In yesterday’s post I looked at some of the esthetic decision points in anterior tooth form and incisal embrasures. The consensus is that esthetic design is about what we and our patient find pleasing, not about specific rules related to embrasure form. On the other hand incisal embrasures serve a very critical functional role. When we violate this functional space in order to alter esthetics the consequences can be broken composite or porcelain. 
Functionally incisal embrasures allow the lower teeth to clear in excursive movements without being trapped. Let’s look specifically at the distal incisal embrasure of the maxillary lateral incisor. If listening to dentists serves as any form of data collection this corner is one of the areas that when restored breaks frequently. In a class one occlusion the cusp tip of the lower canine passes through this embrasure during a lateral excursion. I find more and more of my patients want me to close this space to meet their esthetic desires. Closing this space may be possible, but necessitate altering the shape of the lower canine cusp tip and evaluating how this change affects the patient’s guidance. In these cases having a set of models mounted so I can evaluate the occlusion allows me to answer this question for my patient.
It is critical to mark and adjust all of the lateral and radiolateral excursive movements, making certain that we have distributed the forces and not left any place the patient gets trapped and can apply force. Form and function are intertwined, so whether you approach it form first or function first success depends on synergy between the two.
Well said Dr. Brady ! So many technicians & dentists get hung up on “esthetics” and forget function rules! They should work in harmony!
I couldn’t agree more with Mr. DeVreugd’s comment. It was his anterior waxing course that really cemented these concepts for me especially with respect to the maxillary lateral incisors.