Influence of Contamination on Zirconia Ceramic Bonding

The Effect of Different Chemical Surface Treatments on the Bond Strength of Resin-Matrix Ceramic Repaired with Resin Composite

OBJECTIVE

 This study investigates the effect of different chemical surface treatment protocols with different functional monomers of universal adhesives on the shear bond strength between resin-matrix ceramic and resin composite.

MATERIALS AND METHODS

 Eighty resin-matrix ceramics (Shofu block HC) were built and designed into eight groups of ten specimens and surface treated with HC primer (HC) and/or three universal adhesives (single bond universal [SBU], Scotchbond universal plus [SBP], and Tetric N-bond universal [TNU]) assigning follows; group 1, nonsurface treated; group 2, HC; group 3, SBU; group 4, HC + SBU; group 5, SBP; group 6, HC + SBP; group 7, TNU; group 8, HC + TNU. A template was put on the specimen center, and then pushed packable resin composite. Mechanical testing machinery was used to examine the samples' shear bond strength (SBS) values. To examine failure patterns, the debonded specimen surfaces were examined by a stereomicroscope.

STATISTICAL ANALYSIS

 The one-way analysis of variance method was used to evaluate the data, and the Tukey's test was used to determine the significant level (p < 0.05).

RESULTS

 The highest SBS was obtained in group 6 (39.25 ± 1.65 MPa). Group 1 (4.15 ± 0.54 MPa) had the lowest SBS. Group 6 exhibited the highest percentage of cohesive failure patterns (70%). High SBS values were frequently correlated with the surface treatment groups and the cohesive failure patterns.

CONCLUSION

 The application of HC primer prior to the universal adhesive is an alternative protocol for enhancing the repair bond strength between resin-matrix ceramic and resin composite interfaces. Moreover, the application of HC primer prior to the SBP is the best strategy for resin-matrix ceramic and resin composite repairs.

Effects of various functional monomers' reaction on the surface characteristics and bonding performance of polyetheretherketone

PURPOSE

Polyetheretherketone (PEEK) is a new polymeric material that has received significant attention in dentistry because of its mechanical properties, biocompatibility, and aesthetics. However, the bonding performance of PEEK to other materials is not preferable. This study aimed to analyze the variations in the surface characteristics of PEEK under the chemical action of primers containing different functional monomers or polymers and to evaluate the bonding performance of PEEK and dental cement.

METHODS

Disk-shaped PEEK samples were prepared by dental milling, blasting with alumina oxide, and covering with primers containing functional monomers or polymers. The surface characteristics of the samples were analyzed by microscopy and spectroscopy. The shear bond strength (SBS) between PEEK and dental cement, with and without thermocycling, was tested using a universal testing machine. Finally, the data were statistically analyzed and compared.

RESULTS

Functional monomers or polymers were successfully bonded to the surface of PEEK. This treatment significantly improved its hydrophilicity and surface free energy (P < 0.05). The primer containing pentaerythritol triacrylate had the highest SBS without thermocycling (13.89 MPa). Meanwhile, the primers containing urethane dimethacrylate (UDMA) and methyl methacrylate (MMA) (abbreviated as the HC group) showed the highest SBS and lowest reduction (25.51%) after thermocycling. Notably, all the testing groups achieved the ISO10477 standard of 5 MPa. After thermocycling, adhesive failure accounted for the largest proportion of failures in all the groups except the HC group.

CONCLUSIONS

The chemical priming treatment can significantly improve the SBS of PEEK and dental cement. Moreover, a primer containing both UDMA and MMA can provide improved bonding for PEEK materials.

A Study to Evaluate the Effect of Cleaning Solutions on Shear Bond Strength of Resin Cement to Saliva-Contaminated Lithium Disilicate (LDS) Ceramic

BACKGROUND

One of the greatest benefits of contemporary restorative dentistry is the creation of fixed partial dentures. The retention and durability of the fixed partial dentures may be improved by using a variety of tooth preparation methods, surface treatments, and luting resins.

AIM

To measure the shear binding strength of resin cement to saliva-contaminated lithium disilicate (LDS) ceramic after being exposed to various cleaning treatments.

METHODOLOGY

Over 30 LDS samples were examined. In Group 1, a cleansing solution comprising 15% zirconium oxide (Ivoclean) was employed for a duration of 20 s. This was succeeded by a rinsing phase lasting 15 s utilizing deionized water, followed by a 15-s period for drying. Subsequently, a final stage of air drying was conducted over a span of 15 s. In contrast, Group 2 underwent a washing procedure of 20 s involving a cleansing solution containing 30% sodium silicate. This was then ensued by a rinsing interval of 15 s with deionized water, succeeded by an air-drying process spanning 15 s. After applying cleaning solutions to the surface and adhering the specimens to the composite blocks using resin cement Multilink Automix (Ivoclar Vivadent, Schaan, Liechtenstein), the shear bond strength was assessed.

RESULTS

Using a 30% sodium silicate solution (Group 2), we were able to get the highest mean shear bond strength value after saliva-contaminated LDS. Group 1, 15% zirconium oxide (Ivoclean) had the weakest decontamination agents as measured by mean shear bond strengths. The shear bond strength values of the two groups were found to vary significantly between individuals using the independent sample t-test. LDs ceramic cleaned with a 30% sodium silicate solution had a higher shear bond strength than ceramic cleaned with Ivoclean (p<0.05).

CONCLUSION

The application of a 30% sodium silicate solution rendered the highest shear bond strength for saliva-contaminated LDS ceramic. In comparison, ceramic cleaned with Ivoclean exhibited notably lower shear bond strength values. The outcome of this investigation highlights the potential of diverse cleaning agents in influencing the adhesive qualities of resin cement, thereby contributing to the enhancement of fixed partial denture durability and efficacy.

Cleaning methods of contaminated zirconia: A systematic review and meta-analysis

OBJECTIVES

The aims of this study were to systematically review the literature and statistically analyze the effectiveness of different cleaning methods on the bond strength of resin cement to zirconia in short- and long-term aging conditions.

DATA/SOURCES

The literature was electronically searched in PubMed (MEDLINE), EMBASE, Wiley, Scopus, and Open Access Theses and Dissertations databases to select relevant articles that evaluated the bond strength between contaminated zirconia and resin cements. A manual search was performed by scanning the reference lists of included studies.

STUDY SELECTION

All articles were published online before April 2022 and in English. Meta-analyses were conducted using random effects models to calculate standardized mean differences (SMD) between uncontaminated zirconia and various cleaning methods in two aging conditions (short- and long-term). Statistical heterogeneity was assessed using I-square statistics. The risk of bias of all included studies was assessed. All statistical analyses were conducted using STATA (StataCorp, College Station, Texas).

