Investigation of Color Change of Different Restoration Thickness, Background Color and Resin Cement Shade on CAD/CAM Glass Ceramic Materials

The aim of this study is to investigate the color change of different restoration thicknesses, backgrounds and resin cement colors on lithium disilicate and zirconium reinforced lithium silicate materials in vitro. In this study, IPS emax CAD (LT C14) and Celtra Duo (LT C14) are used as full ceramic materials, and Variolink Esthetic LC (warm, neutral) used as resin cement and Tokuyama Estelite Sigma Quick (A3, A2) is used as composite materials. A total of 160 samples in the form of 40 pieces of 5 × 5 0.4 mm thick 40 pieces of 5 × 5 0.6 mm thick square discs from each of the all-ceramic materials in block form were obtained using a water jet device (DWJ1525-FA;Dardi International Corporation, Nanjing, China). Glass ceramic samples produced in 2 different thicknesses were cemented on 2 different backgrounds with 2 different resin types of cement. Color measurements of the samples before and after cementation were performed on a grey background with spectrophotometer Vita EasyShade V (Vita Zahnfabrik, Bad Sackingen, Germany) and color parameters (L*, a*, b*, ΔE) were calculated according to the CIE Lab (Commission Internationale de L’Eclairage) system. Average values for each group (ΔE) were not affected by ceramic type, material thickness, background color, resin cement color, and the interaction of these four variables (p > 0.05). When the triple interactions between the groups were examined, there were no statistically significant differences (p > 0.05). In the evaluation of pairwise interactions between two groups (material type-material thickness, material type-background color, and thickness of material-background interactions) statistically significant differences (p Implications: The material type, thickness, background and cement color used did not cause any statistically significant color change in lithium disilicate and zirconium-reinforced lithium silicate glass ceramic materials (p > 0.05).

An Experimental Study on the Reinforcement of Weakly-Consolidated Shallow Formation in Deep Water Using an Epoxy Resin-Based Fluid

The mechanical properties of Portland cement differ from the weakly consolidated shallow formation in deep water.This results in undesired abrupt changes in the compressive strength and elastic modulus at the cement–formation interface.In this study,a water-borne epoxy resin was applied as a strengthening material to reinforce the weakly consolidated shallow formation and protect the cement sheath from potential failure.The mechanical properties of the unconsolidated clay were tested,including their changes with increases in the temperature and curing time.In addition,the effects of the seawater,cement slurry alkaline filtrate,and saltwater drilling fluid were evaluated.As confirmed by the results,the strengthening fluid was excellent at reinforcing the unconsolidated clay,with a compressive strength of 2.49 MPa(after curing for 7 days),even at a dosage of 5%.A cement slurry filtrate with a high pH was suitable to produce the required strengthening of the formation,especially its early age strength.It should also be pointed out that the used fluid exhibited good compatibility with the saltwater drilling fluid and seawater behaved well as a diluent for the strengthening fluid.

Embrace WetBond Resin Cement树脂水门汀保存修复折裂牙的临床应用及疗效

目的:通过研究Embrace Wet Bond Resi n Cement树脂水门汀用于粘结折裂牙的临床疗效,旨在为保存修复折裂牙建立一套实用而简便的治疗模式以提高患牙的保存率。方法:选择35例(36颗)折裂牙作为研究对象,先打开患牙的近远中接触点,预成带坏固定后降合,在裂隙俩侧制备双鸠尾洞型,将Embrace Wet Bond Resi n Cement树脂水门汀注入折裂面并及时复位、光照、充填,观察2周后去带环行全冠修复。结果:经6～12月复查:3例折裂牙因反复出现牙周脓肿拔除,2例咀嚼略有不适感,成功率91%。结论:用Embrace Wet Bond Resi n Cement树脂水门丁保存修复折裂牙,弥补了传统粘结法的缺陷,使患牙得以保存,也简便了临床医生的操作。

Effect of Self-adhesive Resin Cement and Tribochemical Treatment on Bond Strength to Zirconia

Aim To evaluate the interactive effects of different self- adhesive resin cements and tribochemical treatment on bond strength to zirconia. Methodology The following self-adhesive resin cements for bonding two zirconia blocks were evaluated： Maxcem （MA）, Smartcem （SM）, Rely X Unicem Aplicap （UN）, Breeze （BR）, Biscem （BI）, Set （SE）, and Clearfil SA luting （CL）. The specimens were grouped according to conditioning as follows： Group 1, polishing with 600 grit polishing paper; Group 2, silica coating with 110 μm Al2O3 particles which modified with silica; and, Group 3, tribochemical treatment - silica coating ＋ silanization. Specimens were stored in distilled water at 37℃ for 24 hours before testing shear bond strength. Results Silica coating and tribochemical treatment significantly increased the bond strength of the MA, UN, BR, B1, SE and CL to zirconia compared to #600 polishing. For both #600 polished and silica coating treatments, MDP- containing self-adhesive resin cement CL had the highest bond strengths to zirconia. Conclusion Applying silica coating and tribochemical treatment improved the bond strength of self-adhesive resin cement to zirconia, especially for CL.

