Microshear Bond Strength Values Research Articles

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.

The Micro-Shear Bond Strength of Various Resinous Restorative Materials to Aged Biodentine.

Introduction:The type of materials and application time of veneering restorations on calcium silicate cements are important factors which influence the interfacial properties. The aim of this study was to measure the micro-shear bond strength of a resin composite (RC) using several adhesive systems and a resin-modified glass ionomer cement (RM-GIC) to different aged Biodentine specimens. Methods and Materials:A total of 15 Biodentine blocks were prepared and assigned to three aging periods: 12 min, one week and one month. Then they were subdivided into five sub-groups to receive cylinders of resinous materials. RC was applied using different adhesive systems: A) no adhesive B) etch and rinse C) two-step self-etch and D) universal adhesive in self-etch mode and E) RM-GIC applied directly over Biodentine. Micro-shear bond strength was measured and the data were analyzed using one-way and two-way ANOVA. The level of significance was set at 0.05. Result:There was significant interaction between Biodentine aging periods and resinous materials (P<0.05). The highest value was obtained in group D bonded to the recently set Biodentine. Increasing the aging period to one week resulted in increased micro-shear bond strength in all groups expect for group D. One-month incubation time led to reduced shear bond strength in group A, C and D. Micro-shear bond strength values of group E increased to the longer aged Biodentine. Conclusion:Group D showed the highest bond strength to freshly mixed Biodentine.

INFLUENCE OF BLEACHING ON COLOUR AND SURFACE ROUGHNESS, AND MIRCOSHEAR BOND STRENGTH OF REPAIR, FOR NOVEL HYBRID CERAMIC

Objective: This study investigated the effect of bleaching on the colour, surface roughness, and microshear bond strength of repair composite to a hybrid ceramic material, CERASMART. Methods: This study was conducted in two parts; first effect of bleach on the colour and surface roughness, secondly effect of bleaching on mirco-shear (µSBS) bond strength. 8 Plate specimens of a CAD/CAM hybrid ceramic (CERASMART, GC) were cut using isomet saw (Beuhler, Germany). To assess colour (ΔE) and surface roughness (Ra) (n= 6) were used; and to assess microshear bond strength (µSBS) 18 specimens were prepared; (n=9) composite micro-cylinders were bonded each to an unbleached and bleached CERASMART plate. Colour and surface roughness were evaluated before, and after bleaching. A spectrophotometer was used to assess colour, surface roughness was assessed using a digital microscope at 120X magnification and an image software were analyzed using WSxM software. MicroShear bond strength (µSBS) was tested in a universal testing machine at a crosshead speed of 0.5 mm/min, using orthodontic wire loop (0.014” in diameter) wrapped around the bonded micro-cylinder. Failure modes were investigated with a digital camera at 35X. Data were analyzed with Test with α = 0.05. Results: (ΔE1.54) was more than 1 and less than 2. Mean (Ra) values were [0.2516 ± 0.0024µm] for unbleached, and [0.2511 ± 0.0025µm] for bleached, showing no statistically significant difference between resultant (Ra) values. Mean microshear bond strength (µSBS) values showed [19.6 ± 5.2 MPa] for unbleached, and [20.1 ± 3.7MPa] for bleached, showing no statistically significant difference between resultant (µSBS). Failure modes were predominately mixed (combined adhesive and cohesive in the repair material). Conclusion: Bleaching did not affect the repair potential of CERASMART material. Colour was affected however, it is not clinically perceptible. Bleaching did not affect surface roughness.Clinical implications repair can be safely performed on bleached hybrid ceramic, even immediately after bleaching without influencing the bond strength.

