人类高分子量唾液粘蛋白抗釉质脱矿的体外超微观察

唾液获得性膜是唾液蛋白对牙釉质表面的选择性吸附 ,是一层非发育性的无细胞结构的薄膜 ,具有屏障保护作用。人高分子量唾液粘蛋白 (ＭＧ1)对羟基磷灰石 (ｈｙｄｒｏｘｙａｐａｔｉｔｅ,ＨＡ)有高度亲和力而成为获得性膜的主要成分之一。我们采用全唾液和纯化ＭＧ1分别在离体牙釉质表面形成获得性膜 ,观察此膜是否能减少有机酸对牙釉质表面的脱矿作用。1.材料和方法 :实验分 3组。第 1组为ＭＧ1组 ,将纯化ＭＧ1按 0 16ｇ/Ｌ溶于 10 7ｍｍｏｌ/ＬＮａＣｌ溶液中 ;第 2组为全唾液组 ,将收集的全唾液 4℃离心 (4 0 0 0ｒ/ｍｉｍ ,15ｍｉｎ) ,…     

获得性膜蛋白成分的免疫生化分析

获得性膜是位于牙齿—唾液界面之间的一层无细胞的有机薄膜。其组成的差异可能引起细菌附着的差异，最终导致细菌聚集和菌斑形成的差异，从而影响龋病的发生和发展。本研究的目的就是探索获得性膜的蛋白组成。材料和方法１．唾液供给者的选择：选择８名唾液供给者，年龄均...     

表面活性剂与实验性获得性膜相互作用的体外研究

为了探索表面活性剂影响细菌对牙面粘附的机理，本文比较了５种表面活性剂与实验性获得性膜的相互作用，结果表明，实验用５种表面活性剂中，阴离子表面活性剂ＺｏｎｙｌＦＳＡ使吸附的唾液蛋白量明显增加，而其余４种阳离子表面活性剂能明显地移去吸附的唾液蛋白，本研究结果提示，表面活性剂与实验性获得性膜的相互作用与其所带的电荷有关，表面活性剂对获得性膜的影响是其菌斑的可能机理之一。     

高相对分子质量唾液粘蛋白保护牙釉质酸蚀脱矿的超微观察

目的 :观察人类高相对分子质量唾液粘蛋白 (MG1)及全唾液在体外形成的获得性膜能否减少有机酸在牙面的脱矿作用。方法 :采用MG1和全唾液溶液体外孵育釉质实验面以形成获得性膜 ,再以 3 4mmol/L枸橼酸处理釉质实验面 1min ,扫描电镜观察釉质表面形态的改变。结果 :有获得性膜区域釉质实验面相对平滑 ,基本无脱矿及轻微脱矿 ,可见正常釉质表面形态 ,无获得性膜区域则是蜂巢状大面积脱矿。结论 :MG1和全唾液形成的获得性膜能在短时间内减少有机酸对牙面的侵袭脱矿作用     

纯钛表面含氢类金刚石镀膜的实验研究

目的:观察纯钛表面不同修饰方法对提高表面润湿性及其与热凝树脂结合强度影响的效果。方法:制作5组纯钛试件,分别镀制含氢类金刚石膜、单纯类金刚石膜、TiN膜、阳极氧化膜以及空白对照组。采用接触角测定仪测量试件的接触角并计算表面自由能,使用万能材料试验机测量修饰后的试件与热凝树脂的结合强度。结果:含氢类金刚石膜的表面自由能与树脂的结合强度大于其余各组,TiN的表面自由能与树脂的结合强度最低,阳极氧化组与单纯类金刚石膜的应用,对于提高纯钛表面的润湿性和提高纯钛与热凝树脂结合强度作用不明显。结论:纯钛表面经含氢类金刚石膜修饰后,提高了表面润湿性和戴用舒适性,同时提高了与热凝树脂的结合强度。     

