μSBS Values Research Articles

The Micro-Shear Bond Strength of Resin Cements to Commercially Pure Titanium Using Universal Adhesives and Alloy Primer.

To evaluate the micro-shear bond strength (μSBS) of different bonding protocols to commercially pure titanium (CP Ti) using two universal adhesives and Alloy Primer. A total of 120 cubes of CP Ti were airborne-particle abraded and then divided into 6 groups (n = 20 each) according to bonding protocol: (1) Scotchbond Universal (SU; 3M ESPE), (2) Alloy Primer (AP; Kuraray) + SU; (3) G-Premio Bond (GP; GC); or (4) AP + GP. The specimens from groups 1 to 4 were cemented with RelyX Unicem (3M ESPE), while those from groups 5 and 6 were cemented using Panavia F2.0 cement (PAN; Kuraray) without and with prior AP application, respectively. After 24 hours, half the specimens were subjected to μSBS measurement and the other half to thermocycling (5,000 cycles) before testing. Data were analyzed using Shapiro-Wilk, two-way analysis of variance, Games-Howell, and independent sample t test (α = .05). The μSBS values obtained from the AP + SU group were significantly higher than from the GP (P = .003) and the AP + GP (P = .022) groups. After thermocycling, the μSBS of both groups treated with SU were significantly higher than those other groups (P < .001). The application of AP could not improve adhesion of resin cements to CP Ti. Thermocycling significantly reduced the μSBS values of the PAN group, whereas it noticeably enhanced the adhesion of SU and AP + SU. The predominant failure mode in all groups was adhesive. The application of AP, followed by SU, produced the most effective bonding to CP Ti, which was able to endure limited thermal aging.

Effect of silica coating and laser treatment on the flexural strength, surface characteristics, and bond strength of a dental zirconia.

This study investigated the effect of irradiation with an erbium-doped yttrium aluminium garnet (Er:YAG) laser and coating with silica on the surface characteristics, bond strength, and flexural strength of dental zirconia. Three hundred and forty-three standard zirconia specimens were created, and 49 were assigned to each of seven surface treatment groups: (i) no treatment; Er:YAG laser (80mJ/2Hz) with pulse widths of 50μs (ii), 100μs (iii), 300μs (iv), or 600μs (v); or tribochemical silica coating at the partially sintered stage (vi) or after sintering was complete (vii). All specimens were sintered after the surface treatments, except for the group in which specimens were sintered before treatment. The study outcomes were roughness, surface loss, microshear bond strength (μSBS), and biaxial flexural strength (BFS). Mean roughness and surface loss values were significantly higher in specimens from irradiated groups than in those from silica-coated groups. Regarding μSBS, after aging, specimens from all experimental groups presented very low and similar μSBS values, irrespective of the surface treatment. Silica coating after sintering yielded the highest BFS (1149.5 ± 167.6MPa), while coating partially sintered specimens with silica resulted a BFS (826.9±60.9MPa) similar to that of the untreated control group (794.9±101.7MPa). Laser treatments, irrespective of pulse width used, significantly decreased the BFS. In the group treated with laser at 300μs pulse width, specimens exhibited the lowest BFS value (514.1±71.5MPa). Adhesion to zirconia was not stable after aging, regardless of the surface treatment implemented.

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

PURPOSEThe 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 METHODSA 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).RESULTSµSBS 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.CONCLUSIONOnly 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.

Bonding to zirconia: Effects of translucency and cusp inclinations using an experimental methodology.

