Recently, a young patient who has just returned home after a few years of studying overseas came to consult me on corrective jaw surgery. She completed a course of orthodontic treatment while she was overseas and was told by the dentist that her jaw is not in the correct position and that he would need surgery and that's why she came to see me. On examination, she has a disproportionately shorter lower jaw compared with the upper, with the upper teeth completely overlapping the lower teeth. However, the orthodontic work has aligned the teeth very nicely. While the back teeth were also biting nicely together, the front teeth were not touching due to the much shorter lower jaw. This then, poses a challenge to the surgery.
Orthodontics and corrective jaw surgery often go hand in hand. You can't change the position of one jaw relative to the other without affecting the way the teeth come together. This is why orthodontics is essential to orthognathic surgery. Very often, patients are afraid of surgery and would want to try out a non-surgical option such as orthodontics to get their teeth aligned and their bite corrected. However, when the orthodontic treatment is completed and they don't get the results that they are looking for, it is not just a simple matter of proceeding on with surgery.
Orthodontics in preparation for orthognathic surgery is very different from orthodontic treatment by itself. In a patient with a skeletal jaw discrepancy, the teeth compensate naturally for the discrepancy. For example, in a patient will a long lower jaw, the front teeth in the lower jaw tilt backwards in an attempt to maintain contact with the upper front teeth as the growth carries the teeth further and further away from the opposing teeth. Surgical orthodontics is needed to neutralize this compensation, by pushing the lower front teeth outwards, just like in a patient with no skeletal discrepancy. In short, surgical orthodontics aligns the teeth into an ideal arrangement within each jaw, without getting the teeth to bite together properly. With the teeth correctly positioned, jaw surgery is done to shift the jaw into the positioned that will achieve the facial aesthetics desired by the patient as well as getting the teeth to come together in a proper way.
While most patients seek corrective jaw surgery to achieve a change in facial appearance, the extent to which the jaws can be repositioned is also limited by the position of the teeth. Sometimes, moving the jaw bones to a position that gives the desired facial appearance may cause the teeth to bite in an unstable position. In such situations, the surgical plan must be altered to enable a proper bite to be established as well.
For this patient who has already completed her orthodontic work, doing surgery now will require her to undergo orthodontics all over again. This is because the orthodontics that she did was not in preparation for surgery but was an end in itself. The teeth were already aligned and straight and any re-positioning of the jaw will disturb the bite. With our currently understanding of jaw surgery and braces, we can proceed with the surgery first, followed by orthodontics to align the teeth within the jaws in their new position.
This surgery-first approach is gaining popularity against the traditional method of do one year of pre-surgical orthodontics to prepare the teeth before surgery. One of the main advantages of doing surgery first is that the orthodontic treatment usually can proceed faster as the jaw bases are in the correct position already. However, this does require accurate prediction planning of the future position of the teeth so as to position the jaws correctly.