Er-YAG激光在牙体硬组织中的应用

随着科学技术的进步,激光技术正以惊人的速度向前发展。激光具有许多优异的性能,已被应用到人类生活的各个领域。伴随激光医学的进展,近来在口腔医学方面的研究已逐步开展起来,除了应用于口腔软组织处理外,激光用于牙体硬组织也得到了越来越多的关注。其中Er-YAG激光在口腔领域的实用性和安全性已得到多方面的认证。该文就激光在口腔医学特别是牙体硬组织中的应用作一综述。     

Er-YAG激光在口腔软组织中的应用

随着科学技术的进步,激光技术正以惊人的速度向前发展。自激光引入口腔治疗中以来,被广泛的应用于口腔硬组织中。由于激光杀菌、消毒等特性研究的广泛报道,近来激光应用于口腔软组织也得到了越来越多的关注。其中Er-YAG激光在口腔领域的实用性和安全性已得到多方面的认证。该文就激光在口腔医学特别是软组织中的应用作一综述。     

Er,Cr:YSGG激光在口腔医疗中的应用研究进展

Er,Cr:YSGG激光是新一代水动力生物激光系统,其特性和优势正在口腔医疗的应用中越来越受到关注,该文对Er,Cr:YSGG激光对于牙体组织的去龋能力、清除玷污层和蚀刻作用以及对于牙周病变牙根表面的杀菌、去除菌斑和牙石的能力等方面的研究进展进行综述。     

激光和生物组织的光热作用及临床应用

激光和生物组织的光热作用机理及在临床上的应用作了全面的论述,同时建立了一个定量描述光热作用的模型。讨论了光热作用中热产生,传导及热效应。     

激光在医学中的应用

本文叙述了几种激光器的优点及其在医学中的应用。它们在治疗过程中的应用方法有很多种,并且还存在有更多种类的激光器,这里选择叙述的是医生和专家常应用的。随着科技的发展,激光技术在医学中的应用将会越来越成熟,旧的激光器也将会被淘汰,越来越先进的激光器一定会问世。本文还将叙述激光的基本理论,以及不同手术中所采用的激光应用技术。     

铥激光在泌尿外科中的应用及进展

铥(Tm)激光是一种新型的医用激光技术,波长范围为1.75μm-2.22μm.铥激光技术具有操作简单安全、损伤小、止血快、精度高等优点,近些年来在泌尿外科中得到快速发展和广泛应用.本文介绍了铥激光的作用原理及优点,回顾了近些年铥激光在泌尿外科领域的各种应用,分析了铥激光在泌尿外科的发展方向及应用前景.     

K T P 绿激光在医学临床中的应用

激光自被应用于医学,临床以来,科学家对其进行了多方面研究,并根据其特性,分别应用于医学诊断与治疗。随着科学技术的发展,在医学领域中应用的激光种类也越来越多,特别是KTP绿激光的多学科应用。为医学临床提供了新的治疗方法。本文就激光的特性、KTP绿激光的发展及医学,临床应用做一简要概述。     

激光照射血液疗法中的组织光学研究及其应用

本文从组织光学的角度 ,对激光照射血液疗法中的发展现状与存在问题进行分析 ,提出该领域应开展的若干研究内容。本文开展了激光照射血液疗法所涉及的若干组织光学研究。获得了中国人血液的吸收系数、散射系数、各项异性因子、全衰减系数等 ;研究获得了人血管的若干光学参数。通ＭｏｎｔｅＣａｒｌｏ模拟计算 ,以及实验测试结果 ,分别从理论与实际上分析对比了激光血管内照射时 ,光在人体血管、血液中的分布情况 ,以及不同的激光入射角 ,发散角 ,不同的血管直径等因素对激光血液照射的影响。根据对应的组织光学的研究结果 ,文中还讨论并提出…     

Anisotropy in hard dental tissues

The critical angle reflection technique was used to determine longitudinal and shear sonic velocity components in the exposed surface of bovine incisors along the tooth axis and perpendicular to it. By grinding a flat on the tooth surface successive layers were exposed and the velocity components measured. Plots of the velocity variation with depth were prepared which show some variation in the enamel, much less in the dentine and a sharp drop at the dentino-enamel junction. Strong evidence of anisotropy is demonstrated, especially in enamel.

