桩冠修复后对根管壁应力分布影响的分析

目的:分析桩冠修复后对根管壁牙本质应力分布的影响。方法:选择一接近标准的上颌中切牙,运用三维有限元法构建前牙桩冠修复体模型,以及牙根及桩的仿真模型。并模拟不同牙合接触形式进行加载,对根管壁牙本质的应力分布情况进行数值分析。结果:无论是锥形桩还是平行桩,随着加载角度的增加和加载点向切端移动,牙根牙本质Von Mises和最大主应力峰值将增大。结论:从力学角度提示:桩冠修复时应尽量减小牙合力与牙体长轴的角度,在下颌做前伸运动时对颌牙应避免与修复体早接触。     

上颌骨Le Fort-Ⅰ型截骨术坚强内固定的有限元研究

目的 研究不同接骨板在上颌骨Le Fort-Ⅰ型截骨正颌手术中固定的生物力学特性,以期找出最佳固定方法.方法 建立正颌Le Fort-Ⅰ型截骨9种内固定方式的三维有限元模型,并分为3组,计算不同固定方法在3种咬合情况下上颌骨的应力及截骨段的位移,对比不同内固定系统,不同形状接骨板,以及接骨板不同放置位置的固定效果.结果 前牙咬合时,颅、上颌复合体中应力主要循双侧鼻上颌支柱向上传递,前磨牙和磨牙咬合时,应力先自咬合处向牙槽突两侧传递,再分别循颈上颌支柱和鼻上颌支柱传递;内固定系统中螺钉与接骨板交接处及接骨板近截骨线处,为应力集中部位.前磨牙咬合时,不同固定方法截骨段位移从大到小依次为:组1 生物可吸收小型板系统(0.396 509 mm)、微型钛板(0.148 393 mm)、小型钛板(0.078 436 mm);组2 单纯鼻上颌支柱固定(0.188 791 mm)、颧上颌支柱固定(0.12l 718 mm)、双支柱固定(0.078 436 mm);组3 直形板(0.091 023 mm)、L形板(0.078 436 mm)、Y形板(0.072 450 mm)、T形板(O.065 617 ram).结论 正颌Le Fort-Ⅰ型截骨术生物可吸收接骨板固定的稳定性和强度相对钛板较小;颧上颌支柱固定效果好于鼻上颌支柱固定;不同形状的钛板在鼻上颌支柱固定的稳定性有差异.     

Finite element study of maxillary Le Fort-Ⅰ osteotomy with rigid internal fixation

Objective To study the biomechanical characteristic of maxillary Le fort- I osteotomy with rigid internal fixation (RIF), so as to choose best fixation method. Methods The 3-dimensional finite element models of maxillary Le Fort- I osteotomy with 9 kinds of RIF methods were established. Then the models were divided into three groups to calculate the stress distribution of the maxilla and the displacement of bone segment under 3 kinds of occlusion condition. The fixation stability of the different RIF methods was evaluated. Results Under the incisor occlusion condition, the stress of the cranio maxillary complex transmits mainly along the nasal-maxillary buttress. Under the premolar and molar occlusion condition, the stress transmits along the alveolar process first, then turns to the nasal-maxillary and zygomatic-maxillary buttress. The focused stress position of the internal fixation system is at the connection between the screws and the plate and at the plate near the osteotomy line. Under the premolar occlusion condition, the displacement of bone segment with different RIF methods was (in a decreasing order) 0.396509 mm ( with bio-absorbable plate), 0.148393 mm (with micro-plate ), 0.078436 mm (with mini-plate ) in group 1;0.188791 mm (fixing at the nasal-maxillary buttress), 0.121718 mm (fixing at the zygomatic-maxillary buttress) , 0.078436 mm (fixing at the both buttress) in group 2;0.091023 mm (with straight plate), 0.078436 mm (with L shape plate), 0.072450 mm (with Y shape plate) , 0. 065617 mm (with T shape plate) in group 3. Conclusions The fixation stability of using the bio-absorbable plate in Le Fort-Ⅰ osteotomy is less stable than using the titanium plate. Fixing at the zygomatic-maxillary buttress is more stable than at the naso-maxillary buttress. The fixation stability is different by using different shapes of plates.     

下颌骨双侧升支矢状劈开坚强内固定的三维有限元分析

双侧升支矢状劈开截骨术（bilateral-sagittal-split-ramus-osteotomy，BSSRO）术后的稳定性一直是正颌学者关注的焦点。本研究是用三维有限元的方法建立了BSSRO小型钛板内固定的模型并对其固定的稳定性进行了计算和分析。     

亚甲蓝混合液注射对50例肛肠病患者术后镇痛效果观察

正肛肠病术后疼痛为肛肠病手术后的首位并发症,是由于局部组织受到不同程度的手术损伤,神经纤维受外源性理化因素的反复刺激所致。肛门部神经分布丰富,术后易引起疼痛,疼痛给病人造成了身体和心理上的伤害。患者术后疼痛的主要临床表现为感觉肛门直肠部位坠胀、刺痛、刀割样持续性疼痛,常常伴发大便困难,尿潴留,情绪紧张,烦躁不安,严重者出现血压升高,休克等,更有甚者诱发心脑血管疾患,乃至危及生命,     

Finite element study of maxillary Le Fort-Ⅰ osteotomy with rigid internal fixation

