Significant Differences In Bond Strength Research Articles

Influence of Water Storage and Bonding Material on Bond Strength of Metallic Brackets to Ceramic.

This study investigated the influence of water storage (24 h and 6 months), and Transbond XT and Fuji Ortho LC bonding materials on the bond strength of metallic brackets bonded to feldspathic ceramic. Four cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 60 s. Each cylinder received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT or Fuji Ortho LC. Light-activation was carried out with 40 s total exposure time using Bluephase G2. Half the specimens for each bonding materials (n=20) were stored in distilled water at 37 °C for 24 h and the other half for 6 months. Shear bond strength testing was performed after storage times at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Data were subjected to two-way ANOVA and Tukey's test (p<0.05). Transbond XT showed significantly higher bond strength (p<0.05) than Fuji Ortho LC. Significant differences in bond strength (p<0.05) were found when 24 h and 6 months storage times were compared between materials. ARI showed a predominance of score 0 for all groups, and higher scores at 1, 2 and 3 for 24 h storage time. In conclusion, storage time and bonding materials showed significant influence on the bond strength of brackets to ceramic.

Tensile Bond Strength between Soft Liners and Two Chemically Different Denture Base Materials: Effect of Thermocycling.

The bond strength of soft denture liner to a recently introduced denture base resin after thermocycling has not been compared to traditional denture base materials. The objective of this study was to investigate the effects of thermocycling on the tensile bond strength of soft denture liners to two chemically different denture base resins, polymethyl methacrylate (PMMA) and urethane dimethacrylate (UDMA). A total of 48 PMMA and UDMA tensile test specimens were fabricated by attaching two different soft denture liners (Molloplast-B, Permaflex) according to the manufacturers' instructions and assigned to two groups. Half of the specimens for each group were stored in water for 1 week, and the other half were thermocycled (5000 cycles) between baths of 5°C and 55°C. Specimens were mounted on a universal testing machine with a 5 mm/min crosshead speed. The data were analyzed with three-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (α = 0.05). The highest bond strength was measured in the specimens from the UDMA/Molloplast groups, and the lowest was seen in the PMMA/Permaflex group. No significant difference in bond strength was detected in PMMA/Permaflex groups after thermocycling (p = 0.082), whereas other groups exhibited significant differences after thermocycling (p < 0.05). Thermocycling decreased the bond strength values in both the PMMA and UDMA groups. Regardless of types of soft liners, PMMA specimens presented lower bond strength values than UDMA specimens, both before and after thermocycling.

Assessment of Tensile Bond Strength of Fiber-Reinforced Composite Resin to Enamel Using Two Types of Resin Cements and Three Surface Treatment Methods

Background: Resin-bonded bridgework with a metal framework is one of the most conservative ways to replace a tooth with intact abutments. Visibility of metal substructure and debonding are the complications of these bridgeworks. Today, with the introduction of fiber-reinforced composite resins, it is possible to overcome these complications. The aim of this study was to evaluate the bond strength of fiber-reinforced composite resin materials (FRC) to enamel. Methods: Seventy-two labial cross-sections were prepared from intact extracted teeth. Seventy-two rectangular samples of cured Vectris were prepared and their thickness was increased by adding Targis. The samples were divided into 3 groups for three different surface treatments: sandblasting, etching with 9% hydrofluoric acid, and roughening with a round tapered diamond bur. Each group was then divided into two subgroups for bonding to etched enamel by Enforce and Variolink II resin cements. Instron universal testing machine was used to apply a tensile force. The fracture force was recorded and the mode of failure was identified under a reflective microscope. Results: There were no significant differences in bond strength between the three surface treatment groups ( P =0.53). The mean bond strength of Variolink II cement was greater than that of Enforce ( P =0.04). There was no relationship between the failure modes (cohesive and adhesive) and the two cement types. There was some association between surface treatment and failure mode. There were adhesive failures in sandblasted and diamond-roughened groups and the cohesive failure was dominant in the etched group. Conclusion: It is recommended that restorations made of fiber-reinforced composite resin be cemented with VariolinkII and surface-treated by hydrofluoric acid. Keywords : Tensile bond strength; surface treatment methods; fiber-reinforced composite resin

RESISTÊNCIA AO CISALHAMENTO DAS JUNTAS ADESIVAS PRODUZIDAS COM TRÊS DIFERENTES ESPÉCIES DE MADEIRAS E ADESIVOS VINÍLICOS PARA APLICAÇÕES NÃO ESTRUTURAIS

Os adesivos utilizados na colagem de madeiras para aplicações não estruturais normalmente contêm uma emulsão de poli(acetato de vinila) (PVAc) estabilizada com poli(álcool vinílico) e alguns aditivos. A ligação adesiva formada com essa classe de adesivo é pobre quando exposta à umidade e à temperatura. Nesse contexto, a classificação prévia dos adesivos utilizados para aplicações não estruturais, com resistência à umidade e à temperatura, é muito importante para a qualidade e durabilidade das juntas adesivas. Neste trabalho, foi estudada a influência de três espécies de madeiras (Fagus sylvatica L., Mimosa scabrella Bentham e Micropholis cf. venulosa Mart. &amp; Eichler) na resistência ao cisalhamento das juntas adesivas preparadas com três adesivos vinílicos, sintetizados com diferentes concentrações do N-butoximetilacrilamida (NBMA). Os ensaios de resistência ao cisalhamento, na linha de colagem, foram realizados sob diferentes ciclos de acondicionamento das juntas adesivas. Os resultados indicaram que há diferenças significativas na resistência de colagem das juntas adesivas e na porcentagem de falha na madeira provocada, tanto pela espécie de madeira quanto pelo tipo de adesivo utilizado. Os adesivos produzidos foram classificados de acordo com a classe de durabilidade, após várias etapas de acondicionamento. Os valores mais altos de resistência ao cisalhamento foram observados nas juntas coladas com as madeiras de Micropholis cf. venulosa Mart. &amp; Eichler e Fagus sylvatica L., com o adesivo AD-3. O menor valor de resistência ao cisalhamento foi observado nas juntas adesivas preparadas com a madeira da espécie Mimosa scabrella Bentham. A madeira Micropholis cf. venulosa Mart. &amp; Eichler mostrou-se mais adequada para a substituição da madeira Fagus sylvatica L.

