The Science of Dental Esthetics
3.15.16 in General
What dictates beauty? Some have said-“the eye of the beholder.” But when creating a smile in dentistry, there are actually some rules to follow. Allowing for differences in every patient, and each patient’s desires, and always staying within the bounds of good function, let’s talk about the science that a dentist must use to beautify a smile. There are only a few areas that we need to address, yet multiple intricate nuances within these areas that will determine whether a smile is beautiful, natural and very functional.
It is said, by anthropologists, that the smile is the first or second detail observed when we first see someone. That can influence us for a long time. So, what details do we observe? (Maybe without even knowing we are observing them). Let’s assume we are dealing with a complete compliment of teeth, first of all.
Are those teeth the right size for the face? Are they too long or too wide? The average proportion of length to width of the upper 2 central incisors is roughly 80%. That means about 8mm wide for a 10mm long incisor, from the edge of the gum to the incisal edge. Obviously everyone’s teeth are different, but the ratio of width to length should be about 80 %. Then there is the question of where in space are the edges of these teeth? The edges of the 2 upper central incisors should fall inside of both lips at rest. The edge should rest just against the inside of the lower lip, and on pronunciation of a quiet “F” or “V” sound, the edges should just touch on the wet/dry border of the lower lip. Moving posteriorly from the center of the mouth, the next 2 teeth (the lateral incisors), should have an edge either at the same level as the central incisors, or up to 1 mm shorter. Moving back yet one more tooth, the tip of the cuspids should be at the same level as the central incisors.
The vertical inclinations of the teeth on each side of the face are parallel, and divergent to a perpendicular line dividing the face. The little triangular notches formed by the edges of the teeth where they touch the tooth next to them are called embrasures. Embrasures should be smallest, front and center, and get larger with each tooth that we move toward the back of the mouth. Also, there is a point where each tooth should touch the tooth next to it. This contact point is nearest to the incisal edge of the front, center tooth. As we move backward in the mouth, the contact point gets closer to the gum.
The incisal edges of the teeth are called the occlusal plane, and should be perpendicular to a vertical line dividing the face in two. This occlusal plane often parallels a plane formed by the pupils of the eyes, though not always.
As we view the overall smile, especially of the upper teeth, there are distinct “proportions of one tooth to the next which determine esthetics. These are called the golden proportions of tooth esthetics. The general rule is this:
When viewing the upper anterior teeth looking straight on, if we use the lateral incisors as a value of 1, the central incisors have a width with a value of 1.6, and the canines have a width of the 1/3 of the tooth viewed of .6.
The heights of the edges of the gum are another factor creating esthetics. The ideal levels of these edges create a picture where the level of gum at the central incisors is at the same level as above the canines. The lateral incisor gum levels should fall either at the same level or 1 mm lower than the other two.
In general, the more tooth, one has showing at rest and with smiling, the more youthful the overall appearance.
As you can see, creating an esthetically pleasing smile is complex, yet within our control when we know some basic principles. One whole other aspect of an esthetic smile is color or shade of the teeth. But that we will save for the next blog. So, stay tuned in and keep smiling. Dr W.