Black triangles after braces
Black triangles are small dark gaps that can show between the teeth near the gumline once braces come off. They appear where the gum doesn't fully fill the space under the point where two teeth touch. They're common after orthodontic treatment, and there are ways to reduce them (Rashid et al., Healthcare) (Sahu et al., F1000Research). Here is why they happen, who is most at risk, and what fixing them involves and costs.
Key points
- Reported in 38% to 58% of people after fixed braces (Rashid et al., Healthcare)
- Tooth shape, crowding, root angle and bone level are the main risk factors (Rashid et al., Healthcare)
- Options include bonding, veneers, gum procedures and hyaluronic acid injections (Sahu et al., F1000Research)
- Bonding costs about $300 to $600 per tooth (Healthline)
What black triangles are
Dentists call them open gingival embrasures. They show where the small point of gum between two teeth, the interdental papilla, is short or missing (Sahu et al., F1000Research). The loss of papilla has several causes, including tooth shape, gum disease and aging (Sahu et al., F1000Research).
Besides the look, they can trap food, make plaque harder to clean away and contribute to gum problems (Rashid et al., Healthcare).
How common they are after braces
A 2022 systematic review of 5 studies found that 38% to 58% of people had black triangles after treatment with fixed braces (Rashid et al., Healthcare). The authors caution that the studies differed too much to draw a firm conclusion about how much braces themselves are responsible (Rashid et al., Healthcare). They aren't limited to braces: a 2025 review describes black triangles as more common in people treated with braces or clear aligners (Sahu et al., F1000Research), so switching to Invisalign doesn't avoid the risk.
Causes and risk factors
The 2022 review identified these factors (Rashid et al., Healthcare):
| Risk factor | What the research found |
|---|---|
| Triangular tooth shape | People whose crowns were triangular at the start of treatment were more susceptible (Rashid et al., Healthcare) |
| Severe crowding | Higher odds in patients with more than 8 mm of crowding (Rashid et al., Healthcare) |
| Root angle | Each degree more that the roots diverge was linked to a 14% to 21% increase (Rashid et al., Healthcare) |
| Bone level | More than 5 mm between the teeth's contact point and the bone crest was associated with black triangles (Rashid et al., Healthcare) |
| Contact point | A short contact point that sits closer to the biting edge (Rashid et al., Healthcare) |
| Age | One study linked age over 20 to more black triangles; another found no link (Rashid et al., Healthcare) |
Can they be prevented?
Not always. The review emphasizes preserving the gum papilla, and recommends changing a pointed contact between two teeth into a broader contact area (Rashid et al., Healthcare). Healthy gums help too: brackets and wires create extra places for plaque to collect, so thorough brushing and flossing during treatment matters (AAO). If you have triangular teeth or severe crowding, ask your orthodontist before treatment how they plan to manage the risk.
Treatment options
| Option | How it works | Things to know |
|---|---|---|
| Composite bonding | Tooth-colored resin added to the sides of the teeth to close the gap (Sahu et al., F1000Research) | One of the least expensive cosmetic procedures, but can chip and stain (Cleveland Clinic) |
| Veneers | Thin shells over the front of the teeth (Sahu et al., F1000Research) | Cost more per tooth than bonding (Healthline) (Healthline) |
| Hyaluronic acid injections | Injected into the gum papilla to help fill the gap (Sahu et al., F1000Research) | Promising in small studies; effects reported to last about 6 to 12 months (Sahu et al., F1000Research) |
| Gum surgery | Grafting or repositioning gum tissue (Sahu et al., F1000Research) | Coronally repositioned and connective tissue flaps are considered the gold standard, but have drawbacks (Rashid et al., Healthcare) |
The evidence for hyaluronic acid comes mostly from small pilot studies and case series, and the review's authors call for larger, longer trials (Sahu et al., F1000Research). Which option suits you depends on the size of the gap, your tooth shape and your gums, so ask both your orthodontist and your dentist.
How much fixing black triangles costs
| Option | Published price |
|---|---|
| Composite bonding (Healthline) | $300 to $600 per tooth |
| Composite veneers (Healthline) | $400 to $2,000 per tooth |
| Porcelain veneers (Healthline) | $925 to $2,500 per tooth |
| Hyaluronic acid or gum surgery | No reliable published price |
Bonding lasts about 3 to 10 years before it needs a touch-up (Cleveland Clinic), and some insurers treat it as cosmetic and won't cover it (Healthline). Ask for a written quote per tooth. See also how to close a gap in teeth.
Questions to ask
- Am I at higher risk of black triangles because of my tooth shape or crowding?
- Can the contacts between my teeth be shaped during treatment to reduce the risk?
- If one appears, which option would you recommend, and who does it?
- How long will the fix last, and what will it cost per tooth?
More on life after braces in getting braces off.
Questions people ask
Why do I have black triangles after braces?
They're gaps where the gum doesn't fully fill the space between teeth near the gumline. Risk factors in research include triangular-shaped teeth, severe crowding before treatment, diverging roots and more than 5 mm between the teeth's contact point and the bone (Rashid et al., 2022).
How common are black triangles after braces?
A 2022 systematic review found an incidence of 38% to 58% after treatment with fixed braces, though the five studies varied too much for a firm conclusion.
Do black triangles go away?
Don't count on it; ask your dentist to check them at your next visit. Treatments include bonding, veneers, gum procedures and hyaluronic acid injections (Sahu et al., 2025).
Can black triangles be fixed?
Often they can be reduced. Options include composite bonding, veneers, gum surgery and hyaluronic acid injections, whose effect has been reported to last about 6 to 12 months in small studies.
How much does fixing black triangles cost?
It depends on the method. Healthline puts tooth bonding at about $300 to $600 per tooth. We haven't found reliable prices for hyaluronic acid or gum surgery.
Sources
- Incidence of gingival black triangles following treatment with fixed orthodontic appliance: a systematic review (Rashid ZJ et al.), Healthcare 10(8):1373. Healthcare (peer-reviewed), via PubMed Central. 2022.
- Investigating the efficacy of hyaluronic acid in minimizing black triangles: a comprehensive analysis (Sahu PP, Nayak S, Uppoor A), F1000Research 13:1481. F1000Research (peer-reviewed narrative review), via PubMed Central. June 19, 2025 (version 2).
- Dental bonding. Cleveland Clinic. Last updated January 5, 2026.
- Teeth bonding: what to expect. Healthline, medically reviewed by Christine Frank, DDS. March 12, 2019.
- What to know before you get dental veneers. Healthline, medically reviewed by Christine Frank, DDS. Updated February 10, 2023.
- Swollen or bleeding gums with braces: causes and what to do. American Association of Orthodontists. October 13, 2026.
Figures are national averages or ranges from these sources. Estimates from our calculator are a model, explained on how we get our numbers.