不同核材料与二氧化锆陶瓷树脂粘接耐久性的研究

目的 研究不同类型核材料与二氧化锆陶瓷树脂间的粘接强度及耐久性。方法 二氧化锆陶瓷盘经研磨后通过2种自粘接型树脂水门汀（Clearfil SA Luting和RelyX U100）与不同核材料包括流动型复合树脂核材料、充填型复合树脂、钴铬合金以及牙本质进行粘接,组成个8实验组。每个实验组再分成2个亚组,分别接受0、10 000次冷热循环后进行剪切粘接强度测试。结果 核材料、树脂水门汀材料及老化条件均会对粘接强度产生明显影响（P<0.001）。冷热循环后,只有Clearfil SA Luting与钴铬合金的粘接强度没有明显降低（P>0.05）,并高于其余各核材料组（P<0.05）;Clearfil SA Luting与钴铬合金、流动型复合树脂核材料及充填型复合树脂间的粘接强度均明显高于RelyX U100相对应的粘接强度（P<0.05）,而Clearfil SA Luting和RelyX U100与牙本质间的粘接强度的差异无统计学意义（P>0.05）。结论 不同类型核材料和树脂水门汀材料能够对二氧化锆陶瓷树脂粘接耐久性产生明显影响。     

自粘接树脂水门汀与两种粗化处理的二硅酸锂陶瓷的粘接性能评价

摘要］目的：评价自粘接树脂水门汀与喷砂和氢氟酸酸蚀两种方式粗化处理的二硅酸锂陶瓷的粘接强度及耐久性。材料和方法：制作二硅酸锂瓷片183个,烧结后随机分为2组分别进行氢氟酸酸蚀和喷砂,随后根据粘接策略的不同分为RU（RelyX Unicem）、RU200(RelyXTM U200)以及RV(silane+RelyX Veneer) 3个亚组分别制作粘接试件。各组试件一半于37℃下水储24h,另一半进行20000次冷热循环,随后测试剪切粘接强度。氢氟酸酸蚀、喷砂及未进行粗化处理的陶瓷试件采用扫描电镜观察表面形貌。结果：氢氟酸组产生显著高于喷砂组的粘接强度（p<0.05）;单纯应用自粘接树脂水门汀组的粘接效果与传统树脂水门汀结合硅烷预处理组无统计学差别（p=0.057）;所有组的粘接强度在老化后均显著降低（p<0.05）。结论：氢氟酸酸蚀可以获得较氧化铝喷砂处理更佳的粘接效果;自粘接树脂水门汀在无需硅烷预处理的条件下用于二硅酸锂陶瓷的粘接可获得较好的粘接效果。     

烧结次数对椅旁计算机辅助设计与制作二硅酸锂玻璃陶瓷贴面不同部位颜色的影响

目的 评价烧结次数和渐变厚度及其交互性对椅旁计算机辅助设计与制作（CAD/CAM）二硅酸锂玻璃陶瓷贴面不同部位颜色的影响。方法 在标准中切牙模型上制备贴面修复模型,用椅旁扫描仪采集光学印模,椅旁CAD/CAM系统制作24个二硅酸锂玻璃陶瓷贴面样本共4组（n=6）,初次结晶组为对照组S0,其余按上釉烧结次数依次为S1、S2、S3组。使用Vita easyshade电子比色仪测定每个贴面的色彩参数L、C、H、a、b,用SAS 9.1.3统计软件采用重复测量多因素方差方法分析不同烧结次数以及不同部位厚度间各颜色指标的差异性。最后扫描电镜（SEM）观察每组贴面的晶体排列和致密度。结果 随着烧结次数增加,试件的L值总体呈减小趋势（P<0.05）。C和b的烧结次数有统计学意义（P<0.05）,其中,除S2组与S3组之间差异无统计学意义外（P>0.05）,其余各组之间的两两比较差异均有统计学意义（P<0.05）。SEM观察发现二硅酸锂晶体随着烧结次数增加,晶体变大,晶体间的孔隙变小,晶体间的锁结变得更为紧密。结论 上釉次数和厚度及其交互性对二硅酸锂玻璃陶瓷的色相、明度、彩度均存在影响。     