Purpose To investigate the effects of translucency and cusp inclination on the micro-shear bond strength (µSBS) of zirconia to self-adhesive resin cement (SARC).Methods Sixty U-shaped zirconia specimens with 1.0 mm thickness consisting of three planes (0°, 20°, and 30°) simulating different cusp inclinations were fabricated from zirconia blocks of high, moderate, and low translucency (n=20). SARC was bonded to the specimen and light-cured for 40 s. The µSBS was tested using a universal testing machine with a cross-head at a speed of 0.5 mm/min and fracture mode was observed using a stereomicroscope (×50). Two-way analysis of variance followed by a post hoc Tukey's honest significant difference test was used for the statistical analyses (α=0.05).Results Varied µSBS values were found in the test groups (7.1-14.9 MPa). Within the zirconia of the same translucency, the µSBS value of the plane 0° specimen was significantly higher than that of the 20° and 30° planes (all p<0.05). Within the zirconia of the same cusp inclination, the µSBS value of highly translucent zirconia was significantly higher than that of moderate and low translucent zirconia (all p<0.05). There was no significant interaction between cusp inclination and translucency (p=0.525). Among the fracture modes, 83.33% were adhesive failure, 11.11% mixed failure, and 5.56% were cohesive failure.Conclusions Translucency and cusp inclination significantly affect the µSBS of zirconia to SARC. The higher the translucency, the greater are the µSBS values; the higher the cusp inclination, the lower are the µSBS values.

Micro-shear bond strengths of resin-matrix ceramics subjected to different surface conditioning strategies with or without coupling agent application.

PURPOSEThis study aimed to assess the influence of various micromechanical surface conditioning (MSC) strategies with or without coupling agent (silane) application on the micro-shear bond strength (µSBS) of resin- matrix ceramics (RMCs).MATERIALS AND METHODSGC Cerasmart (GC), Lava Ultimate (LU), Vita Enamic (VE), Voco Grandio (VG), and Brilliant Crios (BC) were cut into 1.0-mm-thick slices (n = 32 per RMC) and separated into four groups according to the MSC strategy applied: control-no conditioning (C), air-borne particle abrasion with aluminum oxide particles (APA), 2W- and 3W-Er,Cr:YSGG group coding is missing. The specimens in each group were further separated into silane-applied and silane-free subgroups. Each specimen received two resin cement microtubules (n = 8 per subgroup). A shear force was applied to the adhesive interface through a universal test machine and µSBS values were measured. Data were statistically analyzed by using 3-way ANOVA and Tukey HSD test. Failure patterns were scrutinized under stereomicroscope.RESULTSRMC material type, MSC strategy, and silanization influenced the µSBS values (P<.05). In comparison to the control group, µSBS values increased after all other MSC strategies (P<.05) while the differences among these strategies were insignificant (P>.05). For control and APA, there were insignificant differences between RMCs (P>.05). The silanization decreased µSBS values of RMCs except for VE. Considerable declines were observed in GC and BC (P<.05).CONCLUSIONMSC strategies can enhance bond strength values at the RMC - cement interface. However, the choice of MSC strategy is dependent on RMC material type and each RMC can require a dedicated way of conditioning.

Immediate and long-term microshear bond strength of resin-based cements to core build-up materials.

BackgroundTo evaluate the microshear bond strength (μ-SBS) between resin-based cements and core build-up materials after water storage. Material and MethodsCylinders (1x1 mm) of conventional dual-cure resin cement (RelyX ARC, 3M ESPE), universal dual-cure resin cement (RelyX Ultimate, 3M ESPE) or self-adhesive resin cement (RelyX U200, 3M ESPE) were adhered to disks (6x2 mm) made with commercial core build-up materials (Bis-Core, Bisco or LuxaCore Z, DMG) or conventional nanocomposite resin (Filtek Z350 XT, 3M ESPE). The specimens (n=10) were submitted to μ-SBS test using a universal testing machine and fracture pattern analysis at 48 hours or after 9 months of water storage. The data were evaluated by three-way ANOVA for repeated measures and Tukey’s test (α=0.05). ResultsAfter 48 hours, regardless of the resin-based cement used, the μ-SBS to the conventional resin composite (Filtek Z350 XT) was greater compared to other materials. However, after 9 months, there was a statistically significant decrease in μ-SBS values between the conventional resin composite and evaluated luting agents. The μ-SBS values of core build-up commercial materials (Bis-Core and LuxaCore Z) did not change over time. Regardless of the composite used and storage time, there was no statistically significant difference between the resin-based cements. After 48 h, the most prevalent failure was mixed for all groups. However, after 9 months, the core build-up materials showed a predominantly mixed fracture pattern whereas the resin composite presented an adhesive pattern. ConclusionsCommercial core build-up materials achieved stable bonding performance with resin-based cements over time. Key words:Composite resins, resin cement, dental restoration failure.

