Microshear Bond Strength Test Research Articles

The effect of adding chitosan nanoparticles on different properties of the adhesive and high-filled composite resin

PurposeTo evaluate the effect of adding nano-chitosan on different properties of the adhesive and high-filled flowable composite resin (viewing the graphical abstract is suggested). BackgroundIncorporating chitosan might improve the quality of adhesive and high-filled composite resin used in the deep margin elevation (DME) and other restorative methods. Materials and methodsTwo groups of composite disks (without chitosan, with 1 % chitosan) were created to evaluate antimicrobial effects, degree of conversion (DC), solubility and water sorption. Antimicrobial activity was evaluated through biofilm inhibition and disk agar diffusion tests while DC was analyzed using FTIR. For the microshear bond strength test (μSBS), extracted maxillary molars were sectioned 1 mm under the CEJ, undergoing immediate dentin sealing and DME in four groups: control, pretreatment chitosan application, adhesive+1 % chitosan, and composite+1 % chitosan. The forces and the modes of failure were recorded. ResultsAdding chitosan nanoparticles increased the antimicrobial activity, significantly (p < 0.05). The μSBS and DC did not differ significantly between the groups (p > 0.05), and the failures were mostly found in the adhesive mode. The solubility and water sorption increased significantly (p < 0.05), remaining in a clinically acceptable range though. ConclusionAdding chitosan could be a potential option to increase the antibacterial effect in the high-filled composite resin without any negative affect on μSBS or DC, and clinically unacceptable effect on solubility and water sorption. (The graphical abstract has been provided). Clinical significanceAdding chitosan nanoparticles to high-filled flowable composite resin, increases the success rate of related restorative technique by adding the antimicrobial effect without any significant negative influence on other biomechanical properties.

Micro-shear Bond Strength of an Alternative Self-etch Application of "No Wait" Universal Adhesive to Caries-affected and Sound Dentin in Permanent and Primary Teeth.

This study aimed to compare the micro-shear bond strength (μSBS) of caries-affected dentin (CAD) and sound dentin (SoD) in primary and permanent teeth using an alternative self-etch application of "no wait" universal adhesive. Flat midcoronal dentin surfaces from 72 permanent third molars and 72 second primary molars were distributed randomly into 12 groups according to the substrate SoD and artificially-created CAD (pH cycling for 14 days) and the adhesive system (GLUMA Bond5, a two-step etch & rinse adhesive, GLUMA Bond, a one-step self-etch adhesive, and Tokuyama Universal Bond, a one-step self-etch adhesive) (n=12). Bonded dentin resin discs were put through micro-shear bond strength testing after 10,000 thermocycles. The results were evaluated using two-way ANOVA and the Bonferroni test with a significance level of α = 0.05. When compared to SoD, the etch & rinse system's test results on artificially created CAD showed a statistically significant poorer bonding performance in both permanent and primary teeth in all groups (p<0.05). While the bond strengths of permanent teeth using total-etch adhesive on sound dentin were statistically significantly higher than those using Tokuyama Universal Bond adhesive (p<0.05), there was no significant difference in sound dentin in primary teeth (p>0.05). The etch & rinse system performed the poorest of all adhesive systems on CAD. The Tokuyama Universal Bond's adhesive strength was similar in SoD and CAD on primary teeth. The use of Tokuyama Universal Adhesives can speed up restorative treatment in pediatric dentistry.

Influence of Varied Silane Commercial Brands and Adhesive Application on Bond Strength and Stability to Lithium Disilicate Glass Ceramic.

