Three Dimensional Study on the Postoperative Stability after Advancement of Maxilla Using Le Fort I Osteotomy

Le Fort I 골절단술을 이용한 상악골 전진 후 안정성에 관한 3차원적 연구

Purpose: This study evaluated postoperative maxillary stabilities in patients with skeletal Class III malocclusion who were taken both maxillary advancement surgery and mandibular retrusive surgery, using Le Fort I osteotomy, through three-dimensional computed tomography. Methods: We selected 14 patients who were taken postoperative three-dimensional computerized tomography at the time before surgery, immediately after surgery, six months after surgery among the patients undergone both maxillary advancement surgery using Le Fort I osteotomy and mandibular retrusive surgery using bilateral sagittal split ramus osteotomy. We measured and compared the vertical distance of A-point and posterior nasal spine (PNS), the horizontal distance of A-point and PNS in transverse plane and coronal plane of the three-dimensional reconstructed images, respectively. Results: In transverse plane, the distance difference between immediately after surgery ($S_1$) and immediately before surgery ($S_0$) of A-point was $-0.04{\pm}1.80$ mm, $S_2$ and $S_0$ was $-0.15{\pm}1.69$ mm, and between $S_1$ and $S_2$ was $0.11{\pm}0.58$ mm. There were no significant differences between these data (P>0.05). In transverse plane, the distance between $S_1-S_0$ of PNS was $-3.87{\pm}2.37$ mm, $S_2-S_0$ of PNS was $-3.79{\pm}2.39$ mm, and $S_1-S_2$ of PNS was $-0.08{\pm}0.18$ mm. There were significant differences between these data (P<0.05). In coronal plane, the distance between $S_1-S_0$ of A-point was $3.99{\pm}0.86$ mm, $S_2-S_0$ was $3.57{\pm}1.09$ mm, and $S_1-S_2$ was $0.42{\pm}0.42$ mm. There were significant differences between these data (P<0.05). In coronal plane, the distance between $S_1-S_0$ of PNS was $3.82{\pm}0.96$ mm, $S_2-S_0$ was $3.43{\pm}0.91$ mm, and $S_1S_2$ was $0.39{\pm}0.49$ mm. There were significant differences between these data (P<0.05). In transverse plane, it was estimated that PNS has no statistical postoperative stability in the same direction. In coronal plane, it was estimated that both A-point and PNS had no statistical postoperative stability (P<0.05). Conclusion: Clinically, the operation plan needs to take into account of the maxillary relapse.