RESULTS

Of the 1181 studies, 25 studies met the inclusion criteria for qualitative analyses. In short-term aging condition, cleaning contaminated zirconia with water, alcohol, or acid etching reported significantly lower bond strength than uncontaminated zirconia. For long-term aging condition, cleaning contaminated zirconia with water, cleaning agents, alcohol, or acid etching reported significantly lower bond strength than uncontaminated zirconia. Alumina air-abrasion or cleaning with sodium hypochlorite were comparable to uncontaminated zirconia for both short- and long-term aging conditions.

CONCLUSIONS

This meta-analysis appeared to indicate that the cleaning methods of contaminated zirconia restoration have an effect on zirconia bonding.

The effects of applying a novel cleaner on the bonding strength of zirconia surfaces

This study evaluates how pre-treatment with an MDP-containing cleaning agent (Katana Cleaner, Kuraray) influences the micro-shear bond strength (µSBS) of saliva-contaminated zirconia when used with universal adhesive (UA) systems. Rectangular specimens (2 mm × 12 mm × 15 mm) were obtained (IPS, e.max ZirCAD, MO, B65L17, Ivoclar Vivadent) and divided into three groups; a non-contaminated group (control group)(CON), a contaminated and cleaned with isopropyl alcohol group(ISP), and lastly, a group contaminated and cleaned with an MDP-containing cleaning agent(KAC). Each group was then subdivided into three subgroups according to the UAs used (n = 12). Composite cylinders were prepared and bonded to each surface with Panavia V5 (Kuraray, Noritake Dental). A µSBS test was performed and the data were evaluated with the two-way analysis of variance (two-way ANOVA) and multiple comparisons test (α = 0.05). The highest µSBS values were obtained in the non-contaminated group (p < 0.001), regardless of UAs. All subgroups showed lower µSBS values after saliva contamination, but KAC resulted in significantly higher µSBS values than 99% isopropanol (p < 0.001). Overall, the lowest µSBS value was obtained with 99% isopropanol. The KAC-Clearfil UA subgroup resulted in statistically significantly higher µSBS values than the other UAs (p = 0.035 and 0.007), although all three UAs resulted in sufficient µSBS values. This study revealed that applying KAC followed by a UA containing phosphate monomers produces promising results for improving µSBS values of zirconia, greater than results using 99% isopropanol.Clinical relevance: An MDP-containing cleaning agent followed by a phosphate monomer containing a universal adhesive is a promising method to obtain acceptable bonds with saliva-contaminated zirconia ceramics.

Effect of different cleansing methods on the artificially aged bond strength of resin to contaminated zirconia: A systematic review

PURPOSE

The aim of this review was to evaluate studies investigating the effect of cleansing methods on the artificially aged bond strength of resin to contaminated zirconia restorations and determine which cleansing method of contaminated zirconia for resin bonding improvement is more efficient.

METHODS

An electronic search of published studies in English language was carried out until July 2021 on Scopus, Web of Science, and Medline databases. Data from in vitro studies involving the evaluation of the artificially aged bond strength of resin to contaminated zirconia following different cleansing methods were included. In vitro studies in which samples were not subjected to at least 5000 thermocycles, were excluded.

RESULTS

Of 162 articles retrieved initially, 19 were eligible to be included in the systematic review, of which 5 articles were excluded. Therefore, the final sample was 14 in vitro studies. All of the included studies for air abrasion suggested this method as an effective cleansing method, but 6 of 8 included studies reported cleaning paste (Ivoclean) as an effective cleansing method. All of the included studies for NaOCl and a cleaning gel (AD Gel) reported their efficacy. Finally, the results of included studies showed the ineffectiveness of phosphoric acid, water, isopropanol, enzymatic detergents, hydrogen peroxide, and acetone.

CONCLUSIONS

Air abrasion has been reported as an effective cleansing method to improve the bond strength of resin to contaminated zirconia. To improve the effectiveness of cleaning paste in resin bonding, another efficient cleansing method should be followed after this method. However, the superior cleaning potential of air abrasion rather than cleaning paste has been reported. Sodium hypochlorite and cleaning gel seem to be as effective as air abrasion, but extensive water-rinsing is necessary after the application of these cleaning agents.

Shear Bond Strength of a Direct Resin Composite to CAD-CAM Composite Blocks: Relative Contribution of Micromechanical and Chemical Block Surface Treatment

This study aims to compare the shear bond strength (SBS) of a direct resin composite to CAD-CAM resin composite blocks treated with different surface treatments: micromechanical, chemical or a combination of both. Eight CAD-CAM resin composite blocks, namely Brilliant Crios, Cerasmart 270, Vita Enamic, Grandio block, Katana Avencia, Lava Ultimate, Tetric CAD and Shofu Block HC were chosen. The micromechanical surface treatment protocols tested were hydrofluoric acid, polyacrylic acid or sandblasting, and the chemical one was a universal primer. These treated CAD-CAM blocks were tested to determine the SBS of a light-curing composite resin Z100 bonded to their surface. Two-way ANOVA followed by Tukey’s post hoc test was used to investigate the difference in SBS. Failures were analyzed by Fisher’s exact test. Bonding interfaces were examined by scanning electron microscopy. The micromechanical surface treatments give the highest SBS values: sandblasting appears to be the most efficient procedure for dispersed filler composite blocks, while hydrofluoric acid etching is preferable for polymer-infiltrated ceramic network (PICN) blocks. The use of universal primer does not improve SBS values on dispersed filler composite blocks. For PICN blocks, the use of universal primer significantly increases SBS values when combined with hydrofluoric acid etching.

10-Methacryloyloxydecyl Dihydrogen Phosphate (10-MDP)-Containing Cleaner Improves Bond Strength to Contaminated Monolithic Zirconia: An In-Vitro Study

Contamination of zirconia restorations before cementation can impair the resin–zirconia bonding durability. The objective of this study was to evaluate the effect of human saliva or blood decontamination with 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-containing cleaner on the resin–zirconia shear bond strength (SBS). Methods: A total of 220 zirconia specimens were prepared and air-abraded and randomly distributed into 11 groups (n = 20 per group). Except for the control group (no contamination), zirconia specimens were contaminated with either human saliva (five groups) or blood (five groups), and then subjected to one of five cleaning methods: water rinsing, 38% phosphoric acid etchant (Pulpdent Corp., Watertown, MA, USA), 70% isopropanol alcohol (Avalon Pharma, Riyadh, Saudi Arabia), Ivoclean (Ivoclar Vivadent, Schaan, Lichtenstein) and Katana Cleaner (Kuraray Noritake, Tokyo, Japan). The resin–zirconia SBS was tested at 24 h and after thermocycling (10 k cycles). Three-way ANOVA followed by Tukey’s multiple comparisons test were utilized to analyze the SBS data. Failure modes were evaluated using a scanning electron microscope. Results: Both blood and saliva significantly affected resin–zirconia SBS as contaminants. After thermocycling, there was no statistically significant difference between SBS obtained after decontamination with the Katana Cleaner (blood, 6.026 ± 2.805 MPa; saliva, 5.206 ± 2.212 MPa) or Ivoclean (blood, 7.08 ± 3.309 MPa; saliva, 6.297 ± 3.083 MPa), and the control group (no contamination, 7.479 ± 3.64 MPa). Adhesive and mixed failures were the most frequent among the tested groups. Conclusion: Both 10-MDP-containing cleaner (Katana Cleaner) and zirconium oxide-containing cleaner (Ivoclean) could eliminate the negative effect of saliva and blood contamination on resin–zirconia SBS.