Objective To study the biomechanical characteristic of maxillary Le fort- I osteotomy with rigid internal fixation (RIF), so as to choose best fixation method. Methods The 3-dimensional finite element models of maxillary Le Fort- I osteotomy with 9 kinds of RIF methods were established. Then the models were divided into three groups to calculate the stress distribution of the maxilla and the displacement of bone segment under 3 kinds of occlusion condition. The fixation stability of the different RIF methods was evaluated. Results Under the incisor occlusion condition, the stress of the cranio maxillary complex transmits mainly along the nasal-maxillary buttress. Under the premolar and molar occlusion condition, the stress transmits along the alveolar process first, then turns to the nasal-maxillary and zygomatic-maxillary buttress. The focused stress position of the internal fixation system is at the connection between the screws and the plate and at the plate near the osteotomy line. Under the premolar occlusion condition, the displacement of bone segment with different RIF methods was (in a decreasing order) 0.396509 mm ( with bio-absorbable plate), 0.148393 mm (with micro-plate ), 0.078436 mm (with mini-plate ) in group 1;0.188791 mm (fixing at the nasal-maxillary buttress), 0.121718 mm (fixing at the zygomatic-maxillary buttress) , 0.078436 mm (fixing at the both buttress) in group 2;0.091023 mm (with straight plate), 0.078436 mm (with L shape plate), 0.072450 mm (with Y shape plate) , 0. 065617 mm (with T shape plate) in group 3. Conclusions The fixation stability of using the bio-absorbable plate in Le Fort-Ⅰ osteotomy is less stable than using the titanium plate. Fixing at the zygomatic-maxillary buttress is more stable than at the naso-maxillary buttress. The fixation stability is different by using different shapes of plates.     

下颌角在外力加载下的应力分析

目的：应用有限元法分析下颌角在不同受力方向、不同大小外力及受力面积情况下颌骨内应力变化。方法：利用ANSYS软件建立下颌骨三维有限元模型,应用该模型分别计算不同方向、不同大小的外力、不同受力面积作用于下颌角时下颌骨的应力值,分析主应力值以及应力分布情况。结果：（1）下颌角侧方加载力时,同侧下颌角、髁状突颈部、下颌隆突、磨牙后三角区及颏部舌侧面应力较大。下方加载时,双侧髁状突颈部、同侧下颌角下缘、外侧面应力较大。（2）无论下方或侧方加载,随外力增大,应力值以及应力集中区域不断增大。受力面积不变,外力越大,应力值越大,应力大小与力的大小成正比。外力大小不变时,受力面积越大,应力越小。结论：静载荷作用于下颌角时下颌骨各部位应力分布与外力大小、力的方向以及加载面积密切相关。     

跨声门喉癌综合治疗复发后挽救性手术(附1例报道)

跨声门喉癌这一概念被提出已近60年,这期间学者们对其临床、病理学及肿瘤生物学特征的研究方兴未艾。因该病具有病变原发部位隐蔽、易向喉外侵犯及易误诊误治等特点,成为临床诊治中的难点。     

下颌骨双侧升支矢状劈开坚强内固定的生物力学研究

目的:研究下颌骨升支矢状劈开小型钛板和双皮质固位螺钉内同定生物力学特性,为临床提供理论上的指导。方法:用螺旋CT断层扫描技术及ANSYS有限元软件在计算机上建立下颌骨升支矢状劈开小型钛板及3种双皮质同位螺钉内固定的三维有限元模型;计算4种固定方法在三种咬合情况下颌骨的应力、内固定系统的应力以及骨劈开处的位移,对比这些固定方式的固定效果以及不同咬合情况对固定稳定性的影响。结果:在相同咬合情况下,颌骨的应力、劈开处的位移从大到小排列顺序为:2mm双皮质同位螺钉直线形内固定、小型钛板内固定、2mm双皮质同位螺钉倒"L"形内固定、2.7mm双皮质固位螺钉倒"L"形内固定。相同固定方式情况下,颌骨的应力、内固定系统的应力以及劈开处的位移从大到小排列顺序为:前牙咬合、前磨牙咬合、磨牙咬合。结论:下颌骨双侧升支矢状劈开双皮质固位螺钉倒"L"形内固定的固定稳定性要强于小型钛板内固定;直线形内固定固定稳定性相对较差。前牙咬合对同定的不良影响很大,应尽量避免。     

种植修复上部义齿不同牙尖斜度设计的三维有限元分析

目的 :通过对种植修复上部义齿9种不同牙尖斜度设计的三维有限元分析 ,研究单颗种植修复上部义齿牙合面牙尖斜度的优化设计。方法 :利用ANSYS有限元分析软件建立包括下颌骨、种植体及9种不同牙尖斜度设计的上部义齿的三维有限元模型 ,在牙合面上施加两种面载荷 ,比较不同加载方式下不同设计的种植体周围应力分布。结果 :种植体与上部结构交界处、种植体颈部、种植体根尖区、种植体颈部周围骨皮质、种植体根端周围骨松质是应力集中区 ,应力最大值在种植体与上部结构交界处。结论 :不同牙尖斜度设计的种植体上部结构中 ,25°以上牙尖斜度的设计造成种植体颈部折断的危险性显著增加 ,临床设计时应控制在25°牙尖斜度以内