Can silver diamine fluoride or silver nanoparticle-based anticaries agents to affect enamel bond strength?

ObjectivesThe aim of the current study is to investigate the effect of different anticaries agents, such as experimental agents based on silver nanoparticles (SNPs) and silver diamine fluoride (SDF), on the micro-shear bond strength (μ-SBS) of composite resin applied to intact enamel (IE) or demineralized enamel (DE).Materials and MethodsSixty dental enamel fragments were collected from human third molars and categorized into 6 groups (n = 10): positive control (IE), negative control (DE), IE + SDF, DE + SDF, IE + SNP and DE + SNP. Samples from DE, DE + SDF and DE + SNP groups were subjected to pH cycling; superficial microhardness test was performed to confirm demineralization. Resin composite build-ups were applied to the samples (0.75-mm diameter and 1-mm height) after the treatments (except for IE and DE groups); μ-SBS was also evaluated. Samples were analyzed under a stereomicroscope at 40× magnification to identify failure patterns. Data were subjected to one-way analysis of variance, followed by Tukey's and Dunnett's tests (p < 0.05).ResultsThere was no significant difference among the IE, IE + SNP, DE + SDF, and DE + SNP groups. The IE + SDF and DE groups recorded the highest and the lowest μ-SBS values, respectively. Adhesive-type failures were the most frequent for all treatments.ConclusionsAnticaries agents did not have a negative effect on the μ-SBS of composite resin when it was used on IE or DE.

Repair Bond Strength of High-viscosity Glass-ionomer Cements Using Resin Composite Bonded with Light- and Self-cured Adhesive Systems.

High-viscosity glass-ionomer cements (HVGICs) used with atraumatic restorative treatment can be repaired with light- or self-cured adhesive systems; however, the repair bond strength of two-step, self-etching and one-step adhesives in the light-cure mode surpass one-step self-cure adhesives. Working on a feasible self-cure approach in the absence of such in rural areas as well as in war zones is of prime importance.

Effect of ultrasonic vibration on microshear bond strength of flowable composite to enamel

Objective: The present study aimed to assess the influence of vibration effect on microshear bond strength (µSBS) of flowable composite to enamel. Material and Methods: Sixty non-carious extracted human premolar teeth were collected and randomly divided into six groups (n = 10) after being trimmed to produce a smooth flat surface: Flowable composites [Wave (SDI), Wave HV (SDI) and Grandioflow (Voco)] were used as bonding agents without or with vibration using an ultrasonic scaler (Mini Piezon, EMS, Switzerland). Composite resin, with an internal diameter of 0.7mm and height of 1mm, was cured on the substrate. The specimens’ µSBS was tested by a microtensile tester (Bisco, USA) at a crosshead speed of 0.5 mm/min. The bond strength values were analyzed using one-way ANOVA and post hoc Tukey test (p &lt; 0.05). Results: Vibration did not lead to any significant difference in the µSBS values of Wave, Wave HV, and Grandio Flow µSBS values (P=0.690, P=1.000 and P=0.947, respectively). No significant difference was found between flowable composites in terms of micro shear bond strength to enamel (p &gt; 0.05). Conclusions: The application of ultrasonic vibration might not be advantageous in terms of improving the shear bond strength of flowable composites to enamel. KEYWORDS Bond strength; Enamel; Flowable composite; Ultrasonic; Vibration.

The Effects of Silver, Zinc Oxide, and Titanium Dioxide Nanoparticles Used as Dentin Pretreatments on the Microshear Bond Strength of a Conventional Glass Ionomer Cement to Dentin.