Effects of surface modification techniques on zirconia substrates and their effect on bonding to dual cure resin cement - An in- vitro study

Aim

This study aims to evaluate the effect of different surface treatments of monolithic zirconia on the bond strength of resin to zirconia and, to explore alternative methods to improve this bonding.

Settings and Design

In-Vitro study.

Materials and Methods

Fifty rectangular sintered blocks of Yttria-stabilized Tetragonal Zirconia Polycrystal ceramics of dimensions were milled and sintered. These specimens were further divided into five groups (control, air abrasion, etching with primer application, air abrasion with primer application and novel glass infiltrated zirconia surface group), containing 10 samples each. The specimens were analyzed for surface roughness, tensile bond strength to resin cements, and adhesive and cohesive mode of failures.

Statistical Analysis Used

ANOVA and Post-Hoc Tukey test was perform to evaluate the significant differences in the mean values of the groups.

Results

Air-abraded samples showed the highest surface roughness (4.95 ± 0.65) (P < 0.05). The group with air abrasion followed by primer application showed the highest tensile bond strength (7.12 ± 0.69) (P < 0.05). The lowest surface roughness (0.638 ± 0.8093) and tensile bond strength (2.03 ± 0.58) was seen in samples that were subjected to etchant treatment followed by application of methacryloyloxydecyl di-hydrogen phosphate (MDP) primer. The changes in comparison to the control group were statistically insignificant (P > 0.05). Except Groups A (control) and C (etchant followed by primer), all other groups showed a cohesive failure.

Conclusion

Air abrasion of the zirconia surface with 50 μm alumina particles increases the surface roughness without damaging the surface. Air abrasion followed by MDP primer application is the recommended method of surface treatment to achieve superior bonding. Glass infiltration also showed promising results in terms of tensile bond strength.

The effect of silane and universal adhesives on the micro-shear bond strength of current resin-matrix ceramics

PURPOSE

The aim of this in vitro study was to evaluate the effect of silane and universal adhesive applications on the micro-shear bond strength (µSBS) of different resin-matrix ceramics (RMCs).

MATERIALS AND METHODS

A total of 120 slides (14 × 12 × 1 mm) were produced from 5 different RMC materials (GC Cerasmart [GC]; Brilliant Crios [BC]; Grandio blocs [GB]; Katana Avencia [KA]; and KZR-CAD HR 2 [KZR]) and sandblasted using 50 µm Al₂O₃ particles. Each RMC material was divided into six groups according to the surface conditioning (SC) method as follows: control (G1), silane primer (G2), silane-free universal adhesive (G3), silane-containing universal adhesive (G4), silane primer and silane-free universal adhesive (G5), and silane primer and silane-containing universal adhesive (G6). Three cylindric specimens made from resin cement (Bifix QM) were polymerized over the treated surface of each slide (n = 12). After thermal cycling (10000 cycles, 5 – 55℃), µSBS test was performed and failure types were evaluated using a stereomicroscope. Data were analyzed using 2-way ANOVA and Tukey tests (α = .05).

RESULTS

µSBS values of specimens were significantly affected by the RMC type and SC protocols (P < .001) except the interaction (P = .119). Except for G2, all SC protocols showed a significant increase in µSBS values (P < .05). For all RMCs, the highest µSBS values were obtained in G4 and G6 groups.

CONCLUSION

Only silane application did not affect the µSBS values regardless of the RMC type. Moreover, the application of a separate silane in addition to the universal adhesives did not improve the µSBS values. Silane-containing universal adhesive was found to be the best conditioning method for RMCs.

The effect of different cleaning agents and resin cement materials on the bond strength of contaminated zirconia

The purpose of this study was to examine the effect of different cleaning methods and resin cements on the shear bond strength (SBS) of contaminated zirconia. A total of 92 disc-shaped zirconia specimens were contaminated with different procedures. Then, the specimens were grouped according to cleaning methods and resin cements: no cleaning + Variolink Esthetic DC (CN_V ), no cleaning + Panavia V5 (CN_P ), sandblasted + Variolink Esthetic DC (SB_V ), sandblasted + Panavia V5 (SB_P ), Ivoclean + Variolink Esthetic DC (IC_V ), Ivoclean + Panavia V5 (IC_P ), Katana Cleaner + Variolink Esthetic DC (KC_V ), and Katana Cleaner + Panavia V5 (KC_P ). Following an aging protocol in a 37°C for 1 week, SBS analysis was performed with a universal test machine. For the surface topography and elemental analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS) were used. Significance was evaluated as p < .05 and p < .01. The highest SBS results were found in the SB_P group, showing a statistically significant difference from all other groups (p < .05). For the same cleaning method, Panavia V5 showed statistically significantly higher SBS values than Variolink Esthetic DC (p < .01), except the CN_P -CN_V (p = .880) and KC_P -KC_V (p = .082) groups. The most detected surface elements by EDS were Zr, O, C, and N, respectively. The contaminated zirconia surfaces must be cleaned for successful adhesion. The use of phosphate-containing adhesives in combination with sandblasting will increase the adhesion strength, and universal cleaning agents can be a good alternative to sandblasting.

Microshear bond strength of dual-cure resin cement in zirconia after different cleaning techniques: an in vitro study

PURPOSE

This study aimed to compare the microshear bond strength (µSBS) of dual-cure resin cement in CAD-CAM zirconia after different cleaning techniques.

