Microtensile Bond Strength Values Research Articles

Effect of endodontic irrigants on microtensile bond strength of a self-etching adhesive system

Aim: The aim of this in vitro study was to evaluate the effect of two different irrigation solutions, alone or in combination, with different application times on the dentin bond strength of a self-etching adhesive. Materials and Methods: Twenty-eight extracted non-carious human third molars were randomly distributed into seven groups according to the irrigant. The crowns of the molars were sectioned vertically through bucco-lingual direction. Solutions of 5% sodium-hypochlorite (NaOCl), 3% hydrogen-peroxide (H 2 O 2 ), and a combination of NaOCl and H 2 O 2 were applied to the dentin surface for various lengths of time. The adhesive system (Clearfil SE Bond; Kuraray, Japan) was applied according to the manufacturers' directions and then the dentin surfaces were built up with a hybrid composite resin (Clearfil AP-X Kuraray, Japan). Specimens were sectioned into 15 sticks; each of them had a 0.65 mm 2 bonding area. Microtensile bond strength was determined (MPa), and the results were statistically analyzed using one-way ANOVA and Tukey's HSD test. Results: Irrigation with NaOCl alone showed similar micro-tensile bond strength values with the control group ( P > 0.05). In comparison to control group, irrigation with H 2 O 2 alone for 5 min and 30 min and the irrigation with H 2 O 2 /NaOCl combination each for 15 min decreased the microtensile bond strength. Conclusion: The use of H 2 O 2 significantly reduced the bond strengths of the self-etching adhesive when applied alone or in combination with NaOCl for a long time.

An in vitro Evaluation of Microtensile Bond Strength of Resin-based Sealer with Dentin Treated with Diode and Nd:YAG Laser

Smear layer is a negative factor which prevents adhesion of the filling material to the dentinal walls. Recent advances in dental research have incorporated lasers as a potential adjunct in root canal treatment by removing the smear layer before filling the root canal system, enhancing the adhesion of sealers to dentin and improving the sealing ability. To evaluate the microtensile bond strength of AH-Plus resin-based sealer to dentin after treatment with 980 nm diode and 1,064 nm neodymium-doped:yttrium aluminum garnet (Nd:YAG) laser in vitro. Thirty specimens prepared for three groups namely group I (control), group II (980 nm diode-lased specimens) and group III (Nd:YAG-lased specimens). One tooth from each group was observed under scanning electron microscope for evaluation of intracanal root dentin morphology. Remaining specimens were used for making microsections by hard tissue microtome. Specimens for groups II and III were lased with 980 nm diode and 1,064 nm Nd:YAG laser. AH Plus sealer was applied onto specimens and mounted onto Instron universal testing machine for microtensile bond strength testing. Results were subjected to statistical analysis using one-way analysis of variance (ANOVA) and Tukey's test. Group III Nd:YAG had maximum mean microtensile bond strength values (11.558 ± 0.869), followed by group II diode (9.073 ± 0.468) and group I control (6.05 ± 0.036). Statistically significant differences were seen among all the groups. SEM analysis shows removal of smear layer in both groups II and III. Both Nd:YAG and diode laser were more effective than control group in improving the microtensile bond strength of AH Plus sealer to dentin. Lasers have the potential to increase the adhesiveness of root canal sealer to dentin surface, thereby improving the quality of root canal obturation.

Erratum - Effect of ascorbic acid, ethanol and acetone on adhesion between the treated fiber posts and composite resin cores