Charter刷牙法对桥体下牙槽嵴黏膜健康的影响

目的：评价Charter刷牙法局部口腔卫生维护对Co-Cr合金、Vita95瓷两种材料桥体下牙槽嵴黏膜健康的影响。方法：采用随机分组对照试验，要求实验组每天采用Charter刷牙法对桥体进行局部卫生维护，评价并分析实验组和对照组3个月后桥体下牙槽嵴黏膜炎症状况的差异。结果：实验组的炎症程度明显低于对照组，统计学相差显著。烤瓷和金属材料之间比较，在对照组两者对牙槽黏膜的影响有显著差异。结论：局部口腔卫生维护有利于保持桥体下黏膜的健康，而不同桥体材料对黏膜健康的影响在短期内并不显著。     

细菌对口腔内科常用修复材料的粘附

继发龋的发生与细菌对修复材料表面以及材料与洞壁之间的粘附和菌斑的形成有关。修复材料的表面可能形成获得性膜，这种膜的有机的、无机的化学组成，性质及形成速度不同。不同的修复材料表面形成的获得性膜，对细菌粘附的种类和数量完全不同，同时，获得性膜的粘附也具有高度的选择性。这与材料的理化性质和细菌的生物学特性有关，洞型的制备状况和修复体的光洁度也是重要的环境因素。     

粘性放线菌对牙面粘附机理的研究──Ⅰ．实验性全唾液获得性膜蛋白组份的分离纯化

采用羟基磷灰石柱层析形成实验性获得性膜的体外模型，研究全唾液获得性膜蛋白的组成成份。结合离子交换及分子筛层析分离获得８种获得性膜的蛋白成份。根据层析用谱、等电点、氨基酸组成及免疫扩散分析，其中６种可确定为富脯糖蛋白、淀粉酶、ＳＩｇＡ、酸性富脯蛋白、富酪蛋白及富组蛋白。实验结果表明唾液中的蛋白质选择性吸附到羟基磷灰石上，分离纯化的获得性膜蛋白为筛选促进致龋菌在牙面粘附的唾液蛋白受体提供了直接的研究材料。     

人类高分子量唾液粘蛋白抗釉质脱矿的研究

目的 :观察高分子量唾液粘蛋白 (MG1)是否具有抗釉质脱矿作用。方法 :以全唾液、腮腺唾液、颌下 舌下腺唾液和纯化的MG1对实验牙釉质表面进行体外孵育以形成唾液获得性膜 ,观察此膜抗釉质脱矿作用。结果 :全唾液组和腮腺唾液组只有 3 9.7%和 2 1.2 %的最大保护百分度 ,而颌下 舌下腺唾液组和纯化的MG1组能明显抑制脱矿作用 ,其最大保护百分度分别为 96.2 %和 84 .5 %。结论 :唾液获得性膜中的MG1可有效地保护牙釉质抵御有机酸对牙面的短暂脱矿作用。     

口腔修复材料界面对菌斑生物膜的影响

随着口腔医学的发展,各种口腔修复材料被广泛应用于临床治疗中。修复材料不同的表面结构及化学性质会对细菌的黏附定植以及生物膜的发育成熟产生一定的影响。在唾液环境中,虽然获得性膜可在一定程度上弱化不同材料界面的固有特性,但材料界面的某些特性仍能通过远程作用力穿透获得性膜并作用于微生物的初始黏附,从而影响生物膜的发生发展。在生物黏附早期,材料界面主要通过各种力学因素从而对微生物黏附产生影响。此外,修复材料还可通过化学物质的释放来影响生物膜的代谢。复合树脂、玻璃离子黏固剂、陶瓷材料和金属材料是口腔常见的修复材料,探讨常见口腔材料界面对生物膜的影响机制,可为口腔材料的改性研发提供理论支持。     

Thickness of acquired salivary pellicle as a determinant of the sites of dental erosion

