The underlying skeleton is the fundamental determinant of facial appearance. Because the teeth are attached to the upper and lower jaws, the position of these bones determines not only how we look, but also how our teeth fit.
Malocclusion refers to the less than ideal fit between the teeth when one bites. If left untreated, and depending on its severity, malocclusion can lead to the premature wear of the teeth and malfunction in the hinge of the jaws, resulting in pain and disability.
A slight malocclusion, wherein teeth are slightly imperfect, can be corrected with the gradual movement of teeth through braces. When the malocclusion is more severe, its correction can only be accomplished by moving the jaw bones through a procedure called orthognathic surgery. This surgery is usually performed in late adolescence or early adulthood, after the facial skeleton is mature and it is clear that only surgery will treat the problem.
Bristol Palin had an underdeveloped lower jaw with a resultant malocclusion and overbite that could not be treated with braces. The type of surgery she underwent is illustrated in figure 1. The first image shows a retracted lower jaw and, as a result, teeth that don't fit. The dotted lines show where the surgeon cuts the bones and advances them forward. This allows the teeth to fit. Expanding the facial skeleton also stretches the overlying skin envelope and usually makes the face more attractive. Most often, the surgeon will also cut the chin point and advance it as well. Taken together, this operation not only solves the malocclusion problem, but also adds a cosmetic benefit.
Figure 1 As is true for most patients requiring jaw surgery, when properly planned and executed, orthognathic surgery should have both a functional and an aesthetic benefit.
In certain media circles, Bristol and even her mother were chastised for Bristol's having this appearance improving surgery at a young age. But if surgery can correct a functional problem and improve appearance at the same time... why not?