微弧氧化和碱处理技术在多孔钽修复兔颅骨缺损中的应用

目的观察微弧氧化和碱处理对多孔钽表面性状、生物相容性和成骨能力的影响。方法微弧氧化和碱处理多孔钽片后,扫描电镜观察表面微孔数量、表面钙磷沉积和接触角。植入钽片修复兔颅骨缺损模型,在4周和12周观察骨愈合情况。结果扫描电镜显示处理组表面有更多的微孔和钙磷沉积以及更小的接触角(P<0.05)。植入多孔钽片后,所有动物均生长良好,伤口愈合佳。CT观察多孔钽片和周围骨组织耦合良好;钙黄绿素标记检测显示12周时有新生骨长入多空钽材料内部;扫描电镜观察发现4周时多空钽材料内部有新生血管,12周时有骨小梁长入材料内部。结论微弧氧化和碱处理能改变多孔钽材料表面形状,处理后多孔钽片具有良好的生物相容性和成骨能力。     

不同方法处理的纯氧化铝瓷贴面粘接强度的研究

目的:观察喷砂、酸蚀、二氧化硅水溶胶热处理等表面处理方法对纯氧化铝陶瓷贴面与树脂之间粘接强度的影响。方法:选择高纯α-Al2O3烧结的纯氧化铝陶瓷贴面样本30个,将其随机分为A、B、C三组,每组10个。分别应用不同的表面处理方法与同一种树脂进行粘结,A组采用单纯喷砂,B组采用喷砂+二氧化硅表面处理+HF,C组采用喷砂+二氧化硅表面处理+硅烷偶联剂,检测和比较各组的粘接强度。结果:C组的粘接强度最大,为23.84±0.74,明显高于A组和B组(P<0.05),而A组和B组的粘接强度比较差异无统计学意义(P>0.05)。结论:单纯喷砂或二氧化硅水溶胶热处理与HF的联合使用对纯氧化铝陶瓷贴面与树脂之间的粘接强度无明显改善,而采用喷砂以及二氧化硅水溶胶热处理与硅烷偶联剂的联合应用可取得纯氧化铝陶瓷贴面与树脂间的最大粘接效果。     

三种树脂粘接剂对纯氧化铝粘接强度的影响

目的:测定试件经过喷砂、硅溶胶热处理及与硅烷偶联剂结合的表面处理后,三种树脂粘接剂与纯氧化铝贴面的剪切强度。方法:选取高纯度的α-Al_2O_3纯氧化铝试件30个,将其随机分为A(可乐丽菲露SACTM复合树脂粘接剂)、B(Vorilink N树脂粘接剂)、C(RelyXTM Unicem树脂粘接剂)三组,每组10个。与试件粘接,在恒温水浴37℃的环境下静置24 h后测试其剪切粘接强度。扫描电子显微镜下观察各试件粘接界面的破坏形式。结果:Vorilink N粘接强度为(18.37±2.11)、RelyXTM Unicem粘接强度为(9.98±1.22),SACTM树脂粘接材料粘接强度最好,为(25.91±2.97),显著高于Vorilink N树脂粘接剂和RelyXTM Unicem树脂粘接剂,差异具有统计学意义(P0.05)。A组全部为混合破坏,B组出现了粘接剂的内部破坏,C组既有混合破坏也有界面破坏和粘接剂的内部破坏。扫描电镜图显示A、B两组的粘接断面上有很多树脂残留,C组表面相对光滑树脂残留很少。结论:不同树脂粘接剂对纯氧化铝试件的粘接强度有影响,SACTM粘接剂的粘接效果最好。     

567 例手足口病临床疗效观察

目的:比较中西医结合治疗与单纯西医治疗手足口病临床疗效的差异。方法:567例手足口病患者随机分成两组,对照组282例,单纯采用西医治疗,治疗组285例,在西医治疗基础上加用中药汤剂联合治疗,观察两组患者退热时间,皮疹消褪时间,食纳改善时间,比较两组间治愈率,有效率差异。结果:治疗组与对照组有效率均为100%;治愈率治疗组88.1%,对照组86.2%,差异无统计学意义(P>0.05);重症患者治愈率治疗组为83.3%,对照组为74.1%,差异有统计学意义(P<0.05);退热时间治疗组为2.65±0.79天,对照组为3.20±0.82天,差异有统计学意义(P<0.05);食纳改善时间治疗组为2.28±0.85天,对照组为3.35±0.68天,差异有统计学意义(P<0.05);结论:中西医结合治疗手足口病在重症患者治愈率,退热时间,食纳改善时间上优于单纯西药治疗。     