Bond Strength of Self-adhesive Resin Cement to Different Root Perforation Materials

IntroductionDifferent materials have been used for intervening in root perforations. These materials are often in contact with resin cements used for cementation of intraradicular retainers. The aim of this study was to evaluate the bond strength of self-adhesive resin cement to different materials used to treat root perforations (mineral trioxide aggregate [MTA], Portland cement [PORT], and glass ionomer cement [GIC]). MethodsFour discs (10 × 1 mm) of each material (the MTA, PORT, and GIC groups) were embedded into polyvinyl chloride tubes using acrylic resin, ground, and polished until a flat surface was exposed. Afterward, 4 silicone molds were used to prepare self-adhesive resin cement cylinders (0.7 × 1 mm) on each disc surface (N = 16). The specimens were stored in deionized water at 37°C for 24 hours and subjected to a microshear test. Then, the failure modes were examined. Data were submitted to statistical analysis (α = 0.05). ResultsThe MTA and GIC groups showed significantly higher microshear bond strength values (3.36 ± 1.56 and 2.90 ± 1.49 MPa, respectively) than the PORT group (1.39 ± 0.77 MPa) (P < .05). Only adhesive failure modes were observed. ConclusionsWhen PORT was used as a root perforation material, GIC should be used as a base over it to improve shear bond strength with self-adhesive resin cement.

Correlation between antioxidant activity and bonding strength on bleached enamel

Objective: This study used the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method to evaluate the percentage of antioxidant activity (%AA) of green tea (GT) and sodium ascorbate (SA) gel in three concentrations (10%, 20% and 30%), and the influence of these concentrations on the microshear bond strength (μ-SBT) values of bleached enamel, using 10% carbamide peroxide (CP).Materials and methods: Eighty intact third molars were selected to perform the μ-SBT test, and were randomly divided into eight experimental groups: G1: positive control – no treatment; G2: negative control – bleached with CP; G3: PC +10% GT; G4: PC +20% GT; G5: PC +30% GT; G6: PC +10% SA; G7: PC +20% SA and G8: PC +30% SA. After applying the treatments, adhesive procedures were performed using Single Bond 2 and Filtek Z350XT. After 24 h, the samples were tested in a universal testing machine until fracture. The %AA was assessed in triplicate by DDPH method using a UV–VIS spectrophotometer.Results: In the μ-SBT, ANOVA revealed no significant difference between the antioxidants evaluated (p = .625), but did reveal significant effects of the concentrations studied (p = .007). A negative correlation was observed between μ-SBT and solution concentrations. The values of %AA were from 90.58 to 96.75.Conclusions: The reverse results occurred in μ-SBT values, only when the antioxidants were used in a 10% concentration and, %AA did not influence μ-SBT.

Effect of Storage Time on Bond Strength Performance of Multimode Adhesives to Indirect Resin Composite and Lithium Disilicate Glass Ceramic.

To investigate the bond strength performance of multimode adhesives (MMAs) to indirect resin composite and lithium disilicate glass ceramic after 24 hours or one year of water storage. Thirty flat and polished plates of indirect resin composite (Epricord) and thirty lithium disilicate glass ceramic plates (IPS e.max Press) were prepared. Surfaces were pretreated using sandblasting (indirect resin composite) or hydrofluoric acid (glass-based ceramic). Specimens were bonded with one of two MMAs (Scotchbond Universal [SBU] or All-Bond Universal [ABU]) or ceramic primer and hydrophobic bonding (RelyX Ceramic Primer and Adper Scotchbond Multi-Purpose Bond) as a control (n=10). Resin cement cylinders (0.75 mm in diameter × 0.5 mm in height) were bonded to both substrate surfaces using the respective adhesives. After 24 hours or one year of water storage, bonding performance was measured by microshear bond strength (MSBS) testing. Results were analyzed using three-way ANOVA with Bonferroni post hoc tests (α=0.05). For indirect resin composite, significantly higher MSBS values were found for ABU after 24 hours (ABU > SBU = control); however, no significant difference among the adhesives was observed after one year (p>0.05). For glass-based ceramic, significantly different bond strengths were observed among the adhesives after 24 hours (control = ABU > SBU) and one year (control > SBU = ABU; p<0.05). Both MMAs tested can be considered effective alternatives for bonding to sandblasted indirect resin composite after aging, as they showed similar bond performance to that of the control group. However, separate bottles of silane bonding resin showed higher MSBS values and more durable bonding for etched glass-based ceramic.

Active and Passive Application of the Phosphoric Acid on the Bond Strength of Lithium Disilicate.

