What are black triangles?
Black triangles are open gingival embrasures: small spaces between teeth near the gumline. They look dark because the space is not fully filled by gum tissue.
They are usually more of an aesthetic concern than an emergency, but they can also trap food and make cleaning feel awkward.
Why can they appear after orthodontic treatment?
Before treatment, crowding or overlap may hide these spaces. Once the teeth are straightened, the real shape of the teeth and the gum contour become easier to see.
Adults are more likely than younger patients to have triangular tooth shapes, reduced gum fill or past gum changes, which can make black triangles more noticeable.
Common factors that increase the chance
Tooth shape matters. Teeth that are wider at the biting edge and narrower near the gumline leave less room for the contact point to fill the space.
Age, previous gum inflammation, bone support, the amount of crowding and the final position of the contact point can all influence the result.
How can black triangles sometimes be improved?
Depending on the case, options may include selective reshaping or IPR, small composite bonding additions, hygiene improvement when inflammation is a factor, or simply accepting a minor aesthetic imperfection if the bite and tooth health are otherwise excellent.
The right choice depends on tooth shape, gum health and whether the issue is cosmetic, functional or both.
Can black triangles always be prevented?
Not always. Orthodontists can often plan contact points carefully, but they cannot change every aspect of tooth anatomy or gum biology.
Good gum health before and during treatment may reduce avoidable tissue loss, which is one reason adults are often advised to address periodontal issues early.
What should you ask if you are worried?
Ask whether the spaces are mainly due to tooth shape, gum health or the final tooth alignment. Also ask what changes are realistic and whether any improvement would affect retainers or long-term stability.
Sources & further reading
- American Association of Orthodontists — Embrasure space after braces — Discusses food trapping and dark spaces between teeth after orthodontic treatment.
- NHS — Gum disease — Background on gum health, which can influence tissue support around teeth.
These references support general educational information. Your own orthodontist or dentist should advise you based on your teeth, gums, bite, medical history and treatment goals.