How to Approach Problems of Tooth Proportion
In a previous article, I covered the four possible causes for lack of tooth display in patients and how to properly treat them. Continuing on with that subject, I’d like to introduce an 18-year-old patient that presented for treatment because his teeth were too small and he felt that they made him look like an old man. After evaluating him for the four causes of minimal tooth display, I realized an immediate problem that needed to be addressed was tooth proportion. In order to address tooth proportion and ensure an esthetic end result, the proper sequencing of the steps needs to be followed.
Step 1: Determine the correct incisal edge position. Just like any procedure, the first thing I looked at was where the incisal edge should be. To determine this I look at their full smile, lips at rest, and his posterior plane of occlusion to check for wear. I came to the conclusion that I wanted to lengthen his anterior teeth about 1.5 – 2mm to maintain proper esthetics.
Step 2: Determine the correct gingival margin location. I then determined where I wanted the tooth to end up visually in the gingival area; I liked the position of his canines and used those as a reference point. Having a reference point makes it much easier to communicate the treatment plan to the patient (as well as other specialists involved in treating the case). You want to make sure that their expectations match what you’re saying about the treatment plan before you begin the process.
Step 3: Determine the appropriate width given the crown length and gingival margin location. In this step, you will always want to start with the central incisors. Since I know where I want my incisal edge and gingival margins located, I shaped the teeth just by using the midline. If I kept the same width he already had and only increased the length, I would have ended up with a width/length ratio of 69 percent. This would be a very narrow tooth form and in my opinion, not very esthetic. By widening the teeth as well lengthening them, we could better manage the proportion, keeping it somewhere around 80 percent. Once the centrals are taken care of, move onto the lateral and repeat the same steps.
Along with increasing the anterior tooth dimensions, another treatment goal was to correct the retroclined position of his anteriors. To address both of the treatment goals required a combined orthodontic and restorative approach. In this case, the orthodontic treatment was performed by Dr. Vince Kokich Jr., who was able to upright the teeth as well as provide the proper alignment while creating excess interproximal space (the amount and position of the spacing was previously determined during the treatment planning process).
This supplied me with enough room to bond composite to the maxillary anteriors to create the ideal width given the projected proportion. After bonding the composite, the brackets were replaced and the remaining spaces closed.
This same thought process was applied to the lower anteriors: open excess space orthodontically, bond the teeth with composite to give the proper proportion, then replace the brackets and close any remaining space.
Following orthodontic treatment the proper retention time needs to be allowed prior to beginning definitive veneer preparation. I typically wait three to four months before prepping the patient for definitive veneers to ensure that we don’t get any movement after the teeth are prepped.
You can imagine that even a very small amount of movement of the teeth after they have been prepped and provisionalized (which can often occur, as the veneer provisionals do not provide a very stable form of retention by themselves), can be disastrous given that the veneer preparation depths are only around 0.3 – 0.5 mm.
The definitive restorations consisted of veneers from canine to canine on the maxilla and mandible. The interdisciplinary treatment using orthodontics allowed us to create a more pleasing tooth proportion that ultimately improved the esthetic outcome as well as the patient’s self esteem.