【作者】 左艳萍；

【导师】 王洁； 丛斌；

【作者基本信息】 河北医科大学 ， 病理学与病理生理学， 2003， 博士

【摘要】 目的：安氏Ⅱ类错(牙合)的发病率，约15～20％，占口腔正畸科治疗病人的49％。安氏Ⅱ类错(牙合)的主要特征是下颌后缩或下颌发育不足，临床表现为：开唇露齿，上颌前突，下颌后缩，侧面下颌短小，面部明显不调，给患者造成严重的不良心理影响。目前临床上其早期的治疗多采用引导下颌前伸的功能矫治，自1910年Andresen最早设计的功能性矫治器应用于临床以来，国内外学者关于其功能矫治机理、矫治效果进行了大量的研究，但迄今为止仍存在分歧。一些学者认为下颌前伸功能性矫治能够刺激促进下颌骨的生长，促进软、硬组织发生一系列的适应性改变，重建新的功能形态平衡，有效地矫治Ⅱ类(牙合)畸形。有研究认为，下颌前伸功能性矫治对刺激促进下颌骨的生长的作用极小或只能短期刺激颌骨生长，造成颌骨生长量的预支，颌骨的生长总量不能发生改变。 本研究的目的是通过生物力学、动物实验、临床治疗效果分析等手段，探讨功能矫治前伸下颌的矫治机理，了解前伸下颌对下颌骨生长发育的影响，为临床Ⅱ类(牙合)动能矫治提供实验依据。 方法： 1 下颌功能性前伸时下颌骨应力分布的三维有限元分析 选择处于生长发育高峰期的典型Ⅱ类(牙合)患儿，全身发育正常，无正畸史；拍摄CT断层片：以FH(眶耳)平面向下，对整个下颌骨进行断层扫描；在CAD软件中建立下颌骨三维几何模型；在MSC.PATRAN软件中建立三维有限元模型；共划分6148个8节点六面体和6节点三棱柱实体单元，产生7646个节点。肌肉采用薄壳单元，共划分888个四节点单元，生成1032个节点，在MSC.NASTRAN有限元软件中进行分析，分析结果导入MSC.PATRAN中进行后处理。 2 下颌前伸对生长期大鼠下颌形态改建的影响 参照Petrovic及华西医科大学罗颂椒等设计的矫治器，经过作者改良，矫治器由上切牙冠套及斜面导板组成。术前采制实验组动物上 中文摘要中切牙印模，灌制铅代型，并锤造制作带环(0.25mm厚度合金片)于带环唇面焊接斜面导板(规格0-25mm双层)，斜面导板向舌侧倾斜，与牙合平面成25“角。就位粘固后，下切牙恰位于斜面导板唇面且咬合时滑行至对刃或反牙合关系。本实验为了验证下领骨改建，设计了下领过度前伸的固定式斜面导板，咬合时下领前伸，磨牙无咬合。 选择4周龄健康SD(Sprague一Dawley)雄性大鼠40只(由河北医科大学动物实验中心提供)，体重约909，随机等量的分为4组。每组各10只，实验1组配戴矫治器4周，对照1组正常对照，扫描电镜观察下领骨骸状突;实验2组配戴矫治器4周，实验结束前7天及24小时分两次按25m叭g经腹腔注射盐酸四环素(盐酸四环素针剂:为中国药品生物制品检定所所标定的国家标准品。粉剂每支0.59，盐酸四环素纯度0488一200001 98.7%)，左侧下领骨进行四环素荧光染色观察，右侧用于游离下领骨的X线形态学测量;对照2组不配戴矫治器，在实验结束前7天及24小时与实验2组相同，腹腔注射盐酸四环素，与实验组进行对照观察。 所有大鼠均自由饮水和定时摄食，饲料为河北医科大学动物实验中心配置的全价颗粒饲料(饲料成分为玉米、鼓皮、鱼粉等)，饲养温度约27℃。自制上领斜面导板矫治器，用玻璃离子粘固于上中切牙上，引导实验组大鼠下领功能性前伸，24小时戴用矫治器。戴用矫治器后一周内实验组进食浸泡后的软颗粒饲料，实验周期为4周。3功能矫治n类错矜的头影测量分析 选择11例替牙期安氏H类矜患儿童为实验组，男6例，女5例，年龄最大13.25岁，最小10.92岁，平均12.63岁;为替牙期及恒牙早期，无矫治史，且手腕骨片显示生长发育处于FG一G期，头影测量显示上领基本正常，下领明显后缩，ANB>5“，平均治疗和观察时间12.22月。治疗期间戴用使下领适度前伸的磁力Twinblo。k功能矫治器;对照组选择我科同一年龄组同样安氏11类牙都扁人由于各种原因未接受功能矫治，经追踪随访观察其自然生长发育状况，标准与实验组相同，共11例，男5例，女6例，年龄最大12.92岁，最小10.08岁，平均n.gl岁，平均观察11.27月。两组儿童年龄及观察时间经统计学处理无显著差别。两组病人分别做治疗前后和生长前后的X线中文摘要头影测量分析，并对数据进行统计学处理。 结果:1下领功能性前伸时下领骨应力分布的三维有限元分析结果1.1下领应力总体分布情况:下领骨的整体拉应力分布，从下至上拉应力水平逐渐增大，下领体部由下至上高拉应力区从前内侧向后外侧过渡。1.2拉应力分布情况:下领体磨牙区、下领骨下缘、升支舌侧、升支近后缘部分、裸突后斜面近舌侧部位，拉应力水平较高，其中磨牙区牙槽骨近舌侧部分应力值可达o.ZMpa一O.4MPa。1.3压应力分布:下领体的后部及下领角表面压应力水平较高。2下领前伸对生长期大鼠下领形态改建的影响2.1扫描电镜观察 对照组:裸突表面低倍镜下均平整光滑，高倍镜下见表面呈波纹状结构，其表面覆有凝胶状物质。裸突前斜面、顶部、后斜面表面致密均匀;可见胶原纤维排列整齐均匀。 实验组:?更多还原