This study aimed to evaluate the impact of various commercial silane brands with varied chemical compositions with or without the application of an adhesive layer on the microshear bond strength and durability of a resin luting agent to lithium disilicate glass ceramic. Lithium disilicate glass ceramic discs (EMX, IPS e.max Press, Ivoclar Vivadent) measuring 10 mm in diameter and 3 mm in thickness were fabricated (n=240). Surfaces were etched using 5% hydrofluoric acid and randomly assigned to 10 groups based on the commercial brand of silane used (n=24): [RP] RelyX Ceramic Primer (3M ESPE); [PS] Prosil (FGM); [SA] Silano (Angelus); [SM] Silano (Maquira); [SU] Silane (Ultradent); [GL] GLUMA Ceramic Primer (Kulzer); [CB] Ceramic Bond (VOCO); [MB] Monobond N (Ivoclar Vivadent); [CP] Clearfil Ceramic Primer (Kuraray); and [DE] 2-step silane (Dentsply Sirona). Half of the EMXs (n=12) received a thin adhesive layer (+) after the silane and prior to resin luting agent, while the other half (n=12) did not receive an adhesive layer (-). For the microshear bond strength test (μSBS), four light-cured resin luting agent cylinders (1 mm in diameter) were created on each EMX surface. Half of these specimens were tested after 24 hours, while the other half were stored in deionized water for 6 months. The μSBS test was conducted using a universal testing machine (DL 500, EMIC) at a crosshead speed of 1 mm/min until failure. The obtained data underwent statistical analysis using analysis of variance (ANOVA) and the Tukey test (α=0.05). There was significant influence of the silane commercial brand on bond strength. Notably, "universal primers" yielded lower bond strength results compared to "pure" silane solutions. Water storage had a detrimental effect on microshear bond strength for certain silane commercial brands. Additionally, the application of an adhesive layer negatively impacted bond strength results for all silanes. This study confirms the importance of both silane commercial brand and chemical composition in relation to bond strength of resin luting agents to lithium disilicate glass ceramic. Furthermore, the application of an adhesive layer may have an adverse effect on bond stability over time.

The impact of artificial aging using chewing simulator on micro-shear bond strength and micro-leakage of alkasite and bioactive resin based composites: an in-vitro comparative study

Objective The current study was conducted to assess and compare the impact of artificial aging using chewing simulator on the novel bulk fill restorative materials (Cention N) and Bioactive Resin Based Composites (ACTIVA) regarding, micro-shear bond strength and micro-leakage. Tetric N ceram bulk fill composite was used as control. Patients and methods For micro-shear bond strength testing, thirty recently extracted molars were collected, then their occlusal surfaces were cut horizontally using low-speed diamond saw under coolant exposing flat dentin surfaces. Tetric N-Bond adhesive was applied to the dentin surface, then Tygon tubes (three for each tooth) with height 1 mm and internal diameter 1 mm were placed on the flat surfaces, followed by light curing, then the restorative material (10 specimens for each material) was condensed inside the tubes. Half of the specimens is subjected to artificial aging (thermal and dynamic loading using Chewing Simulator). The specimens were mounted in blocks of stones, then placed horizontally in the universal testing machine. The load was applied using a knife-edge chisel till debonding of the composite cylinders from dentin surface. Fifteen extracted human molars were utilized for the purpose of evaluating micro-leakage. A total of thirty class II cavities were meticulously constructed on the mesial and distal surfaces of the teeth. The evaluation of micro-leakage was conducted using a dye penetration test, employing a scoring system ranging from 0 to 4. Results The nonaged specimens of the tested materials did not show significant differences regarding micro-shear bond strength, and micro-leakage. Aging had no significant effect on all of the tested properties in the three tested materials. Conclusion Short-term thermomechaical aging used in this study did not deteriorate micro-shear bond strength and micro-leakage of the tested materials. Alkasite (Cention N) and ACTIVA Bioactive Resin Based Composites are promising materials with physico-mechanical properties comparable to conventional bulk-fill composites. However, further in vitro and in vivo studies are needed to assess the properties of these recently introduced materials.

Can a Self-etching Primer be Effective in Bonding Aligner Attachments to Different Types of Ceramics?

This in vitro study aimed to evaluate the effectiveness of pretreatment with a self-etching primer for bonding aligner attachments to lithium disilicate (LD) and monolithic zirconia (MZ) ceramics. Forty ceramics, including LD (n=20) and MZ (n=20), were divided into four study groups according to the surface pretreatments: LD specimens pretreated with universal primer (Monobond Plus, MP) after hydrofluoric acid etching (Group 1); MZ ceramics pretreated with MP after sandblasting (Group 2); LD ceramics pretreated with self-etching ceramic primer (Monobond etch & prime, MEP) (Group 3); and MZ ceramics pretreated with MEP after sandblasting (Group 4). The aligner composite (GC Aligner Connect) and universal adhesive (GPremio Bond) were used to prepare the resin attachments. The bond strength was evaluated by micro-shear bond strength (SBS) testing (0.1 mm/min) after thermocycling, and the remnant adhesive was scored according to the resin attachment remnant index (RARI). The SBS data were analyzed using ANOVA and Tukey tests, and the RARI scores were analyzed using the chi-square test. Group 1 had the lowest SBS, and group 2 had the highest SBS. There were significant differences between the groups in terms of bond strength (p<0.05). The RARI scores showed no significant differences, regardless of the pretreatment and ceramic type. The use of a self-etching primer increased the bond strength of resin attachments on LD ceramics. For zirconia ceramics, both ceramic primers are recommended for aligner attachment bonding.

