Jaw length in absolute value, has a relative importance. A same length jaw in a retruded or protruded profile makes a whole difference. So the best is to measure facial proportions and indexes, to have a relative idea of the relative length of the jaw compare to other facial structures, such as the nose, cheek bones, and paranasal areas. Also, we have to analyse it in relation with the ocllusal plane. Is it in the context of a long face with high mandibular plane angle, or short face? Different cephalometric analysis might help to measure that, but at the end, the single most important analysis is the clinical facial analysis.
