食醋对乳牙牙釉质组织和形态学改变的研究

目的观察食醋处理离体乳牙不同时间点对釉质组织和形态学的改变。方法采用体视显微镜、偏光显微镜和扫描电镜观察食醋涂擦釉质后釉质表面超微结构和组织学改变。食醋处理为37℃,每天10次,每次5 min,设去离子水为对照组。结果体视显微镜观察表明,对照组未见釉质脱矿,实验组24 h后釉质有轻度改变,随时间延长,釉质表面组织缺损依次严重。偏光显微镜观察磨片浸喹啉后脱矿区呈负性双折射,而浸水呈正性双折射。扫描电镜观察脱矿从晶体中心逐渐向周围扩展。结论食醋可使乳牙牙釉质脱矿。     

不同浓度漂白剂对牙釉质表面微观形态影响的实验研究

目的研究4种常见的漂白方法对离体牙釉质表面微观形态的影响,为临床应用提供实验依据。方法以离体人牙为研究对象,建立离体牙漂白模型,通过扫描电子显微镜、激光共聚焦显微镜等手段,观察4种漂白方法作用后对牙釉质表面微观形态的影响,分析比较牙釉质表面粗糙度的变化情况。结果 7d和14d时,扫描电镜观察各漂白剂处理组釉质表面微观形态较空白对照组均有改变,而且可以观察到釉质脱矿的典型结构。含氟漂白剂虽然在一定程度上有稳定釉质结构的作用,但是延长漂白剂的作用时间仍会加重釉质理化性能的改变。结论目前临床常用的牙齿漂白剂均会改变牙釉质表面的微观形态,使表面粗糙度增加,因此在临床中应加强患者牙齿漂白后再矿化的保护措施。     

牙釉质微观结构的研究进展

牙釉质是人体内矿化程度最高的组织,具有很高的硬度和耐磨性能,这些都与其特有的微观结构密切相关。在人类对牙釉质的研究过程中,研究者们用各种技术方法去阐明人牙釉质的结构特征,如使用偏光光镜、X射线衍射观察釉质组织结构,高倍率电子显微镜对釉柱晶体的观察,原子力显微镜对牙釉质结构纳米范围的扫描,飞行时间二次离子质谱仪研究牙釉质结构内元素成分随结构分布的变化。这些研究对重新认识牙体组织疾病、研制修复     

组合酸不同酸蚀时间对氟斑牙正畸托槽粘接强度的影响

目的:观察组合酸不同酸蚀时间对新鲜离体氟斑牙牙釉质超微结构的影响,寻找增强氟斑牙托槽粘接强度的方法。方法:选择5颗正常恒牙,用37%的磷酸酸蚀作为对照组。将中、重度氟斑牙25颗随机分为5组,用同一组合酸进行酸蚀,时间分别为1、2、3、4和5min,酸蚀后粘接托槽,24h后测定托槽的抗剪切强度,并通过扫描电镜观察去除托槽后树脂-牙釉质界面形态学改变。结果:对照组抗剪切强度为(3.33±2.03)MPa,氟斑牙酸蚀时间1～5min组抗剪切强度分别为(7.81±1.04)MPa,(10.71±2.96)MPa,(5.87±2.70)MPa,(4.02±1.86)MPa,(4.05±2.27)MPa。除氟斑牙酸蚀2min组与对照组比较差异无统计学意义(P>0.05),其余各组与对照组比较差异均有统计学意义(P<0.05)。除氟斑牙酸蚀1min时牙釉质超微结构改变不明显,酸蚀2min时有较明显的蜂窝状改变,随酸蚀时间延长釉质结构溶解破坏增多。结论:组合酸酸蚀氟斑牙2min可获得较理想的粘接强度和形态变化。     

