Effect of cleaning protocol on silica deposition and silica-mediated bonding to Y-TZP

ObjectivesTo evaluate the effect of cleaning methods on the deposition of silica on yttria-stabilized zirconium dioxide (Y-TZP) surface and on the silane-silica mediated bond strength between Y-TZP and resin cement.MethodsY-TZP slabs were air-abraded with 30 μm silica-coated alumina particles and distributed in three groups: no cleaning, cleaning with a stream of oil-free air/water spray for 5 s and cleaning with an ultrasonic bath in water for 10 min. The distribution of Si on the Y-TZP surfaces was recorded using energy dispersive spectroscopy (EDS). After the treatment was applied, Y-TZP slabs (n = 20) received a primer application and resin cement cylinders were built on the surface. After storage (24 h) in water storage or 3 months plus thermocycling; n = 10), microshear bond strength test (μSBS) was performed. X- ray Photoelectron Spectroscopy (XPS) characterized the chemical bonds between the silica layer and the silane-containing primer. Data were analyzed using ANOVA and Tukey test, as well as Weibull analysis (α = 0.05).ResultsCleaning method had a significant effect on the amount of Si deposited on zirconia surface (p < 0.001) and, consequently, on bond strength (p < 0.001). Storage/aging also had a significant effect on bond strength (p < 0.001). Low values of Weibull moduli for bond strength were observed for all groups after aging. XPS showed silane-silica chemical interaction for all groups.SignificanceThe silica deposited by tribochemical coating to Y-TZP was removed by the cleaning methods evaluated, compromising bond strength. Stability of the bonding is also a concern when no cleaning method is applied.     

Effect of tribochemical treatments and silane reactivity on resin bonding to zirconia

Objective

The aim of the study was to assess the roughness, structure and bond strength with zirconia of four grit-blasting treatments combined with three silane types, the reactivity of which was evaluated, as well.

表面硅涂层改性对氧化锆陶瓷与树脂水门汀粘结强度的影响

目的 研究不同浓度和不同厚度硅涂层对Lava氧化锆陶瓷与树脂水门汀粘结强度的影响。方法 制作Lava氧化锆长方体状陶瓷试样共81件(10 mm×10 mm×3 mm),按20%、30%、40% 3种硅涂层浓度及100、200、300 nm 3种硅涂层厚度分为9组(A~I,n=9)对氧化锆陶瓷粘结面进行处理,然后将每组试样与Panavia F树脂水门汀粘结,万能材料实验机测试剪切粘结强度,对结果进行统计分析。结果 A组到I组各组剪切粘结强度值分别为3.09±0.20、3.27±0.22、3.30±0.38、3.17±0.25、5.35±0.39、4.09±0.29、3.16±0.29、3.24±0.23和（4.01±0.28） MPa。不同厚度的硅涂层各组间粘结剪切强度差异具有统计学意义(P<0.05),不同浓度硅涂层间也具有统计学意义(P<0.05),浓度和厚度之间存在交互效应(P<0.05),30%浓度200 nm厚度硅涂层获得的剪切粘结强度值最大。结论 30%浓度涂抹200 nm厚度的硅涂层为较适宜的浓度和厚度,可明显提高氧化锆陶瓷与树脂水门汀剪切粘结强度。     

不同类型粘接底涂剂对氧化锆陶瓷树脂粘接耐久性的影响

目的:评估不同类型粘接底涂剂对致密烧结二氧化锆陶瓷与树脂粘接耐久性的影响。方法:2.5 mm厚氧化锆陶瓷片(Vita Inceram YZ)A3染色后,高温烧结成陶瓷试件。试件表面接受4种粘接底涂剂预处理(n=10):A,Clearfil CeramicPrimer;B,Alloy Primer;C,Metal/Zirconia Primer;D,Alumina/Zirconia primer。处理后的试件与树脂水门汀(Panavia F)的剪切粘接强度在冷热循环10 000次前后测量。试件表面未处理组作为对照组。用单因素方差分析对数据进行统计学处理。结果:冷热循环前,所有实验组的粘接强度均在10 MPa以上。冷热循环显著降低了所有实验组的粘接强度(P<0.001),A组的粘接强度显著高于对照组,对照组的粘接强度又显著高于其他各组(P<0.001)。结论:粘接底涂剂Clearfil Ceramic Primer对氧化锆陶瓷表面进行预处理,能够改善氧化锆陶瓷与树脂水门汀Panavia F的粘接耐久性。     

Effect of surface pre-treatments on the zirconia ceramic-resin cement microtensile bond strength

Objective

To evaluate the influence of different surface treatments on the microtensile bond strength of resin cement to zirconia ceramic.