Dental erosion shows a typical distribution pattern within the dental arches. Tooth protection from erosion by salivary pellicle has been shown in vitro, but the hypothesis that pellicle may differ quantitatively at sites of erosion has not been investigated. This study aimed to determine the thickness of acquired salivary pellicle within the dental arches, investigate the possible relationship of this thickness to the distribution and severity of erosion within the arches, and confirm the protective effect of pellicle against dental erosion. Eight enamel blocks were produced from each of 5 bovine incisors assigned to five volunteers. Each block was further cut into 2 slabs, producing control and experimental slabs. Pellicle developed on experimental slabs located on 8 intra-oral sites after 1 hr of exposure was stained by "sheep anti-human IgGAM-FITC". Slabs were then visualized, and pellicle thickness measured, by confocal laser scanning microscopy. Eroded enamel lesions were produced in experimental and control slabs by means of pure orange juice. The degree of erosion was quantified by transverse microradiography. Pellicle thickness varied significantly within the dental arches and among individuals. An inverse relationship (r = -0.96, p<0.001) was observed between the degree of erosion and pellicle thickness. Significant differences in erosion were observed between slabs with and those without pellicle. This study has shown that the thickness of acquired salivary pellicle varies within the dental arches, which may be responsible for the site-specificity of dental erosion, and that pellicle does protect the teeth from erosion.     

The effect of red wine in modifying the salivary pellicle and modulating dental erosion kinetics

This study investigated the potential of red wine in modulating dental erosion kinetics in the presence or absence of salivary pellicle. Polished human enamel specimens were used in two conditions; presence or absence of acquired enamel pellicle; and subdivided according to exposure: red wine, orange juice, apple juice, or citric acid. The specimens were incubated in clarified whole human saliva (presence of acquired enamel pellicle) or in a humid chamber (absence of acquired enamel pellicle) for 2 h at 37°C, then in the test substances for 1 min, at 25°C, under shaking. This was repeated four times. Surface hardness was measured initially and after each cycle and surface reflection intensity was measured initially and after all cycles. In the presence of acquired enamel pellicle, red wine caused the least surface hardness loss, followed by orange juice, apple juice, and citric acid. Statistically significantly less surface reflection intensity loss was observed for red wine and orange juice than for apple juice and citric acid. In the absence of acquired enamel pellicle, red wine and orange juice caused less surface hardness loss than apple juice and citric acid. Orange juice showed the least surface reflection intensity loss, followed by red wine, citric acid, and apple juice. The polyphenol composition of these drinks can notably modulate the erosion kinetics.     

Formation and photocatalytic decomposition of a pellicle on anatase surfaces

The acquired dental pellicle plays a critical role in the adhesion and detachment of dental plaque bacteria. It has been reported that titanium dioxide biomaterials decompose single-protein films by photocatalysis. However, it is not known whether this can also be achieved with complex structured pellicle films. This in vitro study investigated in real-time the formation and photocatalytic decomposition of human pellicle at anatase-saliva interfaces. Nanostructured polycrystalline anatase layers were deposited on titanium-coated quartz crystals by magnetron-sputtering, serving as a model for titanium implant surfaces. The quartz crystals were used as acoustic sensors in a quartz-crystal microbalance (QCM) system with dissipation. In situ UV irradiation of pellicle-covered anatase caused a statistically significant decrease of the adsorbed salivary mass. In contrast, photocatalytic decomposition of pellicle could not be observed on reference titanium surfaces. Wettability characterization revealed superhydrophilicity of anatase upon UV irradiation, whereas titanium was unaffected. XPS measurements provide further information concerning the decomposition of the salivary films. The results suggest that the photocatalytic activity of polycrystalline anatase-modified biomaterial surfaces is able to decompose complex structured macromolecular pellicle films. Therefore, this study opens the way to surface modifications supporting therapeutic approaches of biofilm removal.     