Effect of ethanolic extract of propolis on antibacterial and microshear bond strength of glass-ionomer restorations to dentin

ObjectivesThis study was conducted to evaluate the effect of ethanolic extract of propolis on antibacterial and microshear bond strength of glass ionomer restorations to dentin. Materials and methodsConventional glass ionomer cement (Equia forte, GC Tokyo, Japan), resin-modified glass ionomer (Fuji II LC, GC Tokyo, Japan) and propolis powder (dried extract from honey bees) materials were used in this study. Both conventional glass ionomer and resin-modified glass ionomer were modified by two different concentrations of ethanolic extract of propolis (10 % and 25 % EEP). For antibacterial test, Streptococcus mutans strain was spread on agar petri dishes using a sterile swab. Discs of both glass ionomer restorative materials (without adding EEP, with 10 % EEP and with 25 % EEP) were fabricated within the agar plates. Antibacterial activity was evaluated by measuring the inhibition zones around each disc. For microshear bond strength test, 60 healthy human permanent molars were prepared by cutting occlusal surface and expose the dentin at the height of contour of all teeth then conditioned using poly acrylic acid conditioner, both glass ionomer restorative materials (without adding EEP, with 10 % EEP and with 25 % EEP) were mixed and applied on conditioned dentin surface by using tygon tube. Microshear bond strength was evaluated by the universal testing machine. ResultsTwo-way ANOVA test revealed that both glass ionomer type and different concentrations of EEP had significant effect on the antibacterial test results and microshear bond strength values (p < 0,05). Glass ionomer restorative material with 25%EEP had the highest antibacterial values whereas glass ionomer restorative material without modifications (control groups) had the lowest values. Resin-modified glass ionomer without any modification (control group) had the highest bond strength while resin-modified glass ionomer with 25%EEP had the lowest bond strength. ConclusionsIncorporation of ethanolic extract of propolis to glass ionomer restorative material increases the antibacterial effects of both conventional GIC and RMGI. Inspite of this advantage, it seems that it has deleterious effect on microshear bond strength to dentin.

In vitro performance of an autocured universal adhesive system in bonding to dentin

BackgroundThe successful integration of resin-based dental adhesives significantly impacts restorative dentistry, providing efficient and aesthetically pleasing caries treatments. Among various adhesives, one-step self-etching adhesives (1-SEAs) have gained popularity due to their simplicity and short application time. However, concerns have been raised regarding their bonding performance and marginal adaptation characteristics, which differ from two-step self-etching adhesives (2-SEAs) and three-step etch-and-rinse adhesives. Additionally, light-cured bonding materials may encounter challenges in deep cavities and inaccessible areas, necessitating extended light irradiation time. Autocured bonding materials are a potential solution, but limited comparative studies have been conducted on their performance.MethodsIn this in vitro study, we evaluated a new autocured universal bonding material (Bondmer Lightless 2) and compared the results with recent light-cured bonding materials. Microshear bond strength (μSBS) tests were performed on 25 human molars using five different combinations of adhesives and composite resins: Bondmer Lightless 2 with Estelite Bulk Fill Flow (BE group), Bondmer Lightless 2 with a prototype composite resin (BO group), Prime&Bond Universal with SDR flow + (PS group), Scotchbond Universal with Filtek Bulk Fill (SF group), and G-Premio Bond with Gracefil BulkFlo (GG group). The bond strengths and failure modes were assessed using a universal testing machine and scanning electron microscope (SEM), respectively. Marginal adaptation was evaluated using swept-source optical coherence tomography (SS-OCT) and confocal laser scanning microscopy (CLSM) on 40 sound bovine maxillary incisors.ResultsThe μSBS test showed no significant differences in bond strength among the tested groups. Most failure modes were observed at the bond interface between the adhesive and the dentin. The autocured bonding material demonstrated significantly higher marginal adaptation (SI%) than PS, SF, and GG. The CLSM images corresponded with gaps observed in the SS-OCT images, indicating improved marginal sealing in the autocured group.ConclusionsThe new autocured universal bonding material exhibited comparable bond strength to a conventional light-cured material while demonstrating a superior marginal adaptation level. This finding suggested that the autocured material could be a valuable alternative, especially when extended light irradiation would pose a challenge. Further clinical studies would be warranted to evaluate the performance of the autocured bonding material in actual restorative dental practice.

