不同螺距种植体集中载荷的有限元分析

目的:用三维有限元方法分析不同螺距种植体-骨界面应力分布状况,确定利于应力均匀分布的最佳螺纹参数设计.方法:建立包含上部结构的牙种植体、局部下颌骨块三维有限元模型,利用Cosmos/works软件分析在垂直、斜向45° 2 种集中载荷下螺距分别为0.6、 0.8、 1.0 mm的3 种种植体与骨界面的应力分布状况.结果:螺距为0.8 mm种植体周围Von-Mises应力、拉应力、压应力峰值较小,应力分布最均匀;同一螺距种植体斜向载荷下应力显著高于垂直载荷;应力集中主要出现于种植体颈部、皮质骨上缘和种植体末端最下一个螺纹处.结论:螺纹种植体螺距影响骨界面的应力分布和(牙合)力传导,为避免应力集中种植体末端螺纹应进行适当的截齿处理,种植义齿设计和修复时应尽可能减小或避免非轴向力.     

全下颌改良杆卡式和传统卡式种植覆盖义齿受载的比较性研究

目的：分析全下颌改良杆卡式种植覆盖义齿受载的应力分布并与传统的杆卡式比较。方法：三维各向异性有限元法。结果：种植体界面骨组织的最大应力出现在种植体颈部周围的骨皮质界面;种植体的最大应力主要位于种植体骨外段的近、远中面;牙弓后部牙槽嵴粘膜中有应力集中;改良式与传统式比较,种植体及其周围骨界面的应力峰值差别不大,但应力分布有一定差异,改良式者更均匀。而两种义齿牙弓后部牙槽嵴粘膜中的应力峰值及应力分布差别不大。结论：改良杆卡式种植覆盖义齿受载的应力分布比传统杆卡式者更均匀。     

螺纹与约束高度影响种植体应力分布的三维有限元分析

目的：研究螺纹与约束高度对于种植体应力分布的影响。方法：利用实体建模技术建立种植体的仿真模型，通过三维有限元的分析方法，对4种模型进行Von Mises应力分析。结果：长种植体约束高度高；在约束高度降低时，种植体应力明显增大，而不带螺纹的种植体应力变化较带螺纹的种植体小；螺纹间距对于应力值及应力分布无显著影响。结论：带螺纹的种植体强度要求高；长种植体的应力分布均匀，应力值小，对提高种植体的成功率有意义。     

全下颌改良杆卡式和传统卡式种植覆盖义齿受载的比较性研究

目的：分析全下颌改良杆卡式种植覆盖义齿受载的应力分布并与传统的杆式卡式比较,方法：三维各向异性有限元法,结果;种植体界面骨组织的最大应力出现在种植体颈部周围的骨皮质界面,种植体的最大应力主要位于种植体骨外段的近,远中面,牙弓后部牙槽嵴粘膜中有应力集中,改良式与传统式比较,种植体及其周围骨界面的应力峰值差别不大,但应力分布有一定差异,改良式者更均匀,而两种义牙弓后部牙槽嵴粘膜中的应力峰值及应力分布差     

AZ91D镁合金种植体三维模型骨界面应力有限元分析

目的：利用三维有限元方法分析AZ91D镁合金种植体和钛合金种植体及周围骨界面的应力分布规律。方法：建立下颌第一磨牙区AZ91D镁合金种植体和钛合金种植体三维有限元模型,根据Von Mises标准计算种植体-骨界面应力水平。结果：不同载荷下,AZ91D镁合金种植体和钛合金种植体模型的种植体-骨界面应力分布基本相同：两模型最大应力均位于种植体第一螺纹及颈部皮质骨处;相同载荷下镁合金种植体模型界面应力值稍高于钛合金模型;皮质骨应力分布相似,松质骨区镁合金模型应力分布更均匀;镁合金种植体在水平载荷50N下最大等效应力值是其屈服强度的98.1%。结论：AZ91D镁合金种植体与钛合金有着极为相似的应力分布,镁合金种植体骨界面应力值稍高但垂直载荷下界面应力分布较均匀且更有利于压应力传导。     

