氟氢酸酸蚀及偶联剂的应用对烤瓷——树脂粘结强度的影响

目的：评价酸蚀及化学偶联剂对树脂—烤瓷粘结强度的影响。方法：烤瓷试件分７组用５％氟氢酸分别酸蚀０～１８０ｓ，然后一半使用偶联剂，另一半不使用偶联剂，与树脂粘结后测试剪切粘结强度。结果：无偶联剂组酸蚀后可使瓷—树脂粘结强度达到３０ＭＰａ（１５０ｓ），对照组为３ＭＰａ；单独使用偶联剂可使粘结强度达２５．２ＭＰａ，若结合酸蚀剂最高可达３４．３ＭＰａ，但酸蚀后使用偶联剂，酸蚀时间对粘结强度无明显影响；结论：瓷酸蚀是瓷粘结修复中重要的处理方法；偶联剂的使用有利于提高粘结强度，并可用较短的酸蚀时间获得理想的粘结强度。     

种植体黏膜下微生物在健康种植体和种植体周炎中的构成与差异：一项横断面研究

目的：探索种植体黏膜下微生物在健康种植体和种植体周炎中的构成与差异,并分析与临床指标存在相关性的菌种,为种植体周炎的病因学研究提供参考。方法：采用横断面研究,共纳入49例患者,20例为健康种植体,29例为种植体周炎,共采集49份黏膜下微生物样本进行16S核糖体RNA(16S ribosomal RNA, 16S rRNA)基因高通量测序。对两组样本的多样性、菌群构成和差异物种进行分析和比较,采用Spearman相关性分析评价菌种与探诊深度(probing pocket depth, PPD)之间的相关性。结果：健康组的α多样性显著低于种植体周炎组[Chao1指数：236.85±66.13 vs. 150.54±57.43,P<0.001; Shannon指数：3.42±0.48 vs. 3.02±0.65,P=0.032]。主成分分析显示,两组样本的群落结构差异有统计学意义[相似性分析(analysis of similarities, ANOSIM),R²=0.243,P=0.001]。与健康种植体相比,种植体周炎黏膜下菌斑中的牙周致病菌显著增加,包括红色...     

用于牙科复合树脂的具有固位力外形的无机填料的研究

本文介绍了一类微细的复合式无机填料。由于具有特殊的表面结构，这类填料与复合树脂中的树脂基质之间有良好的结合力，因此称之为“具有固位力外形的无机填料”。用此类填料配制的试验性复合树脂，不仅其磨耗性能有明显的改善，而且其它机械性能也有不同程度的提高。     

Reaction of surrounding gingiva to permucosal implants of dense hydroxyapatite in dogs

Experimental and histological studies on the reaction of surrounding gingiva to permucosal implants of dense calcium hydroxyapatite were carried out in dogs. Epithelial attachment and connection of supra-alveolar collagen fibres to the implant surface seemed to form a biological seal around implants similar to that around natural teeth. However, excellent oral hygiene is very important for the maintenance of this biological seal.     

An in vitro and in vivo study of the effect of incorporation of chlorhexidine into autopolymerizing acrylic resin plates upon the growth of Candida albicans

Chlorhexidine acetate was incorporated into autopolymerizing acrylic resin and, after studying its ability to diffuse out in vitro, an investigation was made into the potential of the mixture to treat palatal candidosis in the rat. Chlorhexidine was found to diffuse out of acrylic in fungicidal concentrations for up to three weeks when mixed with the acrylic powder in the proportion of 7.5% (w/w). At this concentration it was found that palatal candidosis as produced by the technique of Shakir et al. was cured or prevented. However, rats fitted with chlorhexidine supplemented plates were found not to take sufficient food during the experimental period to maintain their body weight.     

Ordering behaviors and age-hardening in experimental AuCu-Zn pseudobinary alloys for dental applications

Age-hardening mechanisms and related ordering behaviors of the experimental (AuCu)_1−xZn_x alloys with x0.2 were investigated for dental applications. The addition of Zn to equiatomic AuCu greatly increased the age-hardening rate and delayed overaging. It was suggested that the quenched-in excess vacancies were greatly related to the age-hardening rate in the AuCu–Zn pseudobinary alloys. In these alloys, the hardness became maximum during the very initial stage of ordering, and with the development of ordered phase, the hardness began to decrease. Transmission electron microscopy revealed that the age-hardening of AuCu–Zn pseudobinary alloys is caused by lattice distortion that occurred during the very early stage of atomic ordering. The addition of Zn to AuCu effectively increased the density of antiphase boundaries per unit volume of the AuCu II superstructure. This is suggested to be the main cause for the retardation of the overaging in the alloys containing Zn of 5 at% or more. This pronounced effect of Zn addition to AuCu alloy on its age-hardening characteristics may be advantageous for obtaining stable mechanical properties of dental casting gold alloys.     

Curing efficiency and ocular hazards of dental photopolymerization sources

The spectral distributions of a range of dental photocuring sources were measured at the exit window and at a distance of 10 cm. The former enabled the evaluation of a newly proposed photocuring efficiency index which correlates well with the depth of cure of the photopolymerized resins, thus providing a basis for the comparison of different photocuring sources. The spectral irradiante of the sources obeyed the inversesquare law, allowing a comparison with the ACGIH threshold limit values. According to these criteria, no ocular hazard is posed to the patient or clinician by u.v.-A or u.v.-B radiation nor to the patient by the visible light when momentarily exposed to the sources. Similarly the ACGIH criterion indicates that the clinician does not risk chorioretinal injury provided the exposure is restricted to less than 140 s in a 3 h period.     

Structure and properties of methacrylate based dental restorative materials

The chemistry and structure of the dimethacrylate resins and the nature of the filler systems in dental composite resins are reviewed in relation to their influence on the setting behaviour, dimensional stability, aesthetics, fracture behaviour and adhesive potential. It is clear that a deeper understanding of the structure of the polymeric matrix and the mechanism of clinical wear is required. As a result of ongoing research in this area and with the development of dentine adhesives, the future prospects of composite resins are encouraging.     

人前磨牙牙髓牙本质复合体层粘连蛋白的免疫组织化学研究

目的　研究层粘连蛋白在牙髓牙本质复合体内的表达 ,探讨其分布与功能的关系。　方法　收集不同年龄新鲜健康人前磨牙 6 0颗 ,固定 ,脱钙 ,石蜡包埋 ,层粘连蛋白免疫组织化学染色。　结果　层粘连蛋白免疫反应性 ( IR)普遍存在于牙髓、前期牙本质和成熟牙本质小管与成牙本质细胞突起之间 ,以牙髓的神经与血管周围最为丰富 ,冠髓较根髓密集。　结论　层粘连蛋白 IR不仅见于牙髓与前期牙本质 ,而且也见于成熟牙本质 ,它对支持、固定牙髓牙本质复合体各结构的正常位置、形态可能发挥了重要作用