Effect of conditioning methods on the microtensile bond strength of phosphate monomer-based cement on zirconia ceramic in dry and aged conditions

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.

Effect of surface pretreatment and artificial aging on the retention of lithium disilicate crowns cemented to zirconia implant abutments

STATEMENT OF PROBLEM

Recent advancements in restorative dentistry have seen an increase in the use of ceramic restorations and zirconia implant abutments. However, how the pretreatment of a zirconia abutment and different artificial aging protocols affect the bond strength of a cemented, monolithic lithium disilicate crown is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of surface pretreatment on the retentive strength of milled lithium disilicate crowns bonded to custom zirconia implant abutments with different resin cements after thermocycling and long-term aging.

MATERIAL AND METHODS

A total of 144 crowns (n=8) were milled and bonded to 144 abutments. In the experimental groups, 72 abutments were airborne-particle abraded with 50-μm aluminum oxide before bonding. All specimens were stored at 37 °C in 100% humidity for 24 hours. Forty-eight specimens were subjected to thermocycling, and another 48 were subjected to aging for 6 months. Retentive strength was measured by using a pull-off test with a universal testing machine. Retentive strength values were calculated and compared with 3-way analysis of variance and a Tukey-Kramer post hoc test (α=.05).

RESULTS

In the 24-hour aging group, retention for all experimental groups was significantly higher (P<.05) than for the control group, except for Panavia 21 with Clearfil Ceramic Primer. In the thermocycling and long-term aging groups, all cements in the experimental group displayed significantly higher retention than the control. The airborne-particle abrasion of custom zirconia implant abutments with 50-μm aluminum oxide before bonding to lithium disilicate crowns significantly increased the bond strength of the Multilink Hybrid Abutment with Monobond Plus and RelyX Ultimate with Scotchbond Universal cements after 24-hour aging, but not of Panavia 21 with Clearfil Ceramic Primer.

CONCLUSIONS

Airborne-particle abrasion significantly increased the bond strength of all 3 cements after thermocycling and long-term aging.

A Comprehensive Evaluation of Zirconia-Reinforced Glass Ionomer Cement's Effectiveness in Dental Caries: A Systematic Review and Network Meta-Analysis

Dental cements are in a constant state of evolution, adapting to better align with the intricacies of tooth structure and the dynamic movements within the oral cavity. This study aims to evaluate the efficacy of zirconia-reinforced glass ionomer cement-an innovative variant of modified glass ionomer cements-in terms of its ability to withstand compressive forces and prevent microleakage during dental caries reconstruction. An extensive search was conducted across various databases, encompassing PubMed-MEDLINE, Scopus, Embase, Google Scholar, prominent journals, unpublished studies, conference proceedings, and cross-referenced sources. The selected studies underwent meticulous scrutiny according to predetermined criteria, followed by the assessment of quality and the determination of evidence levels. In total, 16 studies were incorporated into this systematic review and network meta-analysis (NMA). The findings suggest that both compomer and giomer cements exhibit greater compressive strength and reduced microleakage values than zirconia-reinforced glass ionomer cement. In contrast, resin-modified glass ionomer cement (RMGIC) and high-viscosity glass ionomer cement (GIC) demonstrate less favorable performance in these regards when compared with zirconia-reinforced glass ionomer cement.

Effect of Dentin and Zirconia Surface Treatments with Laser Irradiation Versus Sandblasting on the Bonding Ability of Zirconia

Objective: This study aimed to investigate the effects of laser irradiation applied to zirconia and tooth surfaces on shear bond strength (SBS) compared with acid etching and sandblasting. Background: The effect of laser irradiation on the bond strength between zirconia and adhesives is a controversial issue for dentin surface treatments. In addition, the effects of different combinations of surface treatments to increase adhesion on both the zirconia and dentin surfaces remain unclear. Materials and methods: A total of 90 tooth samples were assigned into groups according to various pretreatments: control group was left untreated, acid etching, and Erbium, Chromium:Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser irradiation group (15 Hz, 2 W). In addition, the zirconia specimens were separated into three groups (n = 10) according to the different surface treatments performed: sandblasting (120 μm Al2O3), Er,Cr:YSGG laser (15 Hz, 2 W), and as untreated surface. The zirconia samples were cemented to the dentin surface using dual-cure resin cement and subjected to an SBS test at a speed of 0.5 mm/min under a universal testing machine until fractures occurred in the bonding surface. Results: The highest SBS values were observed in Group tooth acid (TA)-zirconia Er,Cr:YSGG laser (ZL), followed by Group tooth Er,Cr:YSGG laser (TL)-zirconia sandblasting (ZS) and Group TA-zirconia control (ZC). The lowest SBS values were found in Group TA-ZS. Significant intergroup difference was noted between Group TA-ZL, Group tooth control (TC)-ZC, Group TL-ZS, and Group TC-ZC. However, no significant difference was noted between Group TA-ZL, Group TL-ZS, and Group TA-ZC. Conclusions: Acid etching and laser treatments applied to the dentin and zirconia surfaces were found to be effective techniques for improving the zirconia-dentin bond, respectively. Clinical Trial Registration number: 33216249-604.01.02-E.24308.

Effect of Surface Treatment of Zirconia on the Shear Bond Strength of Resin Cement: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to evaluate the effect of different surface treatments on the shear bond strength (SBS) values between zirconia and resin cement compared to untreated specimens. The effects of various surface treatments on the bond strength between zirconia and resin cement were investigated by searching relevant articles on PubMed, ScienceDirect, and Google Scholar databases. A total of 13 studies that met the inclusion and exclusion criteria and addressed the research question were selected for statistical analysis. The studies were evaluated for heterogeneity, and a meta-analysis was performed. In total, 13 in vitro studies were included in accordance with the eligibility criteria. All 13 studies consistently demonstrated that silica coating yielded the highest SBS, followed by sandblasting and laser treatments. The meta-analysis using a random-effect model indicated a significant intergroup comparison, except for a few studies. Among the three treatments examined, the silica coating of zirconia was identified as the most effective in enhancing the bond strength between zirconia and resin cement. Further controlled laboratory and clinical studies are necessary to validate these findings and explore additional factors that may influence the effects of these surface treatments.

