Microshear Bond Strength Values Research Articles

Effects of Er,Cr:YSGG Laser Surface Treatments and Composites with Different Viscosities on the Repair Bond Strength of CAD/CAM Resin Nanoceramic.

This study aims to evaluate the repair micro-shear bond strength of the CAD/CAM resin nanoceramic block treated using four different surface treatments and composite resins of different viscosities. For the current study, 96 samples with dimensions of 14 × 12 × 2 mm were obtained from a CAD/CAM resin nanoceramic block (Cerasmart) with a low-speed precision cutting saw under water cooling. The relevant samples were randomly divided into four groups according to the surface treatment processes: grinding with diamond bur, aluminum oxide airborne-particle abrasion, long-pulse laser, and short-pulse laser. Following silane application, universal adhesive was applied to all surface-treated samples and cured with an LED for 10 s. The samples prepared for the repair procedure were divided into two subgroups (microhybrid composite and injectable composite) according to the viscosity of the repair material to be used (n = 12). After the repair procedure, care was taken to keep the samples in distilled water in an incubator at 37 °C for 24 h. The repair micro-shear bond strength values (μSBSs) of CAD/CAM resin nanoceramic-composite resin complexes were tested. In addition, randomly selected samples from each group were examined with a scanning electron microscope to evaluate the surface topography after both surface treatments and the micro-shear bond strength test. Data were analyzed by two-way ANOVA and Bonferroni test. It was determined that the surface treatment preferred in the repair protocol significantly affected the μSBS value (p < 0.001). While the highest μSBS value was obtained with the short-pulse laser airradiation group, the lowest μSBS values were found in samples with long pulse laser irradiation. However, samples grinded with a bur and airborne-particle abrasion showed similar μSBS values (p > 0.05). The preferred composite viscosity in the repair procedure has a significant effect on the μSBS value (p < 0.001). However, the interaction between the surface treatment and the viscosity of the repair composite does not affect the μSBS values in a statistically significant way (p = 0.193). It may be recommended to clinicians to repair CAD/CAM resin nanoceramic restoration surfaces with injectable composites or after treatment with short-pulse lasers.

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.

Comparison of the Micro-Shear Bond Strength of Resin Cements to CAD/CAM Glass Ceramics with Various Surface Treatments.

This study aimed to compare the effect of acid etching, sandblasting, or silica coating on the micro-shear bond strength of dual-cured resin cements to computer-aided design and computer-aided manufacturing (CAD/CAM) glass ceramic materials. Feldspathic, lithium disilicate, and zirconia-reinforced CAD/CAM ceramics were divided into four groups: control group (C), no surface treatment; hydrofluoric (HF) group, 5% HF acid-etched; sandblasting (SB) group, abraded with 50 µm aluminum oxide (Al2O3) particles; silica-coated (CJ) group, abraded with 30 µm silica-modified Al2O3 particles. Roughness values were obtained by using a profilometer. The cements were condensed on the surface-treated specimens and a micro-shear bond test was conducted. The ceramic material (p < 0.001) and surface treatment type (p < 0.001) significantly affected the micro-shear bond strength values. HF acid etching can be recommended for the surface pretreatment of feldspathic, lithium disilicate, and zirconia-reinforced CAD/CAM ceramics. Better bond strengths can be obtained with HF acid etching than with sandblasting and silica coating.

Effect of Different Decontamination Protocols Applied to Blood-Saliva Contaminated Dentin Surfaces of Universal Adhesive Resin Post-Etch on Shear Bond Strength

ABSTRACT This study was performed to evaluate the effect of different decontamination protocols applied to contaminated surfaces on the recovery of adhesion. Different decontamination protocols were applied to molar teeth contaminated with blood and saliva except the control group. 40 third molar teeth were divided into groups according to the applied decontamination protocols: Group 1(control), Group 2 (water rinse), Group 3 (15-sec re-etch), Group 4 (10-sec re-etch), Group 5 (5-sec re-etch), Group 6 (5% NaOCl), Group 7 (2% chlorhexidine gluconate), Group 8 (ozonated water). Universal adhesive resin (Gluma Universal, Heraus Kulzer) was used in the etch and rinse mode according to the manufacturer’s instructions. Nanohybrid composite material was placed in all groups. Then the Shear Bond strengths of all groups were evaluated after applying 5000 thermal cycles (5–55 °C) to each sample. In the limitation of this in vitro study, it has been shown that rinsing with ozonated water of contaminated surfaces with blood and saliva after etching, has increased the micro-shear bond strength (μSBS) values more than that of in control group values. Also, the application of NaOCl, re-etching with 37% phosphoric acid for 15 seconds, and cleaning with CHX, significantly increase the bonding potential.