氧化钛纳米管对即刻种植骨结合影响的实验研究

目的:评价氧化钛纳米管对犬即刻种植骨结合效果的影响。方法:犬拔牙后即刻将光滑表面(对照组)和氧化钛纳米管表面(实验组)种植体植入拔牙窝内,于12周后处死取材,进行显微CT扫描、组织学染色分析以及生物力学检测。结果:扫描电镜显示经过阳极氧化后,钛表面形成了直径为30-80纳米的纳米管状结构;12周后,显微CT扫描结果提示实验组骨体积分数(BV/TV)、骨小梁数目(Tb.N)、骨小梁厚度(Tb.Th)均显著高于对照组,骨小梁间隙(Tb.Sp)显著低于对照组,差异具有统计学意义(P0.05)。术后12周,实验组与对照组骨结合率分别为49.35±11.76%、31.79±13.07%,最大拔出力分别为105.28±27.87N、79.23±20.46N,实验组均显著高于对照组,差异均具有统计学意义(P0.05)。结论:氧化钛纳米管表面有利于促进即刻种植后骨结合的效果。     

预酸蚀乳牙牙本质对自酸蚀粘接系统粘接强度的影响

目的:探讨预酸蚀乳牙牙本质对自酸蚀粘接系统粘接强度的影响。方法:随机选取28颗健康乳磨牙,磨除颊舌面釉质,暴露牙本质粘接面,沿近远中向劈开形成56个样本,随机分为7组(n=8)。直接涂布组(A1组,A2组和A3组)分别涂布AdperTM Easy One(AEO),Xeno-V(XV)和OptiBond All In One(AIO)三种自酸蚀粘接剂,预酸蚀组(B1组,B2组和B3组)在涂布三种自酸蚀粘接剂前先使用35%磷酸酸蚀乳牙牙本质15 s,对照组(C组)使用Prime&Bond NTTM(NT)全酸蚀粘接剂,每个样本用Z350复合树脂堆砌成直径为3 mm的树脂小柱,通过剪切试验测试剪切粘接强度,并通过扫描电子显微镜观察断裂表面形态。结果:B1组,B2组的剪切粘接强度值明显高于A1组,A2组(P<0.001);B3组与A3组的剪切粘接强度值比较无明显差别(P=0.94)。A2组的剪切粘接强度值低于C组(P<0.05);B1组的剪切粘接强度值明显高于C组(P<0.001)。扫描电镜观察结果显示各组试件断裂面形态多为牙本质和复合树脂界面破坏。直接涂布组(A1组,A2组和A3组)断裂多发生在混合层的底部,树脂突较少且低于小管口。B1组和B2组试件断裂面可见多数牙本质小管被树脂突填满,断裂多发生在混合层的中上部。B3组试件断裂面可见牙本质小管空虚,树脂突较少。结论:预酸蚀乳牙牙本质可以提高AEO,XV两种自酸蚀粘接剂的剪切粘接强度。自酸蚀粘接剂处理乳牙牙本质可以达到全酸蚀粘接剂处理的粘接强度,但应用自酸蚀粘接剂前预酸蚀乳牙牙本质可以获得更高的粘接强度。     

三种不同内固定法治疗髌骨骨折82 例临床疗效的分析

目的:观察三种不同内固定法治疗髌骨骨折82例临床疗效及安全性。方法:将82例髌骨骨折患者随机分成三组,其中30人接受双克氏针钢丝环绕法治疗,髌骨周缘环形缝扎处理21例,31人应用镍钛聚髌器治疗。从手术时间、优良率、愈合时间、手术费用及并发症等指标进行评价。结果:三种内固定方法治疗髌骨骨折组的手术时间差异无统计学意义(P>0.05),镍钛聚髌器组的愈合时间、手术费用及术后并发症与双克氏针钢丝环绕法组及髌骨周缘环形缝扎处理组相比,差异具有统计学意义(P<0.05);镍钛聚髌器治疗髌骨粉碎性骨折的优良率与其它两组相比,差异具有统计学意义(P<0.05);三种方法治疗髌骨横断性骨折的优良率相互比较差异无统计学意义。结论:双克氏针钢丝环绕法、髌骨周缘环形缝扎法及镍钛聚髌器法都可以被采纳治疗髌骨横断性骨折;在治疗髌骨粉碎性骨折优先采用镍钛聚髌器法。     