The aim of the present study was to assess the effect of ascorbic acid, ethanol and acetone on microtensile bond strength between fiber posts pre-treated with hydrogen peroxide and composite resin cores.Twenty four fiber posts were pre-treated with 24% hydrogen peroxide and divided into 4 groups as follows: G1: no treatment, as control group; G2: treatment with 10% ascorbic acid solution for 5 minutes; G3: treatment with 70% ethanol solution for 5 minutes; and G4: treatment with 70% acetone solution for 5 minutes. Each fiber post was surrounded by a cylinder-shaped polyglass matrix which was subsequently filled with composite resin. Two sections from each sample were selected for microtensile test at a crosshead with speed of 0.5 mm/min. Statistical analyses were performed using one-way ANOVA and a post hoc Tukey HSD test. Fractured surfaces were observed under a stereomicroscope at ×20 magnification. The fractured surfaces of the specimens were observed and evaluated under a SEM.MEANS OF MICROTENSILE BOND STRENGTH VALUES (MPA) AND STANDARD DEVIATIONS IN THE GROUPS WERE AS FOLLOWS: G1: 9.70±0.81; G2: 12.62±1.80; G3: 16.60±1.93; and G4: 21.24±1.95. G4 and G1 had the highest and the lowest bond strength values, respectively. A greater bond strength value was seen in G3 compared to G2. There were significant differences between all the groups (P<.001). All the failures were of the adhesive mode.Application of antioxidant agents may increase microtensile bond strength between fiber posts treated with hydrogen peroxide and composite cores. Acetone increased bond strength more than ascorbic acid and ethanol.

Comparative evaluation of microtensile bond strength of different solvent based one step and two step adhesive systems to dentin. An in-vitro study

Aim and Objective:To compare and evaluate the micro tensile bond strength of different solvent based one step and two step adhesive systems to dentin.Materials and Methods:Sixty recently extracted human mandibular premolars were subjected for the study and divided into 4 groups of fifteen each. The adhesive materials Single Bond, Prime and Bond XP, Clearfil S3 Bond and G-Bond were applied to flat dentin surfaces according to the manufacturer's instructions. After resin composite build up, teeth were sectioned to obtain beams with an approximate cross sectional area of 2 mm2 and stressed to failure. Data were analysed statistically by ANOVA and student Neuman Keuls multiple comparison tests.Results:The study demonstrated that Single Bond has better bond strength to dentin compared to the other adhesive systems.Conclusion:Ethanol and water based two-step adhesive Single Bond exhibited significantly higher microtensile bond strength values to dentin among all the adhesive systems tested.

Surface characterisation and bonding of Y-TZP following non-thermal plasma treatment

Objectives(1) To chemically characterise Y-TZP surface via X-ray photoelectron spectroscopy (XPS) and evaluate the surface energy levels (SE) after non-thermal plasma (NTP). (2) To test the microtensile bond strength (MTBS) of Y-TZP bonded to cured composite disks, after a combination of different surface conditioning methods. MethodsTwenty-four Y-TZP discs (13.5mm×4mm) were obtained from the manufacturer and composite resin (Z-100) discs with similar dimensions were prepared. All discs were polished to 600 grit and divided into 8 groups (n=3 disks each), four control (non-NTP treated) and four experimental (NTP treated for 10s) groups. All groups received one of the four following treatments prior to cementation with Rely×Unicem cement: sand-blasting (SB), a Clearfil ceramic primer (MDP), sand-blasting+MDP (SBMDP), or baseline (B), no treatment. SE readings and surface roughness parameters were statistically analysed (ANOVA, Tukey's, p<0.05). Mixed model and paired samples t-tests were used to compare groups on MTBS. ResultsXPS showed increase in O and decrease in C elements after NTP. The polar component increased for BP (42.20mN/m) and SBP (43.77mN/m). MTBS values for groups BP (21.3MPa), SBP (31MPa), MDPP (30.1MPa) and SBMDPP (32.3MPa) were significantly higher in specimens treated with NTP than their untreated counterparts B (9.1MPa), SB (14.4MPa), MDP (17.8MPa) and SBMDP (24.1MPa). Conclusions(1) Increase of O and decrease of C led to higher surface energy levels dictated by the polar component after NTP; (2) NTP application increased MTBS values of Y-TZP surfaces.