Materials and methods

Twelve cylinder-shaped (∅ 12 × 5.25 mm high) blocks of a commercial zirconium-oxide ceramic (Cercon^® Zirconia, DENTSPLY) were randomly divided into 4 groups (n = 3), based on the surface treatment to be performed: (1) airborne particle abrasion with 125 μm Al₂O₃ particles (S); (2) selective infiltration etching (SIE); (3) experimental hot etching solution applied for 30 min (ST) and (4) no treatment (C). Paradigm MZ100 blocks (3M ESPE) were cut into twelve cylinders of 4 mm in thickness. Composite cylinders were bonded to conditioned ceramics using a resin cement (Calibra^®, DENTSPLY), in combination with the proprietary adhesive system. After 24 h bonded specimens were cut into microtensile sticks and loaded in tension until failure. Bond strength data were analyzed with Kruskall-Wallis and Dunn's Multiple Range test for multiple comparisons (p < 0.05). Failure mode distribution was recorded and the interfacial morphology of debonded specimens was analyzed using a scanning electron microscope (SEM).

Results

Bond strength values achieved after SIE and ST treatment were significantly higher than after S treatment and without any treatment (p < 0.05). Premature failures were mostly recorded in the S group.

Significance

Conditioning the high-strength ceramic surface with SIE and ST treatments yielded higher bond strengths of the resin cement than when zirconia ceramic was treated with airborne particle abrasion or left untreated.     

Crystallographic and morphological analysis of sandblasted highly translucent dental zirconia

Objective

To assess the influence of alumina sandblasting on four highly translucent dental zirconia grades.

The effect of various sandblasting conditions on surface changes of dental zirconia and shear bond strength between zirconia core and indirect composite resin

PURPOSETo measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes.RESULTSThe volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from 50 µm to 110 µm. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength.CONCLUSIONBased on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of 110 µm is recommended for dental applications to improve the bonding between zirconia core and ICR.     

Effect of various intraoral repair systems on the shear bond strength of composite resin to zirconia

PURPOSE

This study compared the effect of three intraoral repair systems on the bond strength between composite resin and zirconia core.

MATERIALS AND METHODS

Thirty zirconia specimens were divided into three groups according to the repair method: Group I- CoJet™ Repair System (3M ESPE) [chairside silica coating with 30 µm SiO₂ + silanization + adhesive]; Group II- Ceramic Repair System (Ivoclar Vivadent) [etching with 37% phosphoric acid + Zirconia primer + adhesive]; Group III- Signum Zirconia Bond (Heraus) [Signum Zirconia Bond I + Signum Zirconia Bond II]. Composite resin was polymerized on each conditioned specimen. The shear bond strength was tested using a universal testing machine, and fracture sites were examined with FE-SEM. Surface morphology and wettability after surface treatments were examined additionally. The data of bond strengths were statistically analyzed with one-way ANOVA and Tamhane post hoc test (α=.05).

RESULTS

Increased surface roughness and the highest wettability value were observed in the CoJet sand treated specimens. The specimens treated with 37% phosphoric acid and Signum Zirconia Bond I did not show any improvement of surface irregularity, and the lowest wettability value were found in 37% phosphoric acid treated specimens. There was no significant difference in the bond strengths between Group I (7.80 ± 0.76 MPa) and III (8.98 ± 1.39 MPa). Group II (3.21 ± 0.78 MPa) showed a significant difference from other groups (P<.05).

CONCLUSION

The use of Intraoral silica coating system and the application of Signum Zirconia Bond are effective for increasing the bond strength of composite resin to zirconia.     

