Effect of acid etching on marginal adaptation of mineral trioxide aggregate to apical dentin:microcomputed tomography and scanning electron microscopy analysis

The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate （MTA） to apical dentin using microcomputed tomography （micro-CT） and scanning electron microscopy （SEM）. Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials： （i） white-colored MTA （WMTA）, （ii） etched WMTA （EWMTA）, （iii） gray-colored MTA （GMTA） and （iv） etched GMTA （EGMTA）. After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the KruskaI-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of （0.007 1±0.004） mm3, （0.053±0.002） mm3, （0.003 6±0.001） mm3 and （0.005 9±0.002） mm3 respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be （492.3±13.8） μm, （594.5±17.12）μm, （543.1±15.33） μm and （910.7±26.2）μm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found （P〈O.05）. No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA.

Inhibition of matrix metalloproteinases expression in human dental pulp cells by all-trans retinoic acid

All-trans retinoic acid（ATRA） inhibits matrix metalloproteinase（MMP）-2 and MMP-9 in synovial fibroblasts, skin fibroblasts,bronchoalveolar lavage cells and cancer cells, but activates MMP-9 in neuroblast and leukemia cells. Very little is known regarding whether ATRA can activate or inhibit MMPs in human dental pulp cells（HDPCs）. The purpose of this study was to determine the effects of ATRA on the production and secretion of MMP-2 and-9 in HDPCs. The productions and messenger RNA（mRNA） expressions of MMP-2 and-9 were accessed by gelatin zymography and real-time polymerase chain reaction（PCR）, respectively. ATRA was found to decrease MMP-2 level in a dose-dependent manner. Significant reduction in MMP-2 mRNA expression was also observed in HDPCs treated with 25 mmol？L21ATRA. However, HDPCs treated with ATRA had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. Taken together, ATRA had an inhibitory effect on MMP-2 expression in HDPCs,which suggests that ATRA could be a candidate as a medicament which could control the inflammation of pulp tissue in vital pulp therapy and regenerative endodontics.

An in Vitro Investigation of Acid Etching Treatment Prior to Post and Core Cementation and Teeth Fracture Resistance

In order to investigate how to enhance the teeth fracture resistance after the post and core treatment, an in vitro study was conducted to measure the fracture resistance of endodontically treated teeth restored with cast post and core with two kinds of surface treatment technology and acid etching preparation on the dentinal surface. Sixty-four recently extracted human single-rooted first premolars were endodontically treated and sectioned approximately 1.5 mm above the cementoenamel junction to remove the coronal portion. Each specimen received a cast post, core build-up and a metal alloy crown restoration. All teeth were randomly divided into the smooth surface post, core repair group, the sand blasting surface post, and core repair group, each group was divided into 10 s, 30 s, 60 s acid corrosion treatment group and control group. In acid test groups, an acid etching solution was applied for 10, 30 and 60 seconds, respectively, to the root canal wall surface. Each specimen was embedded in acrylic resin block and tested in an electronic universal testing machine. Fracture loads results showed that canal acid etching could increase teeth fracture resistance strength both in smooth groups and sandblasting group, and achieved the best effect when acid etching for 30 s. Sand spray treatment on the surface of the cast metal post can improve the flexural strength of the teeth after postcrown restoration. Acid etching on the root canal wall surfaces and sand spray treatment on the surface of the cast metal post can improve the flexural strength of the root after post-crown restoration. Therefore, these two methods could be used to strengthen the tooth fracture resistance, and maintain the long-term therapeutic effect of cast post and core restoration.

