复合树脂耐磨耗性能的研究—20种复合树脂耐磨耗性能的评价和比较

本研究测试了十九种商品复合树脂(包括大填料、微细填料和混合型填料以及嵌体材料等四种类型)和一种本研究室研制的试验性复合树脂的耐磨耗性能。磨耗性能测试采用本研究室开发的、以橡胶板为对磨偶件的三体磨耗试验机。对磨耗表面的显微结构进行了扫描电镜观察。本研究的目的在于通过对各种类型的复合树脂的体积磨耗量及其磨耗表面微观结构的对比分析,去寻找、发现影响复合树脂耐磨性能的各种因素。实验结果表明,嵌体材料具有较高的耐磨耗性能。而含有相同填料类型的产品,其磨耗性能有很大差异(体积磨耗量可以相差3—4倍)。耐磨耗性能与填料类型之间无明显相关性。本研究将对如何提高复合树脂耐磨性能提供一些有价值的信息。     

牙科复合树脂增韧用单壁碳纳米管的表面改性和微结构

为了使单壁碳纳米管（SWNTs）在牙科复合树脂中获得良好的单分散和牢固的界面结合，将其回流、氧化处理后，用APTE处理，然后用溶胶-凝胶法在其外侧壁包裹一层纳米SiO2颗粒，用硅烷偶联剂对包裹后的SWNTs进行化学改性，用红外光谱和透射电镜检测改性结果，发现透射电镜照片显示在SWNTs外壁上包裹了一层纳米级颗粒；红外光谱上出现SiO2的特征吸收峰；制备纳米复合树脂试件，用透射电镜观察，发现SWNTs镶嵌在树脂基质内的其他填料之间。     

复合树脂类材料耐老化性能的研究：（二）拉伸疲劳老化对复…

实验中通过对圆柱形试件施加径向压缩载荷，使试件内部承受位伸疲劳作用。疲劳试验后，将试件加工成磨耗试件，通过磨耗试验检测评价材料的耐老化性能。研究结果发现，低应力拉伸疲劳对复合树脂充填材料的耐磨耗性能无明显降低作用，个别材料甚至有被增强的趋势。     

CaSO4和MgSO4晶须填料对牙科复合树脂抗弯强度的影响

目的 观察CaSO4晶须和MgSO4晶须对复合树脂的抗弯强度的影响.方法 制备CaSO4晶须和MgSO4晶须,以硬脂酸钠改性剂表面改性,随后分别按质量分数为1%、10%、20%、30%混合添加到复合树脂中,固化后评价其三点抗弯强度,扫描电镜观察断面形态.结果 添加2种晶须的质量分数在10%及以下时,复合树脂的三点抗弯强度均下降,质量分数为20%和30%时,MgsO4晶须组的三点抗弯强度增加.结论 添加适当比例的MgSO4晶须可以提高复合树脂的三点抗弯强度.     

Bis-GMA／（SiO2-ZrO2）纳米复合树脂的制备与性能研究

目的：通过添加纳米无机填料对树脂基质进行增强增韧改性,来满足修复性牙科材料的要求,解决树脂基质耐磨性较差、强度低的问题,制备出合适的临床牙科修复材料。方法：采用原位分散法,双酚A-甲基丙烯酸缩水甘油酯（Bis-GMA）和双甲基丙烯酸二缩三乙二醇酯（TEGDMA）共同作为树脂基质,混合加入经过硅烷偶联剂（KH-570）表面处理的纳米氧化硅（SiO2）和二氧化锆（ZrO2）制备新型复合树脂,同时使用高速搅拌和超声分散等制备工艺来改善纳米填料分散体系,运用X射线衍射（XRD）、扫描电子显微镜（SEM）等实验手段对Bis—GMA纳米复合树脂材料进行性能测试及结构表征。结果：使用高速搅拌和超声分散技术可使经过表面处理的纳米SiO2和ZrO2均匀分散在树脂基质中,达到了纳米级原生粒子分散效果,发挥了不同无机填料间的相互作用,能够有效的提高复合树脂材料的机械性能。结论：该方法制备出的高性能Bis—GMA／nano（SiO2-ZrO2）复合树脂牙科材料,能充分满足临床牙科修复学需要。     

CaSO4和MgSO4晶须填料对牙科复合树脂抗弯强度的影响

Objective The aim of this study was to evaluate the effect of calcium sulphate and magnesium sulfate whiskers on the flexture strengths of dental composite resin.Methods Calcium sulfate whiskers and magnesium sulfate whiskers were prepared.Seven groups of composite resin specimens were prepared including one control group and six groups using either calcium sulfate whiskers or magnesium sulfate whiskers comprising 1%,10%,20%,30% of the material by weight.Before mixing with resin,both whiskers were surface modified by Sodium stearate.The standard resin samples with dimensions of 25 mm×2 mm×2 mm were prepared according to the ISO-10477 criterion(eight for each group),and their flexure strengths were measured by a universal testing machine.The fracture surfaces of selected specimens were examined by a scan electron microscope.Results Neither mixture improved the flexure strength of composite resin when the adding proportions of calcium sulfate and whiskers magnesium sulfate whiskers were under 10%.However,when the adding proportions were 20 wt % and 30 wt%,magnesium sulfate whiskers excerted positive effects.Concluson Appropriate proportions of magnesium sulfate crystal whisker would increase the flexure strength of dental composite resin.     