Effects of coloring procedures on zirconia/veneer ceramics bond strength

PURPOSE

The most common failure seen in restorations with a zirconia core is total or layered delamination of the ceramic veneer. In the present study, the shear bond strengths between veneering ceramics and colored zirconia oxide core materials were evaluated.

MATERIALS AND METHODS

Zirconia discs (15 × 12 × 1.6 mm) were divided into 11 groups of 12 discs each. Groups were colored according to the Vita Classic scale: A3, B1, C4, D2, and D4. Each group was treated with the recommended shading time for 3 s, or with prolonged shading for 60 s, except for the control group. Samples were veneered with 3 mm thick and 3.5 mm in diameter translucent ceramic and subjected to shear test in a universal testing machine with a crosshead speed of 1 mm/min. One-way analysis of variance (ANOVA) and Tukey''s HSD tests were used for comparisons of the groups having the same shading times. A paired t-test was used for groups of the same color (3 s/60 s).

RESULTS

Among the 11 groups investigated C4 (3 s) had the highest bond strength with a value of 36.40 MPa, while A3 (3 s) showed the lowest bond strength with a value of 29.47 MPa.

CONCLUSION

Coloring procedures can affect zirconia/ceramic bond strength. However, the results also showed that bond strengths of all the investigated groups were clinically acceptable.     

介孔二氧化硅涂层对氧化锆桩表面改性后粘接强度的影响

目的:探讨经不同表面处理方法对氧化锆桩与树脂粘接剂之间粘接强度的影响.方法:新鲜拔除的完整下颌单根管前磨牙和氧化锆桩各45个,随机分成3组,每组15个.A组:氧化锆桩进行喷砂+硅烷偶联剂处理,为对照组;B组:氧化锆桩喷砂+30％硅涂层+硅烷偶联剂处理;C组:氧化锆桩喷砂+介孔二氧化硅涂层+硅烷偶联剂处理.用可乐丽菲露树脂粘接剂将桩粘接于牙根管内,医用硬组织切割机将牙横切成高度为2mm的试件,试件于37℃人工唾液中浸泡24 h,在5℃、55℃水浴中进行500个循环周期.测试粘接抗剪切强度;扫描电镜观察粘接界面.结果:A、B、C组的粘接强度(MPa)分别为6.689±0.908、10.363±1.282和13.360±0.803,两两比较,P＜0.05.扫描电镜观察发现介孔二氧化硅涂层处理组氧化锆桩与树脂粘接剂之间界面融合.结论:介孔二氧化硅涂层处理能提高氧化锆桩与树脂粘接剂的粘接强度.     

Influence of polymerization time on properties of dual-curing cements in combination with high translucency monolithic zirconia

Purpose

The aim of this in vitro study was to assess conversion degree (DC), micro-hardness (MH) and bond strength of two dual-curing resin cements employed under translucent monolithic zirconia irradiated with different time protocols.

Improved bonding of zirconia substructures to resin using a "glaze-on" technique

Objective

To investigate the influence of applying thin intermediary coatings of acid-etchable glasses on the shear bond strength between a methacrylate resin based cement and an yttria-stabilized zirconia dental ceramic substrate.

Methods

The upper and lower surfaces of 110 sintered yttria-stabilised tetragonal zirconia polycrystalline disc-shaped specimens were polished using sequential grades of Silicon Carbide, then air-abraded with 25 μm diameter alumina particles. Specimens were randomly allocated to 11 groups (A–K) (n = 10), group A acting as control. The upper surface of Group A specimens was subjected to a tribochemical coating regime (CoJet, 3M ESPE). Five glazing ceramics were applied and fired according to the manufacturer's recommended firing regime. The glaze was etched with 10% HF acid and all specimens coated with a silane primer. Two differing storage regimes were employed (wet storage vs thermocycling). Shear bond strength testing specimens were created by cementing resin-based composite cylinders to the centre of the prepared ceramic surface using Rely-X Unicem (3M ESPE) resin based cement. Shear bond strength testing was performed and load at failure recorded.

