From the Graduate Institute of Craniofacial and Dental Science, Chang Gung University; and the Department of Plastic and Reconstructive Surgery, Department of Craniofacial Orthodontics, and Craniofacial Research Center, Chang Gung Memorial Hospital.
Plast Reconstr Surg. 2021 Feb 1;147(2):421-431. doi: 10.1097/PRS.0000000000007536.
The aim of this study was to investigate the accuracy of bimaxillary orthognathic surgery regarding different sequencing (maxilla-first or mandible-first surgery) and different thicknesses of intermediate splints.
This retrospective cohort study evaluated the accuracy of postoperative outcome in accordance with virtual planning in 57 patients requiring bimaxillary osteotomies with different operation sequence: maxilla-first (n = 31) or mandible-first (n = 26) surgery. The effect of different splint thicknesses (i.e., thick, n = 22; and thin, n = 35) was also evaluated. The 1-week postoperative cone-beam computed tomographic craniofacial images were superimposed onto preoperative simulated images to measure the discrepancy of the three-dimensional cephalometric landmarks.
Neither sequencing approach differed in overall accuracy (1-week postoperative to preoperative simulated image discrepancy): maxilla-first, 1.69 ± 0.53 mm; versus mandible-first, 1.44 ± 0.52 mm. In detailed comparison, mandible-first surgery resulted in more accuracy in the vertical dimension. Thick intermediate splints provided better control (less error) of upper central incisors in the sagittal position (thick splint, 1.38 ± 1.17 mm; thin splint, 2.13 ± 1.38 mm). However, overall accuracy was not affected by splint thickness. Conditions affecting sequencing predilection included skeletal class III with vertical excess, maxillary down-grafting, counterclockwise rotation of the maxillomandibular complex, and simulated mandibular opening for splint fabrication clearance.
Despite both means of sequencing being performed similarly, mandible-first surgery was more precise in the vertical dimension. Thick intermediate splints seemed to yield better control of central incisors in the sagittal position. However, under appropriate selection of intermediate splints to maintain interim condylar position, splint thickness has no effect on overall accuracy.
CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.
本研究旨在探讨双颌正颌手术在不同手术顺序（上颌先行或下颌先行）和不同中间夹板厚度下的准确性。
本回顾性队列研究根据虚拟规划评估了 57 例需要双颌截骨术的患者的术后结果准确性，这些患者的手术顺序不同：上颌先行（n=31）或下颌先行（n=26）手术。还评估了不同夹板厚度（即厚夹板，n=22；和薄夹板，n=35）的效果。将术后 1 周的锥形束 CT 颅面图像与术前模拟图像叠加，以测量三维头影测量标志的差异。
两种手术顺序在整体准确性方面没有差异（术后 1 周与术前模拟图像差异）：上颌先行，1.69±0.53mm；与下颌先行，1.44±0.52mm。在详细比较中，下颌先行手术在垂直方向上更准确。厚中间夹板在矢状位上对中切牙的控制（误差较小）更好（厚夹板，1.38±1.17mm；薄夹板，2.13±1.38mm）。然而，夹板厚度并不影响整体准确性。影响手术顺序倾向的因素包括骨骼 III 类伴垂直过度、上颌骨向下移植、上颌下颌复合体逆时针旋转以及为夹板制造间隙模拟下颌张开。
尽管两种手术顺序的效果相似，但下颌先行手术在垂直方向上更精确。厚中间夹板似乎在矢状位上对中切牙的控制更好。然而，在适当选择中间夹板以维持中间髁突位置的情况下，夹板厚度对整体准确性没有影响。
临床问题/证据水平：治疗性，III 级。