PEP-1 超氧化物歧化酶对大鼠脑缺血再灌注后Bcl-2 的影响

目的:观察细胞穿透肽-铜,锌超氧化物歧化酶(PEP-1-SOD1)预处理对大鼠局灶性脑缺血再灌注损伤的改善作用及其脑保护机制。方法:线栓法建立大鼠局灶性脑缺血6h后再灌注损伤模型,进行神经行为评分,并通过HE染色在光镜下观察神经细胞损伤变化,免疫组化法检测B细胞淋巴瘤基因-2(B-cell lymphoma-2,Bcl-2)蛋白的阳性表达。结果:盐水对照组(缺血再灌注组或模型组)神经障碍显著高于假手术组(P<0.05),与模型组相比,PEP-1-SOD1预处理组可降低神经障碍评分(P<0.05);光镜下,假手术组神经细胞结构正常,PEP-1-SOD1预处理组和缺血再灌注组均有不同程度的缺血再灌注损伤,PEP-1-SOD1预处理组较缺血再灌注组损伤轻;假手术组Bcl-2蛋白表达极弱,缺血再灌注组和PEP-1-SOD1预处理组在脑缺血再灌注后6h在缺血半暗带周围出现Bcl-2蛋白阳性表达,24h达到高峰,48h表达开始减少。与假手术组相比,PEP-1-SOD1预处理组和缺血再灌注组Bcl-2蛋白阳性细胞数显著增多(P<0.05);与缺血再灌注组相比,PEP-1-SOD1预处理组Bcl-2蛋白阳性细胞数显著增多(P<0.05)。结论:PEP-1-SOD1对大鼠局灶性脑缺血再灌注损伤有保护作用,PEP-1-SOD1可通过上调Bcl-2蛋白的表达发挥脑保护作用。     

钙结合蛋白S100A16对胰岛素抵抗的作用研究

目的探究钙结合蛋白S100A16在胰岛素抵抗中的作用。方法用S100A16抗体进行免疫沉淀,然后用蛋白质谱分析寻找与S100A16相互作用的蛋白。实验1转染Vector质粒的HepG2细胞作为对照,用转染shRNA质粒、S100A16过表达质粒干预作为处理组。实验2以慢性胰岛素刺激细胞构建胰岛素抵抗模型,采用转染shRNA质粒的细胞作为对照,用未转染和转染Vector质粒干预作为处理组。实验3以不做任何处理的细胞作为对照,在胰岛素抵抗模型中用吡格列酮干预作为处理组。Western blot检测相关蛋白的表达水平。组间比较采用成组t检验。结果与转染Vector质粒比较,转染S100A16过表达质粒中胎球蛋白A表达(1.39±0.54比2.85±0.25)水平上调(P<0.05);与转染Vector质粒比较,转染shRNA质粒胎球蛋白A蛋白表达(0.36±0.03比0.20±0.03)水平降低(P<0.01)。在胰岛素抵抗条件下,与转染shRNA质粒的细胞比较,未转染和转染Vector质粒的IRS-2蛋白表达(0.11±0.04比1.65±0.48)水平上调(P<0.01);与不做任何处理的细胞比较,用吡格列酮处理的细胞IRS-2表达(0.26±0.11比0.52±0.05)水平上升(P<0.01)。结论S100A16在HepG2细胞中通过胎球蛋白A促进胰岛素抵抗。     

