Effects of Hot Chemical Etching and 10-Metacryloxydecyl Dihydrogen Phosphate (MDP) Monomer on the Bond Strength of Zirconia Ceramics to Resin-Based Cements

Different surface treatments and adhesive monomers for zirconia-resin bonds: A systematic review and network meta-analysis

This review examined the efficacy of surface treatments and adhesive monomers for enhancing zirconia-resin bond strength. A comprehensive literature search in PubMed, Embase, Web of Science, Scopus, and the Cochrane Library yielded relevant in vitro studies. Employing pairwise and Bayesian network meta-analyses, 77 articles meeting inclusion criteria were analyzed. Gas plasma was found to be ineffective, while treatments including air abrasion, silica coating, laser, selective infiltration etching, hot etching showed varied effectiveness. Air abrasion with finer particles (25-53 µm) showed higher immediate bond strength than larger particles (110-150 µm), with no significant difference post-aging. The Rocatec silica coating system outperformed the CoJet system in both immediate and long-term bond strength. Adhesives containing 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) were superior to other acidic monomers. The application of 2-hydroxyethyl methacrylate and silane did not improve bonding performance. Notably, 91.2 % of bonds weakened after aging, but this effect was less pronounced with air abrasion or silica coating. The findings highlight the effectiveness of air abrasion, silica coating, selective infiltration etching, hot etching, and laser treatment in improving bond strength, with 10-MDP in bonding agents enhancing zirconia bonding efficacy.

Adhesive bond strength of monolithic zirconia ceramic finished with various surface treatments

BACKGROUND

This study aimed to investigate different surface treatments thought to increase the bond strength between zirconia ceramic and adhesive resin cement.

METHODS

The samples were prepared in 15 × 10 × 2 mm dimensions by cutting off monolithic zirconia ceramic blocks (Incoris TZI; Sirona, Germany). Surface roughness measurements were made with a profilometer, the average surface roughness (Ra1) was recorded, and five different surface treatments were applied. Group 1: Control group. No surface treatment was applied. Group 2: Sandblasted with Al2O3 under pressure of 50 μm. Group 3: Sandblasted with 30 μm Al2O3 - SiOx under pressure, then tribochemical silica coating, silane bonding agent, and ceramic primer were applied. Group 4: Samples were etched in a hot acid solution containing methanol, HCl, and chloride at 100 °C. Group 5: Samples were coated in a solution containing Grade C Aluminum Nitrite at 75 °C for 15 Sects. 12,000 thermal aging was carried out to all samples. Then, samples were bonded to a composite surface (Filtek Z250) with two different types of adhesive cement (Panavia F 2.0, Rely X U200) (n = 10). A load was applied to the samples attached to the Universal Test Device for the SBS, and the SBS was recorded. The surface roughness measurements of all samples were made again, and the average surface roughness Ra2 was recorded. The data was analyzed with a two-way ANOVA test. Bonferroni correction was used for multiple comparisons of the groups. p = 0.005 was accepted as the statistically significant value.

RESULTS

There was no statistically significant difference between the groups in the Ra1 measurements (p = 0.031). There was a statistically significant difference between the Ra2 values of Groups 4 and 5 and the Ra2 values of Groups 1,2 and 3 in the Ra2 measurements (p < 0.001). There was no statistically significant difference between the SBS values of the groups (p > 0.005). Also, there was no statistically significant difference in the SBS values of all groups for the two different cements tested (p > 0.005).

CONCLUSIONS

None of the surface treatments applied to monolithic zirconia ceramic samples increased the SBS between ceramic and adhesive resin cement.

Effect of hot-etching treatment duration on the shear bond strength of zirconia-to-resin cement

The surface of zirconia was treated with hot-acid etching of different durations to improve its shear bond strength to resin. Zirconia discs were subjected to untreated, sand-blasting, and hot-etching treatments for 10, 30 and 60 min. The discs were bonded to the surface of bovine enamel specimens using RelyX Ultimate resin cement. The bonded specimens were divided into immediate and thermocyling aging groups according to whether they underwent thermal cycling. A universal mechanical testing machine was used to measure the shear bond strength of the specimens. One-way analysis of variance was used to determine the effect of hot-etching time on the shear bond strength. In the immediate and thermocyling aging groups, 60 min of hot-etching provided significantly higher shear bond strength than the other conditions (p<0.05).

