One of the things that can negatively affect the result and success of our cosmetic cases is the appearance of black triangles.
There were two landmark studies and papers that were released in '92 by Tarnow, and Garber and Salama in '98 that talked about where to set the contact points depending on the restorative interfaces relative to the bone to prevent black triangles from forming.
Say, for example:
- Tooth to tooth set at 5 millimeters or less
- Tooth to implant, four and a half millimeters or less
- Implant to implant, three and a half millimeters or less.
- And there are other combinations.
The key is from our end, we have to communicate to the lab and let them know where to set that contact point relative to the margin.
For example, if you're restoring teeth numbers eight and nine and you want to prevent a black triangle from forming between those teeth, you have to let your lab know where to set the contact relative to the margin.
So when you do your bone sounding and say the margins are two millimeters away from the bone, you tell your lab then, "Please set the contact point no more than 3 millimeters away from the margins." This will ensure a distance of 5 millimeters or less from the bone and hopefully, cause papilla to fill that space and not have a black triangle.
The key point is to let your lab know where to set that contact point relative to the margins or through no fault of their own, a black triangle can occur because they didn't know where to set it.