金属烤瓷冠致牙龈炎症原因的文献复习

金属烤瓷修复体兼有金属的强度和瓷的美观。受到患者和医生的普遍欢迎，尤其对前牙修复，因为涉及到美观问题，这种修复方法已经成为某些牙科医生的唯一选择。笔者根据临床经验．结合文献对金属烤瓷冠引起牙龈组织炎症的原因进行分析，本文仅就修复体边缘的位置、修复体的质量及修复体材料对牙龈组织的影响等综述如下。     

复合树脂修复金瓷修复体脱瓷的临床应用(附15例报告)

自金属烤瓷修复体问世以来,因其兼具金属强度及陶瓷美观的优点,已经成为比较普及的齿科修复体。虽然随着制作工艺和材料性能的日臻完善, 金瓷修复体也日渐完美,但是由于陶瓷自身的质地较脆,金属和瓷属于两种不同的材料结合,以及机械磨损等原因,临床上常发生脱瓷现象。损坏后,金属基底很难从口腔中完整取下,而重新制作金瓷修复     

烤瓷熔附金属全冠修复失败的主要原因分析

烤瓷熔附金属全冠又称金属烤瓷全冠是目前在临床较理想的修复体。金属烤瓷全冠的瓷面分为全瓷覆盖和部分瓷覆盖两种形式。金属烤瓷全冠修复体因其强度高，颜色逼真，色泽稳定表面光滑，舒适美观，耐磨性和抗冲击性强，冠颈部边缘密合度好等特点，因此临床修复中广泛应用。口腔美容门诊2006年为90例患者共做金属烤瓷全冠160件，现将其中失败的主要原因分析如下。     

老年人口腔金属烤瓷冠桥修复体会

金属烤瓷冠桥修复在我国始于20世纪70年代末期,并逐步在临床口腔修复中得到广泛应用.此种修复体本身具有固位良好、强度高、形态逼真、表面光滑耐磨损、色泽稳定美观及生物相容性好等特点,是一种较理想的长久性修复体[1].     

金属烤瓷修复体208例临床应用分析

金属烤瓷修复体强度高,耐磨性好,不易磨损,抗腐蚀性好,能按照天然牙进行配色,色泽逼真,表面光滑,不易染色,生物相容性好。笔者于1996年6月至2002年2月共收集了为208例患者制作的339件金属烤瓷修复体的临床资料。其中男111例,女97例,年龄17～75岁,金瓷冠存在有问题27件。现就这些存在的问题进行分析讨论。     

金属烤瓷修复体基牙冠折后冠桥残根的再利用

金属烤瓷修复体具有金属的强度和自然牙的逼真外观,色泽稳定、表面光滑、耐磨性和抗冲击性强及有良好的生物相容性[1],是一种较为理想的修复体.目前,金属烤瓷修复作为一种常规修复手段已被广大的患者和医生接受和应用.但在临床工作中有时可见到因为基牙龋坏或(牙合)力过大等原因,出现基牙冠折而造成金属烤瓷冠或冠桥不能正常使用,需要重新制作的情况.     

口腔金属材料与树脂结合强度的影响因素

随着口腔金属材料铸造支架和金属烤塑冠桥的广泛应用,金属与树脂之间的结合问题越来越受到重视,它关系到修复体的美观、质量和耐久性。尽管某些口腔金属材料与一些树脂材料可获得较高的结合强度,但长期随访结果不太理想。本文就近十年有关提高口腔金属材料与树脂结合强度的方法作一简要评述。     

金瓷修复体的制作工艺对其颜色的影响

金瓷修复体因其兼具金属全冠的强度和瓷全冠的美观,而且还具有耐磨耗、菌斑不易附着、抗腐蚀性强的特点,是一种较为理想的修复体.但其颜色有时未能完全反映天然牙颜色而影响修复效果.影响金瓷修复体颜色的因素很多,其中制作工艺对修复体颜色会有明显影响.制作过程中,遮色瓷和体瓷厚度、瓷表面粗糙度、烧结次数等制作工艺均对其颜色有影响,现就制作工艺对金瓷修复体颜色影响的研究现况做一综述.     

