下颌矢状劈开截骨术不同固定方法的稳定性研究
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摘要
目的：建立下颌骨三维力学模型，对下颌骨矢状劈开截骨术不同固定方法进行力学分析。探讨不同固定方法的功能稳定性。为临床进一步改进术式提供科学依据。
方法：1、选用9具成年男性正常下颌骨，随机将下颌骨标本分三组，分别对三组标本用长裂钻和厚骨凿行下颌矢状劈开截骨术。2、固定（1）第1组以两钉固定，两颗螺钉沿下颌骨升支前缘下牙槽神经管上旋入。（2）第2组以三钉固定，三颗螺钉的位置为两颗沿下颌升支前缘下牙槽神经管上，第三颗位于下颌下缘下牙槽神经管下。（3）第三组于Champy等人提出的张力曲线上以四孔钛板固定。3、将固定好的下颌骨放置于加力试架的人工关节窝，调节下颌平面使之位于水平面（为使每次初始状态相同，采用水平仪进行定位）。在颏部放置观测丝，以观测远心端骨的位移。用一根细金属丝固定双侧喙突，金属丝通过试架上方的小滑轮连接，通过金属丝向上的牵引作用模拟下颌升肌群的咀嚼力。对磨牙，双尖牙，尖牙，切牙13个功能咬合点进行加载，方向与咬合平面垂直。每一个功能荷载点连续加载10次。4、将
两台JDX-2型，50毫米读数显微镜（购于长春市第三光学仪器厂，测量范围为50mm，精度为0.01mm）分别置于模型的两侧及后侧，通过读数加载的数值，即可得出髁状突以及远心端左右及前后的非生理性水平位移。取每个点10次加载所得差值的平均值。应用Origin软件分析处理。并且采用SAS6.12版本软件分别对三种不同固定方法固定术后的髁状突及远心端骨段前后及左右水平位移作t检验。
结果：1、下颌矢状劈开截骨术后，在功能负载条件下两骨断面将产生弯矩，扭矩，剪切力。这些生物力将使髁状突和远心端骨段产生不同方向的非生理性位移。2、功能负载条件下，二钉固定组的近、远心端骨段均产生较大位移。相比较三钉固定组和小夹板固定组所产生的非生理性位移要小于二钉固定组。3、三钉固定组和小夹板固定组相比较，三钉固定组在髁状突向后非生理性后移位上小于夹板固定组。而左右水平位移量上基本无差别。对远心端骨段的位移来说，三钉固定组的位移也要小于小夹板固定组。
讨论：本实验目的是为了对下颌骨矢状劈开截骨术不同固定方法进行力学分析。探讨不同固定方法的功能稳定性。从结果可
以看出两钉固定在对抗髁状突和远心端骨段移位的能力上要远不如三钉固定和小夹板固定。多年以来，大多数学者在使用螺钉固定法时一直采用3个螺钉固定下颌升支矢状劈开截骨后的两个骨段．但Souyris等人首先报告了每侧用2个固位螺钉固定的方法，认为效果同样可靠。临床上一直没有每侧两个螺钉固位稳定性方面样本含量较大的研究报告。 本实验的从力学分析的角度得出两钉固定法髁状突以及远心端骨段对抗移位的能力要比三钉固定和小夹板固定差的结论。
从本实验的结果分析，小夹板固定对髁状突和远心端骨段移位的抗力相对三螺钉固定要弱，但临床中小夹板固定的应用也较广泛。这是因为首先由于小夹板的形状可以根据需要而预备，例如根据近心骨段移动后，近、远心骨段间出现的台阶而预备小夹板形成相应台阶。使其紧密贴台于近、远心骨段颊侧面，而不会对两骨段产生压力，从而减小了髁状突在固定后发生旋转和移位，进而使SSRO术后的复发率下降。 而且由于是单层骨皮质固定，降低了下齿槽神经血管束损伤的风险。口内入路也相对比较好操作。
三钉固定与小夹板固定相比，三钉固定比小夹板固定拥有更
好的抵抗髁状突前后移位以及近、远心端骨段扭转的能力，而两种固定方法在对抗髁状突左右移位的能力上无明显差别。根据实验结果可以得出结论：从力学的角度来讲，三钉固定要比小夹板固定的稳定性要好。但是在实际的临床操作中三钉固定却还是不能完全代替小夹板固定，笔者认为有以下几个原因。
1、螺钉的位置：下颌升支矢状劈开截骨术后固位螺钉的位置通常有两种形式，一种是将3个螺钉均置于下齿槽神经管之上；另一种方式是置两个螺钉于下齿槽神经管之上，第3个螺钉置于下齿槽神经管之下。多数学者提倡后一种方式，更多的临床及实验研究都证实，尽可能较远间隔的安置螺钉能够提供更好的稳定性。但在实践中，因为牙根和下齿槽神经管不能伤及；螺钉还必须位于包括了近、远心骨段的骨皮质里，局部的解剖条件往往限制了螺钉的理想位置。
2、螺钉进入的角度和手术入路的问题：最初Spiess1的方法是经面颊皮肤入路SSRO的螺钉坚固内固定。以后有学者提出口内入路行SSRO的螺钉坚固内固定，以避免皮肤疤痕及面神经损伤。但是口内入路存在很多诸多问题，首先是操作复杂，需要特定的器械。而且口内入路的手术视野较小，所以使螺钉不容易垂
直骨面进入。这势必会对固定的稳定性产生影响。Uckan用实验方法对螺钉以90℃和60℃两种角度进入骨面两种方法做比较，发现60℃的稳定性要比90℃进入差。三钉固定口内入路有相当的难度。这就限制了三钉固定法的临床应用。所以三钉固定要想发挥其稳定的优点，就必须进一步改良手术方法和器械。
结论：1、坚固内固定技术在下颌矢状劈开截骨术中比以往的颌间结扎可以获得更稳定的固定效果，大大减少术后的复发。2、两钉固?
Object The purpose of the present study was to creat a three-dimensional model of mandibular, analysis the mechanics property of varies fixed method. Tt will provide scientific evidencen for clinical.
