载荷骨量对微型种植体稳定性影响的生物力学分析

发布时间：2018-08-08 14:11

【摘要】：目的：正畸治疗成功的前提是有足够的支抗，支抗不足是限制正畸学发展的重要因素。牙弓严重前突、露龈笑、磨牙伸长及推磨牙向后等临床疑难病例常因支抗不足，影响治疗结果。支抗是抵抗不希望发生移动的牙移动的能力，传统的加强支抗的方法如横腭杆、Nance弓、颌间牵引、口外弓等存在稳定性、舒适性、方便性和患者合作性等方面的问题。而微型种植体支抗体积小，植入部位灵活、操作方法简单且可以提供有效的骨性支抗，植入后能够进行即刻加载，在正畸临床上得到广泛应用。然而目前微植体支抗的成功率仍明显低于修复种植体，国内外学者从微型种植体的材料、形态尺寸，操作方法、加力时机及大小等多方面做研究，取得了宝贵的成果，确定了一些影响微植体稳定性的因素和提高初期稳定性的方法。只有具有高水平的初期稳定性，才能使微植体作为临时支抗应用于临床。微植体刚刚植入后，其初期稳定性仅由微植体与周围骨组织的机械嵌合作用决定。而当对微植体进行即刻加载时，其稳定性不仅与机械嵌合力有关，还和微植体周围承受载荷的骨量有密切关系。为了确定在上下颌骨不同位置植入时，载荷骨量和植入角度对微植体即刻加载时的稳定性的影响，本研究采用体外实验法，将微型种植体按到骨边缘的不同距离植入家猪髂骨骨块上，通过生物力学方法分析不同载荷骨量对正畸微型种植体初期稳定性的影响。方法： 1制作骨块模型选择新鲜家猪髂骨作为骨块模型，先沿髂骨长轴在两侧各切去一薄层骨组织，以暴露出髂骨外表面的皮质骨，用游标卡尺测量各髂骨四周的皮质骨厚度，从中选择12块厚度介于1.3-1.5mm的髂骨。用22号的解剖刀剔除髂骨表面的软组织和软骨，用线锯将12个髂骨切割成约长11cm，宽9cm的骨块，然后将骨块嵌入到盛有自凝树脂的模型盒中以固定骨块，自凝树脂在冷的生理盐水下固化以避免聚合过程中散热对骨块的损伤。随后将固定好的骨块模型放入4°C的10㳠福尔马林缓冲液中进行保存。 2植入微型种植体 2.1在骨块上标记微植体植入位点完全去除骨块表面的软组织后，在骨块模型上描点八个点以确定微植体的植入位置，在距离骨块边缘3mm、4mm、5mm和6mm处分别标记两点，相邻两点的间距是10mm。到骨边缘相同距离的两点中左侧的点为垂直植入，右侧的为牙合向45°植入（微型种植体向一侧骨边缘倾斜45°植入）。 2.2在标记点处制作预备洞将手机的转速设定为1100rpm，在预备过程中用冷的生理盐水进行降温。到骨边缘相同距离的两点中左侧的点为向一侧骨边缘倾斜45°植入，右侧的为垂直植入。预备洞的深度固定于7mm，其中预备钻的直径为1.2mm。 2.3拧入微型种植体将微植体按预备洞方向顺时针植入，最后换用扭矩仪再进一步拧入至扭矩值为10Ncm。每一个骨块模型上有8颗微植体。 3生物力学测试使用微机控制电子万能试验机进行拉出力试验。将微植体/骨块模型牢固地夹在万能试验机底座上，微植体颈部通过不锈钢丝与上夹头相连。拉出实验时拉力应平行于骨面且与骨边缘垂直。加载拉力由电脑监控，施力夹板以0.05mm/s的恒定速度向上移动。具体数据以力-位移曲线的形式在电脑显示。当曲线呈现急剧下滑趋势时，停止施力，施力横梁停止移动。记录下所有微植体的（Fmax），即使微植体丧失支抗能力所需的最大拉力。 4皮质骨厚度测量生物力学测试完成后，用线锯小心地将骨块模型沿每颗微植体周围切开，切割成八个方形的小骨块，每个骨块上含有一颗微型种植体，利用游标卡尺测量每个小骨块四周的皮质骨的厚度（CBT），结果取平均值。结果： 1微植体/骨模型形态改变情况在进行拉力实验过程中有一颗种植体被折断，有两颗发生轻微弯曲变形，有两颗被拉出骨块，其它微型种植体在拉力试验完成后仍留在骨块中，仅发生轻微的移动或倾斜。 2不同载荷骨量时种植体生物力学性能的比较： 2.1当种植体垂直于骨面植入时，随着到骨边缘距离的增加，拉力峰值不断增大（P0.05）。 2.2当种植体倾斜45°植入时，随着到骨边缘距离的增加，拉力峰值不断增大（P0.05）。 3不同植入角度时种植体的生物力学性能比较： 3.1种植体距离骨边缘3mm-5mm时，垂直植入组的拉出力峰值均小于45°植入组（P0.05）。 3.2种植体距离骨边缘6mm时，垂直植入组的拉出力峰值与倾斜45°植入组无显著性差别（P=0.052）。 4种植体不同组皮质骨厚度比较： 4.1种植体垂直植入组及倾斜植入组皮质骨厚度均无显著差异(P0.05)。结论： 1.载荷骨量影响微型种植体/骨的生物力学性能。一定范围内，随着微型种植体到牙槽嵴顶距离的增加（即增加载荷骨量），可以提高微型种植体的生物力学性能，增加其稳定性。在临床上应用微植体时，应在其它条件允许的情况下，适当增加微植体到牙槽嵴顶的距离，增大载荷骨量，以提高其支抗能力。 2.植入角度影响微型种植体/骨的生物力学性能。微型种植体承受垂直于骨边缘的载荷时，倾斜植入较垂直植入更有利于微型种植体的稳定。在临床应用微植体时，应尽量根据需要加载的方向选择力矩较小的角度植入微植体，，尤其当载荷骨量较小时应尽量避免植入角度与载荷方向垂直。
[Abstract]:Objective:
The precondition for the success of orthodontic treatment is that there is sufficient anchorage, and the lack of support is an important factor restricting the development of orthodontics. The severe anterior process of the dental arch, the gingival smile, the elongation of the molar and the backwards of the grinding teeth are often caused by the insufficiency of the anchorage, which affects the ability to resist the movement of the teeth that do not want to move. The methods such as the