氟涂料与GC护牙素在牙矫正治疗中釉质脱矿预防效果的对比研究

目的：对比氟涂料与GC护牙素在对牙矫正治疗中釉质脱矿的预防效果。方法随机选择2011年10月—2014年5月巴中市中心医院行固定矫正治疗的患者110例按就诊时间分为观察组(56例,1380颗牙)与对照组(54例,1083颗牙),观察组予GC护牙素处理,对照组予氟涂料处理。观察两组牙矫正治疗前和治疗后1年牙釉质脱矿情况。结果矫正治疗前对照组牙釉质脱矿率为3.23%,观察组为3.77%,两组差异无统计学意义(P>0．05)。矫治治疗后对照组牙釉质脱矿率为8.33%,观察组为4.78%,两组差异有统计学意义(P<0．05)。矫治治疗后两组牙釉质脱矿率均有所上升,且对照组矫正治疗后牙釉质脱矿率明显高于矫正治疗前(P<0．05),观察组矫治前后釉质脱矿率比较差异无统计学意义(P>0．05)。结论 GC护牙素与氟涂料相比可更好地预防牙矫正治疗中釉质脱矿,是改善牙矫正治疗后牙外观和促进患者口腔健康的重要措施。     

氟保护漆对托槽粘接及釉质脱矿影响的研究

目的：探讨采用牙面涂布氟保护漆预防正畸治疗过程中釉质脱矿的可行性。方法：选取临床采用固定矫治的患者30例,采用自身对照的方法分为实验组（282颗牙齿）和对照组（276颗牙齿）,实验组和对照组都采用临床常规材料粘接托槽,实验组粘接托槽后,用氟保护漆涂布牙面。观察两组牙齿12个月内的托槽脱落次数以及釉质脱矿情况。结果：实验组抗釉质脱矿能力强于对照组,但托槽脱落次数与对照组无显著性差别。结论：用氟保护漆预防口腔正畸治疗中的牙釉质脱矿具有可行性,值得临床推广应用。     

冷光美白治疗重度氟斑牙1例

<正>氟斑牙是在牙齿发育矿化时期,人体摄入过量的氟导致的慢性中毒。重度氟斑牙的表现为牙釉质出现白垩色改变,有釉质缺损,表面有黄褐色色斑。该病严重影响患者的美观,甚至对患者的心理造成不良的影响。采用漂白治疗,可以美     

不同方法去除正畸牙面黏接剂残留情况比较

正畸治疗后经过酸蚀粘接处理后的牙面釉质表层会形成树脂突和牙釉质的混合层,造成牙面不同区域折光性能的差异,影响牙齿美观.本试验采用不同方法处理去除托槽后的牙面,并用反射光显微镜观察牙面粘接剂的残留情况,比较不同方法处理牙面的效果.     

光固化复合树脂修复前牙及双尖牙结构异常临床疗效观察

釉质发育不全,氟斑牙,四环素牙是临床上常见的影响前牙美观的疾病。自1994年以来,笔者采用光固化复合树脂修复前牙及双尖牙釉质发育不全77例,现将此方法治疗后1～3年复查的450颗牙的临床资料分析总结如下。     

牙釉质粘合树脂中的釉质涂剂脱敏治疗的临床研究

目的探讨牙釉质粘合树脂中的釉质涂剂对牙本质过敏脱敏治疗的可行性及临床治疗效果。方法用牙釉质粘合树脂中的釉质涂剂对24例78颗牙齿[牙合]面及26例40颗牙颈部无明显缺损的牙本质过敏区域进行涂擦,最多涂擦4次,观察涂擦后的即刻有效率和即刻治愈率。结果用牙釉质粘合树脂中的釉质涂剂对50例患者118颗牙齿的[牙合]面及牙颈部无明显缺损的过敏区域进行涂擦后,即刻有效率为100％,即刻治愈率为90．7％。结论用牙釉质粘合树脂中的釉质涂剂对牙齿[牙合]面及牙颈部无明显缺损的过敏区域进行脱敏治疗是可行的,有效的。     