Method 1. 9 adult mandibles were choosed.and divided into three group random .They were operated sagittal split osteotomy. 2.Fixation (1)group 1 was fixed by two screw which was inserted (2)group 2 Three screw were inserted to stabilize the bone (3)group 3 The bone was stabilized by minipalate according to the themry of Champy .3 .The mandibles were placed in artificial joint fossa .of machinie .regulated them to transverse section . A observation wire placed in chin was to observe the displacement of distal of bone. Coracoids were splinted by two metal wires. Traction of wires wre modelling muscles force. Force was loaded on 13 functional point, molar,incicor.10 times every functional point. 4.Two JD-X2
microscopes were put two sides an- d afterwards of model. Displacement of bone could be measured by microscopes .Average value of each functional point was analysised by Origin software . And analysis the displacement of distal and mesial bone with T test.
Results 1. After sagittal split osteotomy, there are some forces between two section of bone such as bening moment , torsion moment,shear force . They would make condylar and distal bone displacement. 2 Under the condition of functional loading ，the dispacement of the mesial and distal bone was larger in two-screw group than those in the other two groups. 3 The forward –backward displacement of condylar was less in the three-screw group than minipalate group .the right-left displacement of condylar was no obvious different. The displacement of distal bone was less in the three-screw group than minipalate group .
Discussion The aim of the study was to analysis mechanics property of varies fixation methed of saggital split
osteotomy. According to the results, the dispacement of the mesial and distal bone was larger in two-screw group than those in the other two groups. Several years most scholar applied three-screw fixation .but Souyris suggested that the effect of two-screw was reliability.we come to conclusion that the stablity of fixation in two-screw group was less than those in the other two groups.
According to result , the stablity of fixation in minipalate group was less than that in three-screw group. But minipalate fixation was still utilized in clinic. The reason is that the shape of minipalate can be adjusted according to requirement . further more , nerves and blood vessel injury can be voided by this mean .and it can be easily operated.
Compare to minipalate group three-screw group posses better stability.but we can not replace minipalate completely by three-screw in clinic. The reason followed.
1. Position of screw after saggital split osteomy , the
position of screw have two type . One is that placed three screws all were above the inferior alveolar nerves .Another is that two screws were above the inferior alveolar nerves. The third was below the inferior alveolar nerves.Most study demonstrated that disperd distribution can provide better stability. But in clinic , dissection limited ideal position of screw.