Results

A factorial analysis of variance at a 95% significance level demonstrated that all glazing techniques resulted in a significant increase in the shear bond strength compared with using the resin based cement alone (P < 0.01), with the different glazing ceramics resulting in significant differences in mean shear bond strength (P = 0.008). The differences were a function of the storage state (wet storage vs thermocycling (P = 0.013)).

Conclusion

The glazing techniques used in the current investigation resulted in a significantly enhanced shear bond stress to the resin based cement when compared with the current ‘gold standard’ – tribochemical coating.     

Effect of priming agents on shear bond strengths of resin-based luting agents to a translucent zirconia material

Purpose

The purpose of the present study was to evaluate the effect of priming agents and artificial aging with thermocycling on shear bond strengths of two resin-based luting agents to a translucent zirconia material.

Bonding quality of contemporary dental cements to sandblasted esthetic crown copings*

Aim: To evaluate the shear bond strength of current luting cements to sandblasted crown‐coping substrates. Methods: Specimens of nickel‐chromium, pressable glass ceramic, and zirconia crown‐coping substrates were sandblasted in three groups (n = 30 each) with 50 (group 1), 110 (group 2), and 250 μm (group 3) alumina particles at a pressure of 250 kPa. Cylinders of glass ionomer, universal resin, and self‐adhesive resin cements were then built up on the sandblasted substrate surfaces of each group (n = 10). All bonded specimens were stressed to evaluate the cement–substrate shear bond strength. Both the mode and incidence of bond failure were also considered. Results: No difference was noticed between all test groups in terms of cement–substrate bond strength. In comparison to self‐adhesive type, the universal resin cement provided lower bond strengths to both metal and glass–ceramic substrates in group 1. The self‐adhesive resin cement provided the highest bond strengths to the zirconia substrates in groups 2 and 3. The adhesive type of bond failure was common in the metal and zirconia substrates in all groups. Conclusions: Cement–substrate bonding quality is not affected by the size of sandblasting particles. Resin cements bond better to different coping substrates. Self‐adhesive resin cement is the best choice to bond zirconia‐based substrates.     

3种锆瓷表面形貌对氧化锆瓷与饰瓷结合强度的影响

目的探讨计算机辅助设计/计算机辅助制造(CAD/CAM)切削表面形貌对氧化锆瓷与饰瓷结合强度的影响。方法将40个Upcare氧化锆基底材料以CAD/CAM切削烧结瓷块试件,随机等分为4组。其中对照组按常规操作进行打磨、喷砂及抛光等处理。实验组均采用CAD/CAM时预设程序,分别使切削产生的刀路与剪切强度测试加力方向呈垂直(A组)、平行(B组)及突起(C组),并对试件进行喷砂处理。测量并比较各组试件的表面粗糙度和剪切强度。扫描电镜观察断裂界面的情况。结果各组的剪切强度分别为:A组(27.64±4.24)MPa、B组(27.12±5.32)、C组(36.86±7.21)MPa、对照组(24.14±2.74)MPa,其中对照组与A组、B组之间差异均无统计学意义(P>0.05),对照组与C组之间的差异具有统计学意义(P<0.05)。各组的表面粗糙度分别为:A组(5578.34±1165.58)Ra、B组(5227.98±1440.29)Ra、C组(5699.97±1234.28)Ra、对照组(5964.92±1013.834)Ra,各组之间的差异无统计学意义(P>0.05)。Pearson相关性分析显示,试件表面粗糙度与剪切强度之间无线性相关关系(P>0.05)。扫描电镜观察显示C组较其他组氧化锆瓷与饰瓷结合更致密,未见气泡,无孔隙存在。结论固位突起的锆瓷表面形貌可有效增加锆瓷与饰瓷间的结合强度,而表面粗糙度对界面的结合强度无明显影响。     

The effect of preparation order on the crystal structure of yttria-stabilized tetragonal zirconia polycrystal and the shear bond strength of dental resin cements

Objectives

The purpose of this study was to evaluate the effect of preparation order on the crystal structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and the shear bond strength of dental resin cements.

