Postoperative maxillary stability after Le Fort I osteotomy using a u-HA/PLLA system: three-dimensional analysis by surface superimposition based on virtual Le Fort I osteotomy

The postoperative stability achieved with Le Fort I osteotomy (LFI) using bioabsorbable systems remains controversial. A new method – multipoint measurement method – was devised for detailed three-dimensional examination of postoperative stability following LFI, and the stability after LFI when using SuperFIXSORB-MX made of u-HA/PLLA was investigated. Thirty-one patients who underwent LFI using SuperFIXSORB-MX were evaluated retrospectively. The patients were divided into four malocclusion types: open bite, mandibular retrognathia, mandibular protrusion, and facial asymmetry. Seven maxillary reference points were measured three-dimensionally using computed tomography scans obtained preoperatively (T0), 4 days post-surgery (T1), and 1 year post-surgery (T2). Surgical changes (T1–T0) and the postoperative discrepancy (T2–T1) of the maxilla were analysed to evaluate postoperative stability by surface superimposition of the virtual LFI segments. Postoperative discrepancy was the largest for the facial asymmetry type, ranging from 0.75 ± 0.45 mm to 0.98 ± 0.52 mm in three-dimensional distance (minimum to maximum mean ± standard deviation values for the individual reference points). The relapse at U1 was 16% in the transverse axis, and the anterior nasal spine moved further upward by 17% of the amount of movement of the maxilla. Fixation with SuperFIXSORB-MX was considered to be within clinically acceptable limits.