牙科钛表面处理方法的研究进展

烤瓷熔附金属修复因其兼有金属的强度和瓷的美观两方面优点，临床应用广泛，但价格昂贵。镍铬合金抗腐蚀能力较弱，龈染、黏膜过敏等问题有待进一步解决。钛以其优良的生物相容性、耐腐蚀性、理想的物理和机械性能及相对低廉的价格而日益广泛地被应用于固定义齿的制作。烤瓷熔附金属修复体在临床成功应用的关键是钛瓷间有良好的结合力，为此，近年来关于钛表面处理方法的研究日益增多。     

金属烤瓷冠修复的临床应用

金属烤瓷修复体因其能够较好的恢复牙体的形态功能 ,强度高、颜色、外观逼真 ,色泽光亮 ,耐磨性和抗冲击性强 ,是一种理想修复体而深受患者的欢迎。我科经过 16 5例的临床应用 ,现总结分析如下 :1　临床资料1 1　一般资料　 16 5例患者 ,男性 5 1例 ,女性 114例 ,年龄19～ 5 4岁 ,前牙 117例 ,双尖牙 2 8例 ,磨牙 2 0例。1 2　适应症　①发育畸形或发育不良的前牙、扭转牙、错位牙。②氟斑牙、四环素牙、前牙牙冠因失活而变色的牙。③前牙切角、切缘及冠部缺损 ,不宜充填或金属修复体治疗者。④残根、残冠经根管治疗后桩冠修复。⑤龋坏经根…     

Interaction of Basic Drugs with Lipid Bilayers Using Liposome Electrokinetic Chromatography

No HeadingPurpose. This study explores factors influencing the interactions of positively charged drugs with liposomes using liposome electrokinetic chromatography (LEKC) for the development of LEKC as a rapid screening method for drug-membrane interactions.Methods. Liposomes were prepared and the retention factors were measured for a series of basic drugs under a variety of buffer conditions, including various buffer types, concentrations, and ionic strengths as well as using different phospholipids and liposome compositions. LEKC retention is compared with octanol-water partitioning.Results. The interaction of ionizable solutes with liposomes decreased with increasing ionic strength of the aqueous buffer. The type of buffer also influences positively charged drug partitioning into liposomes. Varying the surface charge on the liposomes by the selection of phospholipids influences the electrostatic interactions, causing an increase in retention with increasing percentages of anionic lipids in the membrane. Poor correlations are observed between LEKC retention and octanol-water partitioning.Conclusions. These studies demonstrate the overall buffer ionic strength at a given pH is more important than buffer type and concentration. The interaction of positively charged drugs with charged lipid bilayer membranes is selectively influenced by the pK_a of the drug. Liposomes are more biologically relevant in vitro models for cell membranes than octanol, and LEKC provides a unique combination of advantages for rapid screening of drug-membrane interactions.     

一些酸性药物在正相硅胶/反相洗脱色谱中保留机理研究

用液相色谱法中“溶质计量置换保留模型”(SDM-R)的两个线性公式,分析了正相硅胶/反相洗脱色谱体系中酸性药物分子与固定相和流动相分子间的相互作用机理,研究了流动相pH值、离子强度、温度和强溶剂浓度改变对溶质保留的影响。从而阐明了酸性药物的保留机理为一种以反相色谱为主的与正相色谱共存的混合保留机理。此方法可以作为药物制剂和中药材中酸性药物成分的分离测定方法。     

Comparison of ion-activated in situ gelling systems for ocular drug delivery. Part 2: Precorneal retention and in vivo pharmacodynamic study