Immediate and delayed micro-tensile bond strength of different luting resin cements to different regional dentin

We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin （1 mm below the dentine-enamel junction）, deep dentin （1 mm above the highest pulp horn） and cervical dentin （0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction）. Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mrn/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin （P 〈 0.001）. Micro-ten- sile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions （P 〈 0.001）. Immediate ＂micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements （P 〈 0.001）. It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.

Application of mixture design to optimize cementation of simu-lated spent radioactive ion exchange resins

The aim of this study was to assess the usefulness of a mixture design for spent resin immobilization in cement as well as to examine the cement-slag-ash system for spent resin solidification. Eighteen distinct combina- tions,consisting of Portland cement,blast furnace slag,fly ash,organic ion exchange resins and water,were selected by a mixture design computer procedure to compose representative experiment points. The measured properties of solidified forms resulting from the combinations included 28-day compressive strength,42-day immersion strength,42-day immersion weight and slump. These data were fit to a mathematic model with the aid of Scheffé quadratic polynomial,and the effects of each ingredient on the measured properties were identified through an analysis of the response trace plots and contour plots. Utilization of an optimality function singled out an optimal combination com- prising water=0.16(wt/wt),slag=0.21,ash=0.10,cement=0.27 and resin=0.26 from which the resulting response was 11MPa for the 28-day strength,110mm for the slump and 5.4% for the 42-day increase in strength.

Priming the tooth surface with chlorhexidine and antibacterial activity of resin cement

AIM: To evaluate the effect of priming the tooth surface with 2% chlorhexidine gluconate on antibacteria activity of resin cement. METHODS: Ten patients in whom a single missing tooth was present on both the right and left side in the upper or lower arch were selected. Two fixed partia dentures(FPDs) in each patient on the right and left side were planned. Each FPD was assigned either to the control or test group. In the control group, FPD was luted with resin cement and in the test group, the tooth surface was primed with 2% chlorhexidine gluconate before luting with resin cement. Bacteriological samples were collected at base line level, as the patient came to the outpatient department before the start of any treatment, 5 wk prior to cementation of FPD and at 13 wk(8wk after final cementation). Microbiological processing of all samples was done and the results were statistically analyzed. RESULTS: In the test group, a predominance of aerobic/facultative gram positive cocci rod was seen which indicates a healthy periodontal site, whereas in thecontrol group, a predominance of anaerobic gram negative rods was present which indicates an unhealthy periodontal condition. This is evident by the fact that the anaerobic bacteria percentage in the control sample is 57% and 15% in the test sample after 13 wk, whereas the aerobic/facultative bacteria percentage is 43% in the control sample and 85% in the test sample after 13 wk. The percentage of gram negative bacteria in the control sample is 61% and in the test sample is 20% after 13 wk, whereas the percentage of gram positive bacteria in the control sample is 39% and in the test sample is 80% after 13 wk. The shift from anaerobic gram negative bacteria to aerobic gram positive bacteria is clearly seen from the control to test sample after 13 wk. CONCLUSION: The present study demonstrated that priming the tooth surface with 2% chlorhexidine gluconate may enhance antibacterial activity of the resin cement.

The Influence of Ceramic Surface Treatments on the Microtensile Bond Strength of Resin Cements to Y-TZP Ceramic

The effects of surface conditioning methods on the microtensile bond strength of Y-TZP ceramic were studied based on airborne particle abrasion and resin cements.Eight square-shaped（φ12 mm×5 mm high） Y-TZP ceramic were studied blocks（LAVATM,3M ESPE,USA） and flat occlusal dentin blocks were fabricated,pre-treated（airborne abrasion with 125μm Al2O3 particles,tribochemical silica coating with 110 μm Al2O3 particles modified by silica oxide）,and bonded to each other using resin cements（Panavia F 2.0,RelyX Unicem）.Thereafter the trilayer specimens were cut into microbar specimens with a bonding area of approximately 1.0±0.1 mm2 and then microtensile bond strength tests were performed.The Y-TZP ceramic following airborne particle abrasion with 125μm Al2O3 and silicoating,the surface roughness of Y-TZP and its surface silica content were confirmed to increase.Overall,the Y-TZP ceramic surface treatment with a tribochemical silica coating showed the highest microtensile bond strength of the phosphate monomer-based resin cement to Y-TZP ceramic（mean MPa=18.11±0.27（Panavia F 2.0）,17.45±0.39（Rely X Unicem）.In cases in which a silica coating was applied,there was no significant difference in the bonding strength depending on resin cements（P0.05）.