2.The angle of screw and route of operation Spiessl suggested that operation entrance through cheek .but it can injury cheek . On the other side , entrance by mouth have many problem sunch as that operate was too complicated. Further more operation visual fiend was limited .Uckan contrast the angle of 90℃ a and 60 ℃,he got the result that 90 ℃ was better than 60℃.So as to get better stability ,operation must be improved.
Conclusions 1. Rigid fixation can get better stability than wire fixation.2.Some scholar thought that two-screw can provide enough stability, but we can see that two-screw
was less stability than other two fixation methed. 3.Three-screw processed better stability than minipalate. 4.Minipalate still utilized in clinic commonly because of its conven
方法：1、选用9具成年男性正常下颌骨，随机将下颌骨标本分三组，分别对三组标本用长裂钻和厚骨凿行下颌矢状劈开截骨术。2、固定（1）第1组以两钉固定，两颗螺钉沿下颌骨升支前缘下牙槽神经管上旋入。（2）第2组以三钉固定，三颗螺钉的位置为两颗沿下颌升支前缘下牙槽神经管上，第三颗位于下颌下缘下牙槽神经管下。（3）第三组于Champy等人提出的张力曲线上以四孔钛板固定。3、将固定好的下颌骨放置于加力试架的人工关节窝，调节下颌平面使之位于水平面（为使每次初始状态相同，采用水平仪进行定位）。在颏部放置观测丝，以观测远心端骨的位移。用一根细金属丝固定双侧喙突，金属丝通过试架上方的小滑轮连接，通过金属丝向上的牵引作用模拟下颌升肌群的咀嚼力。对磨牙，双尖牙，尖牙，切牙13个功能咬合点进行加载，方向与咬合平面垂直。每一个功能荷载点连续加载10次。4、将
两台JDX-2型，50毫米读数显微镜（购于长春市第三光学仪器厂，测量范围为50mm，精度为0.01mm）分别置于模型的两侧及后侧，通过读数加载的数值，即可得出髁状突以及远心端左右及前后的非生理性水平位移。取每个点10次加载所得差值的平均值。应用Origin软件分析处理。并且采用SAS6.12版本软件分别对三种不同固定方法固定术后的髁状突及远心端骨段前后及左右水平位移作t检验。
结果：1、下颌矢状劈开截骨术后，在功能负载条件下两骨断面将产生弯矩，扭矩，剪切力。这些生物力将使髁状突和远心端骨段产生不同方向的非生理性位移。2、功能负载条件下，二钉固定组的近、远心端骨段均产生较大位移。相比较三钉固定组和小夹板固定组所产生的非生理性位移要小于二钉固定组。3、三钉固定组和小夹板固定组相比较，三钉固定组在髁状突向后非生理性后移位上小于夹板固定组。而左右水平位移量上基本无差别。对远心端骨段的位移来说，三钉固定组的位移也要小于小夹板固定组。
讨论：本实验目的是为了对下颌骨矢状劈开截骨术不同固定方法进行力学分析。探讨不同固定方法的功能稳定性。从结果可
以看出两钉固定在对抗髁状突和远心端骨段移位的能力上要远不如三钉固定和小夹板固定。多年以来，大多数学者在使用螺钉固定法时一直采用3个螺钉固定下颌升支矢状劈开截骨后的两个骨段．但Souyris等人首先报告了每侧用2个固位螺钉固定的方法，认为效果同样可靠。临床上一直没有每侧两个螺钉固位稳定性方面样本含量较大的研究报告。 本实验的从力学分析的角度得出两钉固定法髁状突以及远心端骨段对抗移位的能力要比三钉固定和小夹板固定差的结论。
从本实验的结果分析，小夹板固定对髁状突和远心端骨段移位的抗力相对三螺钉固定要弱，但临床中小夹板固定的应用也较广泛。这是因为首先由于小夹板的形状可以根据需要而预备，例如根据近心骨段移动后，近、远心骨段间出现的台阶而预备小夹板形成相应台阶。使其紧密贴台于近、远心骨段颊侧面，而不会对两骨段产生压力，从而减小了髁状突在固定后发生旋转和移位，进而使SSRO术后的复发率下降。 而且由于是单层骨皮质固定，降低了下齿槽神经血管束损伤的风险。口内入路也相对比较好操作。
三钉固定与小夹板固定相比，三钉固定比小夹板固定拥有更
好的抵抗髁状突前后移位以及近、远心端骨段扭转的能力，而两种固定方法在对抗髁状突左右移位的能力上无明显差别。根据实验结果可以得出结论：从力学的角度来讲，三钉固定要比小夹板固定的稳定性要好。但是在实际的临床操作中三钉固定却还是不能完全代替小夹板固定，笔者认为有以下几个原因。
1、螺钉的位置：下颌升支矢状劈开截骨术后固位螺钉的位置通常有两种形式，一种是将3个螺钉均置于下齿槽神经管之上；另一种方式是置两个螺钉于下齿槽神经管之上，第3个螺钉置于下齿槽神经管之下。多数学者提倡后一种方式，更多的临床及实验研究都证实，尽可能较远间隔的安置螺钉能够提供更好的稳定性。但在实践中，因为牙根和下齿槽神经管不能伤及；螺钉还必须位于包括了近、远心骨段的骨皮质里，局部的解剖条件往往限制了螺钉的理想位置。
2、螺钉进入的角度和手术入路的问题：最初Spiess1的方法是经面颊皮肤入路SSRO的螺钉坚固内固定。以后有学者提出口内入路行SSRO的螺钉坚固内固定，以避免皮肤疤痕及面神经损伤。但是口内入路存在很多诸多问题，首先是操作复杂，需要特定的器械。而且口内入路的手术视野较小，所以使螺钉不容易垂
直骨面进入。这势必会对固定的稳定性产生影响。Uckan用实验方法对螺钉以90℃和60℃两种角度进入骨面两种方法做比较，发现60℃的稳定性要比90℃进入差。三钉固定口内入路有相当的难度。这就限制了三钉固定法的临床应用。所以三钉固定要想发挥其稳定的优点，就必须进一步改良手术方法和器械。