Influence of sandblasting granulometry and resin cement composition on microtensile bond strength to zirconia ceramic for dental prosthetic frameworks

ObjectivesTo evaluate the effect of the particle size of sandblasting and the composition of the resin cement on the microtensile bond strength (MTBS) to zirconia. MethodsForty zirconia blocks (Cercon, Dentsply) were polished and randomly treated as follows: Group 1 (NT): no treatment; Group 2 (APA-I): airborne particle abrasion (Cobra, Renfert) using 25-μm aluminium-oxide (Al2O3)-particles; Group 3 (APA-II): APA with 50-μm Al2O3-particles; and Group 4 (APA-III): APA using 110-μm Al2O3-particles. Ceramic blocks were duplicated in composite resin. Samples of each pretreatment group were randomly divided into two subgroups depending on the resin cement used for bonding the composite disks to the treated zirconia surfaces. Subgroup 1 (PAN), which was a 10-MDP-containing luting system, used Clearfil Ceramic Primer plus Panavia F 2.0 (Kuraray) and Subgroup 2 (BIF) used Bifix SE (VOCO) self-adhesive cement. After 24h, bonded specimens were cut into 1±0.1mm2 sticks. MTBS values were obtained using a universal testing machine (cross-head speed=0.5mm/min). Failure modes were recorded and the interfacial morphology of the debonded microbars was SEM-assessed. Two-way ANOVA, Student–Newman–Keuls tests, and the step-wise linear regression analysis were performed with the MTBS being the dependent variable (p<0.05). ResultsDespite the sandblasting granulometry, PAN bonded to air-abraded surfaces attained the highest MTBS and frequently showed mixed fractures. BIF recorded no significant differences in MTBS depending on the conditioning method, and registered the highest rates of premature and adhesive failures. ConclusionsThe 10-MDP-containing luting system seems to be the most suitable to bond zirconium-oxide ceramic, mainly after sandblasting.

Bond strength of a dental leucite-based glass ceramic to a resin cement using different silane coupling agents

AimTo evaluate the effect of different types of novel silane coupling agents with two concentrations on the micro-tensile bond strength of a dental glass ceramic with leucite crystals to a dual-cured resin cement using an optimized method of silane application. MethodsLeucite-reinforced feldspathic ceramic blocks were fabricated, wet ground and cleansed. The bonding ceramic surfaces were treated with different organosilane solutions as follows: Control silane: Monobond S; methacryloxypropyltrimethoxy silane and experimental silanes with two concentrations (1.0 and 2.5vol%): amino, isocyanate, styryl, and acrylate silanes. The silane application method consisted of brush application, hot air drying followed by rinsing with hot water and drying. Then a thin layer of an unfilled resin and a dual-cured resin cement was light-cured on the ceramic surfaces. The resin–ceramic blocks were stored in distilled water at 37°C for 24h and sectioned to produce beam specimens (n=17) with a 1.0mm2 cross-sectional area. Specimens were then subjected to thermocycling and tested in a micro-tensile tester device. Data were analyzed using analysis of variance and Tamhane post-hoc test. ResultsThe mean micro-tensile bond strength value for the styryl silane was significantly higher (P<0.05) than the other types of silanes except for the Monobond S. The mean bond strength values for isocyanate silanes were significantly lower than the other silanes tested (P<0.05). No statistically significant difference in the bond strength between the 1.0 and 2.5vol% of experimental silanes was observed (P>0.05). ConclusionsThe micro-tensile bond strength of the leucite-based dental glass ceramic to a resin cement was affected by the type of silane coupling agent and not by the concentration of silane solutions. The best bond strength overall was achieved by methacryloxypropyltrimethoxysilane and experimental styryl silane solutions.

Effects of Surface Treatments, Thermocycling, and Cyclic Loading on the Bond Strength of a Resin Cement Bonded to a Lithium Disilicate Glass Ceramic