氢氟酸处理时间对玻璃陶瓷与树脂粘接耐久性的影响

目的 评价不同氢氟酸处理时间对玻璃陶瓷表面与树脂粘接耐久性的影响,以期为玻璃陶瓷表面氢氟酸处理时间的正确选择提供临床参考.方法 可切削玻璃陶瓷(PmCAD)表面接受4.8%氢氟酸处理0 s(对照组)、30 s(30 s氢氟酸处理组)和60 s(60 s氢氟酸处理组),每组32个陶瓷片.使用三维激光共聚焦显微镜测量陶瓷片表面粗糙度参数(Ra)和表面积.陶瓷片与4种粘接套装(硅烷偶联剂和树脂粘接剂:A:Monobond S和Variolink Ⅱ;B:Clearfil Ceramic Primer和Clearfil Esthetic Cement;C:GC Ceramic Primer和Linkmax HV;D:Porcelain Liner M和SuperBond)粘接形成粘接试件,每组16个陶瓷片直接测量粘接强度,16个陶瓷片经30 000次冷热循环后测量粘接强度.结果 对照组、30和60 s氢氟酸处理组Ra值[分别为(3.89±1.94)、(12.53±0.80)、(13.58±1.10)μm]及表面积[分别为(7.81±2.96)、(30.18±2.05)、(34.16±1.97)mm2]随着氢氟酸处理时间的延长而显著增加(P<0.05).同种粘接套装相同氢氟酸处理时间下冷热循环后试件的粘接强度均显著低于冷热循环前(P<0.05).冷热循环后粘接套装A、B的粘接强度随着氢氟酸处理时间的延长而显著增加[A:分别为(3.59±3.51)、(16.18±2.62)、(20.33±2.45)Mpa;B:分别为(4.74±2.08)、(7.77±1.55)、(13.45±3.75)Mpa];粘接套装D 30 s氢氟酸处理组的粘接强度[(22.00±1.64)Mpa]显著高于相应对照组[(12.96±4.17)Mpa],但与60 s氢氟酸处理组[(20.42±3.01)Mpa]相比,差异无统计学意义(P>0.05);氢氟酸处理时间未对粘接套装C的粘接强度产生显著影响.结论 氢氟酸处理能提高玻璃陶瓷与树脂的粘接耐久性,氢氟酸处理时间的选择不仅取决于陶瓷表面结构的变化,也取决于所使用的粘接套装.     

不同表面处理方法对氧化锆陶瓷微观结构和粘接强度影响的研究

目的 研究不同机械-化学性表面处理对氧化锆陶瓷表面微观形貌、结构及组成的影响,比较不同表面改性后的氧化锆陶瓷与人牙本质的粘接强度。方法 选择氧化锆陶瓷（IPS e.max ZirCAD）,切割并烧结形成长6 mm、宽6 mm、高5 mm瓷块126块,随机分为7组,每组18块,分别进行如下处理。A组：不处理,对照组;B组：50 μm氧化铝喷砂;C组：50 μm氧化铝喷砂+30 μm二氧化硅蚀刻;D组：50 μm氧化铝喷砂+30%硅溶胶涂层;E组：110 μm氧化铝喷砂;F组：110 μm氧化铝喷砂+30 μm二氧化硅蚀刻;G组：110 μm氧化铝喷砂+30%硅溶胶涂层。每组随机抽取2个试件,分别用表面粗糙度轮廓仪测量表面粗糙度（R_a）,X射线衍射（XRD）观察表面晶相结构,能谱分析仪（EDX）分析表面化学元素组成,扫描电镜（SEM）观察表面微观形貌。收集70颗人离体第三磨牙制备成牙本质平面。使用双固化树脂水门汀将氧化锆试件与牙本质平面粘接,万能试验机进行剪切粘接强度（SBS）测试。采用SPSS 17.0软件对结果进行单因素方差分析及多重检验。结果 与对照组相比,表面处理后的氧化锆陶瓷R_a具有显著性差异（P<0.05）。所有表面处理后都发生了四方相（t）到单斜相（m）的晶相转换,且热处理后的m相体积分数最多。表面改性后化学元素组成发生变化,EDX结果显示硅涂层后,硅元素含量显著升高,Zr、Y、Hf减少。SEM图像显示,氧化铝喷砂后的氧化锆陶瓷表面出现一些微小断裂、晶界消失;硅溶胶薄膜烧结后体积明显收缩,可见裂纹与剥离。不同表面处理组的粘接强度有统计学差异（P<0.05）,F和G组SBS值最大,其次为C和D组,显著大于B和E组（P<0.05）,对照组的SBS值最小（P<0.05）。结论 氧化铝喷砂、硅粉蚀刻、硅溶胶涂层法可显著改变氧化锆陶瓷的表面形貌、结构和组成,有利于氧化锆陶瓷与牙体组织粘接时形成微机械嵌合与化学结合作用。氧化铝喷砂后硅涂层处理是一种比较理想的表面改性方法,可显著提高氧化锆陶瓷与牙体组织的粘接强度。     