Influence of ceramic primers on microshear bond strength to zirconia

This study aimed to investigate the effect of two ceramic primers on the microshear bond strength (µSBS) of yttria-stabilized zirconia (Y-TZP) to two types of self-adhesive resin cement and one BisGMA-based resin cement. Zirconia specimens were sandblasted with 27-µm aluminum oxide and composite cylinders were cemented with resin cement with or without the prior use of ceramic primers. Nine groups (n=12) were randomly distributed according to the cement (self-adhesive RelyX U200/3M ESPE, self-adhesive Maxcem Elite/Kerr, and BisGMA-based dual-cure RelyX ARC/3M ESPE) and ceramic primer (Z-Primer Plus/Bisco and Porcelain Liner M/Sun Medical Co.). After luting, the specimens were stored in distilled water at 37°C for 24 hours and then submitted to the µSBS test. The data were analyzed with two-way ANOVA followed by the Scheffe post hoc test (p&lt;0.05). There were significant differences between RelyX U200 and other groups. There were also significant differences between the RelyX U200 group without ceramic primer and other groups without ceramic primers (p&lt;0.05). Self-adhesive resin cement (RelyX U200 and MaxCem) presented higher microshear bond strength (6.17 and 2.32 MPa) than the conventional resin cement (RelyX ARC) when a porcelain primer was not used (0.43 MPa). When using Porcelain Liner M, the results of RelyX ARC (2.94 MPa) were equivalent to the results of self-adhesive cement (3.93 and 2.11 MPa). When using Z-Prime Plus, the results of MaxCem (5.36 MPa) were lower than those of RelyX U200 (9.59 MPa) but equivalent to those of RelyX ARC (6.07 MPa). When using the RelyX ARC, the use of both ceramic primers improved bond strength to zirconia. When using self-adhesive resin cement, Z-Prime Plus improved microshear bond strength values. It can be concluded that, after 24 hours, the highest µSBS results were obtained when using Z-Prime Plus and RelyX U200 self-adhesive cement.

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.

The effect of composite placement technique on the internal adaptation, gap formation and microshear bond strength.

This study aimed to compare the efficiency of placement technique on internal adaptation, gap formation and microshear bond strength (SBS) of bulk-fill composite resin materials. Standardized class V cavities were prepared for microcomputed tomography (mCT) test and divided into four groups (n=12) as follows: Group SDR: Smart Dentin Replacement system/bulk fill; Group SF2: Sonic-Fill system/bulk fill sonic-activated composite placement system; Group CHU: Herculite-XRV-Ultra composite resin inserted with Compothixo/sonic-vibrated composite resin placement system; Group HIT: Herculite-XRV-Ultra composite resin applied with incremental technique. Self-etch adhesive (Optibond-XTR) was used for bonding in all groups. After 10000 thermocycling, mCT scans were taken to reveal gap formation at the toothrestoration interface and universal testing machine was used to test microshear bond strength SBS values (n=10). ANOVA, post-hoc Bonferroni and Tukey HSD tests were used for evaluating the gap formation and SBS values p=0.05. SF2 and CHU showed the best adaptability compared with both SDR and HIT. The difference between groups SDR and HIT was statistically significant (p<0.05).SBS values were found to be the highest for SF2, and the lowest for HIT groups (p>0.05). Bulk-fill composite resins placed either with sonic-activated or sonic-vibrated instrument demonstrated better adaptability, less gap formation and higher bond strength than both the bulk-fill flowable composite and conventional incremental techniques.