Effect of air abrasion, acid etching, and aging on the shear bond strength with resin cement to 3Y-TZP zirconia

This study investigates the effect of acid etching treatment on the surface microstructure, surface roughness, and surface contact angle of zirconia and compares the effects of air abrasion, different etching times, and aging on the shear bond strength (SBS) of resin cement on the zirconia surface. 480 specimens (9 × 10 × 10 mm) were divided into as-sintered and air-abraded groups, and each group was further subdivided into six groups based on etching time (0, 3, 5, 10, 20, and 30 min). The etching solution comprised hydrofluoric acid 25%, sulfuric acid 16%, hydrogen peroxide, methyl alcohol, and purified water. The shear bond strength (SBS), scanning electron microscopy, surface roughness, contact angle, and failure mode were measured. The results indicated that the mean SBS values increased and decreased significantly when the etching times increased to 20 min and 30 min, respectively, in both groups. Further, SBS after aging was lower than that before aging in all groups. Sandblasting, etching time, and aging all showed significant effects (p < 0.001) in the three-way analysis of variance. In addition, the surface roughness increased and the contact angle decreased significantly with an increase in etching time. Thus, the acid-etching treatment induced significant changes on the zirconia surface and increased the SBS of the resin cement. The results of this in vitro study suggest that acid etching is a promising alternative for zirconia surface treatment.

The effect of adhesive surface with porcelain sintering and two silane coupling agents on the adhesive properties of zirconia

Background

To explore the effect of adhesive surface with porcelain sintering and different silane coupling agents on adhesive properties of zirconia ceramics.

Methods

Zirconia blocks (n=72) were randomly divided into two large groups (n=36) according to whether the adhesive surface was treated with sintered porcelain: N (no porcelain sintering), P (porcelain sintering). Then, according to different silane coupling agents, each group was randomly divided into three small groups, six small groups in total (n=12): NN (no porcelain sintering and agent), NM (no porcelain sintering + Monobond-S), NC (no porcelain sintering + Clearfil Repair); PN (porcelain sintering + no agent), PM (porcelain sintering + Monobond-S), PC (porcelain sintering + Clearfil Repair). After surface treatment, RelyX Unicem Cement was used to make ceramic-resin bonding specimens. Then, each of the six small groups was randomly divided into two subgroups; shear bond strength (SBS) was tested and bond failure mode was analyzed before and after thermal cycling 5,000 times.

Results

(I) SBS analysis: the SBS values of the P groups were significantly higher than those of the N groups (P<0.05). The groups treated with silane coupling agents showed higher SBS values than the control group (P<0.05), and the PC groups showed the highest SBS values (P<0.05). The SBS of each group was significantly decreased after thermal cycling (P<0.05). (II) The microcharacteristics under scanning electron microscopy and energy spectrum analysis: the ceramic blocks being treated by porcelain sintering showed more roughness than the control group. A large amount of silicon (Si) appeared on the surface of the ceramic blocks after porcelain sintering.

Conclusions

(I) Treating the adhesive surface by porcelain sintering can improve the bonding strength between zirconia and RelyX Unicem Cement, and the effect was better in conjunction with silane coupling agent. (II) The two kinds of silane coupling agent (Monobond-S, Clearfil Repair) can improve the bonding strength between zirconia and resin cement. The effect of Clearfil Repair is better than that of Monobond-S. (III) Thermal cycling had a significant adverse effect on SBS between zirconia and RelyX Unicem Cement. Clearfil Repair is helpful in improving the durability of zirconia bonding strength.

Influence of Er:YAG laser surface treatment on flexural and bond strengths to glass-infiltrated zirconia-reinforced ceramic

To evaluate the effect of Er:YAG laser conditioning of a glass-infiltrated alumina-based zirconia-reinforced ceramic on its flexural strength and on bonding to a resin cement. Sixteen blocks (5 × 5 × 4 mm) and 50 discs (Ø 12 mm, 1 mm thickness) of In-Ceram Zirconia (ICZ) obtained from CAD-CAM blocks were infiltrated with glass. For the microtensile bond strength (μTBS) test, all blocks were treated with aluminum oxide (AOX) and divided into 4 groups (n = 4): G1 (AOX), no combined surface treatment; G2 (ROC), tribochemical silica-coating; G3 (EY200), Er:YAG laser 200 mJ/15 Hz; and G4 (EY250), Er:YAG laser 250 mJ/10 Hz. The ceramic blocks were silanated and cemented with a resin cement (Panavia F2.0/Kuraray) to composite resin blocks and subjected to the μTBS test. For the flexural strength evaluation, the discs were divided into 5 groups (n = 10) as described above, in addition to a control group (G5 - CTRL, mirror-polished without further treatment). Each surface treatment was submitted to qualitative evaluation under SEM. One-way ANOVA (α = 5%) revealed the highest bond strength value for EY200 with no significant difference from ROC. The groups AOX and EY250 showed similar μTBS values that were statistically lower than those of EY200. For flexural strength, ROC was the only group with significantly lower values when compared with the CTRL. The use of Er:YAG laser at 200 mJ/15 Hz can be considered an innovative and effective alternative for surface conditioning of ICZ since it did not reduce the flexural strength of the ceramic and improved the resin cement bond to this substrate.