SUMMARY Objectives : The aim of this present study was to investigate the effect of two surface treatments, fatigue and thermocycling, on the microtensile bond strength of a newly introduced lithium disilicate glass ceramic (IPS e.max Press, Ivoclar Vivadent) and a dual-cured resin cement. Methods : A total of 18 ceramic blocks (10 mm long × 7 mm wide × 3.0 mm thick) were fabricated and divided into six groups (n=3): groups 1, 2, and 3-air particle abraded for five seconds with 50-μm aluminum oxide particles; groups 4, 5, and 6-acid etched with 10% hydrofluoric acid for 20 seconds. A silane coupling agent was applied onto all specimens and allowed to dry for five seconds, and the ceramic blocks were bonded to a block of composite Tetric N-Ceram (Ivoclar Vivadent) with RelyX ARC (3M ESPE) resin cement and placed under a 500-g static load for two minutes. The cement excess was removed with a disposable microbrush, and four periods of light activation for 40 seconds each were performed at right angles using an LED curing unit (UltraLume LED 5, Ultradent) with a final 40 second light exposure from the top surface. All of the specimens were stored in distilled water at 37°C for 24 hours. Groups 2 and 5 were submitted to 3,000 thermal cycles between 5°C and 55°C, and groups 3 and 6 were submitted to a fatigue test of 100,000 cycles at 2 Hz. Specimens were sectioned perpendicular to the bonding area to obtain beams with a cross-sectional area of 1 mm(2) (30 beams per group) and submitted to a microtensile bond strength test in a testing machine (EZ Test) at a crosshead speed of 0.5 mm/min. Data were submitted to analysis of variance and Tukey post hoc test (p≤0.05). Results : The microtensile bond strength values (MPa) were 26.9 ± 6.9, 22.2 ± 7.8, and 21.2 ± 9.1 for groups 1-3 and 35.0 ± 9.6, 24.3 ± 8.9, and 23.9 ± 6.3 for groups 4-6. For the control group, fatigue testing and thermocycling produced a predominance of adhesive failures. Fatigue and thermocycling significantly decreased the microtensile bond strength for both ceramic surface treatments when compared with the control groups. Etching with 10% hydrofluoric acid significantly increased the microtensile bond strength for the control group.

Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives

The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24h and 5,000thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers' instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24h, 37°C) or thermocycled (5,000cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α=0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin-dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.

Effect of Etching Time on Resin-Primary Dentin Adhesion and Degradation of Interfaces

The purpose of this research was to evaluate the resin–dentin bond degradation in primary teeth after reducing the etching time. The dentin surfaces were bonded with: an etch and rinse adhesive (single bond-SB); a two step self-etching adhesive (Clearfil self etching bond-CSEB); and a one-step self-etching adhesive (one up bond F-OUB). For half the specimens, the recommended etching time was used (the manufacturer’s instructions); for the other half the etching time was reduced by 50%. The bonded teeth were divided according to different challenging procedures: (a) 24 h storage in distilled water and sectioned into beams (1.0 mm2); (b) immersion of the bonded beams in 10% NaOCl aqueous solution for 5 h; (c) load cycled (5000 cycles, 90 N) and then sectioned into beams. The micro-tensile bond strength (MTBS) was measured and fractographic analysis performed. The data were statistically analyzed using an analysis of variance (ANOVA) technique, together with multiple comparisons tests. The results showed that the OUB produced the lowest MTBS values, regardless of the challenging procedure. After NaOCl immersion, the MTBS decreased in all groups, with the Clearfil self etching bond (immersed for half the time) attained the highest MTBS. Following the instructions for each of the adhesive systems, after load cycling, no differences in MTBS were observed in the samples after 24 h. However when the etching time was shortened, a decrease in MTBS were observed for all groups. In conclusion, shortening the etching/conditioning time caused a significant change to the bond strength which was material dependent. The OUB produced the lowest bond strengths, regardless of other variables; and a reduced conditioning time resulted in an increased bond strength for CSEB adhesive.

The potential effect of proanthocyanidins on the stability of resin-dentin bonds against thermal cycling

To investigate the potential effect of proanthocyanidins (PA), a natural cross-linker, on the stability of resin-dentin bonds against thermal cycling. Ten percent, 15% PA-based preconditioners, and 5% glutaraldehyde were prepared for the transient pretreatment of demineralized dentin before bonding. Specimens without pretreatment were used as negative controls (n = 4 teeth for each group). Microtensile bond strength, failure mode, micromorphologies of resin-dentin interface and the collagen degradation of bonded specimens after thermal cycling were evaluated. After thermal cycling, the microtensile bond strength values of resin-dentin bond in groups pretreated with 15% PA for 120 s and 60 s [(23.09 ± 3.19) and (21.88 ± 3.49) MPa] were significantly higher than that in control group [(15.47 ± 3.78) MPa] (P < 0.05). Mixed fractures were the most prevalent failure mode. Specimens with pretreatment presented compact hybrid layer, while some narrow gaps were found in hybrid layer of non-treated specimens. Collagen biodegradation rates in groups with pretreatment were significantly lower than that in control group (P < 0.05). Among them, specimens pretreated by 15% PA preconditioner for 120 s exhibited the lowest biodegradation rates [(0.316 ± 0.019) mg/g]. The application of natural cross-linker PA on demineralized dentin reduced the bond degradation against aging by thermal cycling, and can be helpful to create more durable bonds to dentin.