Methods

One-hundred fifty pre-sintered Y-TZP cylinders (Ø 9 mm × 13.5 mm) were prepared and divided into three groups (control group, SBS group and SAS group). Specimens in control group were not treated. Specimens in SBS group were sandblasted and then densely sintered, and specimens in SAS group were sintered in advance, and then sandblasted. The specimens were analyzed by X-ray diffractometry, confocal laser scanning microscopy and Energy dispersive X-ray spectroscopy before and after sandblasting. All specimens were embedded in polytetrafluoroethylene (PTFE) molds using PMMA and each group was divided into five subgroups. The mixed resin cements (Clearfil SA luting cement, Zirconite, Superbond C&B, Rely-X Unicem, and Multilink) were placed onto the Y-TZP surfaces using PTFE molds with Ø 3 mm × 3 mm, followed by storage in distilled water at 37 °C for 24 h, and thermocycling (5000 cycles at 5 °C and 55 °C with a 30 s dwelling time). All specimens were tested for the shear bond strengths with a universal testing machine, and fractured surfaces were evaluated by SEM. Statistical analysis was performed using one-way ANOVA and Scheffé comparison with α = .05.

Results

Sandblasting of the zirconia significantly increased shear bond strength of resin cements, but the preparation order had no significant influence on the shear bond strength in both test groups. In SEM observation, the natures of the surface faceting of the zirconia grains were totally different between SBS and SAS groups. SBS group exhibited less monoclinic structures than SAS group.

Significance

Sandblasting of pre-sintered Y-TZP and then sintering may induce favorable proportion of tetragonal structures. This might have positive effect on the clinical performance of zirconia restorations.     

不同表面处理对氧化锆与牙釉质黏结强度的影响

目的:比较4种表面处理方法对氧化锆陶瓷与牙釉质黏结强度的影响,为临床应用提供参考。方法:将切割烧结后的Lava氧化锆瓷块(2.7 mm×2.7 mm×5 mm)40件分为4组,分别经喷砂、喷砂/硅烷偶联剂、喷砂/CoJet Sand/硅烷偶联剂、无处理4种表面处理后,用RelyX Unicem与牙釉质黏结,测试剪切黏结强度,采用SPSS20.0软件包对数据进行统计学分析,利用扫描电镜观察断面模式。结果:喷砂/CoJet Sand/硅烷偶联剂组的剪切强度显著高于其他各组(P<0.001),且人工老化试验前、后无显著差异(P=0.595)。电镜观察该组断面模式,未发现“黏结界面破坏型”。结论:氧化锆表面经摩擦化学法硅涂层和硅烷偶联剂联合处理,能够有效提高氧化锆的黏结强度和耐久性。     

Development of a novel surface modification for improved bonding to zirconia

Objective

This report presents a novel pretreatment technique, whereby the zirconia surface is converted to a more reactive zirconium oxyfluoride, enabling improved chemical bonding to other dental substrates via conventional silanation approaches.

Methods

The study leverages a novel gas-phase fluorination process that creates a thin oxyfluoride conversion layer on the surface of zirconia, making it more reactive for conventional adhesive bonding techniques. Zirconia specimens, polished and roughened, were pretreated and composite cylinders bonded using conventional adhesive techniques. All specimens were subjected to a force at a crosshead speed of 0.5 mm/min in an electro-mechanical testing device. Single-factor analysis of variance (ANOVA) at a 5% confidence level was performed for the bonding strength data. Optical microscopy and scanning electron microscopy (SEM) were used to evaluate and quantify failure surfaces.

Results

Shear bond strengths were analyzed using single-factor ANOVA (p < 0.05). Mechanical testing results revealed that fluorinated zirconia specimens (both rough and polished) displayed the highest shear bond strengths as compared to other commercially available treatments. X-ray photoelectron spectroscopy analysis helped determine that this novel pretreatment created a more reactive, 2-4 nm thick oxyfluoride conversion layer with approximate stoichiometry, ZrO₃F₄.

Conclusion

Simple shear bond mechanical tests demonstrated that a fluorination pre-treatment is a viable method to chemically modify zirconia to produce a reactive surface for adhesive bonding.