Anterior projection of the maxillomandibular soft tissue complex after surgical correction of maxillary hypoplasia: a Scottish perspective

After orthognathic surgery the forehead remains unchanged. To produce facial harmony, the planned projection of the maxillomandibular complex must be placed in the correct relations to the unchanged position of the forehead. We have compared the anterior soft tissue projection of the maxillomandibular complex relative to the forehead after Le Fort I advancement surgery for correction of maxillary hypoplasia with that of a local reference group chosen by lay assessors. We retrospectively studied 32 patients (16 men and 16 women) all of whom had previously been treated by Le Fort I maxillary advancement. In addition a panel of 8 lay assessors selected a reference group of 24 women and 16 men. Standard profile photographs were taken, and horizontal measurements made, of several landmarks from a true vertical line (TV) passing through glabella. Together with facial harmony values these were compared between the groups. The orthognathic group had significantly more anterior mandibular projection relative to the forehead than the female reference group (p = 0.03). As a result half of the horizontal harmony values were smaller in the orthognathic group. For men the position of the mandible, particularly the chin, was acceptable even though it was positioned more anteriorly. We have provided values for maxillomandibular projection derived from lay assessors and identified areas where differences from those of a reference group were detected. The projection of the mid and lower face of the local reference group to the forehead should guide preoperative planning.