Effect of Adhesion Conditions on the Shear Bond Strength of 3D Printing Resins after Thermocycling Used for Definitive Prosthesis

Three-dimensional (3D) printing polymers such as urethane dimethacrylate (UDMA) and ethoxylated bisphenol A dimethacrylate (Bis-EMA) are typically used in definitive prosthesis and require surface treatments before bonding. However, surface treatment and adhesion conditions often affect long-term use. Herein, polymers were divided into Groups 1 and 2 for the UDMA and Bis-EMA components, respectively. The shear bond strength (SBS) between two types of 3D printing resins and resin cements was measured using Rely X Ultimate Cement and Rely X U200, according to adhesion conditions such as single bond universal (SBU) and airborne-particle abrasion (APA) treatments. Thermocycling was performed to evaluate the long-term stability. Sample surface changes were observed using a scanning electron microscope and surface roughness measuring instrument. The effect of interaction between the resin material and adhesion conditions on the SBS was analyzed via a two-way analysis of variance. The optimal adhesion condition for Group 1 was achieved when U200 was used after APA and SBU, whereas Group 2 was not significantly affected by the adhesion conditions. After thermocycling, the SBS significantly decreased in Group 1 without APA treatment and in the entire Group 2. Additionally, porosity, along with increased roughness, was observed on both material surfaces after APA.

Effect of Different Surface Treatments on the Micro-Shear Bond Strength and Surface Characteristics of Zirconia: An In Vitro Study

Purpose

To study the effect of different surface treatments on the micro-shear bond strength and surface characteristics of zirconia.

Methods

Two types of zirconia ceramics were tested: opaque (O) and translucent (T). Each type of zirconia was further allotted into four groups based on the type of surface treatment method. The four groups were: control (C), air abrasion with 110 µm Al₂O₃ particles (A), etching with Zircos–E Etching solution for 2 hours (E), and a combination of air abrasion and etching (AE). After the surface treatment, all specimens were ultrasonically cleaned and 10 resin cement cylinders were attached to the zirconia discs in each group. A micro-shear bond strength test was performed in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture surfaces were assessed under a compound microscope. SEM, EDAX, and AFM analyses were done for the zirconia specimens after being subjected to surface treatment. Statistical analysis for the bond strength test was done using the Shapiro–Wilk test, one-way analysis of variance (ANOVA), and Post hoc Tukey test.

Results

The micro-shear bond strength values for the groups were as follows in megapascals (MPa): OC 18.96 (5.54), OA 22.66 (2.51), OE 28.48 (4.50), OAE 28.63 (4.53), TC 22.82 (5.46), TA 25.36 (5.17), TE 28.12 (4.76), and TAE 32.00 (3.47). The one-way analysis of variance (ANOVA) and post hoc Tukey HSD tests were done which showed significant results in the groups. In opaque zirconia, significant differences were seen in the etching and air abrasion with etching groups when compared with the control and air abrasion groups. There was no difference between the etching and air abrasion with etching groups. For translucent zirconia, the only significant difference was seen in the air abrasion with etching group in comparison with the control and air abrasion groups. The mode of failure was majorly adhesive. The surface topography and surface roughness showed significant differences between the groups. The EDAX results showed material loss that occurred due to sandblasting in the air abrasion groups.

Conclusions

Etching with Zircos–E Etching solution significantly increased the bond strength of zirconia to resin cement when compared with other surface treatment methods. In translucent zirconia, the best results can be achieved by combining etching with air abrasion.

Current scenario on adhesion to zirconia; surface pretreatments and resin cements: A systematic review

Several methods have been proposed to increase bonding of zirconia with resin. However, we are still to find the Holy Grail. A systematic literature review was performed through PubMed on international literature from January 2000 to May 2021 with relevant Medical Subject Headings terms. 56 articles were found to be relevant. Of all the different methods proposed, mechanochemical pretreatment of zirconia surface with alumina oxide and use of 10-methacryloyloxydecyl dihydrogen phosphate were found to be most effective as per majority of studies. New methods that require further research also surfaced.

Effect of the nanofilm-coated zirconia ceramic on resin cement bond strength

Background. New surface treatments have been proposed to expand the clinical indications of zirconia prostheses. This study aimed to evaluate the effect of silica and fluorine nanofilms on zirconia ceramic on the resin cement bond strength. Methods. Zirconia blocks and discs underwent different surface treatments: untreated zirconia (CON), sandblasted, silica-coated alumina particles (30 µm) (SC), silica nanofilm (SN), and fluorine nanofilm (FN). Nanofilm deposition was performed through plasma enhanced chemical vapor deposition (PECVD). Zirconia surfaces were characterized on disks by morphology (atomic force microscopy, AFM), chemical analysis (x-ray photoelectron spectroscopy, XPS), and contact angle analysis. A silane coupling agent was applied on each treated surface, and a cylinder of resin cement was built up. Half of the specimens in each group were submitted to 6000 thermal cycles (TC). Bond strength was analyzed using the shear test, and the fractographic analysis was performed with stereomicroscopy and SEM/EDS. Statistical analysis was performed through one-way ANOVA and Tukey test in the non-aged and aged specimens. Results. Nanofilms modified the zirconia surface, which became more hydrophilic and chemically reactive. Chemical bonding between Si-O was found in SN, and FN promoted a fluorination process on the ceramic surface, converting zirconia into zirconium oxyfluoride. Specimens of the SN (TC) group failed on pre-testing. FN (TC) bond strength (3.8 MPa) was lower than SC (TC) and CON (TC) after shearing. Adhesive failure predominated in the experimental groups. Silica nanofilm failure occurred after aging. Conclusion. Silica and fluorine nanofilms deposited by PECVD did not promote effective bonding between zirconia and resin cement.

The effect of repeated surface treatment of zirconia on its bond strength to resin cement

PURPOSE

The aim of this study is to evaluate the influence of repeated surface treatments on wettability and surface roughness for zirconia surface and bond strength of zirconia-based ceramics to resin cement.

MATERIALS AND METHODS

Seventy blocks (10 × 10 × 3 mm) of zirconia-based ceramics were fabricated and divided into two groups according to the surface treatments: (A) 110 µm Al₂O₃ airborne-particle abrasion and (R) 110 µm silica modified Al₂O₃ airborne-particle abrasion. At stage 2, each group was subdivided into 5 groups according to the surface retreatments: (a) 110 µm Al₂O₃ airborne-particle abrasion, (r) 110 µm silica modified Al₂O₃ airborne-particle abrasion, (D) diamond bur, (Da) diamond bur + 110 µm Al₂O₃ airborne-particle abrasion, and (Dr) diamond bur + 110 µm silica modified Al₂O₃ airborne-particle abrasion. Cylinders of self-adhesive resin cement were cemented onto each treated ceramic surface and subjected to micro-shear bond strength test. Additional specimens were prepared for roughness and wettability analyses. The data were subjected to t-test and One-way ANOVA followed by Tukey's post hoc test (α=.05).

RESULTS

At stage 1, group R presented higher bond strength values than group A (P=.000). There was a statistically significant increase of bond strength at stage 2 for group A (P=.003). The diamond bur influenced the surface roughness, increasing the values (P=.023). Group R provided better wettability. Regardless of the applied surface treatment, most of failures were adhesive.