The longitudinal velocity component is larger than previous values for measurements through these hard tissues. Hydroxyapatite and bone models assuming hexagonal symmetry indicate that the surface velocity should be the smaller component. The Katz hexagonally symmetrical bone model shows a significant dip in the velocity along the 45° propagation direction. If it is assumed that prior measurements correspond to the 45° rather than the c-axis direction, a set of elastic constants can be calculated which are an estimate for enamel and dentine. These resemble the Katz bone model.

Enamel C₁₁ 115, C₁₂ 42·4, C₁₃ 30, ₃₃ 125, C₄₄ 22·8

Dentine C₁₁ 37, C₁₂ 16·6, C₁₃ 8·7, C₃₃ 39, C₄₄ 5·7

Katz bone model C₁₁ 31, C₁₂ 14·7, C₁₃ 11·3, C₃₃ 33, C₄₄ 6·2

(all × 10⁹N/m²)

Poisson's ratio for enamel is estimated to be 0·28 and for dentine 0·32.     

A new technique for hard tissues

Fossil tissues generally require specialized processing. Most thin sectioning techniques yield unstained sections or require unwieldy methods to produce stained sections. I outline here two simple techniques for producing stained, ground, thin sections using readily available Romanowsky-type cytology stains and a urine sediment stain. Results are comparable to hematoxylin and eosin stained specimens.     

Electron microscopy of resorbing surfaces of dental hard tissues

Summary The resorbing surfaces of exfoliated or extracted human deciduous molar teeth were studied directly in the scanning electron microscope and indirectly by a single stage carbon replica technique for the transmission electron microscope. Some specimens of resorbing bone were also examined. Some of the material was examined after a simple washing process and some after removal of the organic matrix with hot 12 diamino ethane.The typical crossbanding of collagen could be seen on resorbing cement and dentine surfaces. This is taken as an indication that demineralisation is the first step in resorption. The very highly mineralised peritubular dentine remained proud of the resorbing surfaces thus indicating that its mineral component is in some way selectively protected.Enamel prism sheaths were also found to be selectively resistant to resorption and this is assumed to be related to the protection of the mineral component in these regions by their higher and/or different organic content. No prism sheaths were found next to the enamel-dentine junction and there was only a slight step down from the enamel to the dentine.Large remineralization crystals were found located at the borders between adjacent Howship's lacunae.The natural resorbing surfaces were compared with surfaces subjected to purely physical erosion by 5 keV argon ion beam bombardment (Boyde and Stewart, 1962).Our thanks are due to Mr. A.D.G. Stewart for permission to publish Fig. 5, which was prepared by him. The Cambridge Instrument Company Stereoscan scanning electron microscope was provided by the (U. K.) Science Research Council.     

Caspase‐7 participates in differentiation of cells forming dental hard tissues

Apoptosis during tooth development appears dependent on the apoptotic executioner caspase‐3, but not caspase‐7. Instead, activated caspase‐7 has been found in differentiated odontoblasts and ameloblasts, where it does not correlate with apoptosis. To further investigate these findings, the mouse incisor was used as a model. Analysis of caspase‐7‐deficient mice revealed a significant thinner layer of hard tissue in the adult incisor. Micro computed tomography scan confirmed this decrease in mineralized tissues. These data strongly suggest that caspase‐7 might be directly involved in functional cell differentiation and regulation of the mineralization of dental matrices.     

The effect of mechanical strain on soft (cardiovascular) and hard (bone) tissues

Mechanical stress plays a pivotal role in developing and maintaining tissues functionalities. Cells are constantly subjected to strain and compressive forces that are sensed by specialized membrane mechanosensors and converted in biochemical signals able to differently influence cellular behavior in terms of surviving, differentiation and extracellular matrix remodeling. This review focuses on the effects of mechanical strain on soft and hard tissues.

Unexpectedly, different cells share almost the same membrane mechanosensors and the relative intracellular pathways, but to ultimately obtain very different biological effects. The events occurring in cardiovascular and bone tissues are treated in details, showing that integrins, cadherins, growth factor receptors and ions channels specifically expressed in the different tissues are the major actors of the sight. However, MAPkinases and RhoGTPases are mainly involved in the biochemical intracellular signaling directed to nuclear modifications.