Influence of storage time on bond strength of self-etching adhesive systems to artificially demineralized dentin after a papain gel chemical–mechanical agent application

ObjectivesThe aim of this study was to evaluate the influence of storage time on the bond strength of self-etching adhesive systems to artificially demineralized dentin submitted to application of a papain-based chemical mechanical agent for carious tissue removal. Materials and MethodsTwenty-four blocks of human coronal dentin were randomly divided into 2 groups: (1) restored with a two-step self-etching adhesive system (Clearfil SE Bond); (2) restored with a one-step self-etching adhesive system (One-Up Bond F Plus). After artificial caries induction, the specimens were treated with papain-based gel, received an application of the adhesive system according to the respective group, and blocks of microhybrid resin composite measuring 5.0mm high and 5.0mm wide were fabricated incrementally on the tooth, which would later be cut to obtain sticks with a bond area of around 1mm2, for use in the microtensile tests. After this, half of the sticks obtained from each tooth were submitted to the microtensile test 24h later, while the other half were stored in water, in an oven at 37°C for a period of 180d. The specimens were submitted to the microtensile test in a Universal Test Machine at a speed of 0.5mm/min. The surfaces of the fractured test specimens were examined visually under a stereoscopic loupe in order to classify the fracture type. After exploratory analysis of the data, the two-way Analysis of Variance (ANOVA) and the Tukey test were applied. The data on the fracture types were analyzed by the Exact Fisher test. ResultsNo statistically relevant differences were verified among the means of the microtensile bond strength values of the adhesive systems evaluated in the different storage times. Mixed and adhesive fractures types were observed for both groups. ConclusionStorage time did not influence the bond strength of the two-step or one-step self-etching adhesive systems to artificially demineralized dentin submitted to application of a papain-based chemical mechanical agent for carious tissue removal. Both adhesive systems provided similar bond strength at different storage times.

The Effect of Surface Treatment of the Interfacial Surface on Fatigue‐Related Microtensile Bond Strength of Milled Zirconia to Veneering Porcelain

The success of zirconia-reinforced all-ceramic crowns depends on the formation of a stable bond between the zirconia core and the veneering porcelain. The purpose of this study was to test the effects of liner application and airborne particle abrasion of a postsintered Y-TZP core on the bond strength between the zirconia core and veneering porcelain with or without cyclic loading. Kavo Everest® Y-TZP blank disks were sintered and divided into three treatment groups: airborne particle abrasion, IPS e.max® Ceram Zirliner application, or no surface treatment. The disks were then veneered with IPS e.max® ZirPress veneering porcelain. Half the veneered disks from each group were cyclically loaded. This created six experimental groups: three surface treatment groups cyclically loaded and three not loaded. The disks were then sectioned into microbars for microtensile bond strength (MTBS) testing (40 specimens per group). Specimens were luted to a fixture mount and loaded to failure using a universal testing machine (MTS Insight). The maximum force was measured and bond strength computed. Data were analyzed with a two-way ANOVA and Tukey's HSD test (α= 0.05). Airborne particle abrasion significantly decreased MTBS values (p= 0.043), and ZirLiner application did not have a significant effect on MTBS values compared to control. Cyclic loading did not have a significant effect on MTBS values. The predominant failure mode in all groups was mixed. Airborne particle abrasion of the interfacial surface of the Everest® Y-TZP core significantly decreased the MTBS to ZirPress veneering porcelain when compared to no interfacial surface treatment. Application of ZirLiner to the interfacial surface of the Everest® Y-TZP core did not significantly increase or decrease the MTBS to ZirPress veneering porcelain, compared to the other surface treatments. Cyclic loading did not affect bond strengths in any of the groups, regardless of surface treatment. Neither cyclic loading nor surface treatment affected the failure mode of the specimens.

