In my previous article in this series, I discussed facial profile, and how evaluating it using Glabella, Subnasale, and Pogonion could help assess whether orthognathic surgery would be an appropriate consideration for correcting occlusal and esthetic problems.
In this article I will look at profile again, but from a different perspective, what I call facial balance. The concept of having a specific relationship between the nose, lips and chin from a profile perspective goes back to the 1950s and the work of the orthodontist Dr. Robert Ricketts. Dr. Ricketts was concerned that in the name of occlusion and alignment, orthodontists were actually making the esthetic appearance of some patients worse by not paying attention to what he called the “Esthetic Plane” or “E” plane.
Fundamentally the “E” plane is simply a line drawn from the tip of the nose to the tip of the chin. His key assessment was to look at how the upper and lower lip related to that line. Dr. Ricketts felt that to have a pleasing facial profile, in the average Caucasian face, the lower lip would be 2 mm behind the line, and the upper lip 4 mm behind the line, with variations being normal for patients of different ethnic backgrounds, but with some commonalities applying to all patients. Those commonalities would be that the closer to the “E” plane the lips are, in some cases even being anterior to the plane, the lips and teeth will dominate the smile with the nose and chin appearing weak. And the farther behind the plane the lips are, the more likely the nose and chin will dominate the smile. The key was to evaluate the “E” plane relationship prior to performing orthodontic treatment.
An example of how the “E” plane would be used is a patient with significant crowding of both upper and lower arches. The clinician must decide whether to consider extracting teeth, such as first premolars or expanding the arch. If the lips in profile were on or in front of the “E” plane, the decision would be extraction and anterior retraction, improving the lip to “E” plane relationship. If on the other hand the lower lip is 6 mm behind the “E” plane, the decision would be to align the teeth and expand the arch, moving the anterior teeth and lips to a more anterior and prominent position.
For the non-orthodontist the “E” plane assessment is also valuable. In general the closer the lips are to the “E” plane the more dominate the teeth and lips will appear, the farther behind the “E” plane the lips are, the more dominate the nose and chin appear.
As a rule I always consider these relationships in looking at the size and shape of the anterior teeth in any restoration. Using the central incisor as a reference, we know that the range of normal unworn central incisor lengths in humans is from 9-12 mm, with 10.5 mm being the average. I may alter the size I choose for a patient anywhere from 10-12 mm based upon my “E” plane and some additional findings. If the patient's profile appears very convex, the lips on or anterior to the “E” plane, you must be careful about not making anterior teeth too large or too white, as the teeth in this profile will already dominate the smile.
For concave profiles, where the lips are well behind the “E” plane, it may in fact be beneficial to increase the anterior tooth size both in length and facial prominence with your restoration. In addition these patients often benefit from a slightly lighter final shade, again to provide better balance with the strong nose and chin.
The “E” plane isn’t the only factor affecting your choice of final tooth size and shade. In future articles we’ll be touching on the impact of lip fullness and mobility as additional elements of our assessment that will impact how we restore anterior teeth with regards to size and shade.
(Click this link for more dental articles by Dr. Frank Spear.)