Acquired pellicle as a modulator for dental erosion

Dental erosion is a multifactorial condition that can result in the loss of tooth structure and function, potentially increasing tooth sensitivity. The exposure of enamel to acids from non-bacterial sources is responsible for the progression of erosion. These erosive challenges are counteracted by the anti-erosive properties of the acquired pellicle (AP), an integument formed in vivo as a result of selective adsorption of salivary proteins on the tooth surface, containing also lipids and glycoproteins. This review provides an in-depth discussion regarding how the physical structure of the AP, along with its composition, contributes to AP anti-erosive properties. The physical properties that contribute to AP protective nature include pellicle thickness, maturation time, and site of development. The pellicle contains salivary proteins embedded within its structure that demonstrate anti-erosive properties; however, rather than individual proteins, protein–protein interactions play a fundamental role in the protective nature of the AP. In addition, dietary and synthetic proteins can modify the pellicle, enhancing its protective efficiency against dental erosion. The salivary composition of the AP and its corresponding protein-profile may be employed as a diagnostic tool, since it likely contains salivary biomarkers for oral diseases that initiate at the enamel surface, including dental erosion. Finally, by modifying the composition and structure of the AP, this protein integument has the potential to be used as a target-specific treatment option for oral diseases related to tooth demineralization.     

Amino acid composition of acquired enamel pellicle collected in vivo after 2 hours and after 24 hours

Abstract— The adsorption of salivary proteins to dental enamel during pellicle formation has been shown to be a specific process and dependent on the chemical composition of the surfaces. Most studies on the amino acid composition of the acquired enamel pellicle have, however, been performed on the "2-h-pellicle"under controlled experimental conditions. This may have eliminated some natural factors involved in pellicle formation. The aim of the present study was to investigate the effect of extended time of formation and diet on the pellicle formation. Pellicle material was collected from the same subject after 2 and after 24 h when food and beverages were avoided, and after 24 h with the intake of a normal diet. The collected pellicle materials were hydrolyzed and amino acid analyzed. The results showed that pellicle material collected after 24 h and fasting had a chemical composition similar to the "2-h-pellicle", whereas pellicle material collected after 24 h and a normal diet was different, indicating a dietary contribution to pellicle formation or a bacterial degradation of the pellicle.     

Amino acid composition of acquired enamel pellicle collected in vivo after 2 hours and after 24 hours.

The adsorption of salivary proteins to dental enamel during pellicle formation has been shown to be a specific process and dependent on the chemical composition of the surfaces. Most studies on the amino acid composition of the acquired enamel pellicle have, however, been performed on the "2-h-pellicle" under controlled experimental conditions. This may have eliminated some natural factors involved in pellicle formation. The aim of the present study was to investigate the effect of extended time of formation and diet on the pellicle formation. Pellicle material was collected from the same subject after 2 and after 24 h when food and beverages were avoided, and after 24 h with the intake of a normal diet. The collected pellicle materials were hydrolyzed and amino acid analyzed. The results showed that pellicle material collected after 24 h and fasting had a chemical composition similar to the "2-h-pellicle", whereas pellicle material collected after 24 h and a normal diet was different, indicating a dietary contribution to pellicle formation or a bacterial degradation of the pellicle.     

Enzymes in the acquired enamel pellicle

The acquired pellicle is a biofilm, free of bacteria, covering oral hard and soft tissues. It is composed of mucins, glycoproteins and proteins, among which are several enzymes. This review summarizes the present state of research on enzymes and their functions in the dental pellicle. Theoretically, all enzymes present in the oral cavity could be incorporated into the pellicle, but apparently enzymes are adsorbed selectively onto dental surfaces. There is clear evidence that enzymes are structural elements of the pellicle. Thereby they exhibit antibacterial properties but also facilitate bacterial colonization of dental hard tissues. Moreover, the immobilized enzymes are involved in modification and in homeostasis of the salivary pellicle. It has been demonstrated that amylase, lysozyme, carbonic anhydrases, glucosyltransferases and fructosyltransferase are immobilized in an active conformation in the pellicle layer formed in vivo. Other enzymes, such as peroxidase or transglutaminase, have been investigated in experimental pellicles. Despite the depicted impact of enzymes on the formation and function of pellicle, broader knowledge on their properties in the in vivo-formed pellicle is required. This might be beneficial in the development of new preventive and diagnostic strategies.     