AimThis study was conducted to evaluate the effects of three nanoparticle solutions used as dentin pretreatments on the microshear bond strength (µSBS) of a conventional glass ionomer cement (GIC) to dentin.Materials and MethodsNinety intact human molars were used after sectioning their occlusal surfaces to expose flat dentin surfaces. The specimens were randomly assigned to nine groups (n = 10). Group A was the control group (without using the cavity disinfectant). In groups B, C, D, and E, the prepared dentin surfaces were treated with 1 cc 2% chlorhexidine (CHX), 0.1% silver nanoparticle (SNP), 0.1% titanium dioxide nanoparticle (TNP), and 0.1% zinc oxide nanoparticle (ZNP) solutions for 1 minute, respectively, before applying the conditioner. CHX, SNPs, TNPs, and ZNPs were applied for 1 minute after applying the conditioner in groups F, G, H, and I, respectively. The specimens were restored with a conventional GIC and underwent µSBS testing after 24 hours. The data were analyzed using the one-way analysis of variance and Tukey’s test (p=0.05).ResultsThe applications of the nanoparticles (SNP, TNP, and ZNP) after the conditioner were associated with significantly greater µSBS values compared to that of the control group (p values < 0.05). Significantly higher µSBS values were observed when TNP or ZNP was applied after the conditioner compared to their applications before the conditioner (p values < 0.05). The highest µSBS values were observed when TNP was applied after the conditioner.ConclusionDentin pretreatment with the nanoparticles after applying the conditioner enhanced the bond strength of the GIC to dentin compared with the control group. The best results were obtained for the TNPs applied after the conditioner.

Bonding Effectiveness of Bioactive Self-Adhesive Restorative Material to Enamel and Dentin Using Different Bonding Protocols

Objective: To investigate microshear bond strength of bioactive restorative material to enamel and dentin bonded using universal adhesive in etch and rinse and self-etch mode stored for 24h and 6 m. Methods: Sound bovine incisors were used in this study. ACITVA Bioactive restorative (Pulpdent Corp., Watertown, MA, USA) and Single Bond Universal adhesive (3M ESPE, St.Paul, MN, USA) were used. Teeth were grouped into 6 grouped according to bonding protocol (No bonding agent, bonding in etch and rinse mode and bonding in self-etch mode) and tooth substrate (enamel and Dentin). Specimens were stored for either 24 h or 6 m. Microshear bond strength (µSBS) were tested using universal testing machine and micromorphological observation of the interface were investigated using ESEM. Data were tabulated and statistically analyzed using Two-way ANOVA followed by Bonferroni’s post-hoc test. Results: Enamel bonded in etch and rinse mode recorded the highest µSBS values at both storage periods. Dentin at 24 h showed no significant difference between etch and rinse and self-etch modes while after 6 m, etch and rinse protocol showed significant drop. Control group recorded the lowest µSBS at all experimental groups. Conclusion: Use of bonding agents is recommended with ACITVA to both enamel and dentin. Universal adhesives are preferred in etch & rinse mode with enamel and self-etch mode with dentin. ACITVA is able to preserve bond strength upon storage except for dentin bonded in etch and rinse mode.

Microshear bond strength of contemporary self-adhesive resin cements to CAD/CAM restorative materials: effect of surface treatment and aging