MICROLEAKAGE OF CLASS V RESIN-MODIFIED GLASS IONOMER CEMENT AND COMPOMER RESTORATIONS IN VITRO

Objective To assess the microleakage of Class V restorations made with two resin-modified glass ionomer cements （RMGICs） and two polyacid-modified composite resins （PMCRs）. Methods Restorations of the four materials （ GC Fuji Ⅱ LC, Vitremer^TM, Dyract AP and F2000^TM ） were placed in facial Class V cavity preparations in forty noncarious human molar teeth. Teeth were randomly assigned to 4 experimental groups of 10 teeth each. After thermal cycling（ ×20, 5 -55℃ ） , the interface between dentin and restorations was spattercoated with gold and observed under scanning electron microscopy （SEM）. Then the square and average width of margin gaps of central 1/3 interface were recorded with image analysis software. Results The data indicated no significant differences between all the restorative materials for both occlusal and gingival margins. Further analysis revealed there were statistically significant differences between occlusal margins and gingival margins for VitremerTM and Dyract AP, respectively. Conclusion None of the tested materials guaranteed margins free of microleakage. Resin-modified glass ionomer cements showed similar margin gaps to the polyacid-modified composite resins tested.

环氧树脂乳液改性油井水泥的性能研究

随着油气井勘探领域的不断扩展和深入,油井水泥脆性较大的弊端越来越明显,在复杂的压力和温度条件下,水泥石容易产生裂缝从而造成强度损失,甚至会进一步导致水泥环的完整性失效,对油气井的安全生产有着严重的危害.为克服油井水泥的脆性,聚合物乳液因其能有效改善水泥的韧性、保水性而得到广泛应用.针对深井、超深井高温高压固井需求,制备了水性环氧树脂乳液改性水泥,并对其流变性能、稠化性能、抗折抗压强度和弹性模量等应用性能进行了研究,同时利用X射线衍射(XRD)、固体核磁共振(NMR)和热失重(TG)等表征手段探究了环氧树脂乳液体系在水泥中的作用机理.结果表明,环氧树脂乳液的加入改善了水泥浆的静态滤失性能,对水泥浆的流变性能和稠化行为没有负面影响.改性水泥石的抗折强度显著提高,尤其是当环氧树脂乳液掺量为15%时,90℃养护7 d、14 d和28 d的水泥抗折强度分别提高了25%、111%和100%.同时,与空白试样相比,环氧树脂乳液掺量为5%、15%和20%的水泥弹性模量分别降低了39.4%、42.8%和58.1%.环氧树脂乳液不会改变水泥的水化产物,只会在水泥水化早期起到一定的延缓和阻碍作用;环氧树脂在水泥基体中发生固化交联反应,在水泥水化过程中水化产物之间形成了联结,从而提高了水泥石的抗折性能,降低了水泥石的弹性模量.

基于高岭土增韧环氧树脂水泥基材料的多强度组合指标配比优化法

煅烧高岭土能有效改善环氧树脂水泥基材料的力学性能,实验表明:煅烧高岭土可大大提高环氧树脂水泥基材料的3 d早期抗折、抗压强度,当高岭土掺量为30%时,改性环氧树脂水泥基材料的抗折及抗压强度分别提高了134.28%、106.25%;当高岭土掺量小于30%时,改性环氧树脂水泥基材料具有二次抗折强度,且抗折强度残余率大于50%。根据不同高岭土掺量对改性环氧树脂水泥基材料抗压强度、抗折强度、二次抗折强度的影响规律,提出了适用于不同结构工程受力特点的多强度组合指标配比优化法,获得了考虑二次抗拉强度影响的不同最大拉应力和最大压应力组合条件下最优的高岭土配比,为实际不同结构体不同部位不同受力特征的高岭土改性环氧树脂水泥基材料制备提供了理论依据。

