上颌总义齿(牙合)干扰时基托有限元应力分析

目的:对上颌总义齿腭部基托各部位进行有限元应力分析,探索基托断裂的生物机械力学和结构力学的特性.方法:采用Ansys大型结构分析软件,通过上颌总义齿的实体建模及电子计算机运算,根据各牙实测数据,在不同牙位进行加载,加载方法是采用(牙合)力传感器的测力面对准被测各牙(牙合)面,加载力是根据各牙实测数据.结果:对上颌总义齿右上第一磨牙中央窝造成干扰后,与平衡(牙合)比较,从整个基托来看,应力应变都有明显增加.结论:基托的切牙乳突区为高应力区,右侧腭基托特别是腭中线右侧基托的应变与应力均大于左侧(P<0.01),为义齿维修提供力学近似值参考依据.     

上颌总义齿咀嚼侧干扰时的基托应变分析——微机电测应变实时分析系统的建立及应用

本研究目的在于建立微机应变实时分析系统，可较快速精确自动地实时测定咀嚼运动中上颌总义齿基托各点应变值。选总义齿病人１０例。对上颌总义齿咀嚼侧牙合干扰时的基托应变进行比较研究。为临床修复工作了解义齿基托折断的原因提供理论参考。结果说明：咀嚼侧有无牙合干扰具有不同的应变特征。非平衡咀嚼时其应变值大于衡牙合。非平衡牙合及由此伴发的基托不稳定是引起基托折断的重要因素之一。     

上颌总义齿的力测定及分析

为了进一步了解上颌总义齿基托纵折的有关因素,以及用有限元法探讨上颌总义齿基托及其支持组织应力分析所需的加载数据,有必要对上颌总义齿患者作(牙合)力测定。本文对60例上颌总义齿复查病例,进行了上颌总义齿的(牙合)力测定,为临床科研提供了切合实际的(牙合)力数据。     

电测法测量上颌总义齿基托中线区的应变变化规律

目的观察上颌总义齿基托中线区在咬合平衡及非平衡时的应变变化规律。方法采用口外电测应变法,在固定载荷下记录咬合干扰前后义齿基托中线上各点应变值的变化,并进行统计分析。结果咬合平衡及非平衡时最小应变值均位于基托中部附近,前部最大;非平衡胎时应变值明显大于平衡胎时的应变值。两组数据之间呈高度正相关。结论上颌总义齿基托由前向后应力逐渐减弱,非平衡殆时整个基托应力、应变的重新分布呈不均匀性。     

锤造网状金属结构在上颌总义齿中的应用

上颌总义齿断裂原因很多,除了人造牙排列不当、咬(牙合)关系不平衡、基托过簿或组织面不密合外,主要是(牙合)力超过塑料本身的抗折能力所致。笔者应用锤造白合金片网状结构埋入塑料基托内,提高了义齿基托的抗折能力。经过58例病人3～5年的随访观察,未发现1例折断发生,修复效果满意。     

咀嚼运动各阶段中上颌总义齿基托应变的比较研究

目的：对咀嚼运动各阶段中平衡He与非平衡He时上颌总义齿基托的张应变与压应变进行研究,对数据处理分析方法进行改进,对基托折断原因进行下一步的了解。方法：采用微机化动态电阻应变仪,测定应变值。并获取时间－应变曲线。结果无论平衡He与非平衡He,咀嚼的前期阶段的应变均大于后期阶段（P＜0．01）。在平衡He时左右侧腭斜坡的张、压应变基本相等（P＜0．05）。在左侧第一磨牙造成He干扰时,右侧腭斜坡为张应变,而左侧腭斜坡为压应变,腭基托中线前部的应变大于其他各部（P＜0．01或0．05）。结论：在义齿修复中平衡He是一个重要问题,是上颌总义齿基托折断最重要的原因之一。非平衡He时咀嚼花生米前期阶段腭中线前部为应变集中区,该区易发生折断。     

上颌全口义齿(牙合)面形态对基托应力分布的影响

目的:探讨异常牙合面形态对上颌全口义齿基托应力分布状况的影响。方法:建立正常形态、舌尖磨耗及颊尖磨耗三类不同牙合面形态的上颌全口义齿及其支持组织的三维有限元模型,在全牙列加载下分析基托内应力分布状况。结果:Ⅰ类模型(正常牙合面形态),基托呈现前牙区和后牙区应力均衡分布趋势;Ⅱ类模型(舌尖磨耗)整个中线区均为高应力值区,随牙尖斜度增大,中线区集中趋势愈加明显;Ⅲ类模型(颊尖磨耗),始终呈现基托前部应力集中。结论:异常的牙合面形态可能对上颌全口义齿基托的应力分布状况有明显的影响作用。提示临床行上颌单颌全口义齿修复时,应考虑患者对颌天然牙列的牙合面磨耗形态,必要时先进行下颌牙列异常牙合面形态的调整后再行上颌总义齿的修复。     