The objective of this in vitro study was to investigate the effect of material type, resin cement type, surface treatment, and aging on the microshear bond strength (µSBS) of self-adhesive resin cements (SARCs) to CAD/CAM blocks. CAD/CAM blocks (CeraSmart, CS; Lava Ultimate, LU; Shofu Block HC, HC; Vita Enamic, VE; Vitablocks Mark II, VM) were cut into 3-mm thick slices (96 specimens for each) and divided into groups: no treatment; 9% hydrofluoric acid etching; aluminum-oxide sandblasting; CoJet sandblasting. Following, the specimens were divided into three subgroups according to SARCs applied. Each specimen received four resin cement microtubules (n = 32 per subgroup). After 24 h, the cylinders of SARC were equally assigned into two groups (n = 16): immediate µSBS testing and µSBS testing after thermocycling. A shear force was applied to the adhesive interface through a μSBS testing device. Additionally, specimens were analyzed with a contact profilometer and were evaluated with scanning electron microscopy. The data were analyzed using four-way ANOVA, p < 0.05. Material type, resin cement type, surface treatment, and aging influenced the µSBS values (p < 0.001). A significant decrease in µSBS was recorded for all groups after thermocycling. The most common failure mode was detected as an adhesive failure. The surface treatment and material type influenced the surface roughness with a significant interaction. Sandblasting was more successful for CS, LU, and HC, while HF etching was better for VE and VM. The use of MDP-containing SARCs would be advantageous for the zirconia-containing CAD/CAM materials (LU and HC).

Micro-Shear Bond Strength of Novel MDP Calcium-Fluoride-Releasing Self-Adhesive Resin Cement After Thermocycling.

The purpose of the present study was to (1) investigate the micro-shear bond strength and failure mode of a novel methacryloxydecyl-dihydrogen-phosphate (MDP) calcium-fluoride-releasing self-adhesive resin cement (TheraCem, BISCO) to a tooth structure (enamel and dentin) and to yttrium-stabilized zirconia after thermocycling, and to (2) compare the results with a universal non-MDP-containing self-adhesive resin cement (RelyX Unicem, 3M ESPE) as a control. Enamel and dentin specimens (20 discs each) were obtained by using a diamond saw (IsoMet 4000, Buehler) with copious water coolant. Twenty zirconia plates were obtained from IPS e.max ZirCAD blocks (Ivoclar Vivadent) and sintered in an inFire HTC speed high-temperature furnace (Dentsply Sirona). Resin-cement micro-cylinders were created on the bonded surface and filled with the tested cements (n = 10 for each surface/cement combination): Group A (control) used non-MDP-containing RelyX, whilegroup B (tested cement) used MDP-containing TheraCem MDP. Cements were left to self-cure for 5 minutes. All specimens were thermocycled for 5,000 cycles (THE-1100, SD Mechatronik). Micro-shear bond strength was measured using a universal testing machine, and debonded surfaces were examined for failure mode analysis with all morphologic and ultrastructure changes using a scanning electron microscope (Quanta 250 Field Emission Gun, FEI) attached with an energy dispersive x-ray (EDX) unit. The results were statistically analyzed. TheraCem had a slightly higher micro-shear bond strength (MPa) value than RelyX. Within enamel, TheraCem (6.46 ± 1.37 MPa) had a significantly higher mean μ-SBS value than RelyX (3.04 ± 0.99 MPa) (P = .002). Similarly, TheraCem in dentin (10.67 ± 1.27 MPa) had a significantly higher mean value than RelyX (6.46 ± 1.74 MPa) (P = .014). As for zirconia, TheraCem (39.76 ± 1.18 MPa) had a significantly higher mean μ-SBS value than RelyX (27.04 ± 1.92 MPa) (P < .001). Using MDP-containing calcium-fluoride-releasing self-adhesive resin cement (TheraCem) may improve bond strength to all tested substrates (enamel, dentin, and zirconia) and can be considered a promising cement for many clinicians. Further clinical studies are required to provide long-term clinical success data.

Effect of surface treatments and universal adhesive application on the microshear bond strength of CAD/CAM materials.