通用型粘接剂和树脂水门汀对氧化锆 剪切粘接强度的影响

目的 研究通用型粘接剂和树脂水门汀对氧化锆陶瓷剪切粘接强度和耐久性的影响。方法 氧化锆陶瓷烧结制作20 mm×10 mm×10 mm和10 mm×10 mm×10mm两种尺寸的试件,实验分为12组,将这2种试件分别采用不同的树脂水门汀（RelyX Ultimate树脂水门汀、Clearfil SAC自粘接树脂水门汀）和通用粘接剂（无粘接剂、Scotchbond通用粘接剂、Clearfil SE One粘接剂）在不同的储存条件（水浴、水浴+冷热循环）下进行粘接。测试剪切粘接强度,分析断裂形态。结果 水门汀（F=8.41,P<0.01）和粘接剂（F=30.34,P<0.01）对氧化锆剪切粘接强度的影响有统计学意义;储存条件对剪切粘接强度的影响无统计学意义（F=1.83,P=0.18）。RelyX Ultimate树脂水门汀、无粘接剂、水浴+冷热循环储存时的剪切粘接强度最低（14.02 MPa±6.86 MPa）,RelyX Ultimate树脂水门汀、Scotchbond通用粘接剂、水浴+冷热循环储存时的剪切粘接强度最高（54.12 MPa±8.37 MPa）。结论 通用型粘接剂可提高树脂水门汀对氧化锆的粘接耐久性。非自粘接的树脂水门汀如不使用通用型粘接剂则其粘接耐久性下降。     

通用型粘接剂和树脂水门汀对氧化锆剪切粘接强度的影响

目的 研究通用型粘接剂和树脂水门汀对氧化锆陶瓷剪切粘接强度和耐久性的影响。方法 氧化锆陶瓷烧结制作20 mm×10 mm×10 mm和10 mm×10 mm×10mm两种尺寸的试件,实验分为12组,将这2种试件分别采用不同的树脂水门汀（RelyX Ultimate树脂水门汀、Clearfil SAC自粘接树脂水门汀）和通用粘接剂（无粘接剂、Scotchbond通用粘接剂、Clearfil SE One粘接剂）在不同的储存条件（水浴、水浴+冷热循环）下进行粘接。测试剪切粘接强度,分析断裂形态。结果 水门汀（F=8.41,P<0.01）和粘接剂（F=30.34,P<0.01）对氧化锆剪切粘接强度的影响有统计学意义;储存条件对剪切粘接强度的影响无统计学意义（F=1.83,P=0.18）。RelyX Ultimate树脂水门汀、无粘接剂、水浴+冷热循环储存时的剪切粘接强度最低（14.02 MPa±6.86 MPa）,RelyX Ultimate树脂水门汀、Scotchbond通用粘接剂、水浴+冷热循环储存时的剪切粘接强度最高（54.12 MPa±8.37 MPa）。结论 通用型粘接剂可提高树脂水门汀对氧化锆的粘接耐久性。非自粘接的树脂水门汀如不使用通用型粘接剂则其粘接耐久性下降。     