SWELLING AND WETTABILITY OF LIGHT-CURED METHACRYLATE-BASED DENTAL RESINS PREPARED FROM CHOLIC ACID

2＇-methacryloxy-3α, 7α, I2α- trimethacryloyl cholic acid ethyl ester （CAGE4MA） has been prepared from cholic acid. Photo-polymeric resins were prepared from CAGE4MA. 2,2-bis[4-（2-hydroxy-3-methacrylyloxypropoxy）phenyllpropane （bis-GMA） was used for comparison, triethyleneglycol dimethacrylate （TEGDMA） was used as diluent. The polymerization was initiated by camphoroquinone （CQ）/N, N-dimethylaminoethyl methacrylate （DMAEMA） system. The conversion of CAGE4MA was 39% when the reaction time is 60s, which is lower than bis-GMA and TEGDMA. The swelling value of CAGE4MA resin was 0.41% in distilled water, which is much lower than those of bis-GMA resin （2.04%） and TEGDMA resin （4.77%） under the same conditions. Copolymers from CAGE4MA and TEGDMA have been prepared. With the increase of TEGDMA in mixture, the degree of conversion of CA GE4MA and swelling value increased. The swelling values of photocured resins in 0.1mol/L HCl were also measured.

The Influence of Kidney Stones and Salivary Uric Acid on Dental Calculus Formation and Periodontal Status among Some Saudi Patients Aged 25 - 70 Years

Background: The formation of kidney stones is considered a complicated process. Consequently, there are many questions about the link between kidney stones formation and level of salivary uric acid and calculus formation on the teeth surfaces. Objectives: To evaluate the correlation between the level of salivary uric acid and kidney stones formation and their influence on dental calculus and periodontal status among Saudi patients aged 25 - 70 years. Materials and Methods: 120 Saudi male patients were examined (60 of Kidney stones patients and 60 patients of non-kidney stones patients) for clinical evaluation of plaque index (PLI), gingival index (GI), calculus index of oral hygiene (CI) and clinical attachment loss (CAL). Moreover, lab assessment of uric acid level in the collected salivary samples was done. The findings were analyzed using of ANOVA test and Tukey’s test. Results: There were statistically significant differences in clinical parameters among kidney stones patients and non-kidney stones patients (p < 0.05), but these differences were highly statistically significant in the correlation between calculus index (CI), plaque index (PLI) and gingival index (GI) among kidney stone patients in group II, moreover, PLI and clinical attachment loss (CAL) among kidney stone patients in group III (p < 0.001). The statistical analyses revealed statistically significant differences in the level of salivary uric acid (mg/dl) in the comparison between kidney stones patients and non-kidney stones patients in group I and group III, whereas there were highly statistically significant in the comparison between kidney stones patients and non-kidney stones patients in group III. Conclusion: At the end of this study, we concluded that there was a relationship between dental calculus formation, kidney stones formation, and an increase in the level of salivary uric acid.

Antibacterial Effect of Aqueous Extracts and Bioactive Chemical Compounds of <i>Coffea canephora</i>against Microorganisms Involved in Dental Caries and Periodontal Disease

This study aimed to evaluate the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of Coffea canephora aqueous extract (Cc), trigonelline (Tg) and 5-caffeoylquinic acid (5-CQA) against cariogenic microorganisms: Streptococcus parasanguinis ATCC 903 (SP), Lactobacillus rhamnosus ATCC 9595 (LR);and pathogens related to periodontal disease: Porphyromonas gingivalis ATCC 33277 (PG), Fusobacterium nucleatum ATCC 25586 (FN), Prevotella intermedia ATCC 49046 (PI) and Prevotella nigrescens ATCC 33563 (PN). Different concentrations of Cc (0.15625 to 10 mg/mL), Tg and 5-CQA (0.005 to 10.24 mg/mL) were tested. Chlorhexidine (0.05%) was used as positive control and the substances without the inoculum comprised the blank control. The Cc showed bacteriostatic action against SP (MIC = 5 mg/mL) and LR (MIC = 10 mg/mL). Tg showed bacteriostatic action against SP (MIC = 2.56 to 1.28 mg/mL), LR (MIC = 2.56 mg/mL), PG (MIC = 2.56 to 1.28 mg/mL), FN (MIC = 5.12 mg/mL), PN (MIC = 2.56 mg/mL), and PI (MIC = 2.56 to 1.28 mg/mL). Also, Tg showed bactericide properties against SP (MBC = 2.56 mg/mL), PG (MBC = 2.56 mg/mL), FN (MBC = 10.24 mg/mL), PN (MBC = 5.12 mg/mL), and PI (MBC = 2.56 mg/mL). Although 5-CQA has previously shown activity against Streptococcus mutans, in the present study, it showed no activity against all tested microorganisms. C. canephora extract only showed antibacterial activity against cariogenic microorganisms, not presenting action against periodontal pathogens. It was concluded that trigonelline presented the best effect against all pathogens tested, therefore coffee extracts with higher trigonelline content should be tested against these specific pathogens.

