Why do black triangles appear after orthodontics?
A black triangle is a dark triangular gap left between teeth near the gums. Normally the interdental papilla (the pointed gum that fills the space between teeth) fills that space, but when the papilla can't rise to fill it, the dark space inside shows through and looks black. Quite a few people come back saying, “I finished orthodontics, but the space between my front teeth looks black and empty.”
- As overlapping front teeth straighten, a lack of bone and papilla that had been hidden is revealed (most common in adults)
- The teeth are triangular, narrowing toward the root, so the contact point is near the edge
- The height of the alveolar bone between the teeth has dropped due to periodontitis or age
- Root angles spread during movement, changing where the contact point is
Whether the papilla will fill in is estimated from the distance between the contact point and the top of the bone between the teeth. Research suggests that when this distance is 5mm or less, the papilla fills in most cases, and the proportion drops sharply as the distance grows. An explanation including causes unrelated to orthodontics is summarized separately in why black triangles form.
How are black triangles treated?
| Cause | Treatment |
|---|---|
| Revealed as overlap was corrected; triangular teeth | Slightly reshape the sides to lower the contact point and bring the teeth together to reduce the gap |
| Root angles spread apart | Straighten the roots parallel with orthodontics |
| A small gap remains | Fill in the side shape with composite resin |
| Want to change shape and color too | Thin porcelain veneers after checking how much would be removed |
| Low alveolar bone | Manage inflammation with gum treatment; we don't claim we can fill it with gum |
Reshaping the sides follows the same principle as interproximal reduction and is done only within the enamel. Small spaces can be fixed quickly with front tooth composite resin, but if the space is large, we first check the proportions so the teeth don't look too wide.
Can't the gums be refilled?
Gums over bone that has dropped do not grow back. The interdental papilla only stands on top of the bone height beneath it. There are cases where the gap looks less noticeable once inflammation settles and the swelling goes down, but we don't tell you we can bring receded gums back to their original height. There is also a method of temporarily adding volume with hyaluronic acid filler, but the effect doesn't last long and requires repeated maintenance.
Is it a problem if I leave it?
The dark gap itself isn't painful, but food often gets stuck and the toothbrush doesn't reach well, so it can easily lead to gum inflammation or cavities between the teeth. Some people are also left with a feeling of air leaking when they talk. If it's small and easy to clean, we don't necessarily fill it, and manage it with an interdental brush of the right size. Front teeth are visible right away when you smile, so many people are bothered even by small gaps, and if you want, I'll explain the method that fits the cause.
How we do it at Wonjin Dental
Rather than what will fill it quickly, I first look at the contact point and the bone height. I separate spaces revealed as overlap was corrected from spaces where the bone has already dropped, and I match small spaces with shape, but I don't claim to fill spaces without bone using gum. For people starting orthodontics, I include contact point adjustment and root angles in the plan at the design stage to reduce the size of gaps in advance. I also don't just cover the space by placing porcelain on teeth that stick out.
Frequently asked questions
Does everyone get black triangles after orthodontics?
No. Some mouths are more prone to them depending on the degree of overlap, tooth shape, gum thickness, and age. If you're an adult and your front teeth overlapped a lot, it's good to have the possibility explained in advance.
Is it noticeable if black triangles are filled with composite resin?
If the color and shape match the neighboring teeth, it's often hard to notice at conversation distance. The larger the space, the wider the teeth can look, so the method differs depending on size.
Can black triangles be detected during orthodontic treatment?
As overlapping teeth start to straighten, the gap becomes visible, so it can often be seen at mid-treatment checkups. If contact point adjustment or root angle correction is added to the plan then, the size can be reduced in the finishing stage.
Will using an interdental brush make the gap bigger?
Using the right size gently doesn't enlarge the gap. Forcing in one that's too big can damage the gums. How to choose the size is described in how to use an interdental brush.