English

BACKGROUND Contamination by hemostatic agent and rinsing with different disinfectant solutions can influence on micro shear bond strength between dentin and resin composite. The major objective of this study was to investigate the micro shear bond strengths of an etch and rinse technique and self-etch technique to human dentin contaminated with a hemostatic agent containing AlCl3 followed by chlorhexidine (CHX) and boric acid cleaning. METHODS A 50 non-carious, permanent, third molar teeth were randomly divided into five groups (N = 10 per group); Group 1: Self etch technique (OptiBond All - In - One, Kerr) was used on dentin contaminated with hemostatic agent (Alustat, Cerkamed). Group 2: Etch and rinse technique (Phosphoric acid then OptiBond Universal, Kerr) was used. Group 3: Contaminated dentin was cleaned with CHX for 60 seconds and then self-etch technique was used. Group 4: Contaminated dentin was cleaned with boric acid for 60 seconds and then self-etch technique was used. Group 5: Hemostatic agent was not applied, only self-etch technique was used. Flat occlusal dentin surfaces were prepared and then restored with resin composite rod (Herculite Classic, Kerr) (1 mm diameter × 1 mm height). After thermocycling (1,000 cycles), composite sticks were subjected to microshear until fracture occurred at a crosshead speed of 0.5 mm / min. Statistical analysis was made with one-way analysis of variance (ANOVA) and multiple comparison tests with Tukey. RESULTS The mean microshear bond strength values of group 1 to group 5 were 21.89 ± 12.43, 26.15 ± 22.79, 20.05 ± 12.03, 35.08 ± 13.20 and 19.41 ± 6.53 MPa, respectively. When the values of the groups were compared, the difference was not significant. (P = 0.108). CONCLUSIONS Boric acid and CHX may be used as alternatives to other materials that are used as cavity disinfectants on contaminated dentin by hemostatic agent. KEY WORDS Boric Acid, CHX, Hemostatic Agent, Adhesive Systems, Shear Bond Strength

Effect of Die Spacer Thickness on the Microshear Bond Strength of CAD/CAM Lithium Disilicate Veneers.

Aim The aim of this study was to compare the microshear bond strength of ceramic veneers with digital die spacer settings at 20, 40, and 100 µm. Materials and Methods Eighteen milled lithium disilicate microdiscs (IPS e.max CAD, Ivoclar Vivadent) were divided into three groups (n = 6) according to their digital die spacer settings: group A = 20 µm, group B = 40 µm, and group C = 100 µm. Six randomly selected sound maxillary premolars received three microdiscs each. Each microdisc was 1 mm in diameter and 1 mm in height. The buccal surfaces of the premolars were prepared with a 0.5 mm depth in enamel. After cementation, the specimens were thermocycled for 2,500 cycles between 5 and 55°C. Microshear bond strength testing was performed using a universal testing machine until bonding failure. Failure modes were evaluated using a stereomicroscope. Statistical analyses included one-way ANOVA, Tukey's post hoc test, and chi-square test with a 5% alpha error and 80% study power. Results The mean microshear bond strength values were calculated in MPa for group A = 31.91 ± 12.41, group B = 29.58 ± 5.03, and group C = 13.85 ± 4.12. One-way ANOVA (p ≤ 0.05) showed a statistically significant difference in microshear bond strength among the three groups. Tukey's post hoc test showed significant differences between groups A and C (p=0.004) and between groups B and C (p=0.011). The failure modes were presented as cohesive, adhesive, and mixed failures. Chi-square test indicated that the failure mode distribution was not significantly different among the three groups (p=0.970). Conclusion Higher digital die spacer settings decrease the microshear bond strength of CAD/CAM lithium disilicate veneers.

Comparative evaluation of Emblica officinalis as an etchant and an MMP inhibitor with orthophosphoric acid and chlorhexidine on the microshear bond strength of composite resin: an ex vivo study.