水对3种双固化复合树脂冠核材料弯曲性能的影响

背景：口腔湿热环境会对牙科核材料的力学性能产生影响。 目的：观察水对3种双固化复合树脂冠核材料质量变化率及弯曲性能的影响。 方法：将LuxaCore Smartmix Dual、Para core和Clearfil DC Core 三种牌号双固化复合树脂材料制成      25 mm×2 mm×2 mm标准试件,于(37±1) ℃的蒸馏水中保存 0 d、1 d、1周、2周、3周和1个月后称质量,计算其质量变化率,并在万能试验机上测试三点弯曲性能。 结果与结论：3种复合树脂的质量变化率均随着浸泡时间的增加而增加;对于相同浸泡时间下,3种树脂的质量变化率由大到小排列次序为：LuxaCore Smartmix Dual>ParaCore>Clearfil DC Core。LuxaCore Smartmix Dual树脂强度随浸泡时间的增加而降低;ParaCore树脂强度在浸泡3周内变化不显著(P > 0.05),浸泡时间1个月时强度显著降低(P < 0.05);Clearfil DC Core树脂强度在整个浸泡过程中没有显著性差异(P > 0.05)。LuxaCore Smartmix Dual树脂模量在整个浸泡时间内呈现出下降趋势,但在最初2周的浸泡时间内无明显变化(P > 0.05),当浸泡时间达到3周和1个月时模量显著降低(P < 0.05);与浸泡前比,ParaCore和Clearfil DC Core两种复合树脂的模量值均下降,但这种变化不显著(P > 0.05);3种复合树脂的弯曲性能随着质量变化率的升高而呈现出波动式下降的趋势。综合显示在3种树脂中,Clearfil DC Core的耐水性最佳。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

复合树脂类材料耐老化性能的研究——(一)固化收缩应力对粘合老化的影响

本文提出了模拟口腔复合树脂粘合材料固化收缩应力的耐老化性能测试方法。并用此方法分别在不同温度的水和空气中,探讨复合树脂类粘合材料与金属材料组成的粘合体发生老化破坏的规律。证明固化收缩应力对此类口腔粘合材料在水环境中的老化有显著的加速作用。进而提出,改善粘合材料的耐老化性能,可从阻止水分子侵入和消除或减小固化收缩应力这两个途径入手。     

Experimental and computational approach for evaluating the mechanical characteristics of dental composite resins with various filler sizes

This study aimed to investigate the influence of particle size of fillers on flexural properties of dental composite resins by laboratory testing with computational analysis validation. Four kinds of silica fillers with mean particle sizes of 3.3, 4.3, 7.9, and 15.5 μm were used. Filler content was kept constant at 70 mass% (or 53.8 vol.%). The three-point bending test was performed with a constant loading speed of 1.0 mm/min, and a span length of 20 mm using an Instron machine, in order to measure flexural strength and modulus of composite resins with various particle sizes. Test specimens were 2-mm wide, 2-mm thick, and 25-mm long rectangular bars. Furthermore, a numerical simulation using three-dimensional finite element (FE) analysis was performed to investigate stress distribution in composite resins under loading. As a result, flexural strength decreased with increasing particle size of the filler of the composite resins (p < 0.05). On the other hand, there was no significant difference in Young’s modulus among composite resins with various filler sizes (p > 0.05). Moreover, FE analysis indicated that stress concentration increased with increasing particle size in agreement with experimental results of flexural strength. In conclusion, within the limitations of this investigation, we confirmed that flexural strength of composite resins decreased with increasing filler particle size. In addition, FE analysis was effective for evaluating stress distributions of dental composite resins with various filler sizes.     

Controlled release of fluoride in connection with dental composite resins

A delivery system of F⁻ in connection with dental restorations was tested. The system utilized the gap space which often exists between the restorative material and the tooth structure. A known quantity of fluoride compound was placed at a site within prepared plastic cavity blocks prior to restoring with composite resins. It was found that each specimen exhibited a unique steady-state release of F⁻ during a certain period of the experiment. The rate and duration of the steady-state release of fluoride were independent of the types of composites used. This phenomenon was explained in terms of the gap size which could have been influenced by the manipulation and the nature of the materials. The benefit of this delivery system in dental application is its ability to maintain a high concentration of F⁻ within the gap.     