Atomic layer deposition SiO2 films over dental ZrO2 towards strong adhesive to resin

Atomic layer deposition (ALD) is a self-limiting nanoscale film deposition technology with the advantages of good stability, consistency and conformability. In this study, we proposed to deposit silica (SiO₂) films over dental zirconium-oxide (ZrO₂) by ALD for better SiO₂ films and higher bond strength between ZrO₂ and resin. To investigate the superiority of film deposited by ALD, other surface modification methods such as sol-gel, vapor phase hydrolysis and electrostatic self-assembly were compared in terms of the short-term and long-term bond strength between ZrO₂ and resin, measured by universal testing machine. Meanwhile, the surface morphology and chemical elemental analysis were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR). Results showed that the SiO₂ films deposited by ALD or electrostatic self-assembly were uniform and consistent while sol-gel and vapor phase hydrolysis formed SiO₂ films with cracks or pores, changing the morphology of ZrO₂. ALD had the best results among all methods and increased the bond strength to 16.49 ± 1.60 MPa and 13.44 ± 1.63 MPa before and after aging respectively, which is expected to improve the long-term success rate of clinical dental ZrO₂ prostheses.

Combined application of femtosecond laser and air-abrasion protocols to monolithic zirconia at different sintering stages: Effects on surface roughness and resin bond strength

This study aimed to investigate the effects of femtosecond laser (Fs) and/or air-abrasion protocols on surface roughness (Ra) of zirconia and resin bond strength. Eighty zirconia samples were randomly divided into eight subgroups according to surface treatment protocols: Control (C), Air-abrasion before sintering (ABS), Air-abrasion after sintering (AAS), Air-abrasion before and after sintering (ABS + AAS), Fs laser before sintering (FBS), Fs laser before sintering + air-abrasion after sintering (FBS + AAS), Fs laser after sintering (FAS), and Fs laser after sintering + air-abrasion after sintering (FAS + AAS). Measurements of Ra values were obtained using a surface profilometer. Surface morphological properties were evaluated with scanning electron microscopy (SEM), and crystallographic changes were examined by X-Ray diffractometry (XRD). Self-adhesive resin cement was bonded to zirconia samples, and shear bond strength (SBS) tests were performed. The data were statistically analyzed by one-way ANOVA, followed by Tamhane tests. The control group displayed the lowest Ra and SBS values among all groups. The highest Ra and SBS values were found in the FBS and FBS + AAS groups. Air-abrasion applied before sintering significantly increased the Ra of specimens. FAS, FAS + AAS, and ABS + AAS groups exhibited higher SBS values than AAS and ABS (p < .05). Air-abrasion applied after Fs laser did not produce any significant change in the Ra and SBS compared to Fs laser alone (p > .05). Femtosecond laser application may be a promising method to enhance the surface roughness of zirconia and improve resin bond strength. Air-abrasion at pre- and post-sintered stages may also be a viable surface treatment option.

Impact of multiple firings and resin cement type on shear bond strength between zirconia and resin cements

PURPOSE

The aim of this study was to evaluate the effect of multiple firings on the bond strength between yttria-tetragonal zirconia polycrystals (Y-TZP) and 2 types of resin cements.