不同表面处理方法对纳米复合陶瓷与树脂水门汀粘接强度的影响

目的 评估不同表面处理对纳米复合陶瓷与树脂水门汀剪切粘接强度的影响。方法 将纳米复合陶瓷用计算机辅助设计/计算机辅助制作（CAD/CAM）技术切割成大小为10 mm×10 mm×3 mm的试件150块,并根据表面处理方法不同将试件按随机数字表的方法随机分为5组（n=30）：对照组、喷砂组、喷砂+硅烷组、酸蚀组和酸蚀+硅烷组。各组试件经过相应表面处理后,使用Single Bond Universal通用粘接剂+RelyX ^TM Ultimate Cliker ^TM树脂水门汀将树脂试件粘接于纳米复合陶瓷试件上,37 ℃蒸馏水中水浴24 h和30 d,万能试验机进行剪切粘接强度测试。结果 不同表面处理方法、不同的水浴时间都会影响到剪切粘接强度。喷砂+硅烷组的剪切粘接强度最大,与其他各组间差异均具有统计学意义（P<0.05）;对照组和酸蚀组间差异无统计学意义,但两组与其他组间差异具有统计学意义（P<0.05）;喷砂组和酸蚀+硅烷组之间差异无统计学意义（P>0.05）,但两组与其他组间差异具有统计学意义（P<0.05）。结论 喷砂、喷砂+硅烷、酸蚀+硅烷对纳米复合陶瓷表面处理,均可提高其与树脂水门汀的剪切粘接强度,喷砂+硅烷处理后剪切粘接强度最佳。     

纳米氢氧化锆涂层对10-甲基丙烯酰氧癸二氢磷酸酯提高氧化锆陶瓷粘接强度的影响

目的 研究纳米氢氧化锆在氧化锆陶瓷表面形成碱性涂层后对10-甲基丙烯酰氧癸二氢磷酸酯（MDP）与氧化锆陶瓷粘接强度的影响。方法 制作氧化钇稳定四方相氧化锆（Y-TZP）瓷片140枚,氧化铝喷砂后对其表面进行不同的处理,制作粘接试件并测试剪切粘接强度。以X线光电子能谱（XPS）检测Y-TZP陶瓷表面依次经过纳米氢氧化锆涂层和含有MDP的底涂剂处理后的化学键变化。结果 老化前,与对照组相比,两种碱性涂层均能提高短期粘接强度值,纳米氢氧化锆涂层增强效果更显著。老化后,各组粘接强度值差异无统计学意义,但较老化前均显著降低（P<0.05）。XPS在制备纳米氢氧化锆涂层的Y-TZP瓷片表面检测到-OH键,在制备纳米氢氧化锆涂层的Y-TZP陶瓷应用含有MDP的底涂剂处理后检测出-P-O-Zr键。结论 在氧化锆陶瓷表面制备碱性涂层能够使MDP提高氧化锆陶瓷粘接强度。     

酸蚀对可切削陶瓷表面及内部微观结构影响的研究

目的探讨酸蚀是否对可切削陶瓷的表面形貌、内部微观结构产生影响。方法制备大小为4 mm×4 mm×2 mm的树脂渗透陶瓷、二硅酸锂玻璃陶瓷试件各32个,经打磨、清洗后,随机分为4组(n=8):①4%氢氟酸;②9.5%氢氟酸;③MBEP;对照组。原子力显微镜测量试件的表面粗糙度及三维形貌,X射线能谱仪对树脂渗透陶瓷的元素Si/C、二硅酸锂玻璃陶瓷的元素Si/K比率进行检测。结果两种材料的氢氟酸处理组表面粗糙度参数值均高于对照组。树脂渗透陶瓷的氢氟酸处理组元素Si/C比率均低于对照组。SEM显示两种材料9.5%氢氟酸处理组均有更具侵蚀性的表面酸蚀图案,MBEP组产生与对照组相似的表面蚀刻图案。结论酸蚀对两种可切削陶瓷的表面形貌、内部微观结构产生影响。MBEP有较为温和的酸蚀能力。     