ObjectivesThis study aimed to evaluate Emblica officinalis (Indian gooseberry or amla) as an acid etchant and matrix metalloproteinase (MMP) inhibitor, and to compare its effect on the microshear bond strength of composite resin with orthophosphoric acid (OPA) and 2% chlorhexidine (CHX) as an acid etchant and MMP inhibitor, respectively.Materials and MethodsThe etching effect and MMP-inhibiting action of amla on dentin samples were confirmed by scanning electron microscopy (SEM) and gelatin zymography, respectively. Dentinal slabs (3 mm thick) from 80 extracted human molars were divided into 10 and 20 samples to form 2 control groups and 3 experimental groups. Groups 1, 2, and 4 were etched with OPA and groups 3 and 5 with amla juice. An MMP inhibitor was then applied: CHX for group 2 and amla extract for groups 4 and 5. Groups 1 and 3 received no MMP inhibitor. All specimens received a standardized bonding protocol and composite resin build-up, and were subjected to microshear bond strength testing. The force at which the fracture occurred was recorded and statistically analyzed.ResultsAmla juice had a similar etching effect as a self-etch adhesive in SEM and 100% amla extract was found to inhibit MMP-9 by gelatin zymography. The microshear bond strength values of amla were lower than those obtained for OPA and CHX, but the difference was not statistically significant.ConclusionsAmla has a promising role as an acid etchant and MMP inhibitor, but further studies are necessary to substantiate its efficacy.

Influence of different phosphoric acids before application of universal adhesive on the dental enamel.

There are different etching gels available, which have different composition, different pH, and different viscosity, and there is little information in the literature comparing all these products. To evaluate the mean microshear bond strength and morphological characteristics of tooth enamel by evaluating different phosphoric acids combined with a universal adhesive system. Eighty-four enamel samples were used, which were divided according to the acid conditioning: G1: Scotchbond Etchant (3M Oral Care), G2: Ultra-Etch (Ultradent), G3: Eco-Etch (IvoclarVivadent), G4: ETCH-37 with BAC (Bisco), G5: Etching gel (Densell), G6: Condac 37 (FGM), and G7: Scotchbond Universal Adhesive (3M Oral Care) in self-etch mode. For the adhesive procedure, Scotchbond Universal Adhesive was the one used as indicated the manufacturer's instructions, 0.9-mm-diameter resin cylinders were placed. The microshear bond strength test was performed after being stored for 24 hours in water. The morphological characteristics of tooth enamel were analyzed using the Raman confocal microscope alpha300RA. The analysis of variance (ANOVA) test and Tukey post-test were used to analyze the differences between the groups. The mean microshear bond strength values obtained for groups 1, 4, 5 were significantly greater than groups 2, 3, 6 and 7 (p < .05). All groups presented demineralization after the application of the etching acid, and few signs of demineralization were evident in group 7. Acid-etching with ETCH-37 with BAC, Etching gel, and Scotchbond Etchant improved the adhesive strength in the enamel using an universal adhesive, and acid-etching with Condac 37, Ultra-Etch, and Eco-Etch provides similar adhesive strength values to self-etch mode of universal adhesive. All acid etchants should be considered as different. The test confirms that enamel etching prior to the application of a universal adhesive system depends on the selected acid etchand product.

TiO2 nanotubes improve physico-mechanical properties of glass ionomer cement

ObjectivesThe aim of this study was to determine the physico-mechanical properties of a high viscosity glass ionomer cement (GIC) reinforced with TiO2 nanotubes (TiO2-nt). MethodsTiO2-nt was incorporated into the GIC powder components (Ketac Molar EasyMix™) in concentrations of 0% (control group), 3%, 5%, 7% by weight. Compressive strength (n = 10/group), three point bending for flexural strength (n = 18/group), microshear bond strength to dentin and failure mode (n = 20/group), and surface roughness and weight loss before and after brushing simulation (30,000 cycles) (n = 8/group) were evaluated. Data were submitted to Shapiro-Wilk, ANOVA, Tukey and Chi-square tests (α ≤ 0.05). ResultsAddition of 5% of TiO2-nt into GIC presented the highest values for compressive strength and differed from the control, 3% and 7% groups (p = 0.023). There were no significant differences in flexural strength (p = 0.107) and surface roughness before and after the dental brushing (p = 0.287) among the groups. GIC added with 5% TiO2-nt showed the lowest weight loss values (p = 0.01), whereas the control, 3% or 5% TiO2-nt groups presented similar microshear bond strength values (p ≥ 0.05). The 5% TiO2-nt group featured higher microshear bond strength than the 7% TiO2-nt group (p = 0.034). Cohesive in material was the most representative failure mode for all groups. SignificanceThe incorporation of TiO2-nt did not affect GIC’s adhesiveness to dentin, but improved its compressive strength at 5%. Furthermore, TiO2-nt decreased the percentage of weight loss after GIC’s surface wear.