食醋导致乳牙牙釉质超微结构改变的研究

目的研究食醋对乳牙牙釉质的超微结构的作用。方法采用微量化学分析法检测食醋处理乳牙牙釉质后食醋中钙含量的变化。采用维氏显微硬度仪测定经食醋涂擦后乳牙牙釉质表面显微硬度的变化。结果食醋能导致乳牙牙釉质钙溶出和表面显微硬度下降,随时间延长钙溶出减少,表面显微硬度降低的程度减弱。结论食醋对乳牙牙釉质具有脱矿作用并可使釉质表面显微硬度降低。     

Influence of buffered and unbuffered acetylsalicylic acid on dental enamel and dentine in human teeth: an in vitro pilot study.

An in vitro study was conducted to investigate the erosive effect of buffered and unbuffered acetylsalicylic acid (ASA) on dental enamel and dentine in human teeth by scanning electron microscopy. In order to standardize the specimens and to improve comparability the dental enamel and dentine were superficially abraded. The enamel and dentine specimens were therefore particularly sensitive to the influences of acid agents. Concentrated solution of buffered chewable ASA tablets (500 mg ASA and 300 mg calcium carbonate in 5 ml water) showed no changes in the enamel surface structure after exposure times of 1 min, 5 min and 60 min. In contrast, minimal corrosive effects were already seen after exposure of the enamel surface to the unbuffered ASA solutions for 1 min. After exposure times of 5 min and 60 min erosion of the enamel was more pronounced. Immersion in the unbuffered ASA solution led to clearly visible micromorphological changes on the dentine surfaces even after exposure for 1 min. Exposure of the dentine specimens to the buffered ASA solutions led to only very slight changes in the surface morphology. Therefore, the scanning electron micrograph after exposure to buffered ASA is comparable to the picture of untreated dentine.     

Preparation and characterization of paclitaxel-loaded DSPE-PEG-liquid crystalline nanoparticles (LCNPs) for improved bioavailability

Lipid-based liquid crystalline nanoparticles (LCNPs) have attracted growing interest as a new drug nanocarrier system for improving bioavailability for both hydrophilic and hydrophobic drugs. In this study, self-assembled LCNPs based on soy phosphatidyl choline and glycerol dioleate, which was known possessing low toxicity and negligible hemolysis, were prepared using poly(ethylene glycol)-grafted 1,2-distearoyl-sn-glycero-3-phosphatidylethanolamine (DSPE-PEG) as the dispersing agent. Paclitaxel (PTX) was used as a model hydrophobic drug. The particle size of the optimized DSPE-PEG-LCNPs and PTX-loaded DSPE-PEG-LCNPs were around 70nm. Crossed polarized light microscopy was used to characterize the phase behavior of liquid crystalline (LC) matrices, which showed a fan-like birefringent texture in dark background indicating the coexistence of reversed cubic and hexagonal phase in the optimized LC matrix. Transmission electron microscopy and cryo-field emission scanning electron microscopy revealed its internal water channel and "twig-like" surface morphology. PTX-loaded DSPE-PEG-LCNPs exhibited a biphasic drug sustained release pattern with a relatively fast release at the initial stage and a sustained release afterwards. PTX-loaded DSPE-PEG-LCNPs presented higher AUC (410.942±72.522μg/Lh) when compared with commercial product Taxol (212.670±41.396μg/Lh). These results indicated that DSPE-PEG-LCNPs might serve as a potential sustained release system for poorly water-soluble agents.     

Pseudoxanthoma elasticum--a fresh approach to morphogenesis using tannic acid fixation

A lesion of pseudoxanthoma elasticum at a very early stage was studied by light microscopy and electron microscopy using both tannic acid fixation and the conventional method of fixation. The observations strongly indicated that the primary morphological event arose from alteration in the composition of normal native collagen fiber by way of so-called "elastotically degenerated collagen". Deposition of calcium salts did not appear to initiate degenerative changes in the involved fibers, but merely accompanied the abnormally increased elastic fiber as a secondary phenomenon.     

