline or your teeth appear to be getting longer, it’s worth having your gums checked at the same time.
Tooth shape
Some teeth are more triangular than rectangular. These meet at a narrow point near the top, which leaves more open space lower down between them.
This is something you’re essentially born with. It’s determined by the natural shape of your teeth. Triangular teeth have a wider gap between them lower down even when the contact point at the top is perfectly closed. No amount of orthodontic treatment will change the underlying tooth shape, which is why this type of black triangle often needs to be addressed with a restorative solution rather than further alignment.
Bone loss
Another cause that’s less commonly discussed is bone loss beneath the gum. The interdental papilla is supported by the bone underneath it. If that bone reduces, whether from gum disease, previous extractions, or age-related changes, the gum loses its scaffolding and can no longer maintain its height between the teeth. This is one reason why treating any underlying gum disease is always the starting point before closing a black triangle aesthetically.
Can black triangles be fixed?
Yes — in many cases they can be improved. The right approach depends on why the triangle formed, which is why an assessment comes first. Options can include:
- The Bioclear Method (from $250 per tooth) — a minimally invasive technique that uses tooth-coloured composite resin, shaped with a clear mould, to fill the gap and rebuild a natural contour between the teeth. The result blends seamlessly with the surrounding teeth and, when done well, is virtually undetectable. It’s one of the most conservative options available because it doesn’t require any removal of healthy tooth structure.
- Veneers — in some situations, porcelain veneers may be more suitable, particularly if you’re also looking to change the shape or colour of the teeth more broadly. Veneers can effectively widen the visible surface of the tooth to close the gap, while also improving overall smile aesthetics at the same time.
- Addressing the underlying cause — if gum disease is involved, treating the gums is the priority. Closing a black triangle without first stabilising the gums is unlikely to produce a lasting result. We’ll always check the health of the surrounding tissue before recommending any cosmetic treatment.
It’s also worth noting what won’t work. Brushing more won’t fill a gap that’s already opened, and no toothpaste or mouthwash can restore lost gum tissue. If the triangle is there, it needs a clinical solution and the good news is that solutions exist, and they’re often simpler than people expect.
If your black triangles appeared after braces or Invisalign, or you’ve noticed them developing with age, the Bioclear Method is often a good option to ask about because it can usually close the gap without cutting down healthy tooth structure.
How long does black triangle treatment take?
For most patients, the Bioclear Method can be completed in a single visit. The composite resin is applied, shaped, and polished in the chair, so you leave the same day with a noticeably improved result. Veneers typically require two appointments, one to prepare the teeth and take impressions, and a second to fit the final veneers once they’ve been made. Your dentist will give you a realistic timeline at your assessment based on how many teeth are involved and which approach is most suitable.
What to do next
The best first step is a proper look in person, so the cause can be identified and the most suitable option discussed for your teeth.
You can learn more about how we close these gaps on our Black Triangle Treatment page, or get in touch with Garden Dental to arrange an assessment. We see patients for black triangle concerns regularly, and in most cases there’s a straightforward path forward, it just starts with knowing what you’re working with.