MATERIALS AND METHODS

Sixty 3Y-TZP specimens (LAVA Frame Multi) were divided into 3 groups depending on the following firing procedures: (1) 2-firing cycles, (2) 5-firing cycles, (3) 10-firing cycles. Two samples from each group were investigated by using SEM to determine the morphological changes. All specimens were treated with 125 µm airborne-particle abrasion and the surface roughness of each specimen was measured. The specimens from each firing group were then further divided into 2 subgroups (n = 9) to apply 2 types of resin cement (MDP-free resin cement: RelyX Unicem-RU, and MDP containing resin cement: Panavia F 2.0-PA). The shear bond strength (SBS) test was performed and failure types of all the debonded specimens were classified by using a stereomicroscope as adhesive, cohesive, and mixed. The statistical analysis of surface roughness and SBS data were performed by using 1-way ANOVA and 2-way ANOVA followed by Tukey-HSD tests (α=.05). Failure modes were calculated as a percentage for each group.

RESULTS

The bond strength of RU and PA to the specimens obtained with 2 firings were not statistically different from each other (P=.1). However, the SBS values of PA were found to be significantly higher than RU for the specimens obtained with 5 and 10 firing cycles (P=.001 and P=.02, respectively). Surface roughness analysis revealed no statistical difference between groups (P=.2). The SEM analysis of samples fired 5- and 10- times showed irregularities and boundary loss in zirconia grains, and empty spaces between zirconia grains.

CONCLUSION

The bond strength of PA cement was higher than that of RU to the zirconia subjected to repeated firings (5 and 10 firing cycles). When zirconia is subjected to multiple firings, using MDP-containing resin cement can be recommended.

Construction of a silicate-based epitaxial transition film on a zirconia ceramic surface to improve the bonding quality of zirconia restorations

The effect of a silicate-based epitaxial transition film on zirconia produced by a silicate solution during zirconia-resin bonding was investigated. The airborne-particle abraded zirconia was placed in different concentrations of silicate solutions and heated at 50 °C. The silicate transition film was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), contact angle measurement and profilometry. The silicate-based epitaxial transition film was successfully constructed on the surface of zirconia, and the surface morphology and composition of zirconia changed. After coupling with KH570 hydrolysate, the shear bond strength (SBS) of zirconia-resin after either 24 h water storage or 5000 thermal cycles can be significantly improved by a silicate-based epitaxial transition film on the surface of zirconia, and all the samples had no cytotoxicity. This may provide a new strategy for improving the bonding quality of zirconia restorations.

Effect of Low-Concentration Hydrofluoric Acid Etching on Shear Bond Strength and Biaxial Flexural Strength after Thermocycling

This study evaluated the shear bond strength (SBS) and biaxial flexural strength (BFS) of resin cements according to the surface treatment method using low-temperature hot etching with hydrofluoric acid (HF) on a yttrium-stabilized tetragonal zirconia (Y-TZP) surface; 96 discs and 72 cubes for BFS and SBS tests for Y-TZP were randomly divided into four groups of BFS and three groups of SBS. Specimens were subjected to the following surface treatments: (1) no treatment (C), (2) air abrasion with 50 μm Al₂O₃ particles (A), (3) hot etching with HF at 100 °C for 10 min (E), and (4) air abrasion + hot etching (AE). After treatments, the specimens were coated with primer, and resin cement was applied with molds. The specimens were evaluated for roughness (Ra) via scanning electron microscopy and x-ray diffraction, and the data were analyzed by an analysis of variance (ANOVA) and Kruskal–Wallis tests. Group E produced significantly higher SBS compared to group A and AE before and after thermocycling. The BFSs of all groups showed no significant differences before thermocycling; however, after thermocycling, C and E treatment groups were significantly higher compared to group A and AE. All groups showed phase transformation. Group E was observed lower monoclinic phase transformation compared to other groups.

Influence of Primers and Additional Resin Layer on Zirconia Repair Bond Strength

PURPOSE

To evaluate the influence of alloy/zirconia primer and 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing resin layer treatments on the shear bond strength (SBS) of composite resin to zirconia after aging.

MATERIALS AND METHODS

Sixty zirconia (Y-TZP) blocks were air-abraded (35-µm Al₂ O₃ ) and divided into 6 experimental groups (n = 10) in terms of primer/resin layer as follows: (1) control, without any primer or resin; (2) AP, Alloy Primer; (3) ZPP, Z-Prime Plus; (4) PL/ZPP, Z-Prime Plus with light polymerization; (5) AP+SEB, Alloy Primer along with light-cured bonding resin of a self-etch adhesive system (SE Bond); and (6) ZPP+SEB, Z-Prime Plus with SE Bond. After composite resin placement and light polymerization, the specimens were stored in distilled water (37°C for 4 months) and thermal-cycled for 6000 cycles. The SBS was tested with a universal testing machine. Statistical analysis of the SBS data was performed with one-way ANOVA, followed by HSD Tukey test (α = 0.05).