Effect of metal primers on the bond strength of resin cement to Co-Cr alloy.

To evaluate the effects of adhesive systems and primer systems on microshear bond strength of chemically activated resin cemented to Co-Cr cast dental alloy. Seventy-two rectangular blocks of Co-Cr metal alloy were manufactured and air-abraded with 50-μm Al2O3 particles. Metal primers (alloy primer [AP] or Clearfil ceramic primer [CP]) and adhesives (Adper Scotchbond Multi-Purpose Adhesive activated by Adper Scotchbond Multi-Purpose Adhesive Catalyst [SASC], or Primer & Bond 2.1 activated by Self Cure Activator [PBCA]) were applied and subsequently divided into six groups (SASC; AP+SASC; CP+SASC; PBCA; AP+PBCA; CP+PBCA; N.=12). Then, resin cement (Enforce) was applied. Data about microshear bond strength values were statistically evaluated by analysis of variance and Tukey's test. The bond strength was lower (P<0.001) in groups with adhesive system alone (SASC and PBCA) compared with groups with addition of primers alloy primer (AP+SASC and AP+PBCA) and ceramic primer (CP+SASC and CP+PBCA). The application of primers improves the bond strength of the cement resin to the Co-Cr metal alloy.

Evaluation of bond strength of dual resin cements to CAD/CAM-created lithium disilicate ceramic.

The objective was to examine the microshear bond strength values of different dual resin cements to computer-aided design (CAD)/computer-aided manufacturing (CAM)-created ceramics containing lithium disilicate, which underwent different surface treatments. Two dual resin cements (RelyX ARC and RelyX Ultimate) and three surface treatments of lithium disilicate ceramic blocks (Ceramic Primer (CP; containing silane) plus Adper Scotchbond Multipurpose (ASM) adhesive; CP plus Single Bond Universal (SBU) adhesive; and SBU adhesive alone) were tested. The SBU adhesive includes silane in its formulation. Each sample underwent a microshear test and bond strength values were subjected to analysis of variance (ANOVA) followed by Tukey's test (α=0.05). Fracture patterns were also observed with light microscopy. RelyX ARC treated with CP+ASM or CP+SBU presented resistance values that were significantly higher than the same treatments for RelyX Ultimate. Conversely, for the blocks treated with SBU alone, the mean resistance value for RelyX Ultimate was higher than that of RelyX ARC. Regarding the different types of treatment for each resin, the mean resistance value of RelyX ARC treated with CP+ASM was significantly highest, followed by treatment with CP+SBU and SBU treatment alone. Meanwhile, RelyX Ultimate treated with CP+ASM or CP+SBU presented resistance values that were significantly higher than SBU treatment alone. In all of the groups, an adhesive fracture pattern was predominantly observed. The present results indicate that silanization is important for ASM and SBU adhesives to be effective.

The effect of monowave and polywave light-polymerization units on the adhesion of resin cements to zirconia