种植体 - 复合树脂衬里金瓷冠修复对力的影响

目的：通过在金瓷冠和种植体基台间增加一层复合树脂衬里作为弹性缓冲层,缓冲Ｈｅ力对种植体的作用。方法：采用三维有限元应力分析。结果：垂直加载和水平加载后,复合树脂衬里金瓷冠种植体基台表面的应力值者明显减少,且分布均匀,对水平奕力的缓冲作用大于对垂直应力的缓冲作用;冠Ｈｅ面和侧表面应力无明显改变。结论：复合树脂衬里层可缓冲Ｈｅ力对种植体的作用,使种植体基台受力缓和、均匀,从而可影响种植体骨界面应力的大     

末端种植体倾斜状况的应力研究——向舌侧倾斜

目的：研究下颌种植体舌倾斜时末端种植体应力分布情况。方法：下颌５个种植体，除左侧末端种植体舌倾斜１５°外余为垂直状态。以１００Ｎ分别垂直加载于距末端种植体０、１０、２０ｍｍ的悬臂梁上，在微机上用ＳＡＰ８４软件分析种植体周围应力分布。结果：加载于距末端种植体２０ｍｍ时其种植周围应力均比加载于悬臂梁０、１０ｍｍ时为大。种植体舌侧倾斜时，在近中和舌侧骨界面应力亦较远中和颊侧骨界面的应力大。结论：种植义齿设计时应考虑种植体舌侧倾斜时骨界面舌侧和近中应力状况     

种植体直径和长度对支持组织应力分布的影响

目的：观察种植体直径、长度变化时由种植体支持的下颌种植覆盖义齿,在牙合力作用下其支持组织——牙槽骨及种植体周围的应力分布状况,探讨种植体长度和直径变化对支持组织应力分布的影响规律。方法：用三维光弹应力冻结切片法,对４种不同长度,３种不同直径的种植体支持的种植覆盖义齿,在牙合力作用下的应力状况进行应力冻结,并在相应部位切片观察,以了解各种状况下其支持组织的应力分布状况。结果：种植体长度变化对种植体周围骨界面及牙槽骨应力的大小有较大的影响,两者呈负相关关系;而在临床常用的几种直径种植体中,直径变化对种植体周围骨界面及牙槽骨应力的影响不大。结论：在种植义齿设计时,应着重考虑种植体长度变化对种植体周围骨界面及牙槽骨应力的影响,种植体直径变化可不作考虑。     

螺纹形态和螺距对种植体系统应力影响的三维有限元研究

目的研究根据标准螺纹参数设计的不同螺纹形态和螺距的9种牙种植体受载后牙槽骨及整个种植系统的应力变化,为种植体系统的优化设计及临床应用提供理论依据。方法采用Solidworks软件建立了螺纹形态分别为V形、梯形、锯齿形,螺距分别为0.7 mm、0.8 mm、1.0 mm的9种标准螺纹式种植体模型,配以基台、基台螺丝构成整套种植体系统,根据CT扫描数据重建下颌骨模型,在垂直向和与种植体长轴成15°斜向分别加载100 N力,ANSYS有限元分析软件计算比较种植体系统和周围牙槽骨的应力及位移分布状况。结果综合考虑种植体系统各部件和种植体周围牙槽骨所受应力,9种种植体中,螺纹形态为V形、螺距为0.8 mm的种植体在垂直向和斜向加载时应力较小。9种种植体各部件及周围牙槽骨最大位移量垂直向加载时为2.61μm,斜向加载时为23.78μm,9种种植体的位移差异小。结论螺纹形态为V形、螺距为0.8 mm的种植体力学性能较好。螺纹形态和螺距对种植体系统及周围牙槽骨的位移影响不大。     