In vitro degradation, flexural, compressive and shear properties of fully bioresorbable composite rods

Several studies have investigated self-reinforced polylactic acid (SR-PLA) and polyglycolic acid (SR-PGA) rods which could be used as intramedullary (IM) fixation devices to align and stabilise bone fractures. This study investigated totally bioresorbable composite rods manufactured via compression moulding at ∼100 °C using phosphate glass fibres (of composition 50P₂O₅–40CaO–5Na₂O–5Fe₂O₃ in mol%) to reinforce PLA with an approximate fibre volume fraction (v_f) of 30%. Different fibre architectures (random and unidirectional) were investigated and pure PLA rods were used as control samples.The degradation profiles and retention of mechanical properties were investigated and PBS was selected as the degradation medium. Unidirectional (P50 UD) composite rods had 50% higher initial flexural strength as compared to PLA and 60% higher in comparison to the random mat (P50 RM) composite rods. Similar initial profiles for flexural modulus were also seen comparing the P50 UD and P50 RM rods. Higher shear strength properties were seen for P50 UD in comparison to P50 RM and PLA rods. However, shear stiffness values decreased rapidly (after a week) whereas the PLA remained approximately constant. For the compressive strength studies, P50 RM and PLA rods remained approximately constant, whilst for the P50 UD rods a significantly higher initial value was obtained, which decreased rapidly after 3 days immersion in PBS.However, the mechanical properties decreased after immersion in PBS as a result of the plasticisation effect of water within the composite and degradation of the fibres. The fibres within the random and unidirectional composite rods (P50 RM and P50 UD) degraded leaving behind microtubes as seen from the SEM micrographs (after 28 days degradation) which in turn created a porous structure within the rods. This was the main reason attributed for the increase seen in mass loss and water uptake for the composite rods (∼17% and ∼16%, respectively).     

Colour stability and visual perception of dimethacrylate based dental composite resins

The spectrophotometric method of colour measurement was applied to an investigation of the colour stability of dimethacrylate based composite resins exposed to thermal and photochemical aging. A good correlation was observed between visual perception of colour change and the spectrophotometric colour difference [delta E (FMC-2)] of unexposed and aged specimens, but 50% of the observers considered the colour match of two specimens to be clinically unacceptable when the colour difference exceeded 10.6. Kinetic studies of thermally and photochemically induced colour change showed a sigmoidal dependence of colour change on the logarithm of exposure time. Because the direction and magnitude of the colour change differed for the two procedures, it would appear that different mechanisms are involved.     

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.     

High-pressure infrared and FT-Raman investigation of a dental composite

Composite resins are often used as filling materials on load-bearing surfaces of teeth. As masticatory stresses can be high, here, we study the effect of pressure on the behaviour of a dental composite. Using a polymerized wafer, the IR and FT-Raman spectra of a zirconia-containing proprietary composite (Z100, 3M, Minneapolis, MN, USA) were recorded. The high-pressure IR spectra were also recorded. Band assignments were made for the main peaks of both organic and inorganic components. Breaks in the pressure dependences (dv/dP) of the organic components were found at 22 kbar. Different pressure dependences for different vibrational modes of inorganic components were also observed. These data suggest that the network structure of the composite is compacted under high pressure and that both the atomic distance and bonding angles in the network are altered.     

Effects of postcuring and water sorption on the mechanical properties of composite dental restorative materials

Four commercial dental restorative composites with different filler contents, were tested for the effects of postcuring and water sorption on elastic modulus, compressive strength and ultimate strain. Large variations in mechanical properties were seen; water sorption plasticizes the matrix, causing loss of low molecular weight substances.     

牙本质微结构性质的重新评价

目的相比以前一些模型,蛋白质-矿物质多孔力学模型被验证可以提供更精确的生物材料性质评价。因此,本文对牙本质微结构相互作用对其材料性质的影响进行了重新评价。方法采用蛋白质-矿物质多孔力学模型,讨论了牙小管、管周基质和管间基质相互作用对牙本质微结构性质的影响。结果通过分析发现,牙本质微结构力学性质依赖于牙小管的方向和牙小管中的压力值;同时,牙本质微结构力学性质会随着年龄以及管周基质与管间基质的蛋白质和矿物质分布而改变。结论文章中的理论分析和讨论说明牙小管、管周基质和管间基质相互作用对牙本质微结构性质有一定的影响,说明蛋白质-矿物质多孔力学模型的有效性,以及不考虑相互作用的微结构力学模型具有一定的局限性。     

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.