CONCLUSION

The combination of application and reapplication of Rocatec Plus showed the best results of bond strength. Surface retreatment and recementation might be an indicated clinical strategy.

Influence of zirconia surface treatments of a bilayer restorative assembly on the fatigue performance

PURPOSE

This study evaluated the influence of different surface treatments of zirconia used to enhance bonding with veneering porcelain, and thermocycling on the resistance to porcelain cracking and delamination during fatigue test.

METHODS

Bilayer ceramic discs were made from zirconia blocks (IPS e.max Zircad MO, Ivoclar Vivadent - 0.7 mm thickness) and randomized into 8 groups (n= 15) according to two factors: 'zirconia surface treatment' (Control; Grinding - diamond bur; Air-abrasion - aluminum oxide particles; and Liner - application of a ceramic liner [IPS e.max Zirliner, Ivoclar Vivadent]); and 'thermocycling' (presence - 12,000 thermal cycles; 5-55ºC; or absence). The discs were veneered with porcelain (IPS e.max Ceram, Ivoclar Vivadent - 0.7 mm; totaling 1.4 mm thickness) according to ISO 6872:2015 for biaxial flexure strength testing. Fatigue tests (step-stress approach; 20 to 100 MPa; step of 10 MPa; 10,000 cycles per step; 10 Hz frequency) were run, followed by the data analysis (Kaplan-Meier and Mantel-Cox post-hoc tests). Analysis of roughness, topography, crystallographic phase arranges and fractography were also executed.

RESULTS

The surface treatment and thermocycling did not influence the porcelain crack nor delamination resistance. When only comparing the surface treatments for crack resistance outcome, the liner application depicted the worst fatigue performance in comparison to grinding and air-abrasion, while all groups were similar for delamination.

CONCLUSIONS

Neither the surface treatment of the zirconia nor the thermocycling influences the porcelain crack resistance or the resistance to delamination of the bilayer porcelain-veneered zirconia specimens.

Effects of different silica-based layer coatings on bond strength of Y-TZP to bovine dentin

This study investigated the effects of different silica-based layer coatings on shear bond strength (SBS) between Y-TZP and bovine dentin. Three different silica-based layer coatings were applied to the Y-TZP surface: tribochemical silica coating, vitrification (glaze coating), and composite resin sintering. A silane coupling agent (SIL) was applied to the silica-coated Y-TZP surface in the presence or absence of hydrofluoric acid (HF) treatment. A one-step adhesive was then applied to the silica-coated Y-TZP and cemented to bovine dentin using MDP-free resin cement. The SBS value of the tribochemical silica coating group was lowest among the experimental groups, while the HF+SIL subgroup showed the highest SBS value after vitrification (p<0.05). While hydrofluoric acid etching did not affect the SBS value of the tribochemical silica coating group, it affected the SBS value in the vitrification and composite resin sintering groups (p<0.05).

Graphene oxide-based experimental silane primers enhance shear bond strength between resin composite and zirconia

Despite various mechanical and chemical surface-pretreatment methods, long-term bonding of resin composite to dental zirconia (ZrO₂ ) remains a major concern. In this study, graphene oxide (GO) sheets were infused into two commercially available primers and the enclosed mould shear bond strength (EM-SBS) of resin composite to ZrO₂ was evaluated. Twelve fully sintered ZrO₂ blanks were pretreated and randomly allocated to four groups according to the primers used: RelyX (RX); GO blended RelyX (RXGO); Monobond-S (MB); and GO blended Monobond-S (MBGO). The resin composite stubs were bonded onto the pretreated ZrO₂ surfaces and analysed at baseline and after storage in distilled water for 2 and 4 months. The experimental primers blended with GO sheets influenced the surface morphology, visualized as increased surface roughness, and slightly increased the water contact angle measurements. Moreover, the infusion of primers with GO increased the mass fraction (wt%) of carbon and oxygen. The highest EM-SBS values were found for RXGO, with mean (SD) EM-SBS values of 26.4 (3.7) MPa and 21.5 (5.1) MPa after 2 and 4 months of storage, respectively. Infusion of silane primers with nanometre- to micrometre-size GO sheets enhanced the SBS between resin composite and ZrO₂ .

Bond Strength and Failure Pattern of Orthodontic Tubes Adhered to a Zirconia Surface Submitted to Different Modes of Application of a Ceramic Primer

The aim of this study was to evaluate the shear bond strength of orthodontic tubes adhered to ceramics with the Transbond™ XT bonding resin (3M, Maplewood, MN, USA) while varying the surface treatment. Then, the adhesive remaining index (ARI) was verified, and the representative fracture patterns were evaluated via scanning electron microscopy. Forty-eight zirconia blocks were divided into three groups, varying the number of layers of the 10-methacryloyloxy-decyl dihydrogen phosphate (MDP) primer: one, two, or three applications. In addition, 16 lithium disilicate IPS E.max ceramic disks (Ivoclar Vivadent, Schaan, Liechtenstein) were conditioned with 10% hydrofluoric acid for 20 s and underwent a single-layer primer application regimen. The four groups were further stratified to undergo bond testing after either 24 h (control) or 5000 cycles in a thermocycling machine. A shear bond strength test was performed (0.5 mm/min), and the MPa values obtained were submitted to a two-way analysis of variance and Tukey’s test. There was no statistical difference among the control group ceramics that received the varying surface treatments. After thermocycling, it was verified that both the E.max disks and the zirconia ceramics with three primer applications obtained the highest bond strength values. In the 24 h groups, a total displacement of the resin from the orthodontic tubes was observed (ARI of 1). After thermocycling, the highest prevalence of an ARI of 5 (adhesive failure) was observed among the zirconia ceramics with single-coat primer application, followed by those with triple-coat primer application (mixed failure). Three applications of the MDP-containing ceramic primer achieved the best result in the present study. Zirconia surface should be treated with three coats of MDP primer to achieve a level of bond strength similar to silica-rich phase ceramic.

Silicon-based film on the yttria-stabilized tetragonal zirconia polycrystal: Surface and shear bond strength analysis

AIM

To analyze the effect of a silicon (Si)-based film deposited on yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) on the topography and bond strength of resin cement.

METHODS

Specimens of zirconia were obtained and randomly divided into 4 groups, according to surface treatment: polished group (PG) zirconia; sandblasted group (SG) zirconia with aluminum oxide (100 µm); after polished, zirconia was coated with Si-based film group (SiFG); and after sandblasted, zirconia was coated with Si-based film group (SiFSG). The Si-based films were obtained through plasma-enhanced chemical vapor deposition. Surface roughness and contact angle analysis were performed. Resin cement cylinders were built up on the treated surface of blocks, after applying Monobond-S. The specimens were submitted to thermocycling aging and shear bond strength testing. The Kruskal-Wallis and Mann-Whitney U-tests were performed.

