Matsushita Kazuhiro, Inoue Nobuo, Totsuka Yasunori
Department of Oral and Maxillofacial Surgery, Division of Oral Pathobiological Science, Graduate School of Dental Medicine, Hokkaido University, Kita-ku, Sapporo, Hokkaido, Japan.
Oral Maxillofac Surg. 2011 Sep;15(3):139-46. doi: 10.1007/s10006-011-0266-9. Epub 2011 Mar 4.
Relapse caused by clockwise (opening) rotation of the distal segment (dentate segment) in the sagittal plane is one of the postoperative complications sometimes seen after sagittal split ramus osteotomy. The force involved in this movement is primarily exerted by the masticatory and suprahyoid muscles. For postoperative stability, we have used two plates on each side: a straight plate placed over the vertical osteotomy line at the buccal surface of the first molar and an L-shaped plate placed at the distal or lateral part of the last molar over the osteotomy line, just crossing over the upper-lateral edge of the buccal shelf, to prevent the tail of the distal segment from moving upward. Although postoperative stability was clinically fine, experimental evaluations have not previously been performed. To clarify the effects of the L-shaped plate, we performed an experimental study using a bioabsorbable plate system.
A custom-fabricated jig was made to simulate rotational movement of the segments. Two segments made from polyoxymethylene resin were fixed with a four-hole straight or four-hole box poly-L-lactate bioabsorbable plate. An L-shaped plated was then added for rigidity, and mechanical testing was performed.
The yield load exerted by the four-hole straight plate alone was 152.4 ± 11.0 N. This increased significantly to 273.8 ± 43.7 N with addition of an L-shaped plate (P < 0.05).
Addition of an L-shaped plate significant improves the rigidity of four-hole straight plate fixation in a bioabsorbable plate system.
矢状劈开下颌支截骨术后有时会出现的一种术后并发症是远心段（齿状段）在矢状面内顺时针（开口）旋转导致的复发。参与该运动的力主要由咀嚼肌和舌骨上肌群施加。为了实现术后稳定，我们在每侧使用了两块钢板：一块直板放置在第一磨牙颊侧垂直截骨线的上方，一块L形钢板放置在最后一颗磨牙远心端或外侧截骨线的上方，刚好越过颊侧骨板的上外侧边缘，以防止远心段的尾部向上移动。尽管临床观察到术后稳定性良好，但此前尚未进行实验评估。为了阐明L形钢板的作用，我们使用生物可吸收钢板系统进行了一项实验研究。
制作了一个定制夹具来模拟各段的旋转运动。用一块四孔直板或四孔盒状聚-L-乳酸生物可吸收钢板固定由聚甲醛树脂制成的两段。然后添加一块L形钢板以增强刚性，并进行力学测试。
单独使用四孔直板时的屈服载荷为152.4±11.0 N。添加L形钢板后，该载荷显著增加至273.8±43.7 N（P<0.05）。
在生物可吸收钢板系统中添加L形钢板可显著提高四孔直板固定的刚性。