MATERIALS AND METHODS

Fifty discs of zirconia-based ceramic from Ivoclar Vivadent were embedded in acrylic resin. The discs were divided into five groups according to the cleaning methods used: Group 1: drying with spraying + sandblasting with Al₂O₃; Group 2: washed with water and dried with spraying + sandblasting with Al₂O₃; Group 3: washed with distilled water and dried with spraying + sandblasting with Al₂O₃ + zirconium oxide (Ivoclean); Group 4: washed with distilled water and dried with spraying + sandblasting with Al₂O₃ + potassium hydroxide (Zirclean); and Group 5: washed with distilled water and dried with spraying + sandblasting with Al₂O₃ + 1% NaClO. All of the groups were contaminated with artificial saliva for 1 minute and then cleaned. Statistical analyses were performed using ANOVA and Tukey's tests.

RESULTS

There were statistically significant differences among all groups for µSBS (P < .05). The group treated with zirconium oxide (Group 3) showed the highest µSBS (18.75 ± 0.23 MPa).

CONCLUSION

When applied to zirconia, the cleaning methods affected the bonding with resin cement differently.

Optimizing the fitting-surface preparation of zirconia restorations for bonding to dentin

OBJECTIVES

The aim of this study was to identify the relative strengths and weaknesses of different interfaces within the multilayer structure of a zirconia crown restoration when applying different surface pretreatments. These include the influence on shear strengths of different air abrasion protocols, glaze-on techniques, zirconia primers and self-adhesive cements for either the complex structure: zirconia / self adhesive resin composite cement (RCC) / bovine dentin substrate (part 1) or the RCC / zirconia substrate (part 2).

METHODS

In Part 1, zirconia discs, pretreated by either glaze-on techniques or air abrasion using Rocatec™ Soft, were bonded to bovine dentin substrates with different self-adhesive RCCs. In Part 2, steel-cylinders were bonded to zirconia cuboid substrates, pretreated by either different protocols for air-abrasion or a glaze-on-technique, with different self-adhesive RCCs. Shear bond strengths (SBS) were measured for all interfacial combinations.

RESULTS

In part 1, application of air abrasion using Rocatec™ Soft significantly increased the SBS of zirconia to dentin compared to control specimens without pretreatment, while glaze-on techniques did not increase the SBS. Pretreatment of zirconia surfaces with two primers (either Clearfil Ceramic Primer, or Monobond S) showed significantly higher SBS than the controls. Cementations with RelyX Unicem 2 Automix showed significantly higher SBS than with MaxCem Elite. In Part 2, all air abrasion protocols increased the SBS, but there was no significant difference between these protocols. Again the glaze-on technique did not increase SBS. A significant difference between the two RCCs was again observed. When zirconia substrates were air abraded, regardless of which protocol was applied, the highest SBS were obtained by Calibra with P&B active followed by Panavia with or without Clearfil Ceramic Primer Plus. Calibra applied without P&B active exhibited the lowest SBS.

SIGNIFICANCE

Pretreatment of zirconia substrates using air abrasion and/or ceramic primers increased the SBS of the zirconia cement interface. For all tested glaze-on treatments, in our experimental setting no effect was observed.

Influence of different cleaning procedures on the shear bond strength of 10-methacryloyloxydecyl dihydrogen phosphate-containing self-adhesive resin cement to saliva contaminated zirconia

PURPOSE

To evaluate the effect of different cleaning methods on the shear bond strength (SBS) of a 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing self-adhesive resin cement to zirconia after saliva contamination.

METHODS

Sixty zirconia specimens were randomly divided into four groups (n=15) according to treatment surface. Except for the control group, all samples were contaminated with saliva and were then rinsed with water-spray and air-dried. Subsequently, the specimens were either treated with a cleaning paste (CP), with argon plasma (AP), or did not undergo an additional cleaning process (WS). An MDP-containing self-adhesive resin cement was applied onto the ceramic surfaces. Specimens were stored in water (24 hours) followed by thermocycling (5°C to 55°C for 10.000 cycles). SBS tests were performed in a universal testing machine, and the results (MPa ± SD) were statistically analyzed using ANOVA and Bonferroni post-hoc test. Fractured surfaces were examined to identify the failure types using a stereomicroscopy and SEM.

RESULTS

The surface cleaning treatment (p < 0.05) significantly affected the results. The highest SBS values were observed in the control group (12.16 ± 1.22 MPa) and were statistically comparable to values for the CP group (11.38 ± 1.65 MPa). The AP group (9.17 ± 1.06 MPa) showed significantly higher bond strength than the WS group (6.95 ± 1.20 MPa), but it showed significantly lower strength than the control and CP groups.

CONCLUSIONS

The CP application was the most effective method in removing saliva contamination. The AP treatment could not restore the SBS to the same level as uncontaminated specimens.

Primer-Treated Ceramic Bracket Increases Shear Bond Strength on Dental Zirconia Surface

The purpose of this study is to evaluate the shear bond strength (SBS) of a primer-treated ceramic bracket on dental zirconia and to compare it with conventional ceramic bracket bonding on surface-treated zirconia. Sintered and finished dental zirconia was sandblasted. Samples were divided according to the treated surfaces: no treatment (X), ceramic primer on zirconia (Z), ceramic primer on bracket base (B), and ceramic primer on both zirconia and bracket base (ZB). The ceramic bracket was bonded on zirconia and SBS was measured before (T₀) and after 10,000 cycles of thermocycling (T_f). The failed surfaces were examined under field emission scanning electron microscope (FE-SEM), and adhesive remnant index (ARI) was evaluated. SBS was significantly higher in ZB and significantly lower in X in both T₀ and T_f. There was no significant difference between Z and B. In X and B, adhesive failure occurred while ZB showed mixed failures. There was no apparent change in the zirconia surface except for the existence of some adhesive and resin remnants. The application of ceramic primer on the bracket base increased the bonding strength to the level of conventional bonding with fewer adhesive remnants. The highest bonding strength was obtained when the primer-treated bracket was bonded on the primer-treated zirconia.

Effects of air-abrasion pressure on mechanical and bonding properties of translucent zirconia

OBJECTIVES

The purpose of this in vitro study was to investigate the effects of different air-abrasion pressures on flexural strength and shear bond strength of a translucent zirconia.

MATERIALS AND METHODS

The translucent zirconia surface was treated with 50 μm abrasive alumina particles at different pressure: 0.1 MPa; 0.2 MPa; 0.3 MPa; 0.4 MPa; 0.5 MPa; untreated specimens were used as control group (n = 33). For each group, three-point bending test was used to evaluate the flexural strength, and surface characterizations were analyzed. Following adhesive bonding and water storage for 24 h, specimens were subdivided into groups baseline and aged (5000 thermocycles). Then, shear bond strength was measured and failure mode was recorded. Statistical analysis was performed with one-way ANOVA and Tukey test (α = 0.05).