Statement of problemAlthough newly developed photoinitiators can make up for the limitations of camphorquinone, their absorption spectra are different. However, little attention has been paid to the compatibility of available wavelength spectra of light-polymerization units (LPUs) and photoinitiators within resin cements. PurposeThe purpose of this in vitro study was to evaluate the effect of monowave and polywave light-emitting diode (LED) units on the adhesion of dual-polymerizing self-adhesive resin cements to monolithic zirconia. Material and methodsMonowave LPUs and polywave LPUs were chosen to polymerize 2 dual-polymerizing self-adhesive resin cements. Ninety-six zirconia disks were randomly divided into 4 groups as different combinations of LPUs and resin cements, namely ES-U200, BS-U200, ES-SC, and BS-SC. Resin cements were adhered to zirconia disks, and the microshear bond strength (μSBS) test was conducted after 24 hours of H2O storage (24 h) and 10 000 thermocycles (10k/TC). Failure modes were examined by stereomicroscopy and scanning electron microscopy (SEM). The degree of conversion (DC) was tested both immediately and 24 hours later. In statistical analyses, 2-way ANOVA and the Tukey honestly significant difference post hoc test were performed for μSBS and DC results, and chi-square test was performed for failure mode analysis (α=.05 for all tests). ResultsThe 2-way ANOVA demonstrated that different combinations of LPUs and resin cements, as well as different artificial aging levels, significantly influenced microshear bond strength values (P<.001). The interactions between 2 factors were also significant (P<.001). The BS-SC group possessed relatively high bond strength in both 24-hour and 10k/TC aging levels. For the same resin cement, no significant difference was found in the immediate DC (P=.405 for U200 and P=.708 for SC). At 24 hours, DC and BS-U200 values were significantly higher than ES-U200 values (P=.002), whereas BS-SC values were not significantly different from ES-SC values (P=.284). ConclusionsWithin the limitation of this in vitro study, the emission spectra of LED units significantly influenced the bond strengths, DC, and failure mode of dual-polymerizing self-adhesive resin cements to zirconia at both immediate and artificial aging levels. The LPU should provide light energy to match the absorption wavelengths of photoinitiators in the resin cements.

Do ozonated water and boric acid affect the bond strength to dentin in different adhesive systems?

The aim of this in vitro study was to compare the effects of the application of three different cavity disinfecting agents to dentin on the micro-shear bond strength (μ-SBS) of one self-etch and two universal adhesive systems. In total, 120 caries-free human permanent molar teeth were used in this study. Mid-coronal dentin surfaces were revealed by cutting occlusal enamel and a standard smear layer was obtained by using 600-800-1200 grid silicon carbide abrasive papers. Specimens were randomly assigned to four groups according to the disinfectant used: Group 1: Control (no disinfectant); Group 2: 2% chlorhexidine based (Consepsis); Group 3: 10 ppm ozonated water (TeknO3zone); Group 4: 5% boric acid (Handmade). Each group was divided into three subgroups according to the type of adhesive (Clearfil SE Bond, OptiBond XTR, and Tokuyama Universal). Specimens were bonded using either Clearfil SE Bond, OptiBond XTR or Tokuyama Universal, which were employed according to the manufacturer's instructions. Resin composite microcylinders were bonded using Tygon® tubes for μ-SBS testing. After specimens were stored for 24 h, at 37°C in distilled water, μ-SBS test was measured with a universal test machine (LF Plus, Lloyd, Instrument). μ-SBS results were analyzed by one-way analysis of variance (ANOVA) and Tukey's tests. When the mean microshear bond strength values of the control group were compared, the difference between the subgroups was not significant (P < 0.05). When the mean microshear bond strength values of the chx, ozonated water, and boric acid were compared, the difference between Clearfil SE Bond and Tokuyama Universal was significant (P < 0.05) and the difference between the other groups was not significant (P > 0.05). Ozonated water and boric acid may be as an alternative to other materials used as cavity disinfectants.

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 chitosan incorporation on some properties and antibacterial activity of dental adhesive