RESULTS

There were significant differences between the groups (p < 0.001, F = 116.5). All the groups revealed significantly higher SBS than the control (p < 0.001). ZPP+SEB group exhibited the highest SBS (16.14 ± 2.52 MPa) and AP group the lowest SBS (7.00 ± 1.97 MPa) among experimental groups; both had significant differences with the other groups (p < 0.001). There were no significant differences between ZPP, PL/ZPP, and AP+SEB groups (p > 0.05).

CONCLUSIONS

The bond strength between zirconia ceramic and composite resin was affected by different primers/resin layer. Applying an MDP-containing resin layer along with both primers resulted in significant enhancement of SBS. This improvement for Z-Prime Plus was significantly higher than that of Alloy Primer.

Zirconia Primers Improve the Shear Bond Strength of Dental Zirconia

PURPOSE

Various resin cements and priming agents are available for adhesive luting of zirconia restorations. The purpose of this study was to investigate how cement type and priming protocol affect the shear bond strength on zirconia ceramics.

MATERIALS AND METHODS

Yttria-stabilized tetragonal zirconia polycrystalline ceramic cylinders were bonded to flat zirconia ceramic surfaces using 7 commercially available resin cements. Ten specimens of each cement group were pretreated with a universal primer, and 10 specimens per group were bonded without pretreatment. In addition, 10 specimens per group were pretreated with system-specific zirconia primers, which were available for 3 cements. Altogether, 170 bonded specimens were water-stored, thermal-cycled, and then submitted to shear bond strength tests. The shear bond strength and the fracture types were documented. Differences in shear bond strengths were assessed using 2-way ANOVA with post-hoc test (α = 0.05). A point-biserial correlation was run between the fracture patterns and the shear bond strengths.

RESULTS

The mean shear bond strengths of cements in the unprimed group showed large variations between 2.52 ± 3.01 (mean ± SD) MPa and 33.15 ± 7.35 MPa. Pretreating the specimens with a universal primer improved the shear bond strengths significantly in all groups (p < 0.05) with a range of 21.80 ± 12.51 to 57.20 ± 11.40 MPa. The system-specific primers also improved the shear bond strength significantly, compared to the unprimed group (p < 0.01); however, only one system-specific primer achieved a shear bond strength superior to the universal primer (p < 0.01). There was also a statistical correlation between the fracture type and the shear bond strength (p < 0.0005), with cohesively fractured specimens showing higher shear bond strengths (37.24 ± 19.87 MPa) than adhesively fractured specimens (23.10 ± 17.65 MPa) (p < 0.001).

CONCLUSION

Using universal primer can enhance the maximal shear bond strength of zirconia.

Effect of selective infiltration etching on the bond strength between zirconia and resin luting agents

OBJECTIVE

To evaluate the shear bond strength of resin cements to zirconia treated with the selective infiltration etching technique (SIE).

MATERIALS AND METHODS

Forty-seven zirconia specimens were prepared with a sequence of silicon carbide abrasives, cleaned in an ultrasonic bath. Three samples were separated for atomic force microscope (AFM) analyses (one nontreated for control, one sandblasted, and one selective infiltration etched) and the remaining were randomly distributed in four groups, according to the combination of surface treatment and resin cement: group 1a (sandblasting + Variolink II), group 1b (sandblasting + Panavia SA Plus), group 2a (SIE + Variolink II), group 2b (SIE + Panavia SA Plus). A composite resin cylinder (3 mm × 3 mm) was cemented to the zirconia surface, as per each group's specific protocol. After storing 24 hours in distilled water at 37°C, the specimens were tested for shear bond strength and the results were subjected to statistical analysis.

RESULTS

At 24 hours, the highest SBS values were observed in group 2b, where the SIE technique was used in conjunction with Panavia SA Plus. Lowest values were found in group 1a. Increased surface roughness was observed with SIE.

CONCLUSIONS

SIE significantly enhanced the resin bond strength to zirconia. However, cement selection was also an important factor, for both surface treatments tested.

CLINICAL SIGNIFICANCE

Use of SIE method combined with MDP monomer containing resin cement can provide clinically acceptable bond strength between zirconia and resin cement.