Effects of Hydrofluoric Acid Concentrations, Commercial Brands, and Adhesive Application on the Bond Strength of a Resin Luting Agent to Lithium Disilicate Glass Ceramic.

To evaluate the surface topography/roughness and bond strength of a resin luting agent to a lithium disilicate glass ceramic after etching with different concentrations of hydrofluoric acid (HF) and commercial brands. For bond strength evaluation, 260 lithium disilicate glass ceramic (EMX) discs were randomly distributed into 13 groups based on concentrations of HF and commercial brands (n=20): 5% and 10%, Lysanda (LY5 and LY10); 5% and 10%, Maquira (MA5 and MA10); 5% and 10%, FGM (FG5 and FG10); 4.8%, Ivoclar Vivadent (IV5); 5% and 10%, PHS do Brasil (PH5 and PH10); 5% and 10%, BM4 (BM5 and BM10); 9%, Ultradent Inc (UL10); and Dentsply (DE10). A further random distribution (n=10) was made based on the application (+) or absence (-) of an adhesive layer. Resin luting agent cylinders (1 mm in diameter) were added on EMX surfaces, light-cured, and stored for 24 hours in deionized water at 37°C. On a universal testing machine (DL 500, EMIC), specimens were submitted to a microshear bond strength test at a crosshead speed of 1 mm/min until failure. A representative etched EMX disc from each group underwent surface topography analysis using field-emission scanning electron microscopy (n=1), and five (n=5) etched EMX discs from each group were tested for surface roughness. Data were statistically analyzed using analysis of variance and Tukey test (α=0.05). A less conditioned and smoother surface was observed for 5% HF compared to 10%. Additionally, commercial brands of HF were shown to affect bond strength. When the adhesive layer was not used (-), a 10% concentration promoted higher bond strengths to EMX. However, when adhesive was applied (+), the concentrations of HF and commercial brands had no effect on bond strength results. A 10% concentration of HF results in higher bond strength than a 5% concentration. If an adhesive layer is applied, neither this distinction nor the influence of commercial brands is observed.

A Comparative Study of the Repair Bond Strength of New Self-Adhesive Restorative Materials With a Resin Composite Material.

The aim of the present study is to compare the repair bond strengths (RBSs) of Cention-N (light-cure and self-cure modes), Equia Forte HT Filand a nanohybrid resin composite. Equia Forte HT Fil (GC, Tokyo, Japan), Cention-N (Ivoclar Vivadent, Schaan, Liechtenstein) and Filtek Z550 (3M ESPE, St Paul, MN, USA) were used in this study.EquiaForte HT Fil(EQF), Cention-N self-cure (CSC), Cention-N light-cure (CLC) and Filtek Z550 (Z550) groups were formed.A total of 40 samples were prepared; 10 samples in each group (n = 10).After the polymerization was completed according to the manufacturer's instructions, the samples were polished with OptiDisc (Kerr Corporation, Orange, USA) for 5 s each, from extra-course to extra-fine. After all samples were stored in 37°C water for 24 h, 10,000 cycles of brushing simulator and thermal cycles were applied to the samples.The samples were prepared in accordance with the selected repair protocol, and microshear bond strength (µSBS) test was performed. Fracture analysis on debonded surfaces was visualized by scanning electron microscopy. The conformity of the data to normal distribution was analyzed by the Shapiro-Wilk test. Multiple comparisons were performed using Dunn's test. Z550 showed significantly higher µSBS as compared to the other three groups. There is no differencebetween CSC, CLC and EQF. The use of Cention-N's self-cure or light-cure mode did not affect the RBSvalues. The RBS values of Cention-N and Equia Forte HT Fil materials are lower than those of the composite resin material.