RESULTS

There were significant differences between the surface treatments for each roughness parameter measured. Si-based film increased roughness and decreased the contact angle. Si-based film groups also demonstrated significantly lower bond strength values.

CONCLUSION

Si-based film produced using plasma deposition provided lower bond strength to resin cement compared with conventional treatment; however, the film deposition reduced the contact angle and improved roughness, favorable properties in the long way to prepare an optimum material.

Surface, Microstructural, and Mechanical Characterization of Prefabricated Pediatric Zirconia Crowns

The purpose of this study was to characterize the surface roughness, the microstructure, and mechanical properties of four prefabricated zirconia pediatric crowns. Ten prefabricated crowns from four different manufacturers (Cheng Crowns Zirconia), (EZCrowns), (NuSmile ZR), and (Zirconia Pediatric Crowns) were included in this study. The surface roughness parameters (Sa, Sq, Sz, Sc, and Sv) of all samples were studied by optical profilometry and then the microstructure was studied by Raman spectroscopy. Then, all samples were embedded in epoxy resin and after metallographic polishing, the Martens hardness (HM), indentation modulus (E_IT), elastic index (η_IT), Vickers hardness (HV), and fracture toughness (K_IC) were identified by the Instrumented Indentation Testing (IIT). All data were statistically analyzed by a one-way ANOVA and a Tukey multiple comparison test at α = 0.05. Only the tetragonal phase of zirconia for all materials tested was identified after Raman analysis. However, statistically significant differences were found among the surface roughness parameters, HV and K_IC, while no differences were allocated for HΜ, E_IT, and η_ΙΤ. Although the materials tested shared a similar microstructure, significant differences in surface roughness parameters HV and K_IC were identified and, thus, differences in their clinical performance were anticipated.

Effect of Immediate Dentin Sealing and Surface Conditioning on the Microtensile Bond Strength of Resin-based Composite to Dentin

This study evaluated the microtensile bond strength (μTBS) of resin-based composite (RBC) to dentin after different immediate dentin sealing (IDS) strategies and surface-conditioning (SC) methods and on two water storage times. Human molars (n=48) were randomly divided into eight experimental groups involving four different IDS strategies-IDS-1L with one layer of adhesive, IDS-2L with two layers of adhesive, IDS-F with one layer of adhesive and one layer of flowable RBC, and DDS (delayed dentin sealing) with no layer of adhesive (control)-and two different SC methods-SC-P with pumice rubbing and SC-PC with pumice rubbing followed by tribochemical silica coating. The μTBS test was performed after one week and after six months of water storage, being recorded as the "immediate" and "aged" μTBS, respectively. Composite-adhesive-dentin microspecimens (0.9×0.9×8-9 mm) were stressed in tension until failure to determine the μTBS. Failure mode and location of failure were categorized. Two-way analysis of variance was applied to analyze the data for statistically significant differences between the experimental groups (p<0.05). Two-way analysis of variance revealed no significant differences between the one-week μTBS specimens for IDS strategy (p=0.087) and SC methods (p=0.806). However, the interaction of IDS strategy and SC methods appeared statistically significant (p=0.016). The six-month specimen evaluation showed no significant difference in μTBS for SC (p=0.297) and SC/IDS interaction (p=0.055), but the μTBS of the IDS strategies differed significantly among them (p=0.003). For tribochemical silica-coated IDS, no significant effect of aging on μTBS was recorded (p=0.465), but there was a highly significant difference in μTBS depending on the IDS strategy (p<0.001). In addition, the interaction of IDS and aging was borderline statistically significant (p=0.045). The specimens failed mainly at the adhesive-dentin interface for all experimental groups. Dentin exposure during clinical procedures for indirect restorations benefits from the application of IDS, which was shown to result in higher bond strength. No significant differences were found between cleaning with solely pumice or pumice followed by tribochemical silica coating.

A new approach for Y-TZP surface treatment: evaluations of roughness and bond strength to resin cemen

OBJECTIVE

This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering.

MATERIAL AND METHODS

Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: post-sintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests.

RESULTS

The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08).

CONCLUSIONS

Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement.

The effect of air-particle abrasion and a zirconia primer application on resin cement bonding strength to zirconia

BACKGROUND

This study aimed to evaluate the influence of surface treatments on the bond strength between a zirconia-based ceramic and two resin cements.

METHODS

Eighty blocks (5.25×3.74×4.5 mm) of a zirconia-based ceramic were divided into eight groups (N.=10) according to the factors "surface treatment" (air-particle abrasion with Al2O3 or Al2O3/SiO2 and zirconia primer) and "cement" (conventional resin cement and self-adhesive resin cement). After the surface treatments, cylinders of each resin cement (Ø=3.5 mm, height: 3 mm) were built up on the zirconia surface and photo-activated (40 s). The samples were stored in water for 30 days at 37 °C, followed by shear bond strength test in a universal testing machine (1 mm/min). Data were analyzed by ANOVA and Tukey test (α=0.05).

RESULTS

Regarding the surface treatments, all strategies were statistically different from each other. The Cojet achieved the higher bond strength values, followed by Signum Zirconia Bond. The resin cements were also statistically different from each other, since the U200 achieved higher bond strength values. The interaction between the factors was also significant. Most of the failures were adhesive and mixed.

CONCLUSIONS

Regardless of the cement used, the air-particle abrasion with alumina coated by silica particles improved bond strength.

An in vitro comparison of the effect of various surface treatments on the tensile bond strength of three different luting cement to zirconia copings

Aim:

The aim of this study was to evaluate and compare the tensile bond strength of zirconia copings subjected to three different surface treatment methods and cemented with three different luting agents.

Materials and Methods:

Seventy-two extracted maxillary premolar teeth were prepared to receive zirconia copings milled using computer-aided design/computer-aided manufacturing technology, which were divided into 9 groups of 8 specimens each. Three surface treatment protocols such as hydrofluoric acid etch treatment, air abrasion with 110-μm aluminum oxide (Al₂O₃), and tribochemical silica coating (Rocatec) treatment were carried out, and copings were cemented with three luting agents such as resin-modified glass ionomer cement (RelyX luting 2), 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) resin cement (Panavia F 2.0) and 4-methacryloxyethyl trimellitic acid (4-META) resin cement (G-Cem). Tensile bond strength of the copings was tested in a universal testing machine. Zirconia copings fabricated on the prepared extracted tooth. After the three surface treatments and cementing the zirconia crowns with three luting agents tensile bond strength is tested. The mean and standard deviations (SD) were calculated for the nine groups using one-way ANOVA, followed by Tukey–Kramer post hoc using the SPSS software.

