In dental terminology, these are known as ‘open gingival embrasures’. They exist wherever your gum tissue doesn’t completely fill the space between your teeth along the gumline. Whilst gaps are usually normal, new ones or those which have widened might be a sign of problems.
The shape of the tooth. If your teeth are rectangular, they will be equally wide at both top and bottom. If your teeth are narrower at the gumline, black gaps may develop.
Receding gums. As gums recede, they may also become thinner and stop filling up the natural spaces. The empty spaces look black.
Teeth brushing. If you brush too hard. You can damage the soft tissue between your teeth.
Braces or other orthodontic treatments. As these move your teeth, new gaps may appear.
Bone loss. Your dentist can check to see if this is what is causing your black triangles.
Impact on your health
Black triangles do not cause health problems, but may well be a symptom of a health problem. Your dentist will help you find the cause.
Treatments depend on cause. The most common treatments are:
Brushing and flossing more carefully.
Procedures to cure gum disease.
Braces to bring your teeth closer together.
Applying composite bonding or veneers.
Floss gently. Don’t apply pressure to gums.
Use a soft bristle toothbrush.