Effect of Internal Bleaching on the Microshear Bond Strength of Composite Resin to Dentin in Recently Restored Teeth

Background: This study aimed to assess the effect of internal bleaching on the microshear bond strength of composite resin to dentin in recently restored teeth.&#x0D; Methods: This in vitro, experimental study evaluated 40 sound human premolars. The teeth were sectioned below their cementoenamel junction. Access cavity was prepared, pulpal tissue was removed and filled with glass ionomer. The teeth were then randomly divided into 4 groups. In the control group, no internal bleaching was performed and dentin surface was restored with composite. In group 2, internal bleaching with 35% hydrogen peroxide (Opalescence, ultradent) was performed 4 weeks after composite restoration. Bleaching was performed immediately after restoration of teeth in groups 3 and 4. Teeth were etched with 35% phosphoric acid for 15 seconds, rinsed, dried, and primer and adhesive (Adper Scotchbond Multipurpose) were applied. The teeth were then restored with Z250 (3M ESPE) microhybrid resin composite. Teeth were sectioned into 1 mm2 sections and underwent micro-shear bond strength test. In groups 1 to 3, bond strength was measured after 24 hours while in group 4, it was measured after 1 month. Data were analyzed using one-way ANOVA.&#x0D; Results: The mean micro-shear bond strength of composite to dentin was maximum in group 2 and minimum in group 3. However, the difference in this respect was not significant among the groups (p&gt;0.05).&#x0D; Conclusion: In teeth requiring immediate esthetic restorations, treatments can be performed after non-vital bleaching with no time restriction and adequately high bond strength comparable to non-bleached teeth.

Influence of thickness and degree of opacity of lithium disilicate on the degree of conversion and bond strength of resin cements

The aim of this study was to evaluate the influence of various opacities and thicknesses of lithium disilicate on the degree of conversion (DC) of two resin cements and on their bond strength (BS) to the ceramic. Two hundred and forty ceramic samples of lithium disilicate with high translucency (HT), low translucency (LT), and medium opacity (MO) were obtained from IPS e. max CAD in five different thicknesses. Light-cured and dual-cured resin cements were used for DC (n = 9) and BS (n = 8). Cement samples were light-cured under ceramic samples and analyzed using a Raman confocal spectrometer to determine the DC. For BS, resin cement cylinders were fabricated using ceramic samples which were thsen subjected to a microshear bond strength test. The mean values were provided for statistical analysis. The increase in thickness resulted in a decrease in DC for both cements under all experimental conditions, but only affected the BS of the light-cured cement for the MO ceramic. Comparing the opacities, the most translucent ceramics with particular thicknesses exhibited higher DC values than the less translucent ceramics. The LT and MO ceramics with certain thicknesses exhibited the highest BS values than the HT. The dual-cured cement generally showed highest values in both analyses than the light-cured cement. A thicker and more opaque ceramic material can reduce the DC of the cement. The BS decreases with the increasing thickness of the more-opaque ceramics.

Glass ceramics behave like selectively etched enamel on interfaces produced with self-adhesive/ self-curing resin cement

This work aimed at analyzing the bond strength of different ceramic compositions and dental substrates to a self-adhesive/curing resin cement to determine the reliability of the bonded interfaces. The study groups were Lithium Disilicate (LD), Zirconia reinforced Lithium Silicate (ZLS), Conventional Yttria-stabilized Polycrystalline Tetragonal Zirconia (Y-TZP C), Translucent Yttria-stabilized Polycrystalline (Y-TZP T), Selective Etched Enamel (E + E); unetched Enamel (E); and Dentin (D). Twenty 2 mm thick slice specimens of each group were obtained from a cutting machine, under high speed and refrigeration, followed by polishing and inclusion in PVC tubes with acrylic resin, with their flat surfaces exposed. The self-adhesive/curing resin cement was inserted in a plastic matrix on the surface of each specimen, resulting in cylinders with an internal 1.40 mm diameter x 1 mm height. The specimens were subjected to microshear bond strength test. Qualitative failure analysis was performed by stereomicroscope and scanning electron microscope (SEM). Weibull statistical analysis was performed to obtain the following metrics: probability of failure, Weibull modulus (m) (reliability) and characteristic strength (σ0). The E + E group achieved the highest median value (24.88 MPa), lower probability of failure, greater reliability, and greater characteristic strength among all the study groups. ZLS presented the highest bond strength values (20.07 MPa) and characteristic strength but also the highest data variability. LD group presented greater reliability among ceramic materials. Dentin presented the lowest median (4.51 MPa) among all substrates evaluated. The adhesive failure mode was predominant among the failure types. Adhesive interfaces of glass ceramics presented higher characteristic strength, lower probability of failure and greater reliability, being similar to selectively etched enamel.