Results:

The ANOVA test showed that the measured mean bond strength values were 4.22 MPa (tribochemicalsilica coating and MDP resin), 2.71 MPa (air abrasion and MDP resin), 2.61 MPa (tribochemical treatment with META), and 0.66 MPa (RelyX with air abrasion). According to the pairwise comparison of Tukey's honestly significant difference test, significant differences were exhibited among all the groups (P < 0.05).

Conclusion:

Tribochemical silica coating in combination with 10-MDP and 4-META adhesive resins provided the maximum bonding for zirconia copings.

Ultrastructure and bonding properties of tribochemical silica-coated zirconia

Tribochemical silica coating (TSC) is commonly used to pretreat zirconia surfaces prior to luting. Although many studies demonstrate an adhesion-promoting effect of TSC on zirconia, its actual interaction mechanism has not been fully elucidated. We therefore characterized the ultrastructure of TSC-treated zirconia and tested shear-bond strength. STEM/EDS disclosed a micro-roughened zirconia surface partially covered with fused Al and Si, while residual unfused silica particles could also still be detected. TSC-treated zirconia having received the solely silane primer exhibited a significantly lower shear-bond strength than zirconia on which the combined 10-MDP/silane primer was applied. SEM fracture analysis revealed residual silica particles on both the zirconia and cement sides. Correlative ultrastructural and chemical surface characterization revealed that TSC deposited an inhomogeneous silica layer on the zirconia surface, which explains why the solely silane coupling agent was less effective than the combined 10-MDP/silane ceramic primer for bonding to zirconia pretreated by TSC.

Effect of Adhesive Cementation Strategies on the Bonding of Y-TZP to Human Dentin

This study evaluated the effects of different adhesive strategies on the adhesion of zirconia to dentin using conventional and self-adhesive cements and their corresponding adhesive resins. The occlusal parts of human molars (N=80) were sectioned, exposing the dentin. The teeth and zirconia cylinders (N=80) (diameter=3.4 mm; height=4 mm) were randomly divided into eight groups according to the factors “surface conditioning” and “cement type” (n=10 per group). One conventional cement (CC: RelyX ARC, 3M ESPE) and one self-adhesive cement (SA: RelyX U200, 3M ESPE) and their corresponding adhesive resin (for CC, Adper Single Bond Plus; for SA, Scotchbond Universal Adhesive-SU) were applied on dentin. Zirconia specimens were conditioned either using chairside (CJ: CoJet, 30 μm, 2.5 bar, four seconds), laboratory silica coating (RC: Rocatec, 110 μm, 2.5 bar, four seconds), or universal primer (Single Bond Universal-UP). Nonconditioned groups for both cements acted as the control (C). Specimens were stored in water (37°C, 30 days) and subjected to shear bond strength (SBS) testing (1 mm/min). Data (MPa) were analyzed using two-way analysis of variance and a Tukey test (α=0.05). While surface conditioning significantly affected the SBS values (p=0.0001) (C&lt;RC=CJ=UP), cement type did not (p=0.148) (CC=SA). The interaction terms were significant (p=0.014). Failure types were predominantly adhesive. Air-abrasion and the use of the universal primer improved the bond strength of zirconia to dentin compared to the control group, regardless of the type of resin cement used.

Study of the Mechanical Properties of the Novel Zirconia-reinforced Glass lonomer Cement

OBJECTIVES

The purpose of this in vitro study is to compare the compressive strength (CS) and diametral tensile strength (DTS) of the zirconia-reinforced restorative material (Zirconomer®) with conventional glass ionomers (Fuji 1X) and amalgam.

MATERIALS AND METHODS

Specimens (n = 120) were fabricated from silver amalgam, reinforced glass ionomer cement (GIC) (glass ionomer, Fuji 1X GC Corp.), and zirconia-reinforced glass ionomer (Zirconomer, Shofu Inc.) for testing the CS and DTS. The results were analyzed using analysis of variance, followed by a Tukey post hoc test.

RESULTS

Both CS and DTS were found to be significantly higher for the zirconia-reinforced GIC and silver amalgam compared with GIC (p < 0.001).

CONCLUSION

A newer class of restorative material like Zirconomer helps to overcome the potential hazard of mercury, but retains the strength and durability of amalgam as well as the sustained high-fluoride release of GICs. Furthermore, long-term studies are required to confirm its use as an alternative to the currently available posterior restorative material.

Resin Bonding to a Hybrid Ceramic: Effects of Surface Treatments and Aging

The aim of this study was to verify the effects of different surface treatments on the microtensile bond strength between resin cement and a hybrid ceramic. Thirty-two hybrid ceramic slices (8 × 10 × 3 mm) were produced and allocated among four groups according to the surface treatment: Cont = no treatment, HA = 10% hydrofluoric acid applied for 60 seconds, PA = 37% phosphoric acid applied for 60 seconds and CJ = air abrasion with silica particle coated alumina (Cojet Sand, 3M ESPE, 30 μm/2.8 bar). As a control group, eight blocks of feldspathic ceramic (8 × 10 × 3 mm) were etched by hydrofluoric acid for 60 seconds (VMII). After the surface treatments, the ceramic slices were silanized (except the Cont group) and adhesively cemented to composite resin blocks (8 × 10 × 3 mm ) with a load of 750 g (polymerized for 40 seconds each side). The cemented blocks were cut into beams (bonded surface area of ∼1 mm2). Half of the beams were aged (thermocycling of 5°C-55°C/6000 cycles + water storage at 37°C/60 days), and the other half were tested immediately after being cut. Data were analyzed by Kruskal-Wallis and Dunn tests (non-aged groups) and by one-way analysis of variance and Tukey test (aged groups; α=0.05%). The mode of failure was classified by stereomicroscopy. The surface treatment significantly affected the bond strength in each set of groups: non-aged (p=0.001) and aged (p=0.001). Before being aged, samples in the CJ, HA, and PA groups achieved the highest bond strength values. However, after being aged, only those in the HA group remained with the highest bond strength values. Adhesive failure was found most often. In conclusion, hydrofluoric acid etching should be used for surface conditioning of the studied hybrid ceramic.

Bonding values of two contemporary ceramic inlay materials to dentin following simulated aging

PURPOSE

To compare the push-out bond strength of feldspar and zirconia-based ceramic inlays bonded to dentin with different resin cements following simulated aging.