PURPOSEThe aim of this study was to evaluate the microshear bond strength (µSBS) of four computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three different surface treatment protocols.MATERIALS AND METHODSFour different CAD/CAM blocks were used in this study: (1) flexible hybrid ceramic (FHC), (2) resin nanoceramic (RNC), (c) polymer infiltrated ceramic network (PICN) and (4) feldspar ceramic (FC). All groups were further divided into four subgroups according to surface treatment: control, hydrofluoric acid etching (HF), air-borne particle abrasion with aluminum oxide (AlO), and tribochemical silica coating (TSC). After surface treatments, silane was applied to half of the specimens. Then, a silane-containing universal adhesive was applied, and specimens were repaired with a composite, Next, μSBS test was performed. Additional specimens were examined with a contact profilometer and scanning electron microscopy. The data were analyzed with ANOVA and Tukey tests.RESULTSThe findings revealed that silane application yielded higher µSBS values (P<.05). All surface treatments were showed a significant increase in µSBS values compared to the control (P<.05). For FHC and RNC, the most influential treatments were AlO and TSC (P<.05).CONCLUSIONSurface treatment is mandatory when the silane is not preferred, but the best bond strength values were obtained with the combination of surface treatment and silane application. HF provides improved bond strength when the ceramic content of material increases, whereas AlO and TSC gives improved bond strength when the composite content of material increases.

Evaluation Of The Effect Of Different Surface Treatments, Aging And Enzymatic Degradation On Zirconia-Resin Micro-Shear Bond Strength.

PurposeThe purpose of this study was to evaluate the effect of surface treatments on zirconia-resin bonding and the effect of aging on bond durability for one year.MethodThree hundred and twenty zirconia blocks were divided into 4 equal study groups. Group 1 (control): as-sintered, group 2: (GB): grit-blasted, group 3: (LAS): laser-etched, group 4: (SIE): selective infiltration etching. Composite cylinders were bonded to the zirconia with resin cement and ceramic primer. Aging was performed following 3 different aging protocols: thermocycling, storage in distilled water, or storage in an enzymatic esterase solution. Micro-shear bond strength test (μSBS) was recorded using a universal testing machine. μSBS values were analyzed using two-way Analysis of Variance followed by Tukey post-hoc tests. Level of significance was set at 0.05.ResultsGB, LAS and SIE groups showed significantly higher values when compared to control. Groups GB, LAS and SIE reported a significant decrease up to 50% in μSBS after water storage and enzymatic degradation, while control group reported a 90% decrease. Failure analysis showed mainly adhesive failure for control group, while the percentage of cohesive failure in resin cement was higher in SIE group compared to GB and LAS groups.ConclusionWater aging and esterase solutions played a significant role by increasing bond degradation. A minimum of one-year water and esterase storage medium should be used to evaluate the durability of the bond between resin cement and zirconia.

The micro-shear bond strength of two different repair systems to indirect restorative materials

Introduction The aim of this study was to evaluate the micro-shear bond strength (μSBS) of different repair systems (Clearfil Repair, iGOS Repair) to restorative materials for CAD/CAM (Cerasmart, Lava Ultimate, InCoris TZI , VITA Suprinity, VITA Mark II, IPS e.max CAD, IPS Empress CAD). Methodology The 140 1.2 mm-thick specimens were prepared from CAD/CAM blocks (n=20) and thermocycled (10,000 cycles, 5–55°C, dwell time 20s). The specimens were randomly divided into two groups according to the repair system: Clearfil Repair (40% phosphoric acid+mixture of Clearfil Porcelain Bond Activator and Clearfil SE Bond Primer+Clearfil SE Bond+CLEARFIL MAJESTY ES-2) and iGOS Repair (40% phosphoric acid+ Multi Primer LIQUID+ iGOS Bond+ iGOS Universal). The composite resins were polymerized. All specimens were stored in distilled water at 37°C for 24 hours. The μSBS test was performed with a micro-shear testing machine (at 1 mm/min). The data were analyzed using two-way ANOVA, Tukey’s multiple comparison tests at a significance level of p&lt;0.05. Each failure modes were examined under a stereomicroscope at×16 magnification. Results The type of CAD/CAM restorative material and repair system showed a significant effect on the μSBS (p&lt;0.05). Specimens repaired with the iGOS Repair system showed the highest μSBS values than the Clearfil Repair system among all tested materials except for the InCoris TZI group (p&lt;0.05). Conclusion All groups, except for the InCoris TZI group, repaired with iGOS Repair system showed higher μSBS than Clearfil Repair. The type of restoration and repair material is important in the success of the fracture repair.