一种通用粘接剂对不同CAD/CAM可切削材料的短期粘接成绩

[摘要] 目的 评估一种通用粘接剂对于三种不同类型的CAD/CAM可切削材料的短期粘接成绩。方法 制作氧化钇稳定四方相氧化锆陶瓷,纳米复合陶瓷和二硅酸锂玻璃陶瓷试件各20枚,其中前两者进行喷砂处理,后者进行HF酸蚀处理。各组陶瓷再分为2亚组,分别使用（SBU）或不使用（Ctr）通用粘接剂Single Bond Universal。以上表面处理瓷片与复合树脂柱通过树脂水门汀粘接,制作粘接试件,37℃水储24ｈ后测试剪切粘接强度并记录断裂模式。喷砂处理的氧化锆陶瓷和纳米复合陶瓷,以及酸蚀处理的二硅酸锂玻璃陶瓷通过扫描电镜（SEM）观察表面微观形态。结果SEM观察显示酸蚀处理的二硅酸锂玻璃陶瓷,喷砂处理的氧化锆陶瓷和纳米复合陶瓷相对于粗化处理前呈现出粗糙的表面形态。三种经粗化处理的材料使用通用粘接剂表面处理后,剪切强度较未使用者显著增强。结论 通用粘接剂Single Bond Universal能够增强氧化钇稳定四方相氧化锆陶瓷,纳米复合陶瓷和二硅酸锂玻璃陶瓷三种类型CAD/CAM可切削材料的短期粘接强度。     

Effect of prolonged application of single-step self-etching primer and hydrofluoric acid on the surface roughness and shear bond strength of CAD/CAM materials

This in vitro study aimed to assess the influence of different concentrations and durations of hydrofluoric acid (HF) and Monobond Etch & Prime (MEP) etching on the surface roughness (R_a) of different CAD/CAM materials and on the shear bond strength (SBS) of a self-adhesive resin bonded to the materials. Seventy specimens of hybrid ceramic, leucite-based glass-ceramic, lithium disilicate glass-ceramic, and zirconia-reinforced lithium silicate glass-ceramic were prepared and divided into seven groups according to the surface treatments: Control (C); MEP etching for 60 (MEP₆₀) and 120 (MEP₁₂₀) s; 5% HF etching for 60 (HF-5%₆₀) and 120 (HF-5%₁₂₀) s; 9.5% HF etching for 60 (HF-9.5%₆₀) and 120 (HF-9.5%₁₂₀) s. The R_a was measured using a 3D profilometer. All groups were treated with a universal primer except for the C, MEP₆₀, and MEP₁₂₀ groups. A self-adhesive resin cement was bonded to all specimens, and the bond strengths were measured using a universal testing machine. All surface treatments increased both R_a and SBS values compared to the control in each material. Neither the duration of surface treatments nor the HF acid concentrations had a statistically significant effect on SBS. Within the limitations of this experimental study, it can be concluded that Monobond Etch & Prime may be a preferable method to achieve high bond strength values.     

Influence of Different Surface Pretreatments of Zirconium Dioxide Reinforced Lithium Disilicate Ceramics on the Shear Bond Strength of Self-Adhesive Resin Cement

AimTo analyze the influence of different surface pretreatments of zirconium dioxide reinforced lithium disilicate ceramics on the shear bond strength of self-adhesive resin cement.Materials and methodsEighty-four zirconium reinforced lithium disilicate disc Vita suprinity (Vita Zahnfabrick, Bad Säckingen, Germany) 14x12x2 mm specimens were fabricated according to the manufacturer''s recommendations. The specimens were embedded in acrylic resin blocks and randomly divided in seven groups (n=12/each) accorrding to the treatment: Group 1- 10% hydrofluoric acid; Group 2- silane; Group 3- hydrofluoric and silane; Group 4- sandblasting with silane; Group 5- Er: YAG laser+ silane; Group 6- Nd: YAG laser + silane; and the control group, in which the specimens were not treated. Round shape composite discs (Filtek Bulk fill, 3M ESPE, St.Paul, Minnesota, USA) with 3.5 mm diameter, were made for shear bond strength testing, and then cemented to the ceramic sample surface using composite cement (RelyX U200 Automix, 3M ESPE, Neuss, Germany). After cementing the composite disc on the sample, the samples were subjected to shear bond strength test of 10 N with a “stress rate” of 1 MPa / s. To determine the nature of the fracture (adhesive, cohesive or adhesive-cohesive), the broken samples were examined under a stereomicroscope. The ANOVA test and the Tukey test were used to compare the values ​​of the bond strength characteristics between different types of materials. All tests were performed with a significance level of α = 0.05.ResultsThere was a significant difference in the shear bond strength of self-adhesive cement to dental lithium-disilicate ceramics reinforced with zirconium dioxide after different preparation protocols (p<0, 05). The treatment of lithium disilicate ceramics reinforced with zirconium dioxide by silanization, sandblasting + silanization, Nd: YAG + silanization resulted in significantly higher bond strength compared to the control group. There was statistically higher bond strength of self-adhesive cement after pretreatment of lithium disilicate ceramics Nd: YAG + silanization compared to Er: YAG + silanization (p <0.05). Adhesive fracture dominated in the control group, sandblasting + silanization group, and in the laser groups, while mixed fracture dominated in other groups.ConclusionUnder the limitations of this study, the Nd:YAG irradiation with silanization could be used as pretreatment for providing greater shear bond strength of self-adhesive resin cement to zirconium reinforced lithium disilicate.     