MATERIALS AND METHODS

Occlusal cavities in 80 extracted molars were restored in 2 groups (n=40) with CAD/CAM feldspar (Vitablocs Trilux forte) (FP) and zirconia-based (Ceramill Zi) (ZR) ceramic inlays. The fabricated inlays were luted in 2 subgroups (n=20) with either etch-and-bond (RelyX Ultimate Clicker) (EB) or self-adhesive (RelyX Unicem Aplicap) (SA) resin cement. Ten inlays in each subgroup were subjected to 3,500 thermal cycles and 24,000 loading cycles, while the other 10 served as control. Horizontal 3 mm thick specimens were cut out of the restored teeth for push out bond strength testing. Bond strength data were statistically analyzed using 1-way ANOVA and Tukey's comparisons at α=.05. The mode of ceramic-cement-dentin bond failure for each specimen was also assessed.

RESULTS

No statistically significant differences were noticed between FP and ZR bond strength to dentin in all subgroups (ANOVA, P=.05113). No differences were noticed between EB and SA (Tukey's, P>.05) bonded to either type of ceramics. Both adhesive and mixed modes of bond failure were dominant for non-aged inlays. Simulated aging had no significant effect on bond strength values (Tukey's, P>.05) of all ceramic-cement combinations although the adhesive mode of bond failure became more common (60-80%) in aged inlays.

CONCLUSION

The suggested cement-ceramic combinations offer comparable bonding performance to dentin substrate either before or after simulated aging that seems to have no adverse effect on the achieved bond.

Effect of sandblasting, silica coating, and laser treatment on the microtensile bond strength of a dental zirconia ceramic to resin cements

The purpose of this in vitro study was to evaluate the effect of laser irradiation as well as other surface treatment methods on the microtensile bond strength of a dental zirconia ceramic to the two types of resin cements. Zirconia ceramic blocks (ICE Zirkon) were sintered according to the manufacturer's instructions and duplicated in resin composites. The ceramic specimens were divided into four groups according to the following surface treatments: no surface treatment (control), sandblasting with alumina, silica coating plus silanization, and Nd:YAG laser irradiation. The specimens were divided equally and then bonded with Panavia F2.0 (self-etching resin cement) and Clearfil SA Luting (self-adhesive resin cement) to the composite blocks. The bonded ceramic-composite blocks were stored in distilled water at 37 °C for 72 h, cut to prepare bar-shaped specimens with a bonding area of approximately 1 mm(2), and thermocycled for 3000 cycles between 5 and 55 °C, and the microtensile bond strengths were measured using a universal testing machine. The data were analyzed by ANOVA and Tukey post hoc test. The results showed that the self-adhesive resin cement used in this study did not improve the microtensile bond strength when the zirconia surface was sandblasted by alumina. The use of the Nd:YAG laser did not enhance the bond strength between the zirconia and both types of resin cements. In addition, silica coating of the zirconia surfaces plus silane application significantly improved the bond strength regardless of the type of resin cement utilized.

Surface Treatments of Zirconia to Enhance Bonding Durability

This article reviewed the surface treatments used most often to improve adhesion between zirconia and adhesive cements, focusing on their capacity to provide long-term bonding. Traditional and new treatments for zirconia bonding were searched. Some new treatments were discussed along with topographical views of the modified zirconia. New methods, such as selective infiltration etching and the low-fusing glassy porcelain application are promising, but more research is needed.

An assessment of shear bond strength between ceramic repair systems and different ceramic infrastructures

The purpose of this study was to evaluate of shear bond strengths between two ceramic repair systems and different ceramic infrastructure materials. One hundred cylindrical specimens of ceramic infrastructure were fabricated with non precious metal alloy, zirconia, alumina, galvano, and glass ceramic: 20 non precious metal alloy (NP), 20 zirconia (Z), 20 alumina (A), 20 galvano (G), and 20 glass ceramic (GC). Specimens were divided into 2 subgroups. One half of the specimens were applied by Clearfil™ (CR) repair system and, another half of that were applied by Cimara&Cimara(®) Zircon (CZ) repair system. Bonded specimens were stored in 37°C distilled water for 24 h and were thermocycled at 5-55°C for 1,200 cycles with a 30-sec dwell time and 5-sec transfer time. Shear bond strengths were determined with a mechanical testing device. And mode of failure was recorded. Mann Whitney-U and Kruskal Wallis tests were applied to the data at 95% confidence interval level. Infrastructure groups displayed the following values in megapascals: NP = 10.70 ± 1.88; Z = 9.15 ± 0.80; A = 11.65 ± 0.70; GC = 10.95 ± 0.80; and G = 6.88 ± 0.88. The Mann Whitney-U test results showed no significant difference between the repair systems. The Kruskal Wallis test results demonstrated significant difference between the infrastructures. The lowest bond strength values were observed in G group. In conclusion, average bond strength values were in accordance with previously reported values, therefore it can be suggested that intraoral repair of ceramic restorations can be temporary, but a satisfying alternative for patients.

Effects of multipurpose, universal adhesives on resin bonding to zirconia ceramic

This study evaluated the effects of single-bottle, multipurpose, universal adhesives on the bond strength of resin cement to zirconia ceramic. Polished zirconia ceramic (Cercon base) discs were randomly divided into four groups (n=40) according to the applied surface-conditioning agent: Single Bond 2, Single Bond Universal, All-Bond Universal, and Alloy Primer. Cured composite cylinders (Ø 0.8 mm × 1 mm) were cemented to the conditioned zirconia specimens with resin cement (RelyX ARC). The bonded specimens were subjected to a microshear bond-strength test after 24 hours of water storage and after 10,000 cycles of thermocycling. The surface-conditioning agent significantly influenced the bond strength (p<0.05). Single Bond Universal showed the highest initial bond strength (37.7 ± 5.1 MPa), followed by All-Bond Universal (31.3 ± 5.6 MPa), Alloy Primer (26.9 ± 5.1 MPa), and Single Bond 2 (8.5 ± 4.6 MPa). Artificial aging significantly reduced the bond strengths of all the test groups (p<0.05). After 10,000 cycles of thermocycling, All-Bond Universal showed the highest bond-strength value (26.9 ± 6.4 MPa). Regardless of artificial aging, Single Bond Universal and All-Bond Universal showed significantly higher bond strengths than Alloy Primer, a conventional metal primer.

Evaluation of roughness, wettability, and morphology of an yttria-stabilized tetragonal zirconia polycrystal ceramic after different airborne-particle abrasion protocols

STATEMENT OF PROBLEM

Airborne-particle abrasion is an effective method of roughening a zirconia surface and promoting micromechanical interlocks with luting cements. However, the effect of different airborne-particle abrasion protocols on the micromechanical retention mechanism has been poorly investigated.

PURPOSE

The purpose of the study was to evaluate the effect of airborne-particle abrasion protocols on the surface roughness, wettability, and morphology of an yttria-stabilized tetragonal zirconia polycrystal ceramic.

