Angularis nigra, Latin for 'black angle', also known as open gingival embrasures, and colloquially known as "black triangle", is the space or gap seen at the cervical embrasure, below the contact point of some teeth. The interdental papilla does not fully enclose the space, leading to an aperture between adjacent teeth. This gap has many causes including gingival recession, and gingival withdrawal post-orthodontic work. Interdental "black triangles" were rated as the third-most-disliked aesthetic problem below caries and crown margins. Treatment of angularis nigra often requires an interdisciplinary approach, involving periodontal, orthodontic and restorative treatment. Possible treatments to correct angularis nigra include addition of composite resin in the space, veneer placement, or gum