Does extended air-drying time improve bond strength of universal adhesives to enamel?

To investigate the effect of extended air-drying time on the microshear bond strength (MSBS) of universal adhesives to enamel. The distal and mesial specimens from third molars were wet-ground and randomly assigned to three groups according to adhesives tested (n = 60): Clearfil Bond Universal, Gluma Bond Universal, and G-Premio Bond. The adhesives were applied in etch-and-rinse or self-etch modes, followed by air-drying for 5, 15, or 25 s. Composite buildups were constructed and subjected to the MSBS test after 24-h or thermocycling. MSBS results were evaluated using a four-way ANOVA. The thickness of the adhesive layer and the degree of solvent evaporation were further evaluated. At 24-h, MSBS of G-Premio Bond significantly improved with the 25 s air-drying in both of the etching modes when compared to the 5 s air-drying. After thermocycling, the extended air-drying did not produce a significant difference on the MSBS, regardless of the application strategy. Extended air-drying (25 s) evaporated almost all of the volatile part of Gluma Bond Universal and G-Premio Bond. Extended air-drying times increased solvent evaporation but did not contribute to the bonding effectiveness of the adhesives, regardless of the etching mode. Air-drying applications for more than 5 s had no significant effect on enamel bonding performance of universal adhesives.

Adhesion to lithium disilicate glass-ceramics after aging: Resin viscosity and ceramic surface treatment effects

ObjectiveTo evaluate the influence of intaglio ceramic surface treatments, resin cement viscosities, and storage regimens on the microshear bond strength of lithium disilicate ceramic. In addition, to investigate the dynamic viscosity of the resin-based luting agents. Materials and methodsCeramic slices were randomly allocated into eight groups (n = 19) considering three factors: ceramic surface treatment (hydrofluoric acid followed by silane, HF; or self-etching ceramic primer, E&P), resin cement viscosity (high, HIGH; or low, LOW) and storage regimen (baseline or aging). Surface treatments were performed, resin cement cylinders were built and microshear bond strength tests (μSBS, wire-loop method, speed: 1.0 mm/min) were run according to the storage factor. Failure mode, topographic and dynamic viscosity (37 °C; shear rate of 1.0–100 s−1) of resin cement components (base, high and low catalyst) were also performed. ResultsResin cement viscosity and the association among ceramic surface treatment, resin cement viscosity, and storage regimen were statistically significant factors (p < 0.05). Worse behavior was identified for the E&P_HIGH group compared to the E&P_LOW and HF_LOW in the baseline condition. After aging, the HF_HIGH group (16.78 MPa) presented the worst result among the aged groups (21.44–25.25 MPa). Most of the failures were adhesive. Surface micrographs revealed a distinct pattern after etching, more aggressive by HF and milder by E&P. High viscosity catalyst is 5.3 and 8.5-fold more viscous than the base and low viscosity catalyst, respectively (high > base > low). ConclusionDifferences in filler content can impact the resin viscosity of the material (more fillers increase the viscosity), which in turn can influence the bond strength of a lithium disilicate ceramic, depending on the surface treatment and storage regimen.

Can area delimitation and tube type impact microshear bond strength of adhesives to dental substrates?

