I’ve polished up a presentation tonight that I will be giving tomorrow in Bellevue Washington on Anterior Esthetic Techniques & Materials. One of the concepts we will be looking at is incisal reduction as part of a veneer prep, when do we do it and why? Another way to look at this is when would we not need to create incisal reduction. If we are placing a veneer simply to correct damaged labial enamel on a tooth that has the correct length, incisal edge position, contour and we have underlying dentin that will create exquisite esthetics the tooth can be prepared without incisal reduction.
If we are increasing tooth length to correct display at rest and tooth proportion we want to create adequate incisal reduction. When we wrap porcelain over the incisal edge, we want a minimum of 2mm from the incisal edge of the prep to the incisal edge of the restoration. This dimension of porcelain creates material properties to minimize the risk of fracture. The amount of incisal reduction we need is only to create the 2mm dimension, so when teeth are shorter than the proposal we can be conservative in our tooth preparation. I accomplish this by mocking up the final result with bisacryl from a wax-up, which gives me a reference to the final incisal edge position. I then place my depth cuts into the bisacryl to ensure adequate reduction for the final restoration. Another change in incisal edge position that necessitates incisal reduction is when we want to procline or retrocline an anterior tooth. In the case where want to move the incisal edge anterior, we reduce the incisal edge to give the technician running room for the restoration and avoid an overly thick incisal dimension. The converse would be when we want to move the incisal edge to the lingual, and would have to make the tooth far to thin if we did not prepare the incisal edge.
Another reason that I commonly create incisal reduction is to optimize the esthetics of the final restoration. When the technician has a 2mm wide band of porcelain at the incisal they have the optimal ability to create incisal effects. This preparation design allows the restoration to be cut back, and layers of porcelain added in the incisal edge to create lobes of dentin and incisal translucency. Some of this can be accomplished without a cutback and using stains, but my experience is it limits the technician in what they can accomplish. Very often when I am restoring anterior teeth the existing esthetics is not ideal, the patient has lost incisal translucency, or wants the final result to have characteristics that their natural teeth do not. If you are wondering about this feature, send your technician pre-operative photos, along with a description of what you see as the final esthetic result. Once they have all of this information they can let you know what the need to make create what you are asking. I have even had my technician prepare a model of the teeth to show me the minimal prep parameters they need.