MATERIAL AND METHODS

A total of 140 zirconia specimens (14 × 14 × 1.4 mm) were made from Lava and divided into 7 groups. Their surfaces were treated as follows (n = 20): as-sintered (control); airborne-particle abraded with 50-μm Al2O3 particles; 120-μm Al2O3 particles; 250-μm Al2O3 particles; 30-μm silica-coated Al2O3 particles (Rocatec Soft); 110-μm silica-coated Al2O3 particles (Rocatec Plus); and 120-μm Al2O3 particles followed by Rocatec Plus. The surface roughness (Ra) and wettability analyses were performed on the same specimens of each group. The test liquid used for the wettability analysis was the silane RelyX Ceramic Primer. Two additional specimens (6.0 × 6.0 × 1.0 mm) per group were prepared to evaluate the surface morphology with scanning electron microscopy. The roughness (Ra) data were analyzed by 1-way ANOVA and the Dunnett C test (α = .05), and the wettability data with 1-way ANOVA (α = .05). The Spearman correlation analysis was applied to test for a possible correlation between roughness and wettability.

RESULTS

The control group (0.35 μm) exhibited the lowest mean roughness value (Ra), which was followed by Rocatec Soft (0.40 μm), 50-μm Al2O3 particles (0.52 μm), Rocatec Plus (0.69 μm), 120-μm Al2O3 particles (0.80 μm)/120-μm Al2O3 particles + Rocatec Plus (0.79 μm), and 250-μm Al2O3 particles (1.13 μm). No significant difference was found among the groups concerning wettability. No correlation (rs = -0.09; P = .27) was found between the 2 dependent variables. The scanning electron microscopy analysis indicated that the different airborne-particle abrasion protocols produced differences in the morphologic patterns.

CONCLUSIONS

Although roughness and morphology of the zirconia surface varied according to the airborne-particle abrasion protocol, no close relationship was found between them. The roughness increase seemed to have followed the size of the particles.

Influence of air-particle deposition protocols on the surface topography and adhesion of resin cement to zirconia

OBJECTIVES

This study evaluated the influence of air-particle abrasion protocols on the surface roughness (SR) of zirconia and the shear bond strength (SBS) of dual-polymerized resin cement to this ceramic.

MATERIALS AND METHODS

Sintered zirconia blocks (n = 115) (Lava, 3M ESPE) were embedded in acrylic resin and polished. The specimens were divided according to the 'particle type' (Al: 110 µm Al2O3; Si: 110 µm SiO2) and 'pressure' factors (2.5 or 3.5 bar) (n = 3 per group): (a) Control (no air-abrasion); (b) Al2.5; (c) Si2.5; (d) Al3.5; (e) Si3.5. SR (Ra) was measured 3-times from each specimen after 20 s of air-abrasion (distance: 10 mm) using a digital optical profilometer. Surface topography was evaluated under SEM analyses. For the SBS test, 'particle type', 'pressure' and 'thermocycling' (TC) factors were considered (n = 10; n = 10 per group): Control (no air-abrasion); Al2.5; Si2.5; Al3.5; Si3.5; ControlTC; Al2.5TC; Si2.5TC; Al3.5TC; Si3.5TC. After silane application, resin cement (Panavia F2.0) was bonded and polymerized. Specimens were thermocycled (6.000 cycles, 5-55°C) and subjected to SBS (1 mm/min). Data were analyzed using ANOVA, Tukey's and Dunnett tests (5%).

RESULTS

'Particle' (p = 0.0001) and 'pressure' (p = 0.0001) factors significantly affected the SR. All protocols significantly increased the SR (Al2.5: 0.45 ± 0.02; Si2.5: 0.39 ± 0.01; Al3.5: 0.80 ± 0.01; Si3.5: 0.64 ± 0.01 µm) compared to the control group (0.16 ± 0.01 µm). For SBS, only 'particle' factor significantly affected the results (p = 0.015). The SiO2 groups presented significantly higher SBS results than Al2O3 (Al2.5: 4.78 ± 1.86; Si2.5: 7.17 ± 2.62; Al3.5: 4.97 ± 3.74; Si3.5: 9.14 ± 4.09 MPa) and the control group (3.67 ± 3.0 MPa). All TC specimens presented spontaneous debondings. SEM analysis showed that Al2O3 created damage in zirconia in the form of grooves, different from those observed with SiO2 groups.

CONCLUSIONS

Air-abrasion with 110 µm Al2O3 resulted in higher roughness, but air-abrasion protocols with SiO2 promoted better adhesion.

Evaluation of Resin Bond Strength to Yttria-stabilized Tetragonal Zirconia and Framework Marginal Fit: Comparison of Different Surface Conditionings

The purpose of this study was to evaluate the effect of different surface treatments of yttria-stabilized tetragonal zirconia (Y-TZP) on bond strength durability and marginal discrepancies. For adhesion testing, 144 specimens of VITA In-Ceram YZ ceramic for InLab were obtained (5.25×3.75×4.5 mm) and divided into six groups (n=24) according to the surface treatment: 1) Control (CRTL): untreated; 2) SIL: tribochemical silica coating (CoJet system, 3M/ESPE AG); 3) V1+HF: spray application of low-fusing porcelain glaze (V1, VITA Akzent Spray Glaze) followed by etching with hydrofluoric acid (HF) (one minute); 4) V1+SIL: V1 glazing (VITA Akzent Spray Glaze) followed by tribochemical silica coating; 5) V2+HF: brush application of low-fusing porcelain glaze (VITA Akzent Glaze) plus etching with HF (one minute); and 6) V2+SIL: V2 glazing (VITA Akzent Glaze) plus tribochemical silica coating. After all treatments, the surfaces were silanized for five minutes (ESPE-SIL) and cementation was performed using Panavia F (Kuraray). Half of the specimens in each treatment were tested 24 hours after cementation (dry), with the other half subjected to storage (150 days) and thermocycling (12,000×) (aging), and then a shear test was carried out (1 mm/min). The micromorphological (digital optical profilometry and scanning electron microscopy) and elemental analyses of the treated surfaces were performed. The inner surfaces of 60 Y-TZP infrastructures were conditioned and marginal fit was evaluated. The statistical analysis revealed that the groups treated via surface glaze application followed by hydrofluoric acid etching and silanization showed the highest bond strength (in dry and aging conditions), but the bond strengths were affected by aging. The highest marginal discrepancies were observed in the groups receiving glaze (117.4 ± 29.6 to 105.8 ± 12.2 μm) when compared to other groups (55.3 ± 8.7 and 55 ± 8.5 μm). Low-fusing porcelain glaze + hydrofluoric acid etching changed the morphology of the Y-TZP ceramic and improved the adhesion to the resin cement, but obtaining high and stable bond values to Y-TZP remains challenging. Marginal discrepancies increased with glazing.