结论：1、坚固内固定技术在下颌矢状劈开截骨术中比以往的颌间结扎可以获得更稳定的固定效果，大大减少术后的复发。2、两钉固?
Object The purpose of the present study was to creat a three-dimensional model of mandibular, analysis the mechanics property of varies fixed method. Tt will provide scientific evidencen for clinical.
Method 1. 9 adult mandibles were choosed.and divided into three group random .They were operated sagittal split osteotomy. 2.Fixation (1)group 1 was fixed by two screw which was inserted (2)group 2 Three screw were inserted to stabilize the bone (3)group 3 The bone was stabilized by minipalate according to the themry of Champy .3 .The mandibles were placed in artificial joint fossa .of machinie .regulated them to transverse section . A observation wire placed in chin was to observe the displacement of distal of bone. Coracoids were splinted by two metal wires. Traction of wires wre modelling muscles force. Force was loaded on 13 functional point, molar,incicor.10 times every functional point. 4.Two JD-X2
microscopes were put two sides an- d afterwards of model. Displacement of bone could be measured by microscopes .Average value of each functional point was analysised by Origin software . And analysis the displacement of distal and mesial bone with T test.
Results 1. After sagittal split osteotomy, there are some forces between two section of bone such as bening moment , torsion moment,shear force . They would make condylar and distal bone displacement. 2 Under the condition of functional loading ，the dispacement of the mesial and distal bone was larger in two-screw group than those in the other two groups. 3 The forward –backward displacement of condylar was less in the three-screw group than minipalate group .the right-left displacement of condylar was no obvious different. The displacement of distal bone was less in the three-screw group than minipalate group .
Discussion The aim of the study was to analysis mechanics property of varies fixation methed of saggital split
osteotomy. According to the results, the dispacement of the mesial and distal bone was larger in two-screw group than those in the other two groups. Several years most scholar applied three-screw fixation .but Souyris suggested that the effect of two-screw was reliability.we come to conclusion that the stablity of fixation in two-screw group was less than those in the other two groups.
According to result , the stablity of fixation in minipalate group was less than that in three-screw group. But minipalate fixation was still utilized in clinic. The reason is that the shape of minipalate can be adjusted according to requirement . further more , nerves and blood vessel injury can be voided by this mean .and it can be easily operated.