离子交换强韧化效应对CAD/CAM二硅酸锂玻璃陶瓷机械性能的影响

目的:探究锂-钠离子交换强韧化效应对CAD/CAM二硅酸锂玻璃陶瓷机械性能的影响.方法:制作50个CAD/CAM二硅酸锂玻璃陶瓷圆片状试件,晶化、打磨及抛光后,用4种不同的熔融硝酸钠离子交换工艺进行处理(n=10),分别检测离子交换前后样品的双轴弯曲强度、维氏硬度和断裂韧性.设置未交换组为空白对照.结果:CAD/CAM...     

Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

PURPOSE

The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material.

MATERIALS AND METHODS

A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm × 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 µm silica oxide particles (Cojet™ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at α=.05.

RESULTS

Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001).

CONCLUSION

Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.     

Microtensile Bond Strength of a Resin Cement to Silica‐Based and Y‐TZP Ceramics Using Different Surface Treatments

Purpose

To evaluate the effects of different surface treatments on the microtensile bond strength (μTBS) of bonding between resin cement and lithia or zirconia‐based ceramics using an in vitro study.

Materials and Methods

Three zirconia ceramic blocks (IPS e.max ZirCAD) and three lithium disilicate ceramic blocks (IPS e.max CAD) were sintered and duplicated in resin composite. The zirconia specimens underwent various treatments (n = 1): (i) Sandblast + primer (ZiSa); (ii) sandblast + laser irradiation + primer (ZiSaLa); or (iii) laser irradiation + primer (ZiLa). The lithium disilicate specimens also underwent various treatments: (i) sandblast + HF + silane (LiSaE); (ii) sandblast + silane (LiSa); or (iii) sandblast + laser irradiation + silane (LiSaLa). The ceramic–composite blocks were cemented with resin cement and cut to produce bars with approx. 1 mm² bonding areas. The specimens were thermocycled, and bond strength tests were performed in a universal testing machine. The fracture type was determined by observing the fractured surface under a stereomicroscope. The mean bond strengths of the specimens were statistically analyzed using one‐way ANOVA and Duncan's tests (α = 0.05).

Results

Mean comparison of the μTBS showed no significant difference between LiSaE and LiSa (p > 0.05), but significant differences between LiSaE and other groups (p ≤ 0.01). No significant differences were found between the ZiSaLa and ZiSa groups (p > 0.05). The modes of failure in all groups were mostly adhesive (57% to 80%). The mean bond strengths in laser‐irradiated ceramics were significantly lower than those from other surface treatments. All ZiLa specimens debonded before testing (pretest failure).

Conclusions

Lithium disilicate ceramic surface treated with a combination of sandblasting and silane application provided a bond strength comparable to that provided by sandblasting in combination with acid etching and applying silane. Groups treated with laser irradiation had significantly lower bond strengths than other groups.     

Effects of surface conditioning on bond strength of metal brackets to all-ceramic surfaces