RESULTS

Increasing air-abrasion pressure (0.3 MPa, 0.4 MPa, and 0.5 MPa) decreased the flexural strength. Higher air-abrasion pressure resulted in rougher zirconia surfaces and caused more microcracks. The highest shear bond strength was obtained for zirconia surfaces abraded at 0.2 MPa (15.88 ± 2.70 MPa) and 0.3 MPa (14.32 ± 1.12 MPa). Aging did not decrease the strength for all groups except control group (p < 0.001).

CONCLUSIONS

Air-abrasion with 50 μm abrasive alumina particles at 0.2 MPa could achieve good strength for translucent zirconia ceramics while maintaining adequate and durable bonding with resin cement.

CLINICAL RELEVANCE

A total of 0.2 MPa is recommended for air-abrasion procedure applied before a dental restoration fabricated with translucent zirconia is bonded to resin cement.

Effect of Pressure and Particle Size During Aluminum Oxide Air Abrasion on the Flexural Strength of Disperse-Filled Composite and Polymer-Infiltrated Ceramic Network Materials

Esthetic dental computer-aided design/computer-aided manufacturing (CAD/CAM) polymers such as disperse-filled composites (DFC) and polymer-infiltrated ceramic networks (PICN) should be subjected to surface treatment before bonding. However, such treatment can lead to defect formation and a decrease in strength. Therefore, in this study, we compared the flexural strengths of DFC and PICN materials air-abraded with alumina particles of different sizes at different pressures. In addition to Weibull analysis, the samples (untreated and treated) were characterized by scanning electron microscopy and atomic force microscopy. Both DFC and PICN exhibited the lowest flexural strength at large particle sizes and high pressures. Therefore, we optimized the air abrasion parameters to maintain the flexural strength and significantly increase surface roughness. In the case of DFC, the optimal particle size and pressure conditions were 50 µm at 2 bar and 110 µm at 1 bar, while for PICN, the best performance was obtained using Al₂O₃ particles with a size of 50 µm at 1 bar. This study reveals that optimization of the surface treatment process is crucial in the fabrication of high-performance clinical materials for dental restorations.

[Effects of universal adhesives and resin cement on the shear bond strength of zirconia]

OBJECTIVE

To study the effects of universal adhesives and resin cement on the shear bond strength and durability of zirconia ceramics.

METHODS

Zirconia ceramics were sintered into 20 mm×10 mm×10 mm and 10 mm×10 mm×10 mm specimens. The experiment was divided into 12 groups. The two types of specimens were bonded using two variants of resin cement (RelyX Ultimate and Clearfil SAC self-adhesive resin cement), universal adhesives (non-adhesive, Scotchbond uni-versal adhesive, and Clearfil SE One adhesive), and storage conditions (water bath and water bath-thermal cycling). The shear bond strengths were tested, and the fracture morphologies were analyzed.

RESULTS

The cement (F=8.41, P<0.01) and adhesive (F=30.34, P<0.01) exerted a significant effect on the shear bond strength of zirconia, whereas storage condition showed no significant effect on this property (F=1.83, P=0.18). The lowest shear bond strength (14.02 MPa±6.86 MPa) was exhibited by the group treated with RelyX Ultimate resin cement, non-adhesive, and water bath-thermal cycling, whereas the highest shear bond strength (54.12 MPa±8.37 MPa) was displayed by the group treated with RelyX Ultimate resin cement, Scotchbond universal adhesive, and water bath-thermal cycling.

CONCLUSIONS

Universal adhesives can improve the durability of the bonding of resin cement to zirconia. If non-self-adhesive resin cement is used without a universal adhe-sive, the durability of the bond will be greatly reduced.

Durability of resin bonding to zirconia ceramic after contamination and the use of various cleaning methods

OBJECTIVES

The aim of the study was to evaluate the influence of contamination and different cleaning methods on the tensile bond strength with a phosphate monomer containing luting resin to zirconia ceramic.

METHODS

After the contamination with saliva or silicone disclosing agent, 228 polished and airborne-particle abraded zirconia discs were ultrasonically cleaned with 99% isopropanol. In a second step, the specimens were either treated with argon-oxygen plasma, air plasma, enzymatic cleaning agent or did not undergo an additional cleaning process. Uncontaminated zirconia specimens were used as the control group. X-ray photoelectron spectroscopy (XPS) was used for chemical analysis of the bonding surfaces of specimens. Plexiglas tubes filled with composite resin were bonded to zirconia specimens with a phosphate monomer containing luting resin. Tensile bond strength (TBS) was tested after 3 days or 150 days water storage with 37,500 thermal cycles.

RESULTS

XPS revealed a decrease of the carbon/oxygen ratio after plasma treatment and an increase after treatment with an enzymatic cleaning agent in all groups. All contaminated specimens showed high and durable TBS after cleaning with a combination of isopropanol and a non-thermal atmospheric plasma. After the cleaning with enzymatic cleaning agent the TBS was significantly reduced in all groups after 150 days thermal cycling.

SIGNIFICANCE

The combination of isopropanol and plasma cleaning was effective in removing salvia and disclosing agent contamination. Enzymatic clearing agent was not able to remove contamination effectively and had a negative impact on the TBS of non-contaminated specimens.

Effect of Simplified Bonding on Shear Bond Strength between Ceramic Brackets and Dental Zirconia

The aim of this study was to evaluate the long term stability of shear bond strength (SBS) when 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) containing universal adhesive was used in the ceramic bracket bonding on dental zirconia. Twenty human maxillary incisors were collected. The ceramic bracket was bonded on the buccal enamel surface after the acid-etching and orthodontic primer application (Group CON). Sixty zirconia specimens were sintered, sandblasted and divided into three experimental groups; group CP—ceramic primer followed by an orthodontic primer; group U—universal adhesive; group CU—ceramic primer followed by a universal adhesive. For each specimen, the bracket was bonded onto the treated surface with composite resin (Transbond XT, 3M ESPE). The SBS tested before (CON0, CP0, U0, CU0) and after the artificial aging (CON1, CP1, U1, CU1). The data were statistically analyzed with the Kruskal–Wallis test at a significance level of 0.05. The mean SBS of CON0, CP0, U0 and CU0 were within the clinically acceptable range without significant differences. After the aging process, SBS decreased in all groups. Among the aged groups, CP1 showed the highest SBS. Based on the results, when bonding ceramic brackets to a dental zirconia surface, we can conclude that ceramic primer used with an orthodontic primer, rather than using a universal adhesive, is recommended.

