Black triangle is a term used to describe a cosmetic dental problem.
Let’s explain the black triangle by using the example of a diastema closure by direct bonding. Pre-operatively, you have a diastema, let’s say, of three millimeters. To treat this, you add a millimeter and a half of composite to the mesial of each central. But in shaping this diastema closure, you leave the gingival embrasure so open that it isn’t filled by the gingival papilla. You have created a black triangle. When the patient smiles wide enough to see the gingivae, there will be a triangular area between the teeth that will appear black because there is no gingival tissue there. To fix it, you need to re-do the bonding so that it hugs the gingival papilla more.
Black triangles can be created with bonding or with porcelain veneers. If you have maxillary anterior teeth with multiple spaces between them and your preparations are entirely on the labial surfaces of the teeth, you make it impossible for the laboratory technician to eliminate the black triangles between the teeth. Your preparations need to wrap around the teeth somewhat, and the margins need to be apical enough, especially in the gingival areas, so that you give the technician the ability to add some bulk in these areas.
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