The aim of this study was to determine the effectiveness of bonding brackets to ceramic restorations. Sixty feldspathic and 60 lithium disilicate ceramic specimens were randomly divided into six groups. Shear bond strength (SBS) and bond failure types were examined with six surface-conditioning methods: silane application to glazed surface, air particle abrasion (APA) with 25- and 50-microm aluminium trioxide (Al(2)O(3)), etching with 9.6 per cent hydrofluoric acid (HFA), and roughening with 40- and 63-microm diamond burs. Silane was applied to all roughened surfaces. Metal brackets were bonded with light cure composite, then stored in distilled water for 1 week and thermocycled (x500 at 5-55 degrees C for 30 seconds). The ceramic surfaces were examined with a stereomicroscope at a magnification of x10 to determine the amount of composite resin remaining using the adhesive remnant index. The lowest SBS values were obtained with HFA for feldspathic (5.39 MPa) and lithium disilicate (11.11 MPa) ceramics; these values were significantly different from those of the other groups. The highest SBS values were found with 63-microm diamond burs for feldspathic (26.38 MPa) and lithium disilicate (28.20 MPa) ceramics, and were not significantly different from 40-microm diamond burs for feldspathic and lithium disilicate ceramics (26.04 and 24.26 MPa, respectively). Roughening with 25- and 50-microm Al(2)O(3) particles showed modest SBS for lithium disilicate (22.60 and 26.15 MPa, respectively) and for feldspathic ceramics (17.90 and 14.66 MPa, respectively). Adhesive failures between the ceramic and composite resin were noted in all groups. Damage to the porcelain surfaces was not observed. The SBS values were above the optimal range, except for feldspathic ceramic treated with HFA and silane. With all surface-conditioning methods, lithium disilicate ceramic displayed higher SBS than feldspathic ceramic.     

Scanning electron microscope comparative surface evaluation of glazed-lithium disilicate ceramics under different irradiation settings of Nd:YAG and Er:YAG lasers

Objective:To evaluate the surface of glazed lithium disilicate dental ceramics after irradiation under different irradiation settings of Nd:YAG and Er:YAG lasers using a scanning electron microscope (SEM).Materials and Methods:Three glazed-press lithium disilicate ceramic discs were treated with HF, Er:YAG, and Nd:YAG, respectively. The laser-setting variables tested were laser mode, repetition rate (Hz), power (W), time of exposure (seconds), and laser energy (mJ). Sixteen different variable settings were tested for each laser type, and all the samples were analyzed by SEM at 500× and 1000× magnification.Results:Surface analysis of the HF-treated sample showed a typical surface texture with a homogenously rough pattern and exposed ceramic crystals. Er:YAG showed no effect on the surface under any irradiation setting. The surface of Nd:YAG-irradiated samples showed cracking, melting, and resolidifying of the ceramic glaze. These changes became more pronounced as the power increased. At the highest power setting (2.25 W), craters on the surface with large areas of melted or resolidified glaze surrounded by globules were visible. However, there was little to no exposure of ceramic crystals or visible regular surface roughening.Conclusions:Neither Er:YAG nor Nd:YAG dental lasers exhibited adequate surface modification for bonding of orthodontic brackets on glazed lithium disilicate ceramics compared with the control treated with 9.5% HF.     

Interfacial fracture toughness of different resin cements bonded to a lithium disilicate glass ceramic

Objectives

To evaluate the effect of HF acid etching and silane treatment on the interfacial fracture toughness of a self-adhesive and two conventional resin-based cements bonded to a lithium disilicate glass ceramic.

Methods

Lithium disilicate glass ceramic discs were prepared with two different surface preparations consisting of gritblasted with aluminium oxide, and gritblasted and etched with hydrofluoric acid. Ceramic surfaces with a chevron shaped circular hole were treated by an optimized silane treatment followed by an unfilled resin and then three different resin cements (Variolink II, Panavia F2, and Multilink Sprint). Specimens were kept in distilled water at 37 °C for 24 h and then subjected to thermocycling. The interfacial fracture toughness was measured and mode of failures was also examined. Data were analysed using analysis of variance followed by T-test analysis.

Results

No statistically significant difference in the mean fracture toughness values between the gritblasted and gritblasted and etched surfaces for Variolink II resin cement was found (P > 0.05). For the gritblasted ceramic surfaces, no significant difference in the mean fracture toughness values between Panavia F2 and Variolink II was observed (P > 0.05). For the gritblasted and etched ceramic surfaces, a significantly higher fracture toughness for Panavia F2 than the other cements was found (P < 0.05).

Conclusions

The interfacial fracture toughness for the lithium disilicate glass ceramic system was affected by the surface treatment and the type of luting agent. Dual-cured resin cements demonstrated a better bonding efficacy to the lithium disilicate glass ceramic compared to the self-adhesive resin cement.

Clinical significance

The lithium disilicate glass ceramic surfaces should be gritblasted and etched to get the best bond when used with Panavia F2 and Multilink Sprint resin cements, whereas for the Variolink II only gritblasting is required. The best bond overall is achieved with Panavia F2.