N-甲基亚硝基脲诱导大鼠膀胱肿瘤动物模型的实验研究

目的 观察N-甲基亚硝基脲(MNU)诱导SD大鼠膀胱肿瘤的作用及动态过程.方法 MNU大鼠膀胱灌注2 mg/次,1次/2周,共4次,光镜下对其诱发的膀胱肿瘤过程的不同时期进行动态观察.结果 膀胱灌注6周时有原位癌改变,8周时膀胱内有癌性肿块,10～12周发展为浸润性癌,组织学改变及病理学特征与人膀胱癌十分相似;12周大鼠膀胱癌模型的病理分期与6～10周相比较,其病理分期于第12周有统计学意义(P=0.038).结论 MNU灌注诱导大鼠膀胱癌方法简便、可靠、诱癌率高,是理想的肿瘤动物模型.     

三七对四氯化碳肝损伤小鼠的保护作用及形态学研究

目的：研究三七对CCl4肝损伤小鼠的保护作用及形态学变化。方法：采用CCl4复制小鼠肝损伤模型，测定血清丙氨酸氨基转移酶(ALT)、天门冬酸氨基转移酶(AST)、白蛋白(Alb)、计算A／G比值，并采用光镜、电镜观察组织学变化。结果：与CCl4模型组相比，用三七处理后，ALT、AST均显著降低，Alb增加，并能明显改善肝脏组织病理变化和超微结构变化。结论：三七对CCl4致小鼠肝损伤具有保护作用。     

Kanamycin induced ototoxicity in the laboratory rat

Two comparative experiments on the behavioural, audiometric and histological effects of kanamycin-induced cochleotoxicity in the Wistar rat are reported.In the first experiment kanamycin 400–1,500 mg/kg/day was injected subcutaneously for 20 days and the morphological damage to the organ of Corti assessed. In the second experiment the progression of damage to the organ of Corti was examined in animals given kanamycin 700 mg/kg/day for 4–20 days. Behavioural audiometric studies of threshold shift were undertaken throughout both experiments.In the first study, all the animals were killed after a recovery period of 20 days from the last injection, i.e., day 40, and in the second study groups of animals were killed at 4-day intervals between days 4 and 20 of dosing.One cochlea from each animal was critical point-dried, dissected to expose the organ of Corti and examined by scanning electron microscopy. A vertical section through the contralateral cochlea was examined by light microscopy. The results of the morphological examination of the cochleas were collated with the behavioural audiometry.The morphological damage to the organ of Corti followed a stereotyped pattern of degeneration, the extent of which appeared to be determined both by the number and concentration of the kanamycin administrations. The collateral audiometric examinations indicated that extensive damage had taken place before a shift in the behavioural auditory threshold could be detected by observation of the Preyer reflex.     

A co-doped 2D transition metal dichalcogenide system with the potential of having enhanced photocatalytic properties

Pristine and co-doped tungsten sulfide nanoparticles were successfully synthesized using hydrothermal method. These nanoparticles were characterized using microscopic and spectroscopic techniques. To determine morphological properties, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed. UV–Vis DRS was used to evaluate optical properties for light-harvesting measurements of nanoparticles. Assessing the rate of recombination of the photogenerated electrons and holes, electrochemical impedance spectroscopy (EIS) and photoluminescence spectroscopy (PL) were used. Band edge positions and respective shifts were determined from XPS including the chemical states of the dopants. The co-doping of rare earth metals on the pristine material proved to be light harvesting reducing the band energy gap energy by 0.05 eV of the pristine material resulting in a red shift. Amongst the prepared photocatalyst at different content, 3%Ce/Gd-WS₂ showed to have high photocurrent response, lower rate of recombination and lower charge transfer resistance indicating its potential as in photocatalytic applications such as water-splitting and water treatment.