Effect of ascorbic acid, ethanol and acetone on adhesion between the treated fiber posts and composite resin cores

PURPOSEThe aim of the present study was to assess the effect of ascorbic acid, ethanol and acetone on microtensile bond strength between fiber posts pre-treated with hydrogen peroxide and composite resin cores.MATERIALS AND METHODSTwenty four fiber posts were pre-treated with 24% hydrogen peroxide and divided into 4 groups as follows: G1: no treatment, as control group; G2: treatment with 10% ascorbic acid solution for 5 minutes; G3: treatment with 70% ethanol solution for 5 minutes; and G4: treatment with 70% acetone solution for 5 minutes. Each fiber post was surrounded by a cylinder-shaped polyglass matrix which was subsequently filled with composite resin. Two sections from each sample were selected for microtensile test at a crosshead with speed of 0.5 mm/min. Statistical analyses were performed using one-way ANOVA and a post hoc Tukey HSD test. Fractured surfaces were observed under a stereomicroscope at ×20 magnification. The fractured surfaces of the specimens were observed and evaluated under a SEM.RESULTSMeans of microtensile bond strength values (MPa) and standard deviations in the groups were as follows: G1: 9.70±0.81; G2: 12.62±1.80; G3: 16.60±1.93; and G4: 21.24±1.95. G4 and G1 had the highest and the lowest bond strength values, respectively. A greater bond strength value was seen in G3 compared to G2. There were significant differences between all the groups (P<.001). All the failures were of the adhesive mode.CONCLUSIONApplication of antioxidant agents may increase microtensile bond strength between fiber posts treated with hydrogen peroxide and composite cores. Acetone increased bond strength more than ascorbic acid and ethanol.

Resin bonding to a feldspar ceramic after different ceramic surface conditioning methods: evaluation of contact angle, surface pH, and microtensile bond strength durability

To evaluate the surface pH, contact angle and microtensile bond strength (MTBS) of a resin-cement to feldspathic ceramic after various surface conditioning methods (SC). For pH measurements, 96 glass-ceramic disks were assigned into 12 groups (n = 8): SC1-pH: No ceramic surface conditioning (control); SC2-pH: hydrofluoric-acid (HF) 9% 1 min; SC3-pH: SC2-pH+wash/dry; SC4-pH: SC3-pH+silane; SC5-pH: HF 4% 1 min; SC6-pH: SC5-pH+wash/dry; SC7-pH: SC6 -pH +silane; SC8-pH: HF 5% 1 min; SC9-pH: SC8-pH+wash/dry; SC10-pH: SC9-pH+silane; SC11-pH: SC9-pH +neutralizer+wash/dry+sonic-cleaning; SC12-pH: SC11-pH+silane. For contact angle analysis, 40 disks were divided into 5 groups (n = 8): SC1-ca: no conditioning; SC2-ca: HF 9%+wash/dry; SC3-ca: HF 4%+wash/dry; SC4 -ca: HF 5%+wash/dry; SC5-ca: HF 5%+neutralizer+wash/dry+ultrasonic-cleaning. To evaluate the MTBS, 40 blocks were distributed into 4 groups SC (N = 10): SC1-bond: HF 9% 1 min+silane; SC2-bond: HF 4% 1 min+silane; SC3-bond: HF 5% 1 min+silane; SC4-bond: HF 5% 1 min+neutralizer+wash/dry+ultrasonic cleaning+silane. The resin cement was applied on the treated surfaces and bar specimens were produced that were submitted to 2 conditions: dry: immediate MTBS; TC: storage for 150 days and thermocycling 5000x. Fifty bar specimens were produced per group (n = 50). Contact angle and pH results were submitted to one-way ANOVA and Tukey's test (α = 0.05). Microtensile data were submitted to two-way ANOVA and Tukey's test (a = 0.05). pH values were significantly higher for SC6-ph (11.5 ± 2.6) when compared to those of SC5-pH (2.7 ± 0.4), SC8-pH (2.7 ± 0.2) and SC2-pH (2.2 ± 0.2) (p < 0.00, ANOVA). SC1-ca had the largest contact angle (48 ± 16 degrees) and SC3-ca the smallest (9.4 ± 7.7 degrees). The results of the MTBS test were as follows: independent of the storage condition, SC2-bond = SC1-bond > SC3-bond = SC4-bond. SC4-bond had the lowest MTBS value after TC (10.6 ± 2.6 MPa). The acid neutralization step appears to be dispensable, since the washing/drying promoted similar pH values. That condition promoted a high contact angle and unstable resin microtensile bond strength to glass ceramic.