Effect of silane and MDP-based primers on physico-chemical properties of zirconia and its bond strength to resin cement

ObjectiveTo evaluate the effect of surface treatments on yttria-tetragonal zirconia polycrystal (Y-TZP) characteristics and on resin-mediated zirconia bond. MethodsY-TZP slabs were grit blasted with 45μm alumina or with 30μm silica-coated alumina particles. The chemical treatments were: no-chemical treatment (NC), silane-containing primer (SP), MDP (10-Methacryloyloxydecyl dihydrogen phosphate) and silane-containing primer (MPS), MDP-containing primer (MP) and MDP and silane-containing adhesive (MPA). Contact angle as a function of surface roughness (θm) and surface roughness parameter (Sdr) were measured using Fringe Projection Phase Shifting (FPPS). Surface free energy (γsTOT) was calculated with a goniometer. Chemical interaction between primers/adhesive and zirconia was analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Resin cement microshear bond strength (μSBS) was analyzed at either 24-h or 8-months water storage (37°C). θm values, Sdr values, γsTOT and μSBS values were analyzed using Analysis of variance (ANOVA) and post hoc Tukey test (α=0.05). ResultsChemical treatment had an effect (p<0.001) on all surface parameters analyzed: θm, γsTOT and Sdr. MP-treated group showed higher incidence of P–O–Zr bonds than the other groups, indicating more chemical linkages. Grit blasting (p<0.001) and the interaction chemical treatment*storage (p<0.001) did not affect μSBS; all silane-containing primers showed significant drop in μSBS after aging. SignificanceMDP and/or silane-based solutions affect the physicochemical properties of blasted-zirconia. An MDP-based primer is fundamental to achieve a stable resin-zirconia bonding, but the chemical reactivity of MDP is impaired when this molecule is present in a multicomponent system.

The Effect of Incorporation of 0.5 %wt. Silica Nanoparticles on the Micro Shear Bond Strength of a Resin Modified Glass Ionomer Cement

Statement of the Problem:The clinical success of glass ionomer restorations depends on the strength of resin-modified glass ionomer (RMGI) cement bonding to dentin and there is limited information available regarding the bond strength of resin modified glass ionomers containing silica nanoparticles to dental structures. Purpose: The aim of this study was to compare the microshear bond strength (µSBS) of RMGI with and without silica (SiO2) nanoparticles to dentin of permanent teeth. Materials and Method: In this experimental study, the occlusal surfaces of 30 freshly extracted intact third molars were ground to expose the flat dentin and after conditioning with 20% poly acrylic acid, were randomly assigned to two main groups (n=15). The first group was filled with RMGI (Fuji II LC, GC) and the second group was filled with RMGI plus 0.5%wt. silica nanoparticles. Then, each main group was divided into three subgroups, and then stored in an incubator at 37 oC with 100% humidity for 1, 7, and 30 days. The µSBS test was performed using a universal testing machine (1 mm/min). The data were analyzed by t-test, repeated measures ANOVA and Tukey test (p< 0.05). Results:There were no statistically significant differences between the mean µSBS of the groups with and without nanoparticles along the different storage periods (p> 0.05). There was significant difference in µSBS values among the three different storage periods in all the tested materials (p< 0.05). Conclusion:Incorporation of 0.5 %wt. silica nanoparticles did not compromise the µSBS of Fuji II LC RMGI to dentin.

