Most dentists have a set of models on their desk that they don’t know what to do with. Usually these models are of a patient with significant wear, a deep overbite, an open bite, or multiple missing teeth and any number of other variations. Yet it is interesting to compare the models you don’t know what to do with, to those you do.
If your patient has occlusal issues, like a deep overbite or an anterior open bite, the teeth are definitely in the wrong place. Models don’t tell you where teeth belong; they only tell you the relationship of the teeth to each other. What we need in order to position teeth are photographs of the face.
The face tells us where the maxillary teeth belong, but not the occlusion. The occlusion can only be evaluated and created after maxillary tooth position is first determined. That means you have to evaluate maxillary tooth position to get the answers on how to manage the patient whose models are on your desk.
Evaluating maxillary tooth position
The good news is, you already know how to do it. Every dental student learned how when they did their first denture. You didn’t think about the occlusion to start. You determined where to place the teeth.
In fact, the only teeth we have a reference for in an edentulous mouth are the maxillary central incisors. Once they are positioned, along with the lips and smile, they become the reference for how to position the remaining maxillary teeth to create a pleasing arch form and occlusal plane.
The centrals also become one of the references for how to position the mandibular incisors, which then sets the vertical dimension of occlusion. The process of how to set up a denture has been around for decades.
In 1986, I started using the same protocol to treatment plan patients with teeth. Instead of starting with occlusal relationships, which was how most treatment planning protocols for complex problems had always been planned, it made so much more sense to start with correcting maxillary tooth position prior to starting any occlusal development. I named the process “Facially Generated Treatment Planning.” We still use this term today for the first workshop in our curriculum.
The process is really quite simple. We use the face to position the maxillary central incisors, and the smile to position the remaining maxillary teeth. This process is then followed by altering gingival levels to correct tooth length and then proceeding to develop the occlusion, starting with the mandibular incisors. This then develops the vertical dimension and finally, the mandibular posterior teeth.
Using maxillary central incisor position in severe wear cases
The purpose of this article is to set the stage for why we must evaluate and correct the central position first, before we can move on to the other elements of the treatment plan. To do so, I’ll discuss two example patients, both with severe tooth wear. Each has central incisors less than 6 mm in length. The question is, how should they be lengthened?
Classically, if we worked from models, the temptation may be to open the vertical dimension on each patient to create space for a normal 10.5 mm central, but there is a problem. When tooth wear and occlusal contact are maintained, one of two things has to have happened: the vertical dimension closed, or the teeth erupted to maintain contact, or a little of both. Models won’t tell us whether the teeth erupted or the vertical dimension was lost; we need to see the teeth in the face.
The patient in figures 1 and 2 is 36 years old. She has massive anterior wear but minimal posterior wear.
If the posterior teeth have minimal wear, it is highly unlikely she has lost any vertical dimension, which means her anterior teeth have probably erupted as they have worn. If they have erupted, they would have brought bone and gingiva with them, and most likely her smile will show short anterior teeth with a significant amount of gingiva visible as well.
In fact, the photos show that to be the case; her incisal edge position is fine, and it is the gingiva that needs to be raised 4.5 mm to correct the short tooth form, either through orthodontic intrusion or crown lengthening.
The patient in figures 3 and 4 is in his 60s. He also has severe anterior wear, but he also had severe posterior wear that his dentist treated by doing crowns on individual posterior teeth as they wore or broke.
The worn posterior teeth mean he may have lost vertical dimension, but doesn’t guarantee it, as the posterior teeth may have erupted as they wore, maintaining his vertical.
His face helps tell the story; at rest, he doesn’t show any anterior teeth, and in his biggest smile, he can barely show the edges of the teeth. After evaluation, his treatment plan was to not alter his gingiva at all, but rather to add 7 mm to his central incisors and open the vertical dimension.
(Click this link for more dentistry articles by Dr. Frank Spear.)