The objective of this study was to evaluate the effect of passive or active phosphoric acid (PA) application after hydrofluoric acid (HA) treatment on the microshear bond strength of lithium disilicate. Thirty ceramic discs were made with IPS Emax 2 (10 mm thick and 10 mm diameter). The specimens were divided into 3 groups, A: 9.6% HA application; AF: 9.6% HA application + cleaning with 37% PA in passive mode and AFF: 9.6% HA application + cleaning with 37% PA in active mode. For the microshear test, four tygons (0.9 mm diameter and 0.2 mm high) were filled with resin cement (RelyX Ultimate) and placed on the ceramic disks. After testing, the fracture modes were examined under scanning electron microscopy. Data were analyzed by one-way ANOVA and Tukey's post test (α=0.05). The bond strength values were significantly higher in Group AFF (11.0±2.5 MPa) compared with group A (8.1±2.6 MPa) (p<0.002). AF group was not statistically different (9.4±2.5 MPa) from Group A. It was concluded that the active application of 37% PA after 9.6% HA increases the microshear bond strength values between the resin cement and lithium disilicate ceramic.

EFFICACY OF INTRACORONAL BLEACHING USING NON THERMAL ATMOSPHERIC PRESSURE PLASMA AND ITS EFFECT ON PULP CHAMBER DENTIN. AN INVITRO STUDY

Aim: The aim of this study was to evaluate the efficacy of intracoronal bleaching using non thermal atmospheric pressure plasma and its effect on pulp chamber dentin structure. Materials and methods: Two types of commercially available hydrogen peroxide bleaching systems were used in this study with a concentration of 32% (White smile GmbH). Thirty eight single rooted premolars were collected. The teeth were sectioned in half longitudinally in a mesio-distal direction and specimens were prepared according to the testing method used. Specimens were stained with a prepared standardized coffee solution. The sectioned teeth were divided into four groups according to the type of bleaching protocol used. Color measurements were done by a spectrophotometer before bleaching, one day and one week after bleaching for all the experimental groups. Universal Testing Machine with cross head speed of 1 mm/min was used for measuring microshear bond strength of the four investigated groups before and after bleaching. Data were analyzed statistically by: Duncan Multiple range test for means comparison and Paired t test for evaluating the effect of time and intervals on different parameters within each bleaching protocol. The significance level was set at P ≤ 0.05. Results: The results showed different findings among the bleached groups when evaluated after 1 day and 7 days. It was found that non thermal atmospheric plasma has a stronger bleaching effect than LED light when used as an activating method. Furthermore, the light bleached group showed a significant decrease in the microshear bond strength values after bleaching. While, there was no statistically significant difference in microshear bond strength values of the other three groups. Conclusion: The application of non thermal atmospheric pressure plasma is a promising method for intracoronal bleaching.

Effect of 180-Day Water Storage on Bonding Effectiveness of Self-Adhesive Systems to Occlusal and Proximal Dentin.

This study aimed to evaluate the microshear bond strength (μSBS) values of adhesive systems to occlusal and proximal dentin submitted to water storage aging. Occlusal and proximal dentin surfaces were obtained from 90 molars, polished with 600-grit SiC and divided according to the type of adhesive system: one total-etch and two self-etch. Starch tubing was used to perform 1 mm2 cylindrical composite resin restorations. The specimens were aged in distilled water during different storage times: 24 hours, 3 months, and 6 months (n = 10). The specimens were submitted to μSBS test. The μSBS values in MPa were subject to three-way ANOVA and post hoc Tukey test (p < 0.05). There was no statistical difference in the μSBS values among the storage times (p = 0.72); however, the dentin region (p < 0.01) and the adhesive system (p < 0.01) significantly affected the μSBS. The proximal surface (14.7 ± 3.3 MPa) presented higher μSBS values than the occlusal dentin (10.9 ± 4.1 MPa). The all-in-one adhesive system (GB) achieved the highest μSBS mean (17.0 ± 1.7 MPa). Both material and dentin surface factors affected the composite-dentin bond strength; however, the water storage did not influence bonding effectiveness over time.

Performance of universal adhesives on bonding to leucite-reinforced ceramic.