Evaluation of the effect of silicone residue after different surface treatments on shear bond strength of glass ionomer cement to the dentin surface

Aim:

Use of silicone fit-checking material during cementation of fixed restoration has shown to leave residual silicone film after peeling off of fit checker (FC). This residual film reduced bond strength of cement to the inner surface of restoration. Silicone residue effect on tooth surface needs to be studied. The aim of this study was to evaluate the effect of residual silicone film on shear bond strength (SBS) of glass ionomer cement (GIC) to dentin surface and the efficacy of different surface treatments (STs) on dentin in the removal of silicone residue.

Materials and Methods:

Fifty freshly extracted human molars were individually mounted on acrylic blocks and occlusal surfaces were ground flat until dentine surface was exposed. Specimens were divided into five groups as follows: Group I: without application of FC (n = 10) as control group; Group II: without any ST after peeling off FC (n = 10); Group III: ST using wet pumice after peeling off FC (n = 10); Group IV: ST with 37% phosphoric acid after peeling off FC (n = 10); and Group V: ST with 10% polyacrylic acid after peeling off FC (n = 10). GIC was placed on the dentinal surface using polyvinyl mold and subjected to SBS test using universal testing machine. The debonded specimens were observed under stereomicroscope for the mode of failure. Selected debonded dentinal surfaces from each group were examined under scanning electron microscope. One-way analysis of variance and Tukey's test.

Results:

Group II (1.083 MPa) showed significantly lower SBS. Among the STs, Group III (2.047 MPa) was comparable to the control group whereas Group IV (1.376 MPa) and Group V (1.63 MPa) were significantly lower. There was no significant association between failures and groups at P = 0.257.

Conclusion:

The residue of silicone was demonstrable on dentin surface after peeling off FC and caused a significant reduction in SBS between GIC and dentin. ST with wet pumice is found to be beneficial in removing silicone residue and improving SBS, followed by phosphoric acid and polyacrylic acid.

The effect of Z-primer on the shear bond strength of zirconia ceramic to dentin: in vitro

Background

One of the major limitations of zirconia ceramic is the difficulty to adhere to dental. Said adhesion improves the marginal sealing of the restoration, minimizing microleakage. According to the limitation of zirconia ceramic bonding, zirconia primer enhances bond strengths to Zirconia, Alumina and Metal substrates. Purpose: the aim of the current study was to determine effect of Z-primer on the shear bond strength of zirconia ceramic to dentin.

Material and Methods

28 newly extracted intact premolars and divided into 4 groups (n=7). In group 1, resin-based (Duo-link; Bisco, Schaumburg, IL) cement was used without applying Z-primer. In group 2, resin-based (Duo-link; Bisco, Schaumburg, IL) cement was used with applying Z-primer. In group 3, resin-based cement (Panavia F2; Kurary, Japan) was used without Z-primer. In group 4, resin- based cement (Panavia F2) with Z-primer was used. Zirconia ceramic blocks (4×4×2mm) without sandblasting were applied onto the surface of dentin then cured from 3 dimensions for 20S. Shear bond strength test was carried out after 24h. Stereo microscope was used to evaluate the zirconia ceramic and dentin topography and failure mode.

Results

According to the data, significant difference detected on after application of the Z-primer compared to the other groups (p<0.001). No significant difference detected between 2 types of resin cements (p>0.05). However, the highest SBS observed in second group (Duo-link(+)Zprimer) while lowest detected in first group (Duo-link(-)Zprimer).

Conclusions

These results suggested application of the Z-primer increased shear bond strength between zirconia ceramic and dentin.

Key words:Flexural strength, monolithic zirconia, sintering temperature, sintered-holding time.

Effect of cleaning methods on retentive values of saliva-contaminated implant-supported zirconia copings

OBJECTIVE

The aim of this study was to evaluate the effect of different cleaning regimens on retentive strength of saliva-contaminated implant-supported zirconia copings.

MATERIAL AND METHODS

Seventy solid titanium abutments with 5.5 mm height (Straumann) were attached to the regular neck implant analogs (Straumann). The abutment-analog complex was mounted vertically in an autopolymerized T-shaped acrylic resin block. Seventy zirconia copings with an occlusal loop were made. The copings were contaminated with fresh human saliva for 1 min (except the control group). Afterward, the specimens were washed with water spray for 15 s and dried for 15 s. The copings were divided into seven groups according to cleaning methods (n = 10). Group 1: no contamination (control group); Group 2: water spray rinsing; Group 3: airborne particle abrasion; Group 4: immersion in 96% isopropanol; Group 5: applying Ivoclean (Ivoclar Vivadent); Group 6: applying 1% sodium hypochlorite; and Group 7: applying Monobond Plus (Ivoclar Vivadent). The copings were luted with a resin luting agent (RelyX Unicem; 3M ESPE). After 5,000 thermal cycles, the retentive values of the restorations were tested using universal testing machine. The dislodging forces were analyzed using one-way analysis of variance and the Tukey's HSD tests (α = 0.05).

RESULTS

The copings, which were cleaned with Ivoclean and 96% isopropanol, showed the highest retentive values (204.79 ± 44.49 and 232.65 ± 71.36, respectively). There was a significant difference between the studied groups (F = 2.735; p = .02). Tukey's HSD showed that there was no significant difference between the different cleaning procedures and control group except water rinsing group (p = .14). The lowest retentive value was related to the saliva-contaminated group, which were only cleaned with water rinsing method.

CONCLUSION

The retentive values of zirconia-based restorations were adversely affected by saliva contaminations. These restorations can be cleaned by Ivoclean, 96% isopropanol, airborne particle abrasion, 1% sodium hypochlorite, or applying Monobond Plus before luting procedures.

Effect of air-particle pressures on the surface topography and bond strengths of resin cement to the hybrid ceramics

This study aimed to determine the appropriate pressure for airborne-abrasion by comparing the shear bond strength values for different hybrid ceramic surfaces. Two materials were used to produce hybrid ceramic specimens: Lava Ultimate and MAZIC Duro. The group of specimens whose surfaces were not subjected to airborne-abrasion was set as the control group. In the experimental group, airborne-abrasion was performed at pressures of 0.1, 0.2, and 0.3 MPa. After the adhesive and resin cement was applied, an SBS test was performed. For the MAZIC Duro block, the SBS increased monotonically with the airborne-abrasion pressure increased, peaking at 0.3 MPa. For the Lava Ultimate block, the SBS increased as the airborne-abrasion pressure increased to 0.2 MPa, and then decreased in the 0.3-MPa group, thereby peaking at 0.2 MPa. This study has confirmed that the bonding strength varies with the material used even when applying the same surface treatment.