OBJECTIVE: To evaluate the antibacterial activity of adhesive resin incorporating chitosan as well as the adhesive characteristics. METHOD AND MATERIALS: Modified adhesive was prepared by adding 0.05%, 0.1%, and 0.2% (w/w) chitosan solution to Heliobond adhesive resin. The solution of chitosan was prepared by dissolving 2 g of chitosan powder in 1 liter of 1% (v/v) acetic acid. Heliobond without chitosan was used as a control. The antibacterial activity was evaluated using a direct contact test against Streptococcus mutans. The viscosity, degree of conversion, pH, and microshear bond strength values of modified adhesive to enamel and dentin were evaluated. Data were analyzed using the ANOVA and Tukey’s tests. Statistical significance was set at the .05 probability level. RESULTS: The antibacterial properties of adhesives incorporating chitosan were found to exhibit an inhibitory effect on the growth of Streptococcus mutans compared with the unmodified adhesive resin (P < .05). The viscosity of adhesives increased with increasing the concentrations of chitosan incorporation into the adhesive. However, the degree of conversion and pH values and microshear bond strength values of modified adhesive to enamel and dentin decreased with increasing the concentrations of chitosan incorporation into the adhesive. CONCLUSION: Under the limitations of the present investigation, the following conclusion can be drawn: modified Heliobond adhesive resin with 0.2 wt % chitosan exhibit the best antibacterial activity. The antibacterial properties of modified Heliobond adhesive depend on their pH value. By increasing the concentration of chitosan into Heliobond adhesive system, pH, degree of conversion and bond strength significantly decreased.

Zinc oxide eugenol paste jeopardises the adhesive bonding to primary dentine.

This was to evaluate the influence of root canal filling pastes on microshear bond strength (µSBS) of an adhesive system to primary dentine. Human (32) primary molars were randomly assigned into four experimental groups (n = 8): zinc oxide eugenol paste (ZOE); iodoform paste (Guedes-Pinto paste); calcium hydroxide paste thickened with zinc oxide; and no filling paste (control). Flat dentine surfaces were covered with a 1mm-thick layer of the pastes for 15min at 37°C. The pastes were mechanically removed from dentine surfaces, followed by rinsing and drying. After adhesive application (Adper Single Bond 2, 3M ESPE), starch tubes were placed over pre-treated dentine and filled with composite resin (Z250, 3M ESPE). The µSBS test was performed after 24h of water storage at 37°C. The failure mode was evaluated using a stereomicroscope. The µSBS values (MPa) were analysed with one-way ANOVA and Tukey post-hoc tests (α = 0.05). The lowest µSBS values were achieved when ZOE was used. No difference was found among other filling pastes compared with control group. All specimens showed adhesive/mixed failures. Zinc oxide eugenol paste negatively influenced the bond strength of adhesive systems to primary dentine. Iodoform-based Guedes-Pinto paste and calcium hydroxide paste thickened with zinc oxide did not influence the microshear bond strength values.

Laboratory Study of Micro-shear Bond Strength of Two Resin Cements to Leucite Ceramics using Different Ceramic Primers

To evaluate the effect of Monobond Etch & Prime on the micro-shear bond strength (MSBS) of resin cements to leucite surface and to compare the MSBS of two different resin cements to conditioned leucite surfaces with different primer systems. Twenty-one leucite ceramic disks (10 mm diameter, 2 mm thickness) were divided into three groups (n = 7). Group I: 9.6% hydrofluoric (HF) acid and Monobond S (Ivoclar Vivadent, Liechtenstein), then conventional resin cement was applied. Group II: Monobond Etch & Prime (Ivoclar Vivadent, Liechtenstein), then conventional resin cement was applied. Group III: 9.6% HF acid and with Monobond N (Ivoclar Vivadent, Liechtenstein), then adhesive resin cement was applied. The assigned resin cement was applied in each disk through five plastic tubes with an inner diameter of 1.6 and 1.9 mm height, and then light cured. Micro-shear bond strength was determined by pulling out the resin cement using universal testing machine (Instron®, USA). One-way analysis of variance (ANOVA) and Student's t-test were used to determine statistical difference (a = 0.05) between each two groups. The results showed that group III had the highest MSBS values (7.32 ± 2.47) followed by group II (6.24 ± 2.16), whereas group I had the lowest MSBS values (5.7 ± 2.7). Nevertheless, there was no statistically significant difference between the results of all the groups. Monobond Etch & Prime has shown comparable results to the most popular combination of HF acid and silane. The combination of HF acid and Monobond N and self-adhesive resin cement has shown the best MSBS results, though not statistically significant. The clinicians can use simplified ceramic primer technique (Monobond Etch & Prime) which has comparable MSBS to the most popular combination of HF acid and silane.