Clinical performance of self-etching adhesives with saliva contamination.

The aim of this clinical study was to investigate the influence of salivary exposure on microtensile bond strength of one self-etching adhesive resin. Thirty carious premolars were divided into two groups: a rubber-dam was either inserted before or after cavity preparation and the cavities were restored using direct composite resin. After extraction, the teeth were sectioned into microbars and the microtensile bond strength (MTBS) test was conducted (a = 0.05). Scanning electron microscopy (SEM) and silver nitrate staining to detect nanoleakage were conducted to evaluate the sealing quality of the bonded interface. Statistical analysis revealed that placement of rubber-dam before cavity preparation resulted in significantly higher MTBS values (24 ± 2 MPa) and predominantly cohesive failures (85%). SEM of specimens exposed to saliva revealed the presence of structural defects at the tooth/resin interface and pull-out of shorter resin tags. Silver nitrate nanoleakage confirmed these findings as well. It is recommended to insert a rubber-dam before commencing with cavity preparation in order to ensure strong and durable bond strength.

Influence of resin composite mechanical properties on adhesive microtensile bond strength to dentin.

To determine the influence of mechanical properties of resin-based composites on the microtensile bond strength to dentin of all-in-one adhesives. Microtensile bond strengths were measured with the non-trimming technique for the experimental groups: 1) Bond Force/Estelite Σ (Tokuyama); 2) G-Bond Plus (GC)/Estelite Σ; 3) Bond Force/Gradia Direct Anterior (GC);4) G-Bond Plus/Gradia Direct Anterior; 5) Bond Force/Gradia Direct LoFlo (GC); 6) G-Bond Plus/Gradia Direct LoFlo. The following mechanical properties of the resin-based composites were assessed: tensile strength, flexural strength, tensile elastic modulus, shear elastic modulus, Poisson's ratio, Vicker's hardness, contraction stress. Three-dimensional models of microtensile beams were created for finite element analysis of the first principal stress values and distribution in the adhesive layer during microtensile testing. Statistical tests were applied to microtensile bond strength values (two-way ANOVA) and to data from mechanical tests (one-way ANOVA). In all the analyses, the level of significance was set at p < 0.05. While the adhesive did not significantly influence microtensile bond strength, the composite was a significant factor. Regardless of the adhesive, Estelite Σ yielded significantly higher bond strengths than Gradia Direct Anterior and Gradia Direct LoFlo, that were comparable. Adhesive-composite interactions were not statistically significant. Estelite Σ had the highest Vicker's hardness, the highest tensile and shear elastic moduli, the lowest and closest to dentin Poisson's ratio. A more favorable stress distribution in the adhesive layer occurred in the Estelite Σ model. When comparing the bonding potential of several adhesives with the microtensile technique, the same resin composite should be used in all the experimental groups for building up the coronal portion.

Influence of Surface Nano-roughness of Dental Alumina Ceramic on Bond Strength to Dual-Cure Resin Cements