Bonding effectiveness of self-adhesive and conventional-type adhesive resin cements to CAD/CAM resin blocks. Part 2: Effect of ultrasonic and acid cleaning

The present study assessed the effect of ultrasonic and acid cleaning on resin cement bonding to CAD/CAM resin blocks. One of two resin cements, PANAVIA V5 (PV5) or PANAVIA SA CEMENT HANDMIX (PSA), were bonded to one of 24 CAD/CAM blocks (KATANA AVENCIA BLOCK). Each cement group was divided into four subgroups: no cleaning (Ctl), ultrasonic cleaning (Uc), acid cleaning (Ac) and Uc+Ac. Micro-tensile bond strengths (µTBSs) were measured immediately and 1, 3, and 6 months after water storage. Block surfaces after each treatment were analyzed by scanning electron microscopy. Analysis of variance revealed a statistically significant effect for the parameters 'surface treatment' (p<0.001, F=40), 'resin cement' (p<0.001, F=696) and 'water aging' (p<0.001, F=71). The PV5 group exhibited higher µTBS values than the PSA group. Although cleaning after sandblasting was effective in removing residual alumina particles, it did not affect the long-term bonding durability with non-contaminated CAD/CAM resin blocks.

Quantitative Evaluation of Contamination on Dental Zirconia Ceramic by Silicone Disclosing Agents after Different Cleaning Procedures

The aim of this study was to evaluate the effectiveness of cleaning procedures for air-abraded zirconia after contamination with two silicone disclosing agents. Air-abraded zirconia ceramic specimens (IPS e.max ZirCAD) were contaminated with either GC Fit Checker white or GC Fit Checker II. Untreated zirconia specimens were used as control. Afterwards the surfaces were cleaned either with waterspray or ultrasonically in 99% isopropanol or using a newly developed cleaning paste (Ivoclean). After cleaning X-ray photoelectron spectroscopy (XPS) was performed and the relative peak intensities of Zr, C and Si were used for a qualitative comparison of the residuals. There was no significant difference between the two different silicone disclosing agents. An additional cleaning step with isopropanol led to a significantly lower amount of residuals on the surface, but an additional cleaning process with Ivoclean did not reduce the amount of carbon residuals in comparison to the isopropanol cleaning. Just the silicone amount on the surface was reduced. None of the investigated cleaning processes removed all residuals from the contaminated surface. Standard cleaning processes do not remove all residuals of the silicone disclosing agent from the surface. This may lead to a failure of the resin-ceramic bonding.

Efficacy of various cleaning solutions on saliva-contaminated zirconia for improved resin bonding

PURPOSE

This study aimed to investigate the efficacy of cleaning solutions on saliva-contaminated zirconia in comparison to air-abrasion in terms of resin bonding.

MATERIALS AND METHODS

For saliva-contaminated airabraded zirconia, seven cleaning methods)-no contamination (NC), water-spray rinsing (WS), additional airabrasion (AA), and cleaning with four solutions (Ivoclean [IC]; 1.0 wt% sodium dodecyl sulfate [SDS], 1.0 wt% hydrogen peroxide [HP], and 1.0 wt% sodium hypochlorite [SHC])-were tested. The zirconia surfaces for each group were characterized using various analytical techniques. Three bonded resin (Panavia F 2.0) cylinders (bonding area: 4.5 mm²) were made on one zirconia disk specimen using the Ultradent jig method [four disks (12 cylinders)/group; a total of 28 disks]. After 5,000 thermocycling, all specimens were subjected to a shear bond strength test with a crosshead speed of 1.0 mm/minute. The fractured surfaces were observed using an optical and scanning electron microscope (SEM).

RESULTS

Contact angle measurements showed that groups NC, AA, IC, and SHC had hydrophilic surfaces. The X-ray photoelectron spectroscopy (XPS) analysis showed similar elemental distributions between group AA and groups IC and SHC. Groups IC and SHC showed statistically similar bond strengths to groups NC and AA (P>.05), but not groups SDS and HP (P<.05). For groups WS, SDS, and HP, blister-like bubble formations were observed on the surfaces under SEM.

CONCLUSION

Within the limitations of this in vitro study, some of the cleaning solutions (IC or SHC) were effective in removing saliva contamination and enhancing the resin bond strength.

Class III Restoration of Anterior Primary Teeth: In Vitro Retention Comparison of Conventional, Modified and Air-abrasion Treated Preparations

Background and aims. Anterior esthetic restoration is challenging in pediatric dentistry, due to limited durability and poor retention of the restoration.This study assessed the effect of air abrasion on tensile failure load of composite class III restorations using different preparation techniques. Materials and methods. 100 extracted human anterior primary teeth were divided, based on the preparation methods, into four groups each consisting of 25 subjects : conventional (A), labial surface bevel (B), conventional + air abrasion (C), and labial surface bevel + air abrasion (D). After restoring cavities, tensile failure load of samples was measured in Newton by Universal testing machine at a crosshead speed of 1 mm per minute. The data were analyzed by Kruskal-Wallis and Mann Whitney U tests using SPSS software. Results. There were statistically significant differences between groups A and C (P = 0.003), groups A and B (P & 0.001), groups A and D (P & 0.001), groups B and C (P = 0.028), groups B and D (P = 0.027), and also groups C and D (P& 0.001). Group D demonstrated the highest mean tensile failure load. Conclusion. Labial surface bevel treated by air abrasion showed significantly more retention of composite restoration.

Evidence of yttrium silicate inclusions in YSZ-porcelain veneers

This report introduces the discovery of crystalline defects that can form in the porcelain veneering layer when in contact with yttria-stabilized zirconia (YSZ). The focus was on dental prostheses and understanding the defects that form in the YSZ/porcelain system; however the data reported herein may have broader implications toward the use and stability of YSZ-based ceramics in general. Specimens were cut from fully sintered YSZ plates and veneering porcelain was applied (<1 mm thick) to one surface and fired under manufacturer's recommended protocol. Scanning electron microscopy (SEM) with integrated electron dispersive X-ray (EDAX) was used for microstructural and elemental analysis. EDAX, for chemical analysis and transmission electron diffraction (TED) for structural analysis were both performed in the transmission electron microscope (TEM). Additionally, in order to spatially resolve Y-rich precipitates, micro-CT scans were conducted at varying depths within the porcelain veneer. Local EDAX (SEM) was performed in the regions of visible inclusions and showed significant increases in yttrium concentration. TEM specimens also showed apparent inclusions in the porcelain and selected area electron diffraction was performed on these regions and found the inclusions to be crystalline and identified as either yttrium-silicate (Y2 SiO5 ) or yttrium-disilicate (Y2 Si2 O7 ). Micro-CT data showed that yttrium-silicate precipitates were distributed throughout the thickness of the porcelain veneer. Future studies are needed to determine whether many of the premature failures associated with this materials system may be the result of crystalline flaws that form as a result of high temperature yttrium diffusion near the surfaces of YSZ.