BackgroundThis study aimed to investigate the microshear bond strength of universal bonding adhesives to leucite-reinforced glass-ceramic.MethodsLeucite-reinforced glass-ceramic blocks were polished and etched with 9.5% hydrofluoric acid for 1 min. The specimens were assigned to one of four groups based on their surface conditioning (n = 16): 1) NC: negative control with no further treatment; 2) SBU: Single Bond Universal (3M ESPE); 3) ABU: ALL-BOND Universal (Bisco); and 4) PC: RelyX Ceramic Primer and Adper Scotchbond Multi-Purpose Adhesive (3M ESPE) as a positive control. RelyX Ultimate resin cement (3M ESPE) was placed on the pretreated ceramic and was light cured. Eight specimens from each group were stored in water for 24 h, and the remaining eight specimens were thermocycled 10,000 times prior to microshear bond strength evaluation. The fractured surfaces were examined by stereomicroscopy and scanning electron microscopy (SEM).ResultsAfter water storage and thermocycling, the microshear bond strength values decreased in the order of PC > SBU and ABU > NC (P < 0.05). Thermocycling significantly reduced the microshear bond strength, regardless of the surface conditioning used (P < 0.05). Cohesive failure in the ceramic and mixed failure in the ceramic and resin cement were observed in the fractured specimens. The percentage of specimens with cohesive failure after 24 h of water storage was: NC (50%), SBU (75%), ABU (75%), and PC (87%). After thermocycling, the percentage of cohesive failure in NC decreased to 25%; however, yet the percentages of the other groups remained the same.ConclusionsAlthough the bond strength between resin and hydrofluoric acid-etched glass ceramic was improved when universal adhesives were used, conventional surface conditioning using a separate silane and adhesive is preferable to a simplified procedure that uses only a universal adhesive for cementation of leucite-reinforced glass-ceramic.

Microshear bond strength evaluation of surface pretreated zirconia ceramics bonded to dentin.

Objectives:To comparatively assess the micro shear bond strength (MSBS) of dentin bonded surface pre-treated zirconia ceramics.Materials and Methods:Zirconia blocks were sectioned into 50 cubical blocks. The blocks were further categorized into five groups (n = 10 each). Group I: No treatment was performed on zirconia samples; Group II: The zirconia samples were sand-blasted; Group III: Group II + etched with 9.8% of hydrofluoric (HF) acid for 60 s; Group IV: The sandblasted zirconia samples were selectively infiltrated with low fusing porcelain; and Group V: Group IV + etched using 9.8% HF acid gel. The zirconia specimens were then bonded to dentin samples, and the samples were tested for MSBS evaluation using universal testing machine.Results:The MSBS of all the four experimental groups shows greater value than group I. Among the experimental groups, group V and group IV do not show any statistical significant difference, whereas the mean MSBS of groups IV and V were statistically greater than group III and group II. However, groups I, II, and III do not show any statistical significant difference in mean MSBS values between them.Conclusion:Selective infiltration etching of zirconia ceramics provides the highest bond strength with resin cement.

Effect of Er:YAG laser and diamond drill on hybrid layer morphology obtained with self-etch adhesive – analysis by SEM and confocal laser scanning microscopy (CLSM)