Background he need of delimiting the bonding area on microshear bond strength (µSBS) test remains an unclear issue. In addition, there are different types of tube to perform the resin composite cylinders on µSBS test. The aim of this study was to evaluate the influence of the adhesive area delimitation and type of tube used to build up specimens for µSBS testing of adhesive systems, to enamel and dentin. Methods 120 bovine incisors were ground to achieve flat buccal enamel (n=60) and dentin (n=60) surfaces. Specimens of each substrate were randomly allocated into 6 groups (n=10) according to the adhesive system-a two-step self-etch (Clearfil SE Bond) and a universal adhesive (Scotchbond Universal Adhesive) applied in the self-etch and etch-and-rinse modes– and type of tube used to build up the specimens: starch and polyethylene. 4 resin composite cylinders (Filtek Z250) were made on each surface; in 2 of them the area delimitation was performed. The specimens were subjected to µSBS test after 24 h of water storage at 37°C. Data were submitted to three-way ANOVA and Tukey’s post hoc tests (α=0.05). Results The delimitation of the adhesive area did not influence on the bond strength to dentin (p=0.349) nor to enamel (p=0.158). The type of tube differently affected the ranking of adhesives in both substrates. Conclusions The delimitation of the adhesive area does not influence on the µSBS to enamel and dentin, irrespective of the tube type used to build up the resin composite specimens. The tube type’s impact on the bond strength depends on the dental substrate and adhesive system.

Effect of Multiple Firings on the Microshear Bond Strength Between a Translucent Zirconia and a Resin Cement.

This study investigated the microshear bond strength between a resin cement and a translucent zirconia subjected to multiple characterization firings. 5Y-PSZ zirconia blocks (Katana UTML) were sliced, sintered (1550°C, 2 h), and randomly divided into six groups (n=10) according to the number of characterization firings (0, 1, 2, 3, 5, or 10) and aging (baseline or after thermocycling). Each characterization firing was performed at 750°C for 1 minute. The ceramic surfaces were all sandblasted with 50 μm Al2O3 and silanized. Then, cylinders of resin cement (0.96 mm diameter × 2 mm height) were bonded onto their surfaces. The baseline samples were immersed in distilled water for 24 hours before the microshear bond strength (μSBS) tests. The aged samples were tested after 5000 thermocycles in water (5°C-55°C). The failure modes were classified as adhesive, predominantly adhesive, or cohesive. Scanning electron microscope images of the failure modes and the ceramic surfaces after the firings were taken. The μSBS data were analyzed by two-way ANOVA and Tukey's test. The number of characterization firings and aging affected the bond strength. The highest bond strength values were observed from the 2-firing group at baseline. The μSBS results after 1, 2, or 3 characterization firings were similar at baseline and after aging. On the other hand, 0, 5, and 10 firings revealed the lowest bond strengths. The most frequent failures were adhesive and predominantly adhesive. Zirconia grains were not affected by the multiple firings. One to three characterization firings after sintering improve the bond strength of 5Y-PSZ to the resin cement when compared to none or several (five or ten) firing cycles.

Associação de adesivos universais com silanos na adesão em blocos de CAD/CAM

ABSTRACT Objective: This study assessed whether the use of a silane coupling agent influence the bond strength of two universal adhesives to ceramic or resin CAD/CAM blocks. Methods: Forty-eight samples were obtained from each resin nano-ceramic hybrid block (RCBs) and lithium disilicate ceramic blocks (LD). Samples were treated with silane with MDP (Monobond - S-MDP), silane without MDP (Prosil - PS), and no silane application (Control - Ctr) followed by universal adhesive with silane (UAS) and without silane (UA) (n=8). Three polyurethane tubes (1.5 mm of internal diameter) were positioned in each sample treated surface and filled with a dual cured resin cement. Bond strength was assessed by microshear bond strength test and failure analysis was performed for all samples. Results: For the RCBs, UAS presented the highest bond strength values (p=0.004). Silane application was not significant in bond strength values (p=0.444). For LD, silane application was significant in bond strength values (p&lt;0.001), but the adhesive was not (p=0.066). Failure analysis showed high prevalence of adhesive failures for both substrates. Conclusion: A silane-containing universal adhesive promoted the best bond strength results to the resin nano-ceramic hybrid block. For bonding to a glass-ceramic CAD/CAM material, additional silane (without MDP) application presented the best results.