Recent Advances and Perspectives of Lewis Acidic Etching Route:An Emerging Preparation Strategy for MXenes

Since the discovery in 2011,MXenes have become the rising star in the field of two-dimensional materials.Benefiting from the metallic-level conductivity,large and adjustable gallery spacing,low ion diffusion barrier,rich surface chemistry,superior mechanical strength,MXenes exhibit great application prospects in energy storage and conversion,sensors,optoelectronics,electromagnetic interference shielding and biomedicine.Nevertheless,two issues seriously deteriorate the further development of MXenes.One is the high experimental risk of common preparation methods such as HF etching,and the other is the difficulty in obtaining MXenes with controllable surface groups.Recently,Lewis acidic etching,as a brand-new preparation strategy for MXenes,has attracted intensive attention due to its high safety and the ability to endow MXenes with uniform terminations.However,a comprehensive review of Lewis acidic etching method has not been reported yet.Herein,we first introduce the Lewis acidic etching from the following four aspects:etching mechanism,terminations regulation,in-situ formed metals and delamination of multi-layered MXenes.Further,the applications of MXenes and MXene-based hybrids obtained by Lewis acidic etching route in energy storage and conversion,sensors and microwave absorption are carefully summarized.Finally,some challenges and opportunities of Lewis acidic etching strategy are also presented.

In situ synthesis of SnPS_(3)/Ti_(3)C_(2)T_(x) hybrid anode via molten salt etching method for superior sodium-ion batteries

Recently,SnPS_(3) has gained attention as an impressive sodium-ion battery anode material because of its significant theoretical specific capacity derived from the conversion-alloying reaction mechanism.Nevertheless,its practical applicability is restricted by insufficient rate ability,and severe capacity loss due to inadequate electrical conductivity and dramatic volume expansion.Inspired by the electrochemical enhancement effect of MXene substrates and the innovative Lewis acidic etching for MXene preparation,SnPS_(3)/Ti_(3)C_(2)T_(x) MXene(T=-Cl and-O) is constructed by synchronously phospho-sulfurizing Sn/Ti_(3)C_(2)T_(x) precursor.Benefiting from the boosted Na^(+) diffusion and electron transfer rates,as well as the mitigated stress expansion,the synthesized SnPS_(3/)Ti_(3)C_(2)T_(x) composite demonstrates enhanced rate capability(647 mA h g^(-1) at 10 A g^(-1)) alongside satisfactory long-term cycling stability(capacity retention of 94.6% after 2000 cycles at 5 A g^(-1)).Importantly,the assembled sodium-ion full cell delivers an impressive capacity retention of 97.7% after undergoing 1500 cycles at 2 A g^(-1).Moreover,the sodium storage mechanism of the SnPS_(3/)Ti_(3)C_(2)T_(x) electrode is elucidated through in-situ and ex-situ characterizations.This work proposes a novel approach to ameliorate the energy storage performance of thiophosphites by facile in-situ construction of composites with MXene.

Surface tuning of LaCoO_(3) perovskite by acid etching to enhance its catalytic performance

The stoichiometric LaCoO_(3) and nonstoichiometric LaCo_(1.2)O_(3) perovskite catalysts were prepared by citric acid sol-gel method,and then,LaCoO_(3) perovskite was etched with nitric acid.The structure,surface composition and reducibility of the catalyst were studied by X-ray diffraction(XRD),nitrogen desorption,transmission electron microscope(TEM),temperature program reduction of H_(2)(H_(2)-TPR) and X-ray photoelectron spectroscopy(XPS).It was found that nitric acid etching did not change the crystal structure and the overall morphology of the LaCoO_(3) catalyst,but it can cause the exposure of B-site Co metal to the surface of the catalyst.As a result,after acid etching,the reducibility of the LaCoO_(3) catalyst was improved,leading to the improvement in the catalytic activity of the LaCoO_(3) catalyst for CO oxidation and C_(3)H_(8) combustion.Moreover,the catalytic activity of the LaCoO_(3) catalyst after acid etching was higher than that of LaCo_(1.2)O_(3) and CoOx/LaCoO_(3) catalyst.