transverse palate, the Nance bow, the intermaxillary traction, the extraoral bow and so on exist the problems of stability, comfort, convenience and patient cooperation. However, the microimplant support is small, the implant site is flexible, the operation method is simple and can provide effective bone anchorage, and the implant can be loaded immediately after implantation, and it is widely used in orthodontic clinic. General application.
However, the success rate of microimplant anchorage is still lower than that of the repair implants at present. Scholars at home and abroad have obtained valuable results from the materials, shape, size, operation method, loading opportunity and size of microimplants, and have determined some factors affecting the stability of microplants and methods to improve the initial stability. With a high level of initial stability, microplants can be used as temporary anchorage for clinical use. After the implant is just implanted, the initial stability is determined only by the mechanical chimerism of the microexplants and the surrounding bone tissue. When the microimplant is loaded immediately, the stability is not only related to the mechanical interlocking force, but also to the micro implant. In order to determine the effect of load bone mass and implantation angle on the stability of the microimplant when the implant is implanted in different positions of the maxilla and mandible, in this study, the experimental method was used to implant the microimplants at the different distances of the bone to the bone of the iliac bone of the pig, and the different biomechanical methods were used to analyze the differences. Effect of bone loading on the initial stability of orthodontic Mini implants.
Method:
1 making bone block model
The iliac bone of fresh domestic pig was selected as a bone block, and a thin layer of bone tissue was cut along the iliac long axis to expose the cortical bone on the outer surface of the iliac bone. The thickness of the cortical bone around the iliac bone was measured with a vernier caliper. 12 iliac bones with a thickness of 1.3-1.5mm were selected from it. The soft tissue and soft tissue of the iliac bone surface were removed with the anatomic knife No. 22. Bone, using a wire saw to cut 12 iliac bones into a long 11cm, wide 9cm bone block, and then insert a bone block into a model box with a self condensing resin to fix the bone. The self condensing resin is solidified under cold physiological saline to avoid the damage to the bone during the polymerization. Then the fixed bone block model is put into the 10? Formalin buffer of the 4 degree C. Keep it in it.