In situ gelling systems are viscous polymer-based solutions that exhibit a sol-to-gel phase transition upon change in a physicochemical parameter such as ionic strength, temperature or pH, therefore prolonging the formulations' residence time on the ocular surface. Ion-activated in situ gelling systems, that are able to crosslink with the cations in the tear fluid, have previously been evaluated in terms of their rheological, textural and in vitro release characteristics. The present study describes the ocular irritancy, precorneal retention time and in vivo release characteristics of the same formulations. It was shown that all tested polymer systems were non-irritant. Precorneal retention studies revealed a biphasic rapid release for the solution with less than 40% radioactivity left on the ocular surface after 15 min, while formulations based on gellan gum, xanthan gum and carrageenan seemed to drain at an almost constant rate with more than 80% radioactivity remaining. This was in agreement with the in vivo miotic studies, which demonstrated that the area under the curve and the miotic response at 120 min after administration for gellan gum, xanthan gum and carrageenan formulations of pilocarpine were increased by 2.5-fold compared to an aqueous solution, which demonstrates their potential use in ophthalmic formulations.     

Adsorption and function of recombinant factor VIII at solid-water interfaces in the presence of Tween-80

The adsorption, structural alteration and biological activity of a recombinant Factor VIII was investigated in the presence of the surfactant Tween-80, at hydrophilic and hydrophobic solid-water interfaces. Hydrophilic and silanized, hydrophobic silica surfaces were used as substrates for protein and surfactant adsorption, which was monitored in situ, with ellipsometry. At the hydrophobic surface, the presence of Tween in the protein solution resulted in a reduction in amount of protein adsorbed, while rFVIII adsorption at the hydrophilic surface was entirely unaffected by the presence of Tween. These observations were attributed to high binding strength between Tween and the hydrophobic surface, and low binding strength between Tween and the hydrophilic surface. Colloidal particles bearing hydrophilic and hydrophobic surfaces, and net positive or negative surface charge, were used as substrates for rFVIII adsorption in evaluation of tertiary structure change and biological activity retention at interfaces. Fluorescence emission spectroscopy showed that rFVIII tertiary structure was changed upon exposure to hydrophobic nanoparticle surfaces. Similarly, the biological activity of rFVIII (based on the activated partial thromboplastin time) was reduced at hydrophobic surfaces. At high surfactant concentration, these properties were better preserved. This was attributed to Tween adsorption sterically inhibiting rFVIII adsorption. While hydrophilic surfaces were associated with relatively high rFVIII adsorption, they did not induce large changes in structure or activity. This was attributed to the formation of a tightly packed, ordered adsorbed layer on these surfaces, governed by electrostatic attraction and not mediated by the rFVIII active site.     

Memory formation processes in weakly reinforced learning

Day-old chicks trained on a single-trail passive avoidance learning task, with varying concentrations of the aversive stimulus (methyl anthranilate), truncated retention functions for low concentrations. The retention function for a 20% v/v dilution of methyl anthranilate in absolute ethanol yielded high retention levels until approximately 40 to 45 minutes following learning. This retention function appears to consist of only the short-term and intermediate (phase A) memory stages of Gibbs and Ng's three-stage model of memory formation, with the short-term stage susceptible to inhibition by monosodium glutamate, and the intermediate stage by ouabain and dinitrophenol. The results suggest that processing of memory into the relatively permanent long-term stage may depend on the strength of the reinforcer in aversive learning.     

流动相的离子强度对RP-HPLC中抗生素色谱峰形的影响

在反相高效液相色谱(RP-HPLC)过程中,流动相的离子强度可显著影响可解离的化合物如抗生素的色谱峰形,原因在于流动相的离子强度较低时,色谱填料的固定相易于过载,使离子化的化合物的色谱峰形呈典型的过载特征——峰形接近直角三角形。随着进样量的增加,色谱区带中高浓度的前半部的保留时间减少,但色谱区带均在同一时刻结束,色谱峰的拖尾因子及峰宽均显著增加,同时被测物与有关物质间的分离也随之变差。选择合适的缓冲盐并适当地增加流动相的离子强度即可显著改善抗生素的色谱峰形,色谱峰的拖尾因子及峰宽均随之降低,同时被测物与有关物质间也更加易于分离。     

Practical implications of theoretical consideration of capsule filling by the dosator nozzle system