氧化鱼油对黄颡鱼黑色素合成酶及内分泌激素的影响

实验模拟自然氧化条件制备氧化鱼油, 替代普通鱼油加入饲料中, 研究其对黄颡鱼(Pelteobagrus fulvidraco)表皮黑色素、酪氨酸酶活力、血清与脑内分泌激素含量的影响。处理组分别为未替代组(C组)、50%氧化鱼油替代组(Y50组)和100%氧化鱼油替代组(Y100组), 结果表明: 随着氧化鱼油替代普通鱼油的比例提高, 黄颡鱼5级(黑色素占细胞面积80%以上)黑色素细胞比例上升; 酪氨酸酶活力上升, 但各组差异不显著(P>0.05); 皮质酮(CORT)在血清和脑组织中各组含量差异均不显著(P>0.05); 肾上腺皮质激素(ACTH)在脑组织中含量增加 (P<0.05), 而血清中Y50组含量高于C组及Y100组(P<0.05); 血清中促肾上腺皮质激素释放激素(CRH)含量降低, Y50与Y100组之间差异不显著(P>0.05), 而脑组织中各组差异不显著(P>0.05); 血清中α-黑素细胞刺激素(α-MSH)含量, Y100组高于其他组(P<0.05), 而脑组织中各组差异不显著(P>0.05)。上述结果表明, 随着氧化鱼油替代普通鱼油的比例提高, 5级黑色素细胞比例上升, 黄颡鱼血清和脑组织中能互相转换的ACTH与α-MSH总量提高, 变化趋势与表皮黑色素含量和酪氨酸酶活性相一致。     

Effect of Er,Cr:YSGG Laser at Different Output Powers on the Micromorphology and the Bond Property of Non-Carious Sclerotic Dentin to Resin Composites

Background

The objective of this study was to investigate the influence of Er,Cr:YSGG laser irradiated at different powers on the micromorphology and the bonding property of non-carious sclerotic dentin to resin composites.

Methods

Two hundred bovine incisors characterized by non-carious sclerotic dentin were selected, and the seventy-two teeth of which for surface morphological analysis were divided into nine groups according to various treatments (A: the control group, B: only treated with the adhesive Adper Easy One, C: diamond bur polishing followed by Adper Easy One, D-I: Er,Cr:YSGG laser irradiating at 1W, 2W, 3W, 4W, 5W, 6W output power, respectively, followed by Adper Easy One). The surface roughness values were measured by the non-contact three-dimensional morphology scanner, then the surface micromorphologies of surfaces in all groups were assessed by scanning electron microscopy (SEM); meanwhile, Image Pro-Plus 6.0 software was used to measure the relative percentage of open tubules on SEM images. The rest, one hundred twenty-eight teeth for bond strength test, were divided into eight groups according to the different treatments (A: only treated with the adhesive Adper Easy One, B: diamond bur polishing followed by the above adhesive, C-H: Er,Cr:YSGG laser irradiating at 1 W, 2 W, 3 W, 4 W, 5 W, 6 W output power, respectively, followed by the above adhesive), and each group was subsequently divided into two subgroups according to whether aging is performed (immediately tested and after thermocycling). Micro-shear bond strength test was used to evaluate the bond strength.

Results

The 4W laser group showed the highest roughness value (30.84±1.93μm), which was statistically higher than the control group and the diamond bur groups (p<0.05). The mean percentages ((27.8±1.8)%, (28.0±2.2)%, (30.0±1.9)%) of open tubules area in the 4W, 5W, 6W group were higher than other groups (p<0.05). The 4W laser group showed the highest micro-shear bond strength not only in immediately tested (17.60±2.55 PMa) but after thermocycling (14.35±2.08MPa).

Conclusion

The Er,Cr:YSGG laser at 4W power can effectively improve the bonding property between non-carious sclerotic dentin and resin composites by increasing the roughness and mean percentage area of open tubules.     

微弧氧化后锆铜铝银非晶合金的细胞相容性研究

目的:探讨微弧氧化(micro-arc oxidation,MAO)后的Zr46(Cu4.5/5.5Ag1/5.5)46Al8(at%)(本文简称Zr-Cu-Al-Ag非晶合金)的细胞相容性。方法:按照国家标准制备300 V、350 V和400 V电压MAO处理的Zr-Cu-Al-Ag非晶合金、铸态Zr-Cu-Al-Ag非晶合金以及TI6Al4V合金试件的浸提液用于培养L929细胞,阴性组的L929细胞用含10%小牛血清的DMEM溶液培养,阳性组的L929细胞用含64 g/L苯酚和10%小牛血清的DMEM溶液培养,通过四唑盐(MTT)比色法分析试件的细胞相容性。结果:MAO处理的Zr-Cu-Al-Ag非晶合金细胞毒性评级为0,其浸提液中的L929细胞状态良好,细胞增殖曲线呈上升趋势,三个MAO组的吸光度值高于铸态Zr-Cu-Al-Ag非晶合金组、TI6Al4V合金组和阳性对照组(P0.05),但与阴性对照组无明显差别(P0.05)。结论:MAO提高了Zr-Cu-Al-Ag非晶合金表面的细胞相容性。     

