牙齿组织自体荧光光场仿真分析

利用有限元数值方法对扩散方程进行求解,将激发光场作为荧光传输扩散方程的光源,获得了二维牙齿模型内部自体荧光光场的分布。讨论了牙釉质和牙本质不同散射系数时牙齿上表面的荧光能量分布。发现牙齿上表面荧光能量随牙釉质散射系数的增大而降低,随牙本质散射系数的增大而增大。并对牙釉质和牙本质的散射系数的改变量对荧光能量的影响进行了定量分析,结果表明βe=2.62,βd=0.0502,牙釉质散射系数的改变对荧光能量的影响远远大于牙本质。利用Monte Carlo随机统计方法对牙齿组织自体荧光进行仿真,发现与有限元结果吻合较好,验证了有限元求解组织体荧光光场分布的正确性。     

牙齿洁白产品体外灌流过氧化氢缓释量及其动态变化测定方法的研究

为保证牙齿洁白产品在漂白使用过程中的安全性 ,需建立一种合理的装置和简便的方法来测定该产品的过氧化氢释放量。针对洁白牙贴的使用特点及过氧化氢缓释特性 ,设计了一种体外灌流装置 ,研究了分光光度法测定产品缓释过氧化氢的动态过程。考察了过氧化氢含量测定方法及灌流装置的有效性 ,并应用于几种产品的过氧化氢缓释量测定     

能修补龋齿的牙膏

日本东京FAP牙科研究所的科学家K.Yamagishi和他的合作者最近制造了一种人造牙釉,可以方便地用于修补牙齿上的蚀痕,而蚀痕的出现通常是牙齿损坏的开始。因为这时的孔洞一般小于50μm,常用填充材料不容易附着,牙医只好用钻孔或者用氟化物淋洗患处等处理方法来解决填充材料附着的     

上尖牙远中移动施力方式的光弹性研究和临床实践

本文利用三维光弹性冻结切片法，研究了在各种不同施力方式下，牙周组织的应力分布规律。研究对象是我国１２～１５岁儿童牙齿。光弹模型采用了牙齿、牙周膜和牙槽骨的组合式模型。得出了施加一个水平力的同时再加一个力偶为最佳施力方式，在正畸矫治中它能使牙齿产生较快整体移动的效果。临床实践证明该方法可行疗效显著。     

3D FINITE ELEMENT ANALYSIS OF THE DAMAGE EFFECTS ON THE DENTAL COMPOSITE SUBJECT TO WATER SORPTION

The damage effects of water sorption on the mechanical properties of the hydroxya-patite particle reinforced Bis-GMA/TEGDMA copolymer (HA/Bis-GMA/TEGDMA) have been predicted using 3D finite cell models. The plasticizer effect on the polymer matrix was considered as a variation of its Young's modulus. Three different cell models were used to determine the influence of varying particle contents, interphase strength and moisture concentration on the debonding damage. The stress distribution pattern has been examined and the stress transfer mode clarified. The Young's modulus and fracture strength of the Bis-GMA/TEGDMA composite were also predicted using the model with and without consideration of the damage. The former results with consideration of the debonding damage are in good agreement with existing literature experimental data. The shielding effect of our proposed model and an alternative approach were discussed. The FCC cell model has also been extended to predict the critical load for the damaged and the undamaged composite subject to the 3-point flexural test.     

牙齿化学

本文从化学的角度,介绍牙齿的结构及牙病的化学机理,从而提出牙齿疾病的化学防治和化学保健。     

我国口腔生物力学研究进展与展望

本文综述了我国口腔生物力学研究现状、研究手段、达到的水平以及临床应用状况、并作了展望。      

坚硬食物更益于牙齿

当人们提到"用进废退"时,通常不会想到牙齿。然而在过去的几百年中,一种特殊的牙齿磨损正在不断增加。一项最新研究表明,今天的软嫩、精制食物对牙齿反而有害——85%的牙科患者都有非龋性牙颈部损害(noncarious cervical lesions)或龈线处的楔形损伤。尽管这种损伤并不总是困扰     

THE INFLUENCE OF SHRINKAGE AND MOISTURE DIFFUSION ON IDEALIZED TOOTH STRUCTURE INVOLVING DEBONDING DAMAGE

This study highlights the joint effect of early polymerization shrinkage and longtermmoisture diffusion on the behavior of the restoration-tooth structure. The interphase debonding between particle and polymer resin in dental composite is taken into account by introducing the damage variable. The idealized model is designed and constructed for representing the restorationtooth structure, which consists of enamel, dentin, composite and interphase, each considered as homogenous material. The simulation is carried out using the general-purpose finite element software package, ABAQUS incorporated with a user subroutine for definition of damaged material behavior. The influence of Young‘s moduli of composite and interphase on stress and displacement is discussed. The compensating effect of water sorption on the polymerization shrinkage is examined with and without involving damage evolution. A comparison is made between the influence of hyper-, equi- and hypo-water sorption. Interfacial failure in the specific regions as well as cuspal movement has been predicated. The damage evolving in dental composite reduces the rigidity of composite, thus in turn reducing consequent stress and increasing consequent displacement. The development of stresses at the restoration-tooth interface can have a detrimental effect on the longevity of a restoration.