Evaluation of the Microshear Bond Strength of MDP-containing and Non-MDP-containing Self-adhesive Resin Cement on Zirconia Restoration

OBJECTIVES

The purpose of this study was to measure the microshear bond strength (μSBS) of four different self-adhesive resin cements with/without 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primer to zirconium ceramics and to evaluate the effect of zirconia primers on these self-adhesive resin cements (SARCs).

METHODS AND MATERIALS

Zirconia blocks (20 × 20 × 8 mm³) were prepared and divided into eight groups (n=20). They were sandblasted (50 μm Al₂O₃) and treated as follows: no primer or primer (Z-Primer Plus). Four self-adhesive resin cements (MDP-containing: Permacem 2.0 [PC], Clearfil SA luting [CS]; non-MDP-containing: Rely-X U200 [RU], Maxcem Elite [ME]) were bonded to the zirconia surface. After thermocycling, a μSBS test was performed. The failure mode was analyzed using light microscopy. Statistical analysis of μSBS was performed using one-way analysis of variance and two-sample t-test with post hoc Tukey test. The loss rate was evaluated using the Fisher's exact test and χ² test with post hoc Tukey test (p<0.05).

RESULTS

Within the no primer groups, the PC and CS groups showed higher bond strength than the RU and ME groups. Comparing the μSBS of the no primer and primer groups in the same SARCs, the RU/P group was higher than the RU group, and the ME/P group was higher than the ME group. No significant difference was observed between the PC and PC/P groups and between the CS and CS/P groups.

CONCLUSIONS

Non-MDP-containing SARC showed the increased bonding value with MDP-containing primer to zirconia ceramics. The bond strength of MDP-containing SARCs was not affected significantly by the use of zirconia primer.

Implant-Supported Fixed Partial Prostheses With Different Prosthetic Materials: A Three-Dimensional Finite Element Stress Analysis

PURPOSE

To evaluate the effects of prosthetic material on the degree of stress to the cortical bone, trabecular bone, framework, and implants using finite element analysis (FEA).

MATERIALS AND METHODS

A mandibular implant-supported fixed prosthesis was designed. Different prosthetic materials [cobalt-chromium-supported ceramic, zirconia-supported ceramic, and zirconia-reinforced polymethyl methacrylate (ZRPMMA)-supported resin] were used. FEA was used to evaluate stress under different loading conditions. Maximum principal (σmax), minimum principal (σmin), and von Mises (σvM) stress values were obtained.

RESULTS

Similar σmax, σmin, and σvM values were observed in the cortical and trabecular bones and in implants under both loading conditions, with the exception of the ZRPMMA model, which showed the highest σmax, σmin, and σvM values in oblique loading. The ZRPMMA model had the lowest σvM value in the framework under both loading conditions.

CONCLUSION

ZRPMMA had the lowest stress values in the framework, with increased stress values in the implants and bone tissue. Framework and veneering materials may influence stress values under different loading conditions.

Influence of nano alumina coating on the flexural bond strength between zirconia and resin cement

PURPOSE

The purpose of this in vitro study is to examine the effects of a nano-structured alumina coating on the adhesion between resin cements and zirconia ceramics using a four-point bending test.

MATERIALS AND METHODS

100 pairs of zirconium bar specimens were prepared with dimensions of 25 mm × 2 mm × 5 mm and cementation surfaces of 5 mm × 2 mm. The samples were divided into 5 groups of 20 pairs each. The groups are as follows: Group I (C) – Control with no surface modification, Group II (APA) – airborne-particle-abrasion with 110 µm high-purity aluminum oxide (Al₂O₃) particles, Group III (ROC) – airborne-particle-abrasion with 110 µm silica modified aluminum oxide (Al₂O₃ + SiO₂) particles, Group IV (TCS) – tribochemical silica coated with Al₂O₃ particles, and Group V (AlC) – nano alumina coating. The surface modifications were assessed on two samples selected from each group by atomic force microscopy and scanning electron microscopy. The samples were cemented with two different self-adhesive resin cements. The bending bond strength was evaluated by mechanical testing.

RESULTS

According to the ANOVA results, surface treatments, different cement types, and their interactions were statistically significant (P<.05). The highest flexural bond strengths were obtained in nanostructured alumina coated zirconia surfaces (50.4 MPa) and the lowest values were obtained in the control group (12.00 MPa), both of which were cemented using a self-adhesive resin cement.

CONCLUSION

The surface modifications tested in the current study affected the surface roughness and flexural bond strength of zirconia. The nano alumina coating method significantly increased the flexural bond strength of zirconia ceramics.