2 implant microimplant
2.1 labeling the implant site on the bone block
After completely removing the soft tissue on the surface of the bone, eight points were traced to determine the position of the implant on the bone block model. The two points were marked at 3mm, 4mm, 5mm, and 6mm at the edge of the bone block. The distance between the two points was perpendicular to the left point of the two points with the same distance from the bone to the edge of the bone, and the right one was implanted into the 45 degree (miniaturized). The implant sloped 45 degrees to one side of the bone.
2.2 make a preparation hole at the mark point
The rotational speed of the cell phone is set to 1100rpm, and the cold physiological saline is used to cool down during the preparation process. The left point on the left side of the two points with the same distance to the bone edge is 45 degrees to one side of the bone edge, and the right one is implanted vertically. The depth of the preparation hole is fixed to 7mm, and the diameter of the reserve drill is 1.2mm.
2.3 unscrewed microimplants
The micro-implants were clockwise implanted in the direction of the prepared cavity, and then further screwed in with a torque meter until the torque value was 10Ncm. There were eight micro-implants on each bone block model.
3 biomechanical test
The micro-computer controlled electronic universal testing machine is used to carry out the pulling force test. The microimplant / bone block model is firmly clamped on the base of the universal testing machine. The neck of the micro implant is connected with the upper clamp with stainless steel wire. The tensile force should be parallel to the bone surface and perpendicular to the edge of the bone. The loading force is monitored by the computer and the force splint is constant in 0.05mm/s. Velocity moves upwards. The concrete data is displayed in the form of a force displacement curve in the form of a force displacement curve. When the curve presents a sharp downward trend, the force stops and the force beam stops moving. Record all the microplants (Fmax), even if the microimplant loses its maximum support.
4 cortical bone thickness measurement
After the biomechanics test was completed, the bone block was cut carefully around each microimplant with a wire saw and cut into eight square small bone blocks, each of which contains a micro implant. The thickness of the cortical bone around each small bone (CBT) was measured with a vernier caliper. The results were averaged.
Result:
Morphological changes of 1 micro implant / bone model
During the tension test, one of the implants was broken, two were slightly curved, two were pulled out of the bone, and the other micro implants remained in the bone after the tension test was completed, only slightly moving or inclined.
2 Comparison of biomechanical properties of implants with different bone loads.
2.1 When the implant is perpendicular to the bone surface, the peak value of tensile force increases with the increase of the distance to the bone edge (P0.05).
2.2 when the implant tilted at 45 degrees, the peak value of tension increased with the increase of the distance to the edge of the bone (P0.05).
3 biomechanical properties of implants at different implant angles:
3.1 the peak value of pullout force in the vertical implant group was less than that in the 45 degree implant group (P0.05) when the implant was 3mm-5mm away from the bone edge.
3.2 there was no significant difference in the pullout peak between the vertical implant group and the 45 degree implant group (6mm) when the implant was at the edge of the bone edge (P=0.052).
The thickness of cortical bone in different groups of 4 implants was compared.
4.1 there was no significant difference in cortical bone thickness between vertical implant group and inclined implant group (P0.05).
Conclusion:
The biomechanical properties of microimplants / bones are affected by 1. load bone. Within a certain range, the increase in the distance between the microimplants and the crest of the alveolar ridge (that is, increasing the load of the bone) can increase the biomechanical properties of the micro implant and increase its stability. The distance between the micro implant and the alveolar ridge will increase the load bone mass to enhance the anchorage ability.
The 2. implantation angle affects the biomechanical properties of the micro implant / bone. When the micro implant bears the load perpendicular to the edge of the bone, the tilt implantation is more conducive to the stability of the micro implant. In the clinical application of microimplant, the microimplant should be implanted in a small angle, especially when the load is required, especially when the load is loaded. When the bone mass is small, the angle of implantation should be avoided as far as the load is concerned.
【学位授予单位】：河北医科大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R783.5

【参考文献】