I had the opportunity this afternoon to begin the process of restoring a single maxillary central. Without question this is the most challenging thing I do in esthetics. One of the critical pieces of getting an exquisite match will be to mimic the surface morphology of the other central incisor. Surface morphology creates so many aspects of the appearance of the tooth. The primary interaction between surface morphology and our perception of the tooth has to do with light reflection. When light hits the tooth, some of it is reflected back to our eye, and the rest is reflected away. This light reflection is what our eye uses in determining the value of the tooth as well as the size and proportion, so it is critical when matching existing natural teeth.
The laboratory can easily match the surface morphology, but only if we communicate it well. One way we send this information to the lab is in the impression, which they then turn into a model. Unfortunately, this may only send them a portion of the information. Inaccuracies and loss of detail occur at the level of the impression, and again when the model is poured. In addition stone differs immensely in it’s light reflective capacities, so doesn’t give the technician important visual cues.
Photography is a critical piece of lab communication and transferring information about surface morphology. There are some key steps in taking a photograph to communicate surface morphology.
- Retract the lips.
- Dry the teeth thoroughly, as moisture fills in the minute details on the surface of the tooth making it appear flatter.
- Place a black contraster behind the teeth.
- The camera lens should be perpendicular to the labial surface of the teeth.
It is critical that the camera lens be at the correct angle, or the image will not contain information about surface morphology. The last piece of the puzzle is to make sure that the photographs get to the lab, so the technician has this information at hand.