Acid etching process for fabrication of Bi_2Sr_2CaCu_2O_(8+x) stack

We adopted a new method, acid etching process, to fabricate the intrinsic Josephson junctions based on the Bi2Sr2CaCu2O8+x single crystals. By soaking the crystals into the dilute hydrochloric acid, we fabricated a junction stack successfully, and meantime made the surrounding area insulated. A certain concentration of hydrochloric acid was used to maintain the roughness of the modified layer. The cur-rent-voltage characteristic was achieved through the four terminal measurement. We could control the junctions' number by changing the concentration and the soaking time. We also found that the thick-ness of the stack was equal to the average height of the insulation layer. Such a simple, convenient and controllable fabrication method with a high yield might widen the applications of the intrinsic Joseph-son junctions.

Dental evaluation is helpful in the differentiation of functional heartburn and gastroesophageal reflux disease

BACKGROUND Heartburn is identically the key symptom of both,gastroesophageal reflux disease(GERD)and functional heartburn(FHB),making the differential diagnosis resource-intensive.Oral manifestations of GERD can be easily examined;therefore,their exploration might be a cheap,widely available,and useful tool in the differentiation of GERD and FHB.AIM To evaluate the prevalence of dental erosions(DE)and periodontal diseases(PD)in patients with heartburn and their association with GERD and FHB.METHODS A total of 116[M/F:51/65,mean age:54(17-80)years]consecutive patients with heartburn were enrolled for detailed esophageal function and orodental examinations.RESULTS Dental disorders were detected in 89%(103/116).Patients with PD+DE had significantly more often pathologic reflux(90.0%vs 27.8%;P<0.05),higher esophagitis scores(1.8 vs 0.9;P<0.05),and a significantly different mean impedance curve(P=0.04)than those without any dental diseases.The opposite approach established that patients with GERD had significantly higher prevalence of DE and PD,especially if both were present(28.9%vs 2.0%;P<0.01),more severe PD(1.5 vs 1.0;P<0.01),and longer history of heartburn(15 years vs 9 years;P<0.01)than those with FHB.CONCLUSION The dental evaluation of patients with heartburn seems to be useful in the differential diagnosis of GERD and FHB.Among the studied parameters,the co-appearance of DE and PD seems to be the best predictor of GERD,whereas the absence of dental disorders was mostly observed in FHB.

Dental Treatment with 30% Trichloroacetic Acid in a Patient with Moderate Hemophilia A

We present the case of a 51-year-old moderate hemophiliac with gingival bleeding due to papillary inflammation and adherence in the molar area 47. After dental diagnosis a calculus was removed and 30% trichloroacetic acid was placed by a pressurized applicator for five seconds;the procedure was repeated until the bleeding stopped, then tranexamic acid was placed by a gauze. The patient chewed the gauze for 30 minutes and was discharged after repeating the same procedure for 30 minutes more. We observed how local treatment with trichloroacetic acid combined to tranexamic acid placed on the hemorrhagic site was able to stop the bleeding.