一种耐酸耐碱高强树脂的合成及性能

小套管二次固井是一种新型的固井工艺,针对目前由于水泥自身脆性大易气窜和水窜且为碱性固化体、易受压产生裂缝、易受酸性介质破坏的问题,以D-33二元醇和顺丁烯二酸为原料,苯乙烯作为活性稀释剂合成了一种不饱和型聚酯树脂。在树脂体系中引入填料,提高产品韧性及抗压强度。采用傅里叶变换红外光谱仪对树脂进行表征;通过万能试验机对树脂体系进行性能评价。结果表明,目标产物包含羰基、碳碳双键和苯环对位取代结构的特征峰,固化体系为过氧化二苯甲酰/N,N-二甲基苯胺,其在50℃、60℃和70℃条件下的添加量分别为0.2%/0.02%、0.1%/0.02%、0.1%/0.01%,万能试验机测试结果显示,在50℃、60℃和70℃下养护24h后的抗压强度分别约为50MPa、70MPa、90MPa。实验获得了一种聚合时间可调、黏度小、抗压强度高且耐酸耐碱的固井材料,有望在水平井重复压裂改造中大规模使用。

釉涂层技术对氧化锆表面特性及粘接强度的影响

目的探讨釉涂层技术对氧化锆陶瓷表面特性及粘接强度的影响。方法制作100块完全烧结的氧化锆试件,随机分成5组,每组20块。采用5种方式对各组试件氧化锆表面进行处理,A组为空白对照,B组为氧化铝喷砂,C组为涂釉+1次氢氟酸(HF)蚀刻,D组为涂釉+1次HF蚀刻+硅烷偶联剂,E组为涂釉+2次HF蚀刻+硅烷偶联剂。比较各组氧化锆试件表面微观形貌、化学元素成分、粗糙度及氧化锆与树脂粘接剂之间的粘接强度。结果氧化锆试件表面粗糙度从高至低依次为C组[(0.68±0.05)μm]、D组[(0.57±0.06)μm]、E组[(0.48±0.04)μm]、B组[(0.14±0.04)μm]、A组[(0.06±0.01)μm],各组间两两比较,差异有统计学意义(P<0.05)。扫描电子显微镜观察结果显示,A组氧化锆试件表面可见交错纵横的横线,B组氧化锆试件表面形成不规则的凹坑,C组、D组、E组氧化锆试件表面出现均匀分布的凹坑,且D组、E组凹坑相较于C组更为密集、细小。氧化锆试件表面化学元素成分能谱分析结果显示,A组仅含锆和氧元素,B组含有锆、氧和铝元素,C组、D组、E组均含有锆、氧和硅元素。氧化锆试件剪切粘接强度从高至低依次为E组[(12.71±0.81)MPa]、D组[(10.82±0.75)MPa]、C组[(7.06±0.54)MPa]、B组[(4.98±0.49)MPa]、A组[(3.13±0.47)MPa],各组间两两比较,差异有统计学意义(P<0.05)。结论釉涂层技术提高了氧化锆表面的粗糙度及其粘接强度,适度延长HF酸蚀时间可进一步提升氧化锆表面粘接强度,但酸蚀时间不宜过长,且需注意釉涂层厚度的控制。

二硅酸锂基玻璃陶瓷单端树脂粘接桥修复个别前牙缺失的临床应用

目的探讨二硅酸锂基玻璃陶瓷单端树脂粘接桥修复个别前牙缺失的临床效果,为个别前牙缺失修复方式的选择提供参考。方法本研究已通过单位伦理委员会审查批准,并获得患者知情同意。选取42例单颌前牙缺失数量在两颗内的患者,采用二硅酸锂基玻璃陶瓷单端树脂粘接桥修复,修复后6个月、1年、2年、3年进行随访,评价美学、功能修复效果及牙周健康状况,并采用视觉模拟评分量表(VAS)调查患者的满意度。结果观察期间,42例二硅酸锂基玻璃陶瓷单端树脂粘接桥修复的患者中有1例3个月内连接体发生断裂,1例2年内发生脱粘;美学修复效果的等级均评定为A级;修复后牙周健康状况良好,基牙及桥体下的软硬组织无临床吸收现象,评价指标均为A级;患者总满意率为100%。结论对于个别前牙缺失,二硅酸锂基玻璃陶瓷单端树脂粘接桥可达到微创、固位牢靠、美观舒适和生物相容性好的修复效果,患者满意度高,在临床中可以考虑作为一种理想的修复方式。