The effect of alumina and aluminium nitride coating by reactive magnetron sputtering on the resin bond strength to zirconia core

PURPOSE

Although several surface treatments have been recently investigated both under in vitro and in vivo conditions, controversy still exists regarding the selection of the most appropriate zirconia surface pre-treatment. The purpose of this study was to evaluate the effect of alumina (Al) and aluminium nitride (AlN) coating on the shear bond strength of adhesive resin cement to zirconia core.

MATERIALS AND METHODS

Fifty zirconia core discs were divided into 5 groups; air particle abrasion with 50 µm aluminum oxide particles (Al₂O₃), polishing + Al coating, polishing + AlN coating, air particle abrasion with 50 µm Al₂O₃ + Al coating and air particle abrasion with 50 µm Al₂O₃ + AlN coating. Composite resin discs were cemented to each of specimens. Shear bond strength (MPa) was measured using a universal testing machine. The effects of the surface preparations on each specimen were examined with scanning electron microscope (SEM). Data were statistically analyzed by one-way ANOVA (α=.05).

RESULTS

The highest bond strengths were obtained by air abrasion with 50 µm Al₂O₃, the lowest bond strengths were obtained in polishing + Al coating group (P<.05).

CONCLUSION

Al and AlN coatings using the reactive magnetron sputtering technique were found to be ineffective to increase the bond strength of adhesive resin cement to zirconia core.

A Review of Surface Treatment Methods to Improve the Adhesive Cementation of Zirconia-Based Ceramics

In spite of high mechanical strength, zirconia-based ceramics (ZrO2) has poor bond strength after conventional bond cementation procedures, requiring different surface treatment methods (STMs). This review gathered information about the STM for adhesive cementation (AC) to ZrO2 in the PubMed database, considering in vitro studies pertaining to AC for acid-resistant ceramics (ZrO2) limited to peer-reviewed papers published in English between 1965 and 2013 in dental journals. Different STMs have been proposed for ZrO2: air-abrasion (laboratory or chairside) with silica- (Si-) coated aluminum particles, the use of materials containing phosphate monomers, primer or silane application, laser irradiation, Si vapor phase deposition, and selective infiltration etching. In conclusion, STMs improve bond strength of resin luting cement to ZrO2 mainly when tested in short time. STMs must be correlated to the type of ZrO2 and the resin cement.

Air-particle abrasion on zirconia ceramic using different protocols: effects on biaxial flexural strength after cyclic loading, phase transformation and surface topography

This study evaluated the effect of different air-particle abrasion protocols on the biaxial flexural strength and structural stability of zirconia ceramics. Zirconia ceramic specimens (ISO 6872) (Lava, 3M ESPE) were obtained (N=336). The specimens (N=118, n=20 per group) were randomly assigned to one of the air-abrasion protocols: Gr1: Control (as-sintered); Gr2: 50 µm Al2O3 (2.5 bar); Gr3: 50 µm Al2O3 (3.5 bar); Gr4: 110 µm Al2O3(2.5 bar); Gr5: 110 µm Al2O3 (3.5 bar); Gr6: 30 µm SiO2 (2.5 bar) (CoJet); Gr7: 30 µm SiO2(3.5 bar); Gr8: 110 µm SiO2 (2.5 bar) (Rocatec Plus); and Gr9: 110 µm SiO2 (3.5 bar) (duration: 20 s, distance: 10 mm). While half of the specimens were tested immediately, the other half was subjected to cyclic loading in water (100,000 cycles; 50 N, 4 Hz, 37 °°C) prior to biaxial flexural strength test (ISO 6872). Phase transformation (t→m), relative amount of transformed monoclinic zirconia (FM), transformed zone depth (TZD) and surface roughness were measured. Particle type (p=0.2746), pressure (p=0.5084) and cyclic loading (p=0.1610) did not influence the flexural strength. Except for the air-abraded group with 110 µm Al2O3 at 3.5 bar, all air-abrasion protocols increased the biaxial flexural strength (MPa) (Controlnon-aged: 1,030 ± 153, Controlaged: 1,138 ± 138; Experimentalnon-aged: 1,307 ± 184-1,554 ± 124; Experimentalaged: 1,308 ± 118-1,451 ± 135) in both non-aged and aged conditions, respectively. Surface roughness (Ra) was the highest with 110 µm Al2O3(0.84 µm. FM values ranged from 0% to 27.21%, higher value for the Rocatec Plus (110 µm SiO2) and 110 µm Al2O3 groups at 3.5 bar pressure. TZD ranged between 0 and 1.43 µm, with the highest values for Rocatec Plus and 110 µm Al2O3 groups at 3.5 bar pressure.

Ceramic Primer Heat-Treatment Effect on Resin Cement/Y-TZP Bond Strength

The purpose of this study was to evaluate the effect of different heat-treatment strategies for a ceramic primer on the shear bond strength of a 10-methacryloyloxydecyl-dihydrogen-phosphate (MDP)-based resin cement to a yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic. Specimens measuring 4.5 × 3.5 × 4.5 mm3 were produced from Y-TZP presintered cubes and embedded in polymethyl methacrylate (PMMA). Following finishing, the specimens were cleaned using an ultrasound device and distilled water and randomly divided into 10 experimental groups (n=14) according to the heat treatment of the ceramic primer and aging condition. The strategies used for the experimental groups were: GC (control), without primer; G20, primer application at ambient temperature (20°C); G45, primer application + heat treatment at 45°C; G79, primer application + heat treatment at 79°C; and G100, primer application + heat treatment at 100°C. The specimens from the aging groups were submitted to thermal cycling (6000 cycles, 5°C/55°C, 30 seconds per bath) after 24 hours. A cylinder of MDP-based resin cement (2.4 mm in diameter) was constructed on the ceramic surface of the specimens of each experimental group and stored for 24 hours at 37°C. The specimens were submitted to a shear bond strength test (n=14). Thermal gravimetric analysis was performed on the ceramic primer. The data obtained were statistically analyzed by two-way analysis of variance and the Tukey test (α=0.05). The experimental group G79 without aging (7.23 ± 2.87 MPa) presented a significantly higher mean than the other experimental groups without aging (GC: 2.81 ± 1.5 MPa; G20: 3.38 ± 2.21 MPa; G100: 3.96 ± 1.57 MPa), showing no difference from G45 only (G45: 6 ± 3.63 MPa). All specimens of the aging groups debonded during thermocycling and were considered to present zero bond strength for the statistical analyses. In conclusion, heat treatment of the metal/zirconia primer improved bond strength under the initial condition but did not promote stable bonding under the aging condition.