Various Effects of Sandblasting of Dental Restorative Materials

Background

Sandblasting particles which remain on the surfaces of dental restorations are removed prior to cementation. It is probable that adhesive strength between luting material and sandblasting particle remnants might exceed that with restorative material. If that being the case, blasting particles adhere to sandblasted material surface could be instrumental to increasing adhesive strength like underlying bonding mechanism between luting material and silanized particles of tribochemical silica coating-treated surface. We hypothesize that ultrasonic cleaning of bonding surfaces, which were pretreated with sandblasting, may affect adhesive strength of a resin luting material to dental restorative materials.

Methods

We therefore observed adhesive strength of resin luting material to aluminum oxide was greater than those to zirconia ceramic and cobalt-chromium alloy beforehand. To measure the shear bond strengths of resin luting material to zirconia ceramic and cobalt-chromium alloy, forty specimens of each restorative material were prepared. Bonding surfaces were polished with silicon abrasive paper and then treated with sandblasting. For each restorative material, 40 sandblasted specimens were equally divided into two groups: ultrasonic cleaning (USC) group and non-ultrasonic cleaning (NUSC) group. After resin luting material was polymerized on bonding surface, shear test was performed to evaluate effect of ultrasonic cleaning of bonding surfaces pretreated with sandblasting on bond strength.

Results

For both zirconia ceramic and cobalt-chromium alloy, NUSC group showed significantly higher shear bond strength than USC group.

Conclusions

Ultrasonic cleaning of dental restorations after sandblasting should be avoided to retain improved bonding between these materials.     

Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding

The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilyl)ethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future.     

Shear bond strength between different materials bonded with two resin cements

doi: 10.1111/j.1741‐2358.2011.00565.x
Shear bond strength between different materials bonded with two resin cements Background: The aim of this study was to compare the shear bond strength between Ni–Cr alloy specimens bonded to air‐abraded Ni–Cr, bur‐abraded Ni–Cr, etched ceramic and etched enamel substrates using the resin cements RelyX ARC or Enforce. Materials and methods: Ni–Cr specimens were made and sandblasted with Al₂O₃ airborne‐particles. Disc‐shaped patterns were made for each of the four experimental substrates: Ni–Cr treated with Al₂O₃ airborne‐particles, Ni–Cr treated with diamond bur abrasion, etched enamel and etched ceramic. Results: Significant differences in shear bond strength were found between the different materials and luting agents evaluated. The Ni–Cr alloy cylinders bonded to Ni–Cr surfaces sandblasted with 50 μm Al₂O₃ particles and bonded with Enforce achieved the highest bond strength when compared with other substrates (28.9 MPa, p < 0.05). Bur‐abraded metal discs had lowest values, regardless the cement used (2.9 and 6.9 MPa for RelyX and Enforce, respectively). Etched enamel and etched ceramic had similar shear bond strengths within cement groups and performed better when RelyX was used. Conclusions: Bonding Ni–Cr to Ni–Cr and ceramic may result in similar and higher bond strength when compared to Ni–Cr/enamel bonding. For metal/metal bonding, higher shear bond strength was achieved with resin cement Enforce, and for metal/ceramic and metal/enamel bonding, RelyX had higher results.     

Influence of silicone oil modification on properties of ramie fiber reinforced polypropylene composites

This paper focused on the analyses of the composition, microstructure, thermal stability and mechanical behavior of modified ramie fiber and its reinforced polypropylene composites. Ramie fiber (RF) was treated with epoxy-silicone oil (ESO) at 160 °C in argon gas. The FTIR and XRD analyses indicated that some silicone molecular chains were bonded on the surface of modified RF, which decreased the crystallinity of the fiber without changing the crystalline type of cellulose. The SEM results of fracture surface showed that the modified RF/PP composite had better interfacial bonding between RF and PP. The mechanical tests showed that the impact strength and the elongation at break of RF/PP were increased by 17.0% and 196% after modification, respectively. The tensile strength of 30RF/PP was improved from 18.95 MPa to 25.96 MPa compared to pure PP. The results of TGA showed that fiber treatment could improve the degradation temperature of RF/PP composites.     