热凝MMA全口义齿基托折断原因分析及处理

热凝甲基丙烯酸甲酯(Heat Curing Merhacry-late MMA)义齿基托折断是全口义齿修复中的一个十分常见问题,其折断原因有生理、咀嚼、制作,材料等因素。近年来很多学者对全口义齿基托折断采用有限元法、光弹法、电测法、激光全息干涉会、碎漆法进行研究,分析基托断裂原因,为临床修复提供预防措施。 一、热凝MMA全口义齿基托折裂的原因 1.生理因素:张少锋等人用三维有限元方法,对上颌全口义齿及其支持组织在正中垂直(牙合)力下进行应力和位移分析。实验证明较大的压应力作用于牙槽嵴上。特别是前牙和前磨牙区。认为造成无牙颌后牙槽嵴吸收明显,及前牙区出现纤维性松软牙槽嵴是戴全口义齿后受力结果。同时,在切牙乳头,腭隆突、腭皱襞的压力也大,此外覆盖的粘膜较薄,易形成支点,其托翘动造成基托折断。 久戴义齿的患者由于牙槽嵴进行性生理性吸收,使基托组织面与口腔粘膜不贴合,当义齿行使功能时产生支点,基托翘动造成基托正中折断。 2.咀嚼力:Craig采用三维光弹分析全口义齿受力情况。近来,李国珍采用光弹法模拟唇系带切迹,在静态和动态条件下,加载观察基托受力情况。发现上颌全口义齿不同唇系带切迹形状可造成不同的应力集中,“V”型切迹最大(7级条纹)、“U”型切迹最小(4级条纹),在双尖牙为高应力区。     

上颌总义齿不同牙位干扰时基托应变的比较研究

目的：在上颌总义齿不同牙位干扰时，对基托中线的应变变化进行比较研究。方法：采用口外静态电测应变法，分别在平衡及正中干扰非平衡状态下测量基托中线各点应变值。干扰点依次分别定位于两侧第一前磨牙和第二磨牙上。结果：不同牙位干扰点所产生的四组应变值之间无显著性差异，但都明显高于平衡时应变值。沿基托中线：前部的应变均大于后部。结论：就对义齿基托的破坏力而言，有无干扰比干扰点的具体部位更为重要。     

基托折断口内修理法

总义齿基托纵折,可摘部分义齿基托折断或裂开,如基托组织面没破坏,义齿正中(牙合)时牙尖锁结良好者,可在口腔内进行修理。修理时口腔粘膜应无炎症,涂50％甘油于承托区粘膜上,而后将基托折断线两侧的磨光面制备成45°的斜面,并在斜面上作鸠尾扣,勿破坏基托     

Oral cancer: molecular technologies for risk assessment and diagnosis

Purpose: The effective biomarkers related to diagnosis, metastasis, drug resistance and irradiation sensitivity of oral cancers will help the pathologist and oncologist to determine the molecular taxonomy diagnosis and design the individualization treatment for the patients with oral cancers.     

Stimulated whole saliva components in children with Down syndrome

The authors report on the components of stimulated whole saliva from children with Down syndrome—including pH, flow rate, sialic acid and protein concentrations, and amylase and peroxidase activity. Saliva samples were collected from 35 children aged 6–10 years. Of the participants, 17 had Down syndrome and 18 did not. To stimulate saliva production, the children chewed a piece of parafilm for 10 minutes before the sample was collected. Soon after collecting the saliva sample, the authors measured pH using a portable pH-meter. Sialic acid levels were determined with a thiobarbituric acid assay. Protein content was determined with Folin's phenol reagent. Amylase was assayed and the authors measured the maltose produced by the breakdown of starch and peroxidase using ortho-dianisidine.
No statistically significant difference was observed in levels of sialic acid (free and total) between the two groups. Protein concentration was about 36% higher in the group with Down syndrome. However, the salivary flow rate, pH, and amylase and peroxidase activities were lower among the children with Down syndrome.     

柠檬精油对牙周致病菌抑制作用及其安全性初步研究

目的:探讨柠檬精油对牙周致病菌的体外抗菌活性及对细胞增殖的影响。方法:采用微量液体稀释法测定柠檬精油对Pg、Fn、Aa、Pi的最小抑菌浓度(minimal inhibitory concentration,MIC)及最小杀菌浓度(minimum bactericidal concentration,MBC);以较低浓度的MIC为标准稀释LEO作为实验组,采用MTT法测定柠檬精油对HUVECs的毒性作用,明确抑菌浓度下LEO的安全性。结果:柠檬精油对牙周主要致病菌均有抑菌作用,Pg、Fn、Aa、Pi的MIC分别是9.0 g/L、4.5 g/L、4.5 g/L、9.0 g/L,Aa、Fn的 MBC是9.0 g/L,Pg、Pi的MBC未测得。1/2MIC、1/20MIC浓度的LEO能够抑制人脐静脉内皮细胞的生长,而低于1/200MIC浓度的LEO则对人脐静脉内皮细胞的生长没有影响,其中1/200MIC浓度的LEO作用明显优于0.02%的CHX。结论:体外环境中,柠檬精油对牙周致病菌Pg、Fn、Aa、Pi具有抗菌活性,低浓度应用对机体相对安全。     

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.     

Computer-assisted planning for maxillofacial prosthodontic rehabilitation

Computerized tomography (CT) planning and the use of CT derived surgical templates for implant placement have shown promise for restoring function within months after surgical reconstruction of acquired post-oncologic defects.     

牙髓再生的研究现状

目前,根管治疗术在临床上已得到了广泛的应用并成功的保存了患牙,但其仍有许多术后并发症。随着组织工程技术在口腔领域的应用,构建一种组织工程化牙髓进行牙髓-牙本质复合体的再生治疗成为可能。近年来国内外已有很多关于牙髓再生的研究,并且已经取得了一定成果。本文将对目前国内外牙髓再生的研究进展现状作一综述。     

Effect of Pingyangmycin on human venous malformation endothelial cells

Purpose: Venous malformations are common vascular anomalies with a propensity of the head and neck. Intralesional injection of Pingyangmycin (PYM, bleomycin A5 hydrochloride) is a widely used sclerotherapy method for the treatment of venous malformation.     

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.