Effect of Dentin Conditioning and Erosive Coca Cola Challenge on the Micro-shear Bond Strength and SEM Evaluation of Resin-Modified Glass-Ionomer Cement- in vitro study

Objective: This study was designed to evaluate the role of an erosive beverage, Coca cola, on the microshear bond strength of a nano-fill resin modified glass-ionomer cement to dentin, after different conditioning protocols, no conditioning, GC conditioner and KN primer. Materials and Methods: The occlusal enamel of forty two third molar teeth was removed, exposing the coronal dentin. Thirty prepared teeth were randomly divided into three main groups (n=10). Group 1, flat dentin surface was left unconditioned (control). Group 2, GC cavity conditioner was applied. Group 3, Ketac Nano Primer was applied. Three pieces were cut from a polyethylene micro-bore tygon tube, for each specimen. KN resin modified glass ionomer cement was applied. Each group was further distributed into two subgroups (n=5). Subgroup i, teeth were immersed in artificial saliva (control). Subgroup ii, teeth were subjected to Coca Cola pH cycles. Each specimen was stressed in shear using a load cell of 5 KN at a crosshead speed of 0.5 mm/min. The remaining 12 teeth were divided according to the previously mentioned grouping system, and observed using SEM. Results: The data collected for µSBS were subjected to two-way ANOVA test, followed by Tukey’s post hoc test. Considering the dentin conditioning factor, with storage in artificial saliva; the control group revealed the least µSBS values, followed by the group conditioned with KNP and GC conditioning, respectively. Control group posses a significant decrease in the µSBS compared to either GC or KNP groups. With Coke pH cycling; the control group revealed the least µSBS values, followed by KNP and GC conditioning, respectively. All the tested groups are significantly different from each other Considering the erosive pH cycling factor, all the teeth revealed significant decrease in the µSBS values, when exposed to erosive Coke pH cycling. Most failure modes are adhesive, followed by mixed failures. The SEM examination showed a filler‑free zone in the conditioned groups, with the greatest thickness with KNP. Cylindrical shaped resin tags, were observed when dentin is conditioned with KNP, whereas budding configuration is formed with GC conditioner. Smear layer has been completely removed with GC conditioner. Dentin conditioning with KNP revealed partial removal of smear layer with partial obliteration of dentinal tubules, while smear layer remains unaffected in case of control group. In groups stored in AS, there is intimate adaptation between the RMGIC and dentin, whereas the groups subjected to Coke erosive cycles showed variable degrees of separation at the RMGIC/dentin interface. Conclusions: Dentin conditioning before RMGIC application is an essential step to improve bonding ability to dentin. Since Coca cola beverage revealed a deteriorating effect on bonding of RMGICs, evaluation of different acidic foodstuffs, acidic drinks and mouthwashes on the bonding efficiency of different types of glass-ionomer cements is required.

Influence of Er:YAG laser pulse duration on the long-term stability of organic matrix and resin-dentin interface.

The purpose of this study was to explore the influence of Er:YAG laser irradiation with different pulse durations on the organic matrix, micromorphology of the hybrid layer (HL), and bond strength over time. Sixty caries-free human molars were cut to obtain flat dentin surfaces which were randomly divided into 4 groups: control (not irradiated-G1) and laser groups (80mJ/2Hz) with pulse duration ranging between 50 (G2), 300 (G3), and 600μs (G4). A self-etch adhesive system (Universal 3M ESPE) was applied on pre-treated dentin surfaces and cylinders of resin composite were built up and stressed in a universal testing machine (μSBS) at 24h and after12months (n = 12). In addition, 3 other dentin-bonded specimens were prepared as previously described for each group with the adhesive doped with 0.1wt% Rhodamine B to analyze hybrid layer morphology under Confocal Laser Microscope Scanning (CLMS). Organic matrix and collagen fibrils were analyzed by second harmonic generation (SGH). Two-way ANOVA and Tukey's test detected significantly higher μSBS values for the control group, whereas the lower values were observed in all laser groups at 24h (p < 0.05). Storage in artificial saliva did not reduce μSBS in all groups. The low signal emitted by SHG images below the irradiated area demonstrated thermal damage of the collagen matrix. CLMS images of laser groups exhibited thicker and irregular resin-dentin interfaces than the control group. Regardless of the pulse duration, Er:YAG laser pre-treatment altered the organic matrix and HL formation which resulted in low μSBS values at 24h. The alterations on dentin's organic structure did not jeopardize the μSBS after 1year of saliva storage.