This study aimed to evaluate the effect of Er:YAG (L) and diamond drills (DD) on: 1) the microshear bond strength (MPa); 2) the adhesive interface of two-step (TS) – Adper Scotchbond Multipurpose and one-step (OS) adhesives – Adper EasyOne, both from 3M ESPE. Material and methods:According to the preparation condition and adhesives, the samples were divided into four groups: DD_TS (control); DD_OS; L_TS and L_OS. 60 bovine incisors were randomly divided into experimental and groups: 40 for microshear bond strength (n = 10) and 20 for the adhesive interface morphology [6 to measure the thickness of the hybrid layer (HL) and length of tags (t) by CLSM (n = 3); 12 to the adhesive interface morphology by SEM (n = 3) and 2 to illustrate the effect of the instruments on dentine by SEM (n = 1)].To conduct the microshear bond strength test, four cylinders (0.7 mm in diameter and 1 mm in height with area of adhesion of 0.38 mm) were constructed with resin composite (Filtek Z350 XT – 3M ESPE) on each dentin surface treated by either L or DD and after adhesives application. Microshear bond strength was performed in universal testing machine (EMIC 2000) with load cell of 500 kgf and a crosshead speed of 0.5 mm / min. Adhesive interface was characterized by thickness of hybrid layer (HL) and length of tags (t) in nm, with the aid of UTHSCSA ImageTool software. Results: Microshear bond strength values were: L_TS 34.10 ± 19.07, DD_TS 24.26 ± 9.35, L_OS 33.18 ± 12.46, DD_OS 21.24 ± 13.96. Two-way ANOVA resulted in statistically significant differences only for instruments (p = 0.047). Mann-Whitney identified the instruments which determined significant differences for HL thickness and tag length (t). Concerning to the adhesive types, these differences were only observed for (t). Conclusion: It can be concluded that 1) laser Er:YAG results in higher microshear bond strength values regardless of the adhesive system (TS and OS); 2) the tags did not significant affect the microshear bond strength; 3) the adhesive interface was affected by both the instruments for cavity preparation and the type of adhesive system used.

Repair on silorane-based composite

Silorane-based composites have low polymerization shrinkage and good color stability. However, the effectiveness and the best surface treatment to carry out repairs to this type of restoration is unclear. Objective: To evaluate the effect of different types of repair made on a silorane-based composite. Material and methods: 80 disks of silorane-based composite were prepared (Filtek P90, 3M ESPE) and divided into eight groups (n = 10), according to the surface treatment being carried out before repairs of either the same silorane composite or a dimethacrylate material (Filtek Z350, 3M ESPE) were conducted. In two groups the immediate adhesion without repair (positive control) was evaluated. In other two groups repairs without any surface treatment (negative control) were evaluated. Surface treatments before the repair of the four remaining groups included the application of adhesive systems specific to silorane (Silorane System Adhesive, 3M ESPE) or to dimethacrylate (Adper Single Bond 2, 3M ESPE) and roughening followed by application of adhesive system. All groups were stored into distilled water at 37°C for 1 week prior to the microshear bond strength evaluation. Results: The group immediate adhesion silorane-dimethacrylate and group repair silorane-dimethacrylate without surface treatment showed lower microshear bond strength values and were statistically different from groups with surface treatment and immediate adhesion silorane-silorane (p &lt; 0.05). Conclusion: Surface treatments with application of adhesive systems compatible with the repair material or roughening prior to the application of these adhesive systems are suitable for repairing silorane-based composites.

CPP–ACP pretreatment effect on microshear bond strength of simplified etch-and-rinse adhesive systems plus a flowable composite to enamel

This study evaluated the effect of a casein phosphopeptide–amorphous calcium phosphate based paste (MI Paste) on the microshear bond strength (MSBS) of different simplified etch-and-rinse adhesive systems on enamel. Roots were removed from 90 bovine incisors, and the facial enamel was ground flat. Teeth were randomized into nine groups, according to the enamel pretreatment (without or with application of MI Paste for 1 or 2 min) and the adhesive system used (Single Bond, Stae, or Ambar). Composite cylindrical blocks (2 mm height × 1 mm diameter) were built, stored in water for 24 h, and subjected to the microshear test in a universal testing machine with a load of 0.5 mm/min. Failure modes were analyzed using scanning electron microscopy. Data were submitted for statistical analysis by a two-way ANOVA, followed by multiple comparisons with Tukey test (α = 5%). The Ambar group presented the highest MSBS values. Pretreatment with MI Paste for 2 min improved bonding in the Single Bond and Stae groups. In all groups, adhesive failures were most frequent. In conclusion, Ambar presented better performance and did not need any pretreatment. The enamel MSBS of the other simplified adhesive systems was improved by the pretreatment with MI Paste, depending on the time of application.

Does the light source affect the repairability of composite resins?