单组分室温固化有机硅防水剂乳液的制备及性能研究

以 α , ω -二羟基聚二甲基硅氧烷、MQ硅树脂、甲基三乙氧基硅烷 (MTES )、月桂醇聚氧乙烯醚-3、十二烷基硫酸钠为主要原料,利用机械乳化法制得单组分室温固化有机硅防水剂乳液,并用于水泥基材料的防水,研究了基础聚合物黏度、MQ硅树脂用量、MTES用量、乳化剂用量对有机硅防水剂乳液性能的影响。结果表明,当 α , ω -二羟基聚二甲基硅氧烷黏度为20 000 mPa · s,MQ硅树脂质量分数为6%,MTES质量分数为7%,复配乳化剂质量分数为10%时,所得有机硅防水剂乳液的性能较佳,其处理的水泥基材料吸水率比为6.32%,贮存12个月无分层。

改性环氧树脂在抗腐蚀水泥浆中的应用

在CCUS井中,水泥石抗腐蚀能力和力学性能是确保水泥环密封完整性的关键。抗腐蚀水泥浆体系最常用的是胶乳等成膜堵孔类聚合物材料通过提高水泥石致密性,降低水泥石渗透率,进而降低提高CO_(2)的侵入阻力。但胶乳等材料会导致水泥石抗压强度较低的问题,不利于CCUS井前期压裂、后期的反复注采中保持水泥环长期完整性。本研究采用可固化树脂代替胶乳,起到降低扩散速率作用的同时,提高水泥石力学性能。利用脂肪醇聚氧乙烯醚对环氧树脂改性,优选2-乙基-4-甲基咪唑为固化剂,形成的树脂与固化剂体系可直接混入配浆水中,现场作业简便,且树脂的固化反应与水泥浆的稠化反应相互独立,树脂水泥浆复合体系的耐温能力强,130℃条件下流动性好、稠化时间可调,7d抗压强度最高达51.1MPa,杨氏模量低至4.97GPa。树脂固化体可有效提高水泥石致密性,降低水泥石渗透率,进而降低提高CO_(2)的侵入阻力,形成的树脂水泥浆复合体系具有良好的抗腐蚀性能。

掺再生砖集料水泥稳定碎石力学性能研究

为了改善掺再生砖集料水泥稳定碎石的力学性能,研究了不同强化剂类型和掺量对再生砖集料的强化效果,并在此基础上研究了掺再生砖集料水泥稳定碎石的力学强度。结果表明:有机硅树脂在降低再生砖集料压碎值、吸水率和提高粘附性性能远远优于硅烷偶联剂和水玻璃溶液;随着再生砖集料掺量的增加,掺再生砖集料水泥稳定碎石无侧限抗压强度逐渐降低,而劈裂强度却逐渐提高。

一种添加自交联环氧树脂乳液的防腐韧性水泥浆

酸性气体中H_(2)S和CO_(2)要与硅酸盐水化物发生反应,导致水泥石的渗透率增大、抗压强度大幅降低,使油井水泥环受到严重腐蚀,影响井筒完整性。为此,合成一种自交联环氧树脂乳液,用于增强油井水泥耐H_(2)S和CO_(2)腐蚀的能力。在H_(2)S分压为2.0 MPa、CO_(2)分压为1.5 MPa下,对水泥石的防腐蚀性能和作用机理进行评价与分析。研究结果表明:①交联环氧树脂乳液加量增加,抗压强度增大,超过一定加量后抗压强度增加不明显甚至减小,而弹性模量降低显著,增幅逐渐减少;②自交联环氧树脂乳液能够提高油井水泥石耐H_(2)S和CO_(2)腐蚀的能力,随着自交联环氧树脂乳液加量的增大,水泥石受H_(2)S和CO_(2)的腐蚀深度、渗透率降低,抗压强度先增加后降低;③自交联环氧树脂乳液包裹水泥石的水化产物,阻隔了硅酸盐水泥石水化产物与H_(2)S和CO_(2)等酸性气体的接触,提高了水泥石对H_(2)S和CO_(2)等酸性气体的耐腐蚀能力;④自交联环氧树脂乳液防腐韧性水泥浆常规工程性能良好,固井水陈化时间、自交联环氧树脂加量、温度变化对稠化时间不敏感,现场应用可操作性强。在6口井开展了防腐韧性水泥浆试验,固井质量平均优质率达到90%以上,合格率为99%以上。结论认为,自交联环氧树脂乳液充填和成膜包裹水泥水化产物,使水泥石具有防腐韧性性能,在川东北高含硫区块具有良好的推广应用前景。