One of the most challenging restorative situations is matching a single central incisor. There are many factors that affect our ability to fool the eye and have a restored central appear to be an identical match to it’s neighbor. One of the factors that is often missed and easy to control is facial embrasure form. Part of the reason we miss this aspect of tooth shape is you can only see it from a different perspective, incisal edge down. When I am shaping provisionals, direct composite or completing a wax-up with intention I shape the facial embrasure form.
Both the width of the embrasure from the height of contour to the contact, and the shape are critical. Between the mesial and distal facial embrasures the labial reflective zone is created. This zone, which impacts the reflection of light to our eyes is critical in the visual perception of the width of a tooth. When we are matching a tooth, we need to match the dimension of this reflective zone. Other times we have two teeth that need to appear to match, yet have different actual widths. In this case if we match the dimension of this reflective zone we can have the teeth “appear” to be the same size.
This week a patient came in concerned that her Invisalign was not going as planned because her two maxillary centrals were not lined up. After examining her teeth, I reached for my camera and snapped a mirror shot down the incisal edge of the centrals. Showing her the photo I asked “What do you notice about your two front teeth?”. She looked at the photo for less than thirty seconds before responding, “The edges are lined up, the issue is the teeth aren’t the same shape”. This difference in the shape of the mesial facial embrasure impacts the appearance of the position of the tooth,perceived value and size,