Compare to minipalate group three-screw group posses better stability.but we can not replace minipalate completely by three-screw in clinic. The reason followed.
1. Position of screw after saggital split osteomy , the
position of screw have two type . One is that placed three screws all were above the inferior alveolar nerves .Another is that two screws were above the inferior alveolar nerves. The third was below the inferior alveolar nerves.Most study demonstrated that disperd distribution can provide better stability. But in clinic , dissection limited ideal position of screw.
2.The angle of screw and route of operation Spiessl suggested that operation entrance through cheek .but it can injury cheek . On the other side , entrance by mouth have many problem sunch as that operate was too complicated. Further more operation visual fiend was limited .Uckan contrast the angle of 90℃ a and 60 ℃,he got the result that 90 ℃ was better than 60℃.So as to get better stability ,operation must be improved.
Conclusions 1. Rigid fixation can get better stability than wire fixation.2.Some scholar thought that two-screw can provide enough stability, but we can see that two-screw
was less stability than other two fixation methed. 3.Three-screw processed better stability than minipalate. 4.Minipalate still utilized in clinic commonly because of its conven
引文
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12．刘春丽，朴正国，吴安平。下颌骨骨折三维力学模型研究及钛小夹板骨折固定功能稳定性评价，口腔医学研究2002, 18(4):262-264.
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15.Anucul B,Waite PD, Lemons JE (1992) In vitrostrength analysis of sagittal split osteotomyfixation: noncompression monocortical platesversus bicortical position screws.J OralMaxillofac Surg 50:1295–1299.
16.Pistner H, Reuther JF,Ordung R, Bill J,Voges I(1997) Osteosyntehese nach sagittaler Spaltungdes Unterkiefers. Biomechanische Festigkeitenverschiedener Verfahrenin- einemSchweinekiefermodell.Mund Kiefer GesichtsChi 1:199–204.
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Craniomaxillofac Surg. 1995 Oct;23(5):321-4.
18.Mehra P, Castro V, Freitas RZ, Wolford LM.Complications of the mandibular sagittal split ramus osteotomy associated with the presence or absence of third molars. J Oral Maxillofac Surg. 2001 Aug;59(8):854-8; discussion 859.
19.Uckan S, Schwimmer A, Kummer F, Greenberg AM. Effect of the angle of the screw on the stability of the mandibular sagittal split ramus osteotomy: a study in sheep mandibles.Br J Oral Maxillofac Surg. 2001 Aug; 39(4): 266-8.
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12．刘春丽，朴正国，吴安平。下颌骨骨折三维力学模型研究及钛小夹板骨折固定功能稳定性评价，口腔医学研究2002, 18(4):262-264.
13.Prium GJ , De jone HJ .Forces acting on the mandibular during bilateral static bite at different bite force levels . J Biomech .1980;13:755.
14.Tucker MR , Terry BC , White RP . Rigid fixation for maxillofacial surgery . Lst ed .Philadelphia: JB Lippiincstt. 1991;161-191.
15.Anucul B,Waite PD, Lemons JE (1992) In vitrostrength analysis of sagittal split osteotomyfixation: noncompression monocortical platesversus bicortical position screws.J OralMaxillofac Surg 50:1295–1299.
16.Pistner H, Reuther JF,Ordung R, Bill J,Voges I(1997) Osteosyntehese nach sagittaler Spaltungdes Unterkiefers. Biomechanische Festigkeitenverschiedener Verfahrenin- einemSchweinekiefermodell.Mund Kiefer GesichtsChi 1:199–204.
17.Hammer B, Ettlin D, Rahn B, Prein J Stabilization of the short sagittal split osteotomy: in vitro testing of different plate and screw configurations. J
Craniomaxillofac Surg. 1995 Oct;23(5):321-4.
18.Mehra P, Castro V, Freitas RZ, Wolford LM.Complications of the mandibular sagittal split ramus osteotomy associated with the presence or absence of third molars. J Oral Maxillofac Surg. 2001 Aug;59(8):854-8; discussion 859.
19.Uckan S, Schwimmer A, Kummer F, Greenberg AM. Effect of the angle of the screw on the stability of the mandibular sagittal split ramus osteotomy: a study in sheep mandibles.Br J Oral Maxillofac Surg. 2001 Aug; 39(4): 266-8.