The Adhesion AND Growth of Both the Human Primary Gingival Epithelial Cells and Streptococcus Mutans on Micro-Arc Oxidized Titanium

With good osseointegration properties, micro-arc oxidation has now gradually become the key point in basic research and clinical trials, but interface between the implant surface treated by micro-arc oxidation and gingival soft tissues has been seldom reported. The influences of micro-arc oxidation surface treatment on the biological behavior of primary human gingival epithelial cells (hGEC) and common pathogen Streptococcus mutans have been studied. MTT method was taken to test the adhesion and growth of hGEC on different treated surfaces. No significant changes were found between with or without MAO- treated surface. However, higher growth rate was observed in MAO group at first and third days, although it showed no significant difference at fifth and seventh day. Secretions of EGF of the cells grown on both surfaces were also no big changes (P > 0.05). RT-PCR showed adhesion gene of hGEC, E-cad on the first day of micro-arc oxidation surface treatment, expression level is higher than that of polishing group (P < 0.05), but no significant difference of the expression levels of Itgβ1, PCNA, and EGF. Finally, easier adhesion and high growth rate of Streptococcus mutans were found at MAO-treated surface (P < 0.05). In conclusion, our data suggested MAO-treated Ti surface may favor epithelial cell adhesion, but it also increase the risk of bacterial infection.     

Effect of pre-processing methods on bond strength between acrylic resin teeth and acrylic denture base resin

doi: 10.1111/j.1741‐2358.2011.00480.x
Effect of pre‐processing methods on bond strength between acrylic resin teeth and acrylic denture base resin Objectives: This study evaluated the effects of various pre‐processing methods on the bond strength between resin and denture teeth. Backgrounds: Debonding of acrylic resin teeth from denture base material is a problem for patients wearing complete dentures. Materials and Methods: Four experimental groups (n = 30) were investigated by subjecting tooth–resin bonding to tensile loading. Specimens were prepared and tested according to the methods of the International Standards Organization (ISO 22112:2005) using a special assembly. Four pre‐processing surface treatments of teeth were applied: (i) ST₁, no treatment applied (control); (ii) ST₂, wax solvent (Dewaks, Faber Kimya & Ilaç, Turkey); (iii) ST₃, boiling water followed by conditioning with methyl methacrylate (MMA) monomer (Meliodent, Bayer Dental, Germany); (iv) ST₄, boiling water followed by wax solvent agent and finally MMA monomer application. Bond strength test was performed using a universal testing machine. Results: All the strength values of the test groups were within clinically acceptable limits. The lowest values were from the ST₁ group and the highest values were in the ST₄ group. Conclusions: Wax elimination methods affected bonding strength. Application of wax solvent and MMA monomer to the ridge lap surfaces of the teeth gave the best results. In clinical practice, this application procedure may decrease the bonding failure of denture teeth.     

Effects of Acid Treatment on Dental Zirconia: An In Vitro Study

The aim of this study was to evaluate the effects of hydrofluoric (HF) acid, acetic acid, and citric acid treatments on the physical properties and structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) at ambient temperature. In total, 110 bar-shaped zirconia specimens were randomly assigned to 11 groups. The specimens in the control group (C) received no surface treatment, while those in the Cage group were hydrothermally aged at 134°C and 0.2 MPa for 20 h. Ten specimens each were immersed at ambient temperature in 5% and 40% HF acid for 2 h (40HF0), 1 day (5HF1, 40HF1), and 5 days (5HF5, 40HF5), while 10 each were immersed at ambient temperature in 10% acetic acid and 20% citric acid for 7 (AC7, CI7) and 14 days (AC14, CI14). X-ray diffraction (XRD) was used to quantitatively estimate the monoclinic phase. Furthermore, flexural strength, surface roughness, and surface Vickers hardness were measured after treatment. Scanning electron microscopy (SEM) was used to characterize the surface morphology. The Cage group specimens exhibited an increased monoclinic phase and flexural strength. Furthermore, 40% HF acid immersion decreased the flexural strength and surface hardness and deteriorated the surface finish, while 5% HF acid immersion only decreased the surface hardness. All the HF acid-immersed specimens showed an etched surface texture on SEM observations, while the other groups did not. These findings suggest that the treatment of Y-TZP with 40% HF acid at ambient temperature causes potential damage, while treatment with 5% HF acid, acetic acid, and citric acid is safe.