末端种植体倾斜状况的应用研究——向舌侧倾斜

目的：研究了下颌种植舌倾斜时末端种植体应力分布情况，方法：下颌５个各植体，除左侧末端种植体舌倾斜１５°外余为垂直状态，以１００Ｎ分别垂直加载于距末端种植体０，１０，２０ｍｍ的悬臂梁上，在微机上用ＳＡＰ８４软件分析种植体周置应力分布，结果：加载于距末端种植体２０ｍｍ时其种植周围应力分布。结果：加载于距末端种植体２０ｍｍ时其各植周围应力均比加载于悬臂梁０，１０ｍｍ时为大，种植体舌侧倾斜时，在近中和舌侧     

Clinical and pathological aspects on some odontogenic tumors

Odontogenic tumors constitute a very diverse group of lesions that reflects the complex processes of odontogenesis. Controversies over their classification/subtyping, terminology and diagnosis have been persisted, which has direct bearings on therapeutic and/or prognostic implications.     

Can you be too old for oral implants? An update on ageing and plasticity in the oro‐facial sensorimotor system

This review focuses on the capacity of the brain for plasticity and the utility and efficacy of oral implants in helping to restore oro‐facial sensorimotor functions, especially in elderly patients. The review first outlines the components of the oro‐facial sensorimotor system which encompasses both oro‐facial tissues and a number of brain regions. One such region is the sensorimotor cortex that controls the activity of the numerous oro‐facial skeletal muscles. These muscles are involved in a number of functions including reflexes and the more complex sensorimotor functions of mastication, swallowing and speech. The review outlines the use by the brain of sensory inputs from oro‐facial receptors in order to provide for exquisite sensorimotor control of the activity of the oro‐facial muscles. It highlights the role in this sensorimotor control played by periodontal mechanoreceptors and their sensory inputs to the brain, and how oral implants in concert with the plastic capacity of the brain may, at least in part, compensate for reduced sensorimotor functioning when teeth are lost. It outlines findings of ageing‐related decrements in oro‐facial sensorimotor functions and control. The changes in oro‐facial tissues and the brain that underlie these ageing‐related functional alterations are also considered, along with adaptive and compensatory processes that utilise the brain's capacity for plasticity. The review also notes the evidence t hat rehabilitation that incorporates adjunctive approaches such as sensorimotor training paradigms in addition to oral prostheses such as implants may enhance these processes and help maintain or facilitate recovery of sensorimotor functioning in the elderly.     

Tumor microenvironment in oral cancer: novel approaches for immunotherapy

Squamous cell carcinoma of the head and neck (SCCHN), which arises from the squamous mucosal epithelium of the oral cavity, pharynx and larynx, is a major health problem in the US and other parts of the world, especially in developing countries.     

CBCT与RVG对下颌恒切牙根管形态评估的对比研究

目的:对比CBCT法与数字化X线成像法(RVG)对下颌恒切牙根管形态评估的差异。方法:对101颗离体牙进行唇舌向及近远中向数字化X线片拍摄和CBCT高清牙列模式扫描,对图像进行根管数目、Vertucci根管分型、根管钙化和根尖口开口位置的评估,并通过CBCT图像建立偏角度投照的三角函数模型,计算偏向投照的角度。结果:CBCT法显示有30颗为双根管,RVG近远中向投照显示有36颗为双根管,卡方检验显示对根管数目和Vertucci根管分型两种方法均具有显著性差异(P<0.05)。两种方法对根管钙化和根尖口开口位置的评估均不具有显著性差异。30颗双根管牙中下颌恒切牙唇舌向双根管的最大距离(LaL)在0~1.5 mm之间的,85.7%的为Vertucci III型,LaL在1.5~2 mm之间的,66.7%为Vertucci IV和V型。以根尖片上双根管显示距离为1 mm计算,LaL在1~2 mm之间的,偏向投照角度为26.6°~45.0°,LaL在0.1~1 mm之间的,偏向投照角度为45.0°~84.3°。结论:CBCT高清牙列模式扫描和RVG投照对于根管数目和Vertucci根管分型的评估具有显著性差异,对于根管钙化和根尖口开口位置的评估不具有显著性差异。LaL在1~2 mm之间时,偏角度投照的临床可操作性较强。     

Integrating other therapies with radiation for head neck cancer: search for optimal solution

Purpose: To review the role of concurrent chemoradiotherapy protocols with special emphasis on selection of appropriate chemotherapy drug, its timing and schedule with respect to radiation fractionation.     