The goal of this research is to evaluate the effect of sandblasting and silica coating on the nano-roughness and on the microtensile bond strength (MTBS) of glass-infiltrated alumina bonded to different resin cements. Six slabs of In-Ceram Alumina (Vita) were randomly treated according to the following groups: (1) no treatment; (2) sandblasting (125 μm Al2O3-particles); and (3) tribochemical silica-coating (50 μm silanated silica particles). Nano-roughness (Ra) was assessed under an atomic force microscope (AFM). Such surface treatments were also applied to nine In-Ceram Alumina CAD/CAM blocks. Ceramic blocks were duplicated in composite resin, and composite samples were bonded to the conditioned surfaces. Each pre-treatment group was divided into three subgroups depending on the resin cement system: (1) Clearfil Ceramic Primer plus Clearfil Esthetic Cement (CEC, Kuraray); (2) RelyX Unicem (RXU, 3M); and (3) Calibra Silane plus Calibra Resin Cement (CAL, Dentsply). After 24 h, the bonded specimens were cut into 1±0.2 mm2 sticks. The MTBS values (MPa) were obtained using a universal testing machine (crosshead speed: 0.5 mm/min). Failure modes were recorded using a scanning electron microscope (SEM). Nano-roughness and MTBS data were analyzed by ANOVA and Student–Newman–Keuls tests (α =0.05). No significant changes in nano-roughness occurred after conditioning. The MTBS of CEC and RXU were comparable despite the surface treatment. All CAL-sticks debonded prematurely. Ceramic pre-treatments, such as sandblasting or silica coating, do not affect the alumina's surface nano-roughness or bond strength. The MDP monomers dissolved in the CEC Primer and the functional dimethacrylate monomers present in the self-adhesive RXU may be the key to successful bonds to alumina.

Bond strength and nanoroughness assessment on human pretreated cementum surfaces

Objectives To determine the bond strength of seven adhesive systems to human cementum, and to assess the promoted surface roughness. Methods Extracted human canines were used for the present study. The mesial surface from the cervical third of the roots were ground flat with wet 600-grit silicon carbide paper and bonded. Seven adhesive systems were employed: an etch-and-rinse adhesive (Single Bond), two two-step self-etching (Clearfil SE Bond and Resulcin Aquaprime) and four one-step self-etching (One-up Bond F, Prompt-L-Pop, Etch and Prime 3.0 and NRC+Prime&Bond NT). Composite build-ups were constructed and stored in a humid environment for 24 h at 37 °C. Specimens were sectioned into 1 mm 2 beams and tested for microtensile bond strength (MTBS). Additional surfaces were conditioned for atomic force microscopy (AFM) analysis. Results were analyzed with ANOVA and Student–Newman–Keuls tests ( P < 0.05). Results Single Bond showed the highest MTBS values. No differences were found between Resulcin Aquaprime, One-up Bond and Prompt-L-Pop. Clearfil SE Bond, Etch and Prime and NRC+Prime&Bond NT obtained the lowest bond strength values. H 3PO 4 acid treatment of cementum and Resulcin Aquaprime showed the highest nanoroughness parameters and One-up Bond the lowest. Conclusion The etch-and-rinse adhesive and the two-step self-etching adhesive with the lowest pH value promoted the highest bond strength to human cementum surfaces.

Effect of Different Bonding Strategies on Adhesion to Deep and Superficial Permanent Dentin

To evaluate the effect of different bonding strategies on the microtensile bond strength to deep and superficial permanent dentin. Forty-eight teeth were randomly flattened according to the dentin depth: superficial dentin (SD) and deep dentin (DD). Subsequently, three adhesive systems were applied (n=8): an etch-and-rinse (Adper Single Bond 2 - SB), a "mild" two-step self-etching (Clearfil SE Bond - SE) and a one-step self-etching adhesive system (Futurabond - FB). Each specimen was restored with a composite resin and sectioned into 1.0-mm(2) thick slabs. After 24 hours, resin-dentin sticks were submitted to tensile stress in a universal testing machine (0.5 mm/min). Data were submitted to two-way ANOVA and Tukey's test at a level of 0.05%. Superficial dentin showed the highest microtensile bond strength values, which differed statistically from those obtained in the deep dentin, irrespective of the adhesive system used. FB yielded the highest bond strength values, which were statistically similar to the bond strength values of SE, but statistically different from those obtained when the SB adhesive was used. Bond strength obtained in superficial dentin was significantly higher than in deep dentin, for all adhesive systems tested. Adhesion was affected by the different bonding strategies: the one-step, low pH, acetone-based self-etching adhesive promoted the higher bond strength values, which were statistically similar to those obtained with the two-step, water-based self-etching adhesive.