灰岩酸蚀裂缝软化区域力学特性与微观特征

碳酸盐岩储层常采用酸化酸压工艺进行改造,酸蚀后岩石表面的微观结构被溶蚀破坏,岩石力学特性发生显著变化,进而影响最终的改造效果。为明确酸蚀对灰岩力学特性和微观孔隙结构变化的影响规律,开展了酸蚀前后灰岩力学特性实验、表面形态特征扫描电镜研究和微观孔隙结构核磁共振表征。结果表明,酸蚀后岩石表面出现了一定厚度的酸蚀软化层,厚度约为11.61μm。值得注意的是,由于酸蚀软化层的存在,灰岩抗压强度、弹性模量与表面硬度均降至酸蚀前的约40%。酸蚀后表层岩石内部产生了大小不一的溶蚀孔洞,并在溶蚀孔洞周边引发应力集中,改变了酸蚀软化层的应力分布。在高闭合应力作用下,溶蚀孔洞易于发生挤压变形或坍塌破坏,这也是酸蚀软化层力学性质改变的主要原因。结合核磁共振T2谱,发现孔径尺寸在1nm~1μm的孔隙数量变化最大,酸液溶蚀改变了灰岩软化层内部的孔隙结构,进而显著影响酸蚀后岩石的力学性质。

不同环境下酸性闪长岩沥青混合料长期水稳性能评价研究

通过浸水马歇尔试验、冻融劈裂试验以及车辙试验评价了采用酸碱复合集料、单掺水泥(2%水泥替代矿粉)、消石灰(30%消石灰水浸泡石料)以及抗剥落剂(0.3%抗剥落剂改性沥青)的酸性闪长岩沥青混合料的短期水稳性能,再通过反复冻融劈裂试验、反复冻融烘劈裂试验以及反复酸蚀冻融劈裂试验测试处置酸性闪长岩沥青混合料在不同环境下的长期水稳性能。结果表明:酸性闪长岩的物理力学性能均满足规范要求;处置后酸性闪长岩沥青混合料的短期水稳性能显著提升,满足规范使用要求;但经0.2%抗剥落剂处置的酸性闪长岩沥青混合料在高温下的长期水稳性能较差;经30%消石灰水处置的酸性闪长岩沥青混合料具有良好的长期水稳性能,可推荐应用于工程中。

三种不同树脂粘结系统对纤维桩粘结效果的影响

目的评价全酸蚀粘结系统、自酸蚀粘结系统及自粘结树脂对纤维桩粘结效果的影响。方法选取2021年10月至2022年3月于泰州职业技术学院口腔门诊部行前牙纤维桩修复的82例患者(共122颗前牙)作为研究对象,按照不同树脂粘结系统将其分为全酸蚀组(28例,40颗)、自酸蚀组(26例,40颗)及自粘结组(28例,42颗)。全酸蚀组使用Tetric-N Bond全酸蚀树脂粘结剂对纤维桩进行粘结,自酸蚀组使用All-Bond Universal自酸蚀树脂粘结剂对纤维桩进行粘结,自粘结组使用Relyx Unicem自粘结树脂对纤维桩进行粘结,完成纤维桩粘结后行全瓷冠修复。比较三组纤维桩核的稳固率及全瓷冠修复体的红色美学指数(PES)、白色美学指数(WES)评分。结果粘结6、12、18个月后,三组纤维桩核的稳固率组间及组内比较,差异无统计学意义(P>0.05)。粘结18个月后,三组全瓷冠修复体的PES、WES评分比较,差异无统计学意义(P>0.05)。结论三种树脂粘结系统对纤维桩的粘结效果在短期内相当,远期效果还需进一步的观察。

Acid-etching induced metal cation competitive lattice occupancy of perovskite quantum dots for efficient pure-blue QLEDs

Low efficiency and spectral instability caused by the surface defects have been considerable issues for the mixed-halogen blue emitting perovskite quantum dots light-emitting diodes(PeQLEDs).Here,an in situ surface passivation to perovskite quantum dots(PeQDs)is realized by introducing the metal cations competitive lattice occupancy assisted with acid-etching,in which the longchain,insulating and weakly bond surface ligands are removed by addition of octanoic acid(OTAC).Meanwhile,the dissolved A-site cations(Na^(+))compete with the protonated oleyl amine and are subsequently anchored to the surface vacancies.The preadded lead bromide,acting as inorganic ligands,demonstrates strong bonding to the uncoordinated surface ions.The as-synthesized PeQDs show the boosted photoluminescence quantum yield(PLQY)and superior stability with longer lifetime.As a result,the PeQLEDs(470 nm)based on the OTAC-Na PeQDs exhibit an external quantum efficiency of 8.42%in the mixed halogen PeQDs(CsPb(Br_(x)Cl_(1−x))_(3)).Moreover,the device exhibits superior spectra stability with negligible shift.Our competition mechanism in combination with in situ passivation strategy paves a new way for improving the performance of blue PeQLEDs.