The aim of this study was to examine the effect of the light source on the microshear bond strength of different composite resins repaired with the same substrate. Thirty cylindrical specimens of each composite resin--Filtek Silorane, Filtek Z550 (3M ESPE), Gradia Direct Anterior (GC), and Aelite Posterior (BISCO)--were prepared and light-cured with a QTH light curing unit (LCU). The specimens were aged by thermal cycling and divided into three subgroups according to the light source used--QTH, LED, or PAC (n = 10). They were repaired with the same substrate and a Clearfil Repair Kit (Kuraray). The specimens were light-cured and aged for 1 week in distilled water at 37 °C. The microshear bond strength and failure modes were assessed. There was no significant difference in the microshear bond strength values among the composite resins, except for the Filtek Silorane group that showed significantly lower bond strength values when polymerized with the PAC unit compared to the QTH or LED unit. In conclusion, previously placed dimethacrylate-based composites can be repaired with different light sources; however, if the composite to be repaired is silorane-based, then using a QTH or LED device may be the best option.

The effect of resin infiltration and oxidative pre‐treatment on microshear bond strength of resin composite to hypomineralised enamel

Reduced bond strengths of resin composites to hypomineralised enamel increase restorative failure. To investigate if the adhesion of resin composite to hypomineralised enamel can be improved by pre-treatments: resin infiltration, oxidative pre-treatment followed by a resin infiltration, or oxidative pre-treatment. Twenty-one enamel specimens in each of five Groups: 1) Normal enamel; 2) Hypomineralised enamel; 3) Hypomineralised enamel pre-treated with a resin infiltrant, (Icon(®)); 4) Hypomineralised enamel pre-treated with 5.25% sodium hypochlorite then treatment with resin infiltrant; 5) Hypomineralised enamel pre-treated with 5.25% sodium hypochlorite. A resin composite rod was bonded to each specimen using Clearfil™ SE bond as the adhesive (hereafter termed 'routine bonding'), then subjected to microshear bond strength (MSBS) testing. Overall, the mean MSBS between the five groups differed significantly (P = 0.001). Pre-treatment of hypomineralised enamel with 5.25% sodium hypochlorite with or without subsequent resin infiltration in Groups 4 and 5 prior to routine bonding resulted in increased mean MSBS compared to Groups 2 and 3, with mean MSBS values not differing significantly when compared to routine bonding to normal enamel. Increased bond strength of resin composite to hypomineralised enamel was obtained by pre-treatment of hypomineralised enamel specimens with 5.25% sodium hypochlorite with or without subsequent resin infiltration.

Starch tubing: an alternative method to build up microshear bond test specimens.

To evaluate an alternative device using starch tubes to build up resin composite specimens for microshear bond tests. Twenty human molars were selected and sectioned mesiodistally to obtain two sections. The teeth were randomly divided into 4 groups (n = 10) according to the adhesive system - a two-step etch-and-rinse adhesive (Adper Single Bond) and a two-step self-etching adhesive (Clearfil SE Bond) - and the type of tube, starch or polyethylene. The tubes were evaluated under a stereomicroscope at 25X magnification to observe the variation in internal diameter. The resin composite was bonded to flat enamel surfaces using one of the adhesive systems and tube types. After 24 h storage in distilled water, the microshear bond strength (µSBS) was determined and the fracture pattern was analyzed under a stereomicroscope (400X magnification). The microshear bond strength values were subjected to two-way ANOVA. The chi-square test was used to compare pre-test failures and fracture patterns between the groups (p < 0.05). The type of tube, the adhesive system, and their interaction did not influence the bond strength values (p = 0.062, p = 0.122, and p = 0.301, respectively). No significant differences were observed for pre-test failures or fracture patterns (p = 0.320 and p = 0.561, respectively). Using starch tubes is an alternative to build up composite resin specimens for microshear bond strength testing with the two tested adhesive systems.

Evaluation of micro-shear bond strength of resin modified glass-ionomer to composite resins using various bonding systems

Aim:The aim was to compare the micro-shear bond strength between composite and resin-modified glass-ionomer (RMGI) by different adhesive systems.Materials and Methods:A total of 16 discs of RMGI with a diameter of 15 mm and a thickness of 2 mm were randomly divided into four groups (n = 4). Four cylinders of composite resin (z250) were bonded to the RMGI discs with Single Bond, Clearfil SE Bond and Clearfil S3 Bond in Groups 1-3, respectively. The fourth group was the control. Samples were tested by a mechanical testing machine with a strain rate of 0.5 mm/min. Failure mode was assessed under a stereo-microscope.Results:The means of micro-shear bond strength values for Groups 1-4 were 14.45, 23.49, 16.23 and 5.46 MPa, respectively. Using a bonding agent significantly increased micro-shear bond strength (P = 0.0001).Conclusion:Micro-shear bond strength of RMGI to composite increased significantly with the use of adhesive resin. The bond strength of RMGI to composite resin could vary depending upon the type of adhesive system used.