【Abstract】 Objective: The incidence of Angle II malocclusion accounts for 15-20% of people and 49% of the patients who received orthodontic therapy. The main features of Angle II are retrusive or deficient mandible. The clinical appearance showed short upper lip, protrusive maxilla, retrusive and short mandible. These usually gave patients some bad psychological effects. Right now, early functional treatment to reduce the mandible forward was adopted to treat Angle II malocclusion. Since the functional appliance (FA) designed by Andresen in 1910 had been used, although many scholars in the world made a lot of studies, the exact mechanism and effect involved are unclear. Some studies showed that FA could promote or the mandible growth and remodel soft and hard tissue to a new balance, so that the treatment of malocclusion was performed. Other studies showed that FA might play a few roles in the jaw growth or only for a short time. Some reported that FA placed a "mortgage" on mandibular growth, and did not result in mandibular length increased.In this study, we applied bio-mechanics, animal model and clinical assays to analyze the mechanism of FA involved in mandibular protraction, and to know the effect on the growth of the mandible forwarded. We intended to provide an experimental basis for the early treatment to Angle II malocclusion.Method:1 A three-dimensional finite element analysis of mandibular stress distribution on a state of mandibular protractionPatients with typical Angle II malocclusion in a period of peak were entered into this study. All the children were of normal development and had not received orthodontic therapy.Transverse sections of mandible were taken by means of CT: Transverse sections of mandible below the FH plane were scanned by means of CT.The three-dimensional geometric model of mandible was re-established in CAD software.Three-dimensional finite element model was constructed in MSC.PATRAN software. Six thousand one hundred and forty-eight 8-point hexahedron and 6-point three-square entity units were set off and 7646 points were produced. Thin-shell unit was used in muscles and 888 4-point were set off and 1032 points were produced.The results were treated and analyzed by MSC.NASTRAN and MSC.PATRAN software.2 The effect of mandible forward on mandibular shapes of the growing ratsThe design of the appliance: the appliance was consisted of the upper crown and the inclined plane. Before surgery the upper incisor moulages and the lead molds were got, then bands (alloy flake with 0.25mm thick) jointed inclined plane lingually by 25?were made. On adhering, the lower incisor was just on the labial inclined plane and the mandible was in an edge-to-edge or even cross-bite position when the rats bit. In order to remodel mandible, the inclined plane was designed to ensure the mandible on a forward position and molars untouched.Forty 4-week-old male SD rats were selected and divided into four groups randomly (2 groups were the experiments and 2 groups were the controls), each group included 10 rats. The experimental group animals wore protrusive-type appliances for four weeks, while the control animals did not wear appliances. The mandibular condyles (from both experimental group 1 and control group 1) were observed by scanning electron microscope (SEM).The experimental rats (from both experimental group 2 and control group 2) at 7th day and 1st day before killed were injected tetracycline25mg/ per kg in abdominal cavity (tetracycline was provided by Chinese Medical and Biological Production Institute). The samples of left mandible were used for fluorescent observation and the samples of right mandible were used for the morphologic measurement. The control rats were observed comparatively. 3 Cephalometric analysis of Angle II malocclusion by FAEleven patients with Class II malocclusion at the stage of mixed dentition were selected. All patients showed retrusive mandible and normal maxilla by X-ray cephalometric measurement and the ANB angle was 5? They were更多还原