Shear bond strength of composite to demineralized enamel conditioned with resin infiltration

Aim: The aim of this in vitro study was to evaluate the influence of resin infiltration on bond-strength of composite resin to demineralized enamel. Methodology: Thirty bovine incisors were used in this study. Buccal enamel surfaces of bovine incisors were wet polished and then were divided into three groups: sound enamel; demineralized enamel; demineralized enamel infiltrated with a low-viscosity resin (ICON, DMG, Hamburg, Germany). After acid-etching with 37% phosphoric acid for 20 seconds, a two-step, total-etch adhesive (Single Bond 2, 3M ESPE, St. Paul, MN, USA) was applied using a microbrush for 20 seconds, followed by gentle air-drying for 5 seconds. The adhesive was light-cured for 10 seconds. Following the adhesive application, flowable composite resin (Filtek Supreme Flowable, 3M ESPE, St. Paul, MN, USA) was gently placed into a microtubule and was photopolymerized using an LED curing unit (Elipar Deep Cure; 3M ESPE, St. Paul, MN, USA). The microshear bond strength (µSBS) tests were performed using a microshear testing machine at a cross-head speed of 0.5 mm/min. One-way ANOVA and Bonferroni tests were used to analyze the data (5%). Results: Significant differences were found according to the ANOVA (p &lt; 0.05). Pair-wise comparison results of µSBS (mean ± SD) were: sound enamel (25.16 ± 2.3); demineralized enamel (17.93 ± 2.1); demineralized enamel infiltrated with a low-viscosity resin (28.51 ± 3.76). Conclusion: Resin infiltration applied to demineralized enamel before composite application increased the bond strength. No difference was found in the bond strength values obtained for sound enamel and resin infiltrated enamel. How to cite this article: Durukan SM, Gümüştaş B, Şişmanoğlu S. Shear bond strength of composite to demineralized enamel conditioned with resin infiltration. Int Dent Res 2022;12(Suppl.1):114-19. https://doi.org/10.5577/intdentres.441 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Influence of Optional Crystallization Firing on the Adhesion of Zirconia-Reinforced Lithium Silicate before and after Aging

This study proposed to evaluate the influence of the crystallization firing process and the hydrothermal degradation on the bond strength between different reinforced glass-ceramics and resin cement. Material and Methods: zirconia-reinforced lithium silicate (ZLS) and lithium disilicate (LD) were divided into six groups according to aging simulation (baseline or after thermocycling) and restorative approach (ZLS without firing; ZLS with firing; LD with firing). ZLS and LD surfaces were etched with 5% hydrofluoric acid for 30 s and 20 s, respectively, and then received a layer of silane coupling agent (Monobond-N). Then, cylinders of resin cement (1 mm diameter × 2 mm height) were bonded onto their surfaces. The baseline samples were immersed in distilled water for 24 h before the microshear bond strength (µSBS) test, while half of the specimens were tested after 6000 cycles of thermocycling aging. The types of failures were analyzed through stereomicroscopic and scanning electron microscope. The failure modes were classified as adhesive, predominantly adhesive, cohesive in ceramic, or cohesive in cement. The µSBS data were analyzed by two-way ANOVA and Tukey’s test. A restorative approach (p = 0.000) and aging (p = 0.000) affected the bond strength. The highest bond-strength values were observed in the ZLS without the optional crystallization firing. The most frequent failures were adhesive and predominantly adhesive. The cementation of zirconia-reinforced lithium silicate without the optional crystallization firing process leads to high bond-strength values with resin cement.

Effect of Fluorographene Addition on Mechanical and Adhesive Properties of a New Core Build-Up Composite.

This study aims to develop a restorative material having such mechanical and adhesive properties that it can be used both as a reconstruction material and as a luting cement. The experimental core build-up composite (CBC) was derived from a self-adhesive cement by the modification of its chemical formula, requiring the use of dedicated dentin and ceramic primers. The adhesive properties to zirconia and dentin were analyzed with a micro-Shear Bond Strength test (mSBS). The mechanical properties were analyzed by a flexural strength test. The results were compared with those obtained for other commercially available cements and core build-up materials, both before and after addition of 2 wt.% fluorographene. The CBC obtained average values in the mSBS of 49.7 ± 4.74 MPa for zirconia and 32.2 ± 4.9 MPa for dentin, as well as values of 110.9 ± 9.3 MPa for flexural strength and 6170.8 ± 703.2 MPa for Young's modulus. The addition of fluorographene, while increasing the Young's modulus of the core build-up composite by 10%, did not improve the adhesive capabilities of the primers and cement on either zirconia or dentin. The CBC showed adhesive and mechanical properties adequate both for a restoration material and a luting cement. The addition of 2 wt.% fluorographene was shown to interfere with the polymerization reaction of the material, suggesting the need for further studies.