Postoperative changes in the position of anterior nasal spine and A-point after Le Fort I osteotomy

PurposeThis study focused on the postoperative changes in the position of the anterior nasal spine (ANS) and A-point after Le Fort I osteotomy (LFI).Materials and methodsThirty-two patients underwent LFI, and cephalograms and computed tomography (CT) images were taken to assess skeletal changes immediately (T1) and 1 year (T2) postoperatively. In each cephalogram and 3D-CT analysis, changes in the coordinates (X, Y, Z) of the A-point, ANS, and PNS were evaluated between the T1 and T2 periods.Results3D-CT analyses demonstrated a significant difference in the identification of the Y-coordinate of ANS: 89.2 ± 4.1 mm in T1 and 87.0 ± 3.6 mm in T2 (P = 0.04). The median of Y-coordinates of ANS on 3D-CT was 2.0 mm backward (range 0.44–7.3 mm). No significant differences were identified in SNA on conventional cephalometric analysis. Both 3D-CT and conventional cephalometric analyses showed that no significant differences were identified in PNS between the T1 and T2 periods.ConclusionANS tends to move backward after LFI, while the A-point tended to simultaneously move backward and downward. 3D-CT superimposition is more precise than conventional cephalograms in consideration of changes in the positions of ANS and the A-point for the evaluation of surgical stability after LFI. It may be possible to improve the reliability of 3D-CT and cephalometric analyses for determining maxillary bone stability by considering that ANS and the A-point tend to move backward and PNS is a more reliable reference point than ANS and the A-point after LFI.