Adhesion of Streptococcus sanguinis to dental implant and restorative materials in vitro

Bacterial adhesion to tooth surfaces or dental materials starts immediately upon exposure to the oral environment. The aim of this study, therefore, was to compare the adhesion of Streptococcus sanguinis to saliva-coated human enamel and dental materials - during a one-hour period - using an in vitro flow chamber system which mimicked the oral cavity. After fluorescent staining, the number of adhered cells and their vitality were recorded. The dental materials used were: titanium (Rematitan M), gold (Neocast 3), ceramic (Vita Omega 900), and composite (Tetric Ceram). The number of adherent bacterial cells was higher on titanium, gold, and ceramic surfaces and lower on composite as compared to enamel. As for the percentage of adherent vital cells, it was higher on enamel than on the restorative materials tested. These results suggested that variations in the number and vitality of the adherent pioneer oral bacteria, S. sanguinis, in the in vitro system depended on the surface characteristics of the substratum and the acquired salivary pellicle. The in vitro adhesion model used herein provided a simple and reproducible approach to investigate the impact of surface-modified dental materials on bacterial adhesion and vitality.     

Erosion — chemical and biological factors of importance to the dental practitioner

The intrinsic and extrinsic aetiology factors responsible for dental erosion are well understood as are the chemical events leading the initial mineral dissolution, softening and eventual loss of the dental surface. Of greatest importance are the pH, titratable acidity, phosphate and calcium concentration, fluoride content of the erosive challenge which determines the degree of saturation with respect to the tooth mineral, and thus the driving force for its dissolution. Of the biological modifying factors affecting the erosion process, the protective properties of saliva and its contribution to pellicle formation are considered of greatest importance. Unstimulated salivary flow rate and buffering capacity have been directly associated with dental erosion. The acquired pellicle has been shown to have a protective effect against acid erosion by acting as a diffusion barrier. There is considerable overlap between the aetiology of dental erosion and that of dentinal hypersensitivity. Patient education on the causes and prevention of dental erosion are essential to prevent progression. In addition to reducing or eliminating exposure to acidic soft drinks and juices, modified acid beverages with reduced potential to cause erosion can be recommended to patients. Frequent application of high concentration topical fluoride may be of some benefit in preventing further demineralisation and increase the abrasion resistance of erosion lesions.     

The oral cavity—a key system to understand substratum-dependent bioadhesion on solid surfaces in man

One of the greatest challenges in life sciences and biomaterials research is adhesion of biomolecules and bacteria to solid surfaces in aqueous solutions. An example concerning everybody is biofilm formation in the oral cavity on dental materials and dental hard substances, respectively. The main characteristics typical for any bioadhesion can be observed excellently in the oral cavity. Initially, a proteinaceous layer termed pellicle is formed. It mediates the interactions between solid substrata, oral fluids and microorganisms. Numerous different materials with differing physico-chemical properties and possible impact on the acquired pellicle are present in the oral cavity such as enamel, dentine, restorative materials or dental implants. Despite the fact that in vitro studies demonstrate considerable differences of experimental pellicles formed on these materials, the in situ pellicles seem to be relatively similar and level off the different properties of the underlying substrates. However, the bacterial colonisation of pellicle-coated surfaces under in vivo conditions differs considerably. Long-range forces and detachment of biofilm layers may account for this phenomenon despite the masking effect of the pellicle. Accordingly, low-energy surfaces are desirable for restorative materials exposed to the oral cavity to minimise bacterial adhesion. The oral cavity is an easy accessible in vivo model for understanding bioadhesion and for investigation of protein–surface interactions noninvasively. For evaluation of biofilm formation on dental materials, in situ or in vivo studies are preferable.