Microshear bond strength of self-etching systems associated with a hydrophobic resin layer

To evaluate in vitro the microshear bond strength of adhesive systems applied to dentin according to manufacturers' instructions, associated or not with a hydrophobic layer of unfilled resin. Six self-etching adhesives (Clearfil SE Bond, Kuraray Medical; AdheSE, Ivoclar Vivadent; Xeno III, Dentsply; I Bond, Heraeus-Kulzer; Bond Force, Tokuyama; Futurabond DC, Voco) were tested. The labial dentin of sixty bovine incisors was exposed, and the teeth were divided into two groups according to the application or not of an extra hydrophobic resin layer (Scotchbond Multi Purpose Plus, bottle 3). Six composite cylinders (Filtek Z250, 3M ESPE) were built up on each treated surface. Specimens were stored in distilled water at 37ºC for 24 h and then subjected to the microshear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. Microshear bond strength values were analyzed by 2-way ANOVA and Tukey's post-hoc test. Failure mode was determined using a stereomicroscope under 20X magnification. The application of the hydrophobic resin layer did not affect bond strength, except for AdheSE. However, the bond strengths with the hydrophobic layer were similar among the six tested systems (Clearfil: 17.1 ± 7.9; AdheSE: 14.5 ± 7.1; Xeno lll: 12.8 ± 7.7; I Bond: 9.5 ± 5.8; Bond Force: 17.5 ± 4.1; Futurabond: 7.7 ± 2.3). When used as recommended by the manufacturers, Bond Force presented statistically higher bond strength than AdheSE and I Bond (p < 0.05) (Clearfil 10.4 ± 4.9; AdheSE 1.6 ± 1.6; Xeno lll: 9.0 ± 3.8; I Bond: 3.0 ± 1.5; Bond Force: 14 ± 3.9; Futurabond: 8.8 ± 3.8). Failure mode was predominantly adhesive. The bond strength of the self-etching systems tested was not significantly affected by the application of a hydrophobic layer, but a significant improvement was observed in AdheSE.

Bonding strategies to pulp chamber dentin treated with different endodontic irrigants: microshear bond strength testing and SEM analysis.

To evaluate the effect of 6 irrigant regimens on the microshear bond strength of different adhesives to pulp chamber dentin and to determine their interfacial morphology by SEM. Forty-three human molars were split into halves and ground to provide flat pulp chamber dentin. Eighty-five halves were used. The specimens were assigned to 6 groups according to the irrigant regimen used. Group I (n=10) was irrigated with distilled water (control). The remaining 5 groups (n=15 each) were irrigated with 5.25% NaOCl followed by either 5.25% NaOCl, 17% EDTA, benzalkonium chloride (Tubilcid Plus) or MTAD (Biopure), either rinsed or not. Irrigated specimens were bonded using Clearfil S3 Bond or Adper Single Bond 2, which was employed with or without etching. Resin composite cylinders were bonded using tygon tubes for microshear bond strength testing. Data were analyzed using two-way ANOVA followed by Tukey's post-hoc test. Representative specimens of each group were prepared from 17 further molars for interfacial SEM examination. The different irrigant regimens used did not significantly alter the microshear bond strength values using either of the bonding systems, except NaOCl, which significantly reduced the microshear bond strength values with Adper Single Bond 2. Bonding irrigated specimens directly using the Adper Single Bond 2 without prior etching provided significantly reduced values. The irrigant regimens examined could be used safely prior to bonding except for the NaOCl, which should be negated if it is to be followed by Adper Single Bond 2, and the etching step cannot be omitted if an etch-and-rinse adhesive system is the adhesive of choice.