Le Fort III Distraction: Part I. Controlling Position and Vectors of the Midface Segment

Abstract

Direction of movement and resultant change in position of the Le Fort III segment during distraction are directly related to the location and direction of force application. Translation forward, with minimal rotation, was achieved when the force was applied at a location 55 percent above the occlusal plane (between the occlusal plane and the nasion) and in a direction parallel to the maxillary occlusal plane.

Three-dimensional position changes of the midface following Le Fort III advancement in syndromic craniosynostosis

“…In this study, we showed that despite the combination of skeletal and dental anchorage of the fixation threads, unwanted counterclockwise movements still occur. Recent articles have shown that by using more rigid anchorage, improved vector control is possible even when solely dental anchorage is applied (Shetye et al, 2010;Lim et al, 2012). Fearon et al demonstrated a more rigid anchorage between the dental splint with an additional midline superior point of traction at the base of the nasal bone (Fearon, 2005).…”

“…Rold an et al reported better directional control of the segment by using self-cutting screws through the nasal bone and piriform aperture (Rold an et al, 2011). According to Shetye et al, more rigid anchorage between the bar and the dental and/or skeletal anchorage points is preferable (Shetye et al, 2010). In taking into account literature findings with our data, it seems that more rigid anchorage as well as knowledge and understanding of the center of mass and other variables such as age, gender, previous surgery, etc.…”

“…However, in a significant number of cases, counterclockwise movement is observed, which can lead to an unfavorable anterior open bite. Shetye et al have performed a retrospective study in 18 patients with LF external DO to determine the response of the bony LF III segment to variations in vector location and direction (Shetye et al, 2009). In relation to the location and direction of force application, four different movements were observed: anterior translation, clockwise movement, counterclockwise movement, and anterocaudal translation.…”

“…Ideally, an anterior translation of the LF III segment should occur to correct the midface hypoplasia. Unfortunately, various authors report a counterclockwise rotation of the LF III segment, which can cause an anterior open bite and which reduces the advancement of the orbitozygomatico complex (Denny et al, 2003;Fearon, 2005;Nout et al, 2008;Shetye et al, 2009). Additional orthognathic surgery is frequently indicated to correct the anterior open bite (Nout et al, 2011).…”

“…However Rold an et al described a controlled advancement of the LF III segment in 1 SCS patient (Rold an et al, 2011). Shetye et al described the importance of the location and direction of force application and the change of position of the LF III segment in a cephalometric study with 18 SCS patients (Shetye et al, 2009). In the present study, the change in position of the LF III segment, based on analysis of three-dimensional (3D) movements of the LF III segment using pre-and postoperative computed tomography (CT) data of patients with SCS, is reported.…”