酸腐蚀工艺对硅片表面粗糙度的影响

为了缩减工艺成本,提高硅片表面光泽度,降低表面粗糙度,降低表面金属含量,提高生产效率,对HNO_(3)∶HF∶CH_(3)COOH混合酸体系的反应机理进行了分析,通过改变酸腐蚀去除量,腐蚀液温度等工艺参数可有效控制超薄硅片腐蚀反应速度,降低表面粗糙度,提高表面光泽度。发现去除量达到100μm以后,表面粗糙度可达到0.065μm,同一条件下,腐蚀液温度为45℃时,表面粗糙度最小,反射率最高。

基于裂缝闭合理论和3D打印的导流能力预测方法

酸蚀裂缝导流能力对于酸压方案的优化和产能评估具有十分重要的意义,但是在酸蚀导流能力测试过程中存在高闭合压力下岩心柱破裂情况,影响实验数据的准确性。基于以上问题,综合采用3D扫描和3D打印技术以及受压情况下裂缝闭合理论对酸蚀裂缝导流能力进行研究。首先对岩样进行酸蚀实验,通过逆向建模技术获取到酸蚀后岩心三维模型,采用SLA3D打印技术制备含粗糙壁面的三维岩心模型,对酸蚀岩心和3D打印岩心开展不同围压下渗流实验。运用离散化数据处理方法,结合赫兹接触模型和N-K模型编写导流能力预测界面,使用数值模拟方法反映闭合应力下裂缝形变情况。研究结果表明,结合真实岩体三维数字模型及SLA3D打印技术制备真实岩样,为制作复杂裂缝岩心模型提供了有效途径;酸蚀岩心和3D打印岩心导流能力实验结果、3D打印岩心实验结果和数值模拟结果误差均小于7.7%,数值模拟与碳酸盐岩心实验值的误差小于9.6%;以低闭合压力下实验和模拟结果为基础可以预测高闭合压力下裂缝导流能力,提出的研究方法为定量化表征酸蚀裂缝导流能力提供了可靠途径。

碳酸盐岩储层闭合酸化模拟研究

酸压裂缝生产一段时间后导流能力会逐渐降低,常采用闭合酸化来提高已酸压裂缝的导流能力,闭合酸化模拟对闭合酸化设计意义重大,因此,针对该问题进行闭合酸化建模及数值模拟。首先,基于达西定理、物质平衡原理、酸岩反应动力学建立闭合酸化数学模型;然后通过地质统计学中的序贯高斯模拟算法生成具有非均质性和空间关联性的初始裂缝宽度空间分布和裂缝表面基质渗透率分布;利用有限体积法对模型进行数值求解,用C++编制模拟计算程序;最后基于该模型进行广泛的数值模拟研究,分析酸液分布规律、裂缝表面溶蚀规律、酸液作用距离的影响因素及规律,并形成各种条件下的酸液作用距离图版。研究表明,初始裂缝宽度和裂缝表面粗糙度对裂缝表面溶蚀形态起主导作用,裂缝面溶蚀形态有均匀推进、指进溶蚀和沟槽溶蚀;裂缝宽度越小、粗糙度越大,裂缝表面溶蚀竞争越强烈,越容易形成沟槽,酸液作用距离越远;排量、注酸量正相关于活酸作用距离,酸液传质系数负相关于活酸作用距离;典型的施工排量、酸液用量、常用的酸液类型下,闭合酸化中酸液作用距离为20~60 m。此模型可以预测不同条件下酸液作用距离和酸蚀裂缝表面溶蚀形态,优化闭合酸化参数,为现场闭合酸化施工设计提供理论依据和指导。