牙槽骨再生正畸治疗伴牙槽骨缺损的成人错畸形远期疗效评价

目的：评价牙槽骨再生正畸治疗伴牙槽骨缺损的成人错畸形的远期疗效。方法伴牙槽骨缺损的成人错畸形3例,平均年龄29岁。经正颌-正畸联合会诊制订治疗计划,按照牙槽骨再生正畸及正颌-正畸联合治疗模式,分别进行系统治疗并随访2~3 a。结果3例患者均顺利完成治疗,面型及咬合关系获得良好改善;牙槽骨缺损区正畸牙移动到位且未见医源性牙周并发症,牙槽骨缺损区骨量增加明显且远期效果稳定。结论针对伴牙槽骨缺损的成人患者,牙槽骨再生正畸是一种较为理想的技术。     

Chemotherapy using new superselective intra-arterial infusion for advanced oral cancer

Purpose: We developed a new method of superselective intra-arterial infusion via the superficial temporal artery (HFT method: Hattori, Fuwa and Tohnai reported) and preoperatively performed daily concurrent radiotherapy and chemotherapy with docetaxel (DOC) and cisplatin (CDDP) using this method for 46 patients with stage Ⅲ, Ⅳ oral cancer.     

Navigation-guided oral and maxillofacial surgery (reconstructive and plastic, orthognathic, oncology)

Purpose: Advance in the field of compeer assisted surgery enables the surgical procedures to be less invasive and more accurate for the support of diagnosis imaging, pre-operative simulation and intraoperative navigation.     

Clinical evaluation of demineralized bone allograft in a hyaluronic acid carrier for sinus lift augmentation in humans: a computed tomography and histomorphometric study

OBJECTIVES: Natural and synthetic graft materials are used routinely in sinus floor augmentations to help support implants in atrophic maxillary ridges. This clinical study was based on the hypothesis that the clinical effectiveness of demineralized freeze-dried bone allograft/demineralized bone matrix (DFDBA/DBM) in sinus lifts varies when used in combination bone graft substitute materials. To test this hypothesis, DFDBA was used together with one of three materials: in saline plus anorganic bone (DFDBA: Bio-Oss; in hyaluronic acid (DFDBA: HY, 32 : 68, w/w; DBX alone; DBX plus Bio-Oss; and DBX plus tricalcium phosphate granules (beta-TCP). MATERIAL AND METHODS: Thirty-two sinus lift procedures, eight per group, were performed on 26 patients. Before surgery and at 8 months post-surgery when implants were placed, ridge heights were visualized by computed tomography (CT) and measured by morphometric analysis. Cores of bone were removed by trephine at the sites of implant placement; these biopsies from the graft sites were used for histomorphometric analysis. RESULTS: All 32 sinus lift elevations were successful when measured by CT, increasing from an average 2.84+/-0.2 mm before treatment to 15.2+/-0.6 mm after treatment. The percent of each biopsy that was occupied by new bone and incorporated bone graft materials varied with each treatment: DFDBA+Bio-Oss, DBX+Bio-Oss, or DBX alone was higher than that for DBX+beta-TCP by approximately 10%. When comparing only newly formed bone, DBX+beta-TCP treatment resulted in 50% less bone than the other three preparations. All grafted sites received implants as per the treatment plan for each patient. CONCLUSIONS: This study confirmed the hypothesis that new bone formation is dependent on the DFDBA formulation used and demonstrated that DBX, alone or in combination with other materials, can be used successfully for sinus floor elevation.