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.

Impaction-modified densely sintered yttria-stabilized tetragonal zirconium dioxide: methodology, surface structure, and bond strength

The objectives of the study were to describe a novel method for producing zirconium dioxide specimens with a cementation surface that allows adhesive cementation techniques, to describe the surface structure and to evaluate the bond strength. Forty-eight pairs of specimens were fabricated and adhesively luted together. Three different surfaces were tested: impaction-modified surfaces created by using glass granules (G), impaction-modified surfaces created by using polymer granules (P) and a nonmodified control surface (C). Two bonding systems were used, Variolink(®)II (VA) or Panavia™F 2.0 (PA). During the different fabrication steps, the surfaces were examined under light microscope and analyzed with an optical interferometer. All groups were thermocycled and subjected to shear bond strength test. The groups with modified cementation surfaces showed significantly higher shear bond strength: 34.9 MPa (VA-G), 30.9 MPa (VA-P), 29.6 MPa (PA-P), and 26.1 MPa (PA-G) compared with the relevant control group: 20.5 MPa (VA-C) and 17.8 MPa (PA-C). The groups with surface modification showed a rougher surface structure and significantly fewer fractures between the cement and the zirconium dioxide surfaces compared to the control groups where all failures were adhesive. Impaction modification with an impaction medium pressed into the cementation surface of zirconium dioxide-based reconstructions can be used in combination with an additive production technique to increase bond strength. Both modification techniques described in the study result in a rougher surface structure and higher shear bond strength compared to the control groups.

Effect of air abrasion and dye on the surface element ratio and resin bond of zirconia ceramic

The purpose of this study was to evaluate the effect of the surface element composition and roughness of dyed or non-dyed zirconia ceramic by air abrasion on the bond durability to resin luting cement. The sintered zirconia ceramic specimens were divided into four groups as follows: polished, dyed/polished, abraded, dyed/abraded. The surface roughness of each group was measured by a 3D laser scanning microscope. Energy-dispersive spectroscopy was applied for identifying and quantifying the elemental composition of the zirconia ceramic surfaces Each group had 20 shear test specimens of zirconia to Panavia F and was divided into two subgroups (n = 10) after 0 or 10 000 thermal cycles to receive the shear test. Compared with polishing, air abrasion significantly reduced the oxygen atom and weight ratio, increased the zirconium atom and weight ratio, increased R(a) and R(y) of zirconia ceramic surface, and also increased the bond strength of dyed and non-dyed zirconia ceramic to Panavia F after 0 and 10 000 thermal cycles. The dying procedure could affect the abraded and non-abraded zirconia ceramic surface oxygen and zirconia element ratios and surface characteristics. However, the dying procedure does not affect the resin bond strength and durability of zirconia ceramic.Corrections were made to this article on 3 November 2011. The footnote for the corresponding authors was incorrectly labelled.

Determination of resin bond strength to zirconia ceramic surface using different primers

OBJECTIVE

To evaluate the effect of different primers on the bond strength of adhesive resin cement to zirconia ceramic surface in vitro.

MATERIAL AND METHODS

Thirty zirconia disk-shaped ceramic specimens (10×2 mm²) were divided into three equal groups for the application of different primers: Monobond-S, Clearfil Ceramic Primer and Signum Zirconia Bond. A further 10 specimens served as a control group. Forty composite resin blocks (6×2 mm²) were cemented (Panavia F 2.0) to zirconia ceramic specimens. Shear bond strengths were measured. Treated zirconia ceramic surfaces were examined using scanning electron microscopy.

RESULTS

One-way ANOVA showed that the application of different primers affected the shear bond strength of adhesive resin cement to zirconia ceramic. The highest test values were obtained with application of Signum Zirconia Bond, and the lowest values were obtained in the control group.

CONCLUSION

Signum Zirconia Bond is effective for increasing the bond strength of adhesive resin cement to zirconia ceramic.

Combination treatment of tribochemical treatment and phosphoric acid ester monomer of zirconia ceramics enhances the bonding durability of resin-based luting cements

The aim of the present study was to evaluate the bonding durability of resin-based luting cement to partially stabilized tetragonal zirconia (Y-TZP) achieved by combination treatment of tribochemical (TBC) treatment and two different phosphate acid ester monomers. Two phosphate acid ester monomers (EP: Epricord opaque primer, AZ: AZ primer) were applied to each surface modification followed by application of resin-based luting cement (Rely-X ARC). Bonding specimens were placed in deionized water at 37 degrees C and stored for 24 h. The other groups were subjected to 30,000 cycles of a thermal stress for the durability test. Shear bond tests were done using a universal testing machine at 1 mm/min. Shear bond strengths of combination treatments using EP and AZ on TBC treatment after thermal stress showed no significant difference (p>0.05) compared with those of storage after 24 h. Combination treatment using phosphoric acid ester monomer could achieve a durable bond.

Influence of air-abrasion on zirconia ceramic bonding using an adhesive composite resin

OBJECTIVES

Air-abrasion as bonding conditioning method for zirconia ceramic might compromise the mechanical strength of zirconia restorations. The purpose of this study was to evaluate the influence of surface conditioning parameters, i.e., air-abrasion with reduced pressure or no air-abrasion and priming with adhesive primers on the long-term resin bond strength to zirconia ceramic.

METHODS

Zirconia ceramic disks were polished with 600 grit abrasive paper. Plexiglas tubes filled with composite resin were bonded with RelyX Unicem luting composite resin to the conditioned zirconia disks. Three surface conditions (unconditioned, air-born particle abrasion at 0.05 or 0.25 MPa) and four priming conditions (no priming, priming with Metal/Zirconia Primer, priming with Alloy Primer, priming with Clearfil Ceramic Primer) were tested. Sixteen specimens of each combination were bonded. Subgroups of eight bonded samples were stored in water either for 3 days or 150 days with 37,500 thermocycling. Tensile bond strengths (TBSs) were determined with a universal testing machine at a crosshead speed of 2mm/min.

RESULTS

Without priming, RelyX Unicem showed durable bond strength to 0.25 MPa airborne-particle abraded ceramic. When combined with 10-methacryloyloxy-decyl dihydrogenphosphate containing primers, air-abrasion resulted in a durable TBS to zirconia ceramic even at a reduced abrasion pressure. However, combined with Metal/Zirconia Primer air-abrasion did not provide a durable TBS to zirconia ceramic.

SIGNIFICANCE

Using a self-adhesive luting resin composite (RelyX Unicem), air-abrasion at 0.25 MPa or the combination of low pressure air-abrasion and priming with MDP-containing primers seems to be useful to achieve durable long-term bonding to zirconia ceramic.