Zhang Y K, Shen Z X, Zhang R, Dong L J, Tian Y, Lu L, Yang M L, Yan G Q
Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang 110002, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2025 Jun 9;60(6):635-643. doi: 10.3760/cma.j.cn112144-20241206-00462.
To evaluate the mechanical stability of the bone block after LeFort Ⅰ osteotomy with maxillary advancement using absorbable plates fixed with tenon-and-mortise structures. This study developed three finite element models: one for the maxillary LeFort Ⅰ osteotomy with anterior advancement fixed with absorbable plates (Model 1); another for the maxillary LeFort Ⅰ osteotomy with anterior advancement fixed with absorbable plates assisted by tenon-and-mortise structures (Model 2); and the last one for the maxillary LeFort Ⅰ osteotomy with anterior advancement fixed with titanium plates and screws (Model 3). Simulated occlusal forces were applied on the anterior and posterior teeth in each model. The displacement changes of the nasal-palatine point (NP) and posterior nasal spine point (PNS) in the finite element coordinate system were compared and analyzed. The Mises equivalent stress distributions of the metal and absorbable plates were also examined to assess the mechanical stability of the three finite element models. Clinical data from 45 patients with dentofacial deformities treated from January 2017 to January 2023 at the Stomatology Hospital of China Medical University were collected. The age of the patients was 21±3 years. Among these, 15 patients had absorbable plates for fixation, 15 had absorbable plates assisted by tenon-and-mortise structures, and 15 had titanium plates and screws fixation after maxillary advancement. All patients underwent preoperative (T0), postoperative 3 days (T1), and 6 months (T2) spiral CT scans. The CT data in DICOM format were input into digital software, which was used to calculate the distances from the NP and PNS points to the horizontal plane (HP), right sagittal plane (FZSR), and coronal plane (CP) at T1 and T2. The distances at T1 and T2 were statistically analyzed using the Wilcoxon signed-rank test with SPSS 20.0, and a P value of<0.05 was considered statistically significant. The finite element analysis showed that in the absorbable plate-only fixation group, the maximum displacement of the NP point (mm) under anterior and posterior tooth force conditions were 0.6 and 0.12, respectively, and for the PNS point, the maximum displacements were 0.5 and 0.11. In the tenon-and-mortise-assisted absorbable plate fixation group, the displacement of the NP point was 0.40 and 0.02 mm, and the displacement of the PNS point was 0.5 and 0.015 mm. In the titanium plate-screw fixation group, the NP point displacement was 0.33 and 0.055 mm, and the PNS point displacement was 0.16 and 0.1 mm. The Mises equivalent stress on the absorbable plates with tenon-and-mortise structure was significantly lower than that in the absorbable plate-only fixation group, while the titanium plate experienced the highest Mises equivalent stress. The clinical data analysis showed that in the horizontal direction, the postoperative stability of the three fixation methods was similar. However, in the vertical and anterior-posterior directions, the absorbable plate-only fixation group showed significant differences in the distances of PNS-HP, PNS-CP, and NP-CP between T1 and T2 (=0.018, =0.009, =0.017), suggesting significant postoperative bone displacement. In contrast, the tenon-and-mortise-assisted absorbable plate fixation group and the titanium plate-screw fixation group showed no significant differences in displacement during surgery and postoperatively(all >0.05), demonstrating higher stability. The tenon-and-mortise-assisted absorbable plate fixation provides comparable stability to titanium plate fixation in clinical results, and it is more stable than absorbable plate-only fixation. In the mechanical study, when force was applied on the anterior teeth, the stability of the tenon-and-mortise-assisted absorbable plate fixation was slightly less than that of titanium plate fixation, but when posterior teeth were used, its stability exceeded both titanium plate fixation and absorbable plate-only fixation. The tenon-and-mortise-assisted absorbable plate fixation serves as an effective alternative to titanium plate fixation after LeFort Ⅰ osteotomy.
为评估采用榫卯结构固定的可吸收接骨板进行上颌前徙的LeFort Ⅰ型截骨术后骨块的机械稳定性。本研究建立了三个有限元模型：一个是采用可吸收接骨板固定进行上颌前徙的LeFort Ⅰ型截骨术模型（模型1）；另一个是采用榫卯结构辅助的可吸收接骨板固定进行上颌前徙的LeFort Ⅰ型截骨术模型（模型2）；最后一个是采用钛板和螺钉固定进行上颌前徙的LeFort Ⅰ型截骨术模型（模型3）。在每个模型的前牙和后牙上施加模拟咬合力。比较并分析有限元坐标系中鼻腭点（NP）和后鼻棘点（PNS）的位移变化。还检查了金属接骨板和可吸收接骨板的米塞斯等效应力分布，以评估三个有限元模型的机械稳定性。收集了2017年1月至2023年1月在中国医科大学口腔医院接受治疗的45例牙颌面畸形患者的临床资料。患者年龄为21±3岁。其中，15例患者采用可吸收接骨板固定，15例采用榫卯结构辅助的可吸收接骨板固定，15例在上颌前徙后采用钛板和螺钉固定。所有患者均接受术前（T0）、术后3天（T1）和6个月（T2）的螺旋CT扫描。将DICOM格式的CT数据输入数字软件，用于计算T1和T2时NP点和PNS点到水平面（HP）、右矢状面（FZSR）和冠状面（CP）的距离。使用SPSS 20.0软件的Wilcoxon符号秩检验对T1和T2时的距离进行统计学分析，P值<0.05被认为具有统计学意义。有限元分析表明，在仅使用可吸收接骨板固定组中，在前牙和后牙受力情况下，NP点的最大位移（mm）分别为0.6和0.12，PNS点的最大位移分别为0.5和0.11。在榫卯结构辅助的可吸收接骨板固定组中，NP点的位移为0.40和0.02 mm，PNS点的位移为0.5和0.015 mm。在钛板螺钉固定组中，NP点的位移为0.33和0.055 mm，PNS点的位移为0.16和0.1 mm。榫卯结构的可吸收接骨板上的米塞斯等效应力明显低于仅使用可吸收接骨板固定组中的应力，而钛板的米塞斯等效应力最高。临床数据分析表明，在水平方向上，三种固定方法术后的稳定性相似。然而，在垂直和前后方向上，仅使用可吸收接骨板固定组在T1和T2之间的PNS-HP、PNS-CP和NP-CP距离上存在显著差异（分别为=0.018、=0.009、=0.017），表明术后骨位移明显。相比之下，榫卯结构辅助的可吸收接骨板固定组和钛板螺钉固定组在手术中和术后的位移均无显著差异（均>0.05），显示出更高的稳定性。榫卯结构辅助的可吸收接骨板固定在临床结果上提供了与钛板固定相当的稳定性，并且比仅使用可吸收接骨板固定更稳定。在力学研究中，当前牙受力时，榫卯结构辅助的可吸收接骨板固定的稳定性略低于钛板固定，但当后牙受力时，其稳定性超过了钛板固定和仅使用可吸收接骨板固定。榫卯结构辅助的可吸收接骨板固定是LeFort Ⅰ型截骨术后钛板固定的有效替代方法。