Eight lactose size fractions with mean particle sizes ranging from 15.6 to 155.2 micrometers were characterized by their failure properties using a Jenike shear cell. The effective angle of internal friction was found to be constant for all size fractions, with a mean value of 36.2 degrees. Jenike flow factors could only be obtained for the two most cohesive size fractions presumably due to limitations of the shear cell. Angles of wall friction, phi, were determined for all size fractions on face ground and turned stainless steel surfaces. These decreased with increasing particle size up to around 40 micrometers, above which they became effectively constant for both surfaces. The rougher turned plate gave consistently higher values of phi for each particle size. Simple retention experiments with a dosator nozzle and a range of powder bed bulk densities showed good retention was possible only up to a particle size of around 40 micrometers. Retention was difficult or impossible above this size. Values of phi were applied to equations derived in the theoretical approach described previously (Jolliffe et al 1980). This showed that the strength required within a powder to ensure arching increases with increasing particle size up to around 40 micrometers. Above this size, this strength requirement becomes constant. This is related to the powder retention observations. Finally, the failure data was used to calculate the minimum compressive stresses required to ensure powder retention within the dosator nozzle, by employing the equations described by Jolliffe et al (1980). This suggested that, as powders became more free flowing, a larger compressive stress is necessary and that the angle of wall friction should be lower to ensure stress is transmitted to the arching zone.     

Ion pair-HPLC of some aromatic amino- and hydroxycarboxylic acids

Various factors influencing the ion-pair-HPLC separation of some aromatic amino- and hydroxycarbon acids were described and discussed. Distinct effects of the ion pair formation of organic acids with quarternary alkylammonium salts (CTAB) are recognized on condition that the carboxylic group is not blocked by intramolecular H-bonding or partial betain structure. If the carboxylic group is unconnected the retention time increases depending on the pka of the acid with increasing pH if no complete ionization exists. In order to separate similar compounds at low retention time with distinct resolution an organic modifier of suitable strength and high selectivity have to be added to the mobile phase.     

Undefined role of mucus as a barrier in ocular drug delivery

Mucus layer covers the ocular surface, and soluble mucins are also present in the tear fluid. After topical ocular drug administration, the drugs and formulations may interact with mucus layer that may act as a barrier in ocular drug delivery. In this mini-review, we illustrate the mucin composition of the ocular surface and discuss the influence of mucus layer on ocular drug absorption. Based on the current knowledge the role of mucus barrier in drug delivery is still undefined. Furthermore, interactions with mucus may prolong the retention of drug formulations on the ocular surface. Mucus may decrease or increase ocular bioavailability depending on the magnitude of its role as barrier or retention site, respectively. Mechanistic studies are needed to clarify the role of mucin in ocular drug delivery.     

Mechanisms of Mucoadhesion of Poly(acrylic Acid) Hydrogels

It has been proposed that mucoadhesives which adhere to the gastric mucus layer may be used to prolong gastric retention time of oral dosage forms. Preliminary studies, using acrylic hydrogels, have established that the density of carboxyl groups on the polymer chain is important for mucoadhesion. To understand the role(s) of the carboxyl groups in mucoadhesion, acrylic acid–aerylamide random copolymers [P(AA-co-AM)] were synthesized, and the adhesion strength of the cross-linked polymers to the gastric mucus layer was examined as a function of the pH, initial concentration of the cross-linking agent, degree of swelling, and carboxyl-group density. From the study on mucoadhesion of various P(AA-co-AM), it was found that at least 80% of the vinyl groups of the polymer must possess carboxyl groups in the protonated form. The dependence of mucoadhesion on pH and carboxyl-group density suggests that mucoadhesion occurs through hydrogen bonding. In addition, the density of the cross-linking agent significantly affects mucoadhesion. As the density of the cross-linking agent is lowered, the mucoadhesive strength increases, although the density of carboxyl groups in the test surface area is reduced. It is concluded that for mucoadhesion to occur, polymers must have functional groups that are able to form hydrogen bonds above the critical concentration (80% for vinyl polymers), and the polymer chains should be flexible enough to form as many hydrogen bonds as possible.