Bond Strength of Different Restorative Materials to Light-Curable Mineral Trioxide Aggregate

The aim of the present study was to evaluate the bond strength of methacrylate-based (MB) composites, silorane-based (SB) composites, and glass-ionomer cement (GIC) in comparison to TheraCal and to compare those findings with the reference pulp capping material (MTA). A total of 90 acrylic blocks were prepared. Each of the blocks were prepared as 15 mm high and 10 mm diameter and the blocks had a 2 mm high and a 5 mm diameter central hole. In 45 of the samples, the holes were fully filled with TheraCal and in the other 45 samples, the holes were fully filled with MTA. The TheraCal and the MTA samples were randomly divided into 3 subgroups of 15 specimens each: Group-1: Methacrylate-based (MB) composite; Group-2: Silorane-based (SB) composite; and Group-3: Glass-ionomer cement (GIC). For the shear bond strength (SBS) test, each block was secured in a universal testing machine. After the SBS test, the fractured surfaces were examined under a stereomicroscope at ×25 magnification. The analysis of variance that compared the experimental groups revealed the presence of significant differences among the groups (P < 0.001). The highest (19.3 MPa) and the lowest (3.4 MPa) bond strength value were recorded for the MB composite-TheraCal and the GIC-TheraCal, respectively.There were significant differences in bond strength between the TheraCal and the MTA groups for the MB composite subgroup (P < 0.001) and the SB composite subgroup (P < 0.05); however, there was no significant difference in bond strength for the GIC subgroup (P ≯ 0.05). Conlusions: The results from this in vitro study suggest that the new pulp capping material, known as light-curable MTA, showed clinically acceptable and higher shear bond scores compared to MTA when used with the MB composite.

Comparative Evaluation of Shear Bond Strength of Luting Cements to Different Core Buildup Materials in Lactic Acid Buffer Solution.

The core buildup material is used to restore badly broken down tooth to provide better retention for fixed restorations. The shear bond strength of a luting agent to core buildup is one of the crucial factors in the success of the cast restoration. The aim of this invitro study was to evaluate and compare the shear bond strength of luting cements with different core buildup materials in lactic acid buffer solution. Two luting cements {Traditional Glass Ionomer luting cement (GIC) and Resin Modified Glass Ionomer luting cement (RMGIC)} and five core buildup materials {Silver Amalgam, Glass ionomer (GI), Glass Ionomer Silver Reinforced (GI Silver reinforced), Composite Resin and Resin Modified Glass Ionomer(RMGIC)} were selected for this study. Total 100 specimens were prepared with 20 specimens for each core buildup material using a stainless steel split metal die. Out of these 20 specimens, 10 specimens were bonded with each luting cement. All the bonded specimens were stored at 37(0)c in a 0.01M lactic acid buffer solution at a pH of 4 for 7days. Shear bond strength was determined using a Universal Testing Machine at a cross head speed of 0.5mm/min. The peak load at fracture was recorded and shear bond strength was calculated. The data was statistically analysed using Two-way ANOVA followed by HOLM-SIDAK method for pair wise comparison at significance level of p<0.05. Two-Way ANOVA showed significant differences in bond strength of the luting cements (p<0.05) and core materials (p<0.05) and the interactions (p<0.05). Pairwise comparison of luting cements by HOLM-SIDAK test, showed that the RMGIC luting cement had higher shear bond strength values than Traditional GIC luting cement for all the core buildup materials. RMGIC core material showed higher bond strength values followed by Composite resin, GI silver reinforced, GI and silver amalgam core materials for both the luting agents. Shear bond strength of RMGIC luting cement was significantly higher than traditional GIC luting cement for all core buildup materials except, for silver amalgam core buildup material. RMGIC core material showed highest shear bond strength values followed by Composite resin, GI Silver Reinforced, GI and Silver Amalgam core materials irrespective of luting cements.

Effect of simplified ethanol-wet bonding on dentin bonding durability of etchand-rinse adhesives.

This in vitro study evaluated the effects of simplified ethanol-wet bonding technique on dentin bonding durability of two etchand-rinse adhesives to bovine dentin. Sixteen freshly extracted bovine incisors were divided into four groups according to bonding technique (water-wet or ethanol-wet bonding) and adhesive (Single Bond 2 or Prime & Bond NT). After etching and rinsing, dentin surfaces were left either water-moist or immersed in ethanol. Following adhesive application and composite build-up, bonded teeth were sectioned into sticks for microtensile bond strength (µTBS) testing conducted after 24-h and 12-month water storage. There were no significant differences in bond strength among the groups at 24 h. At 12 months, the bond strengths of adhesives to dentin were significantly decreased (p<0.05). Simplified ethanol-wet bonding did not improve the resin-dentin bonding durability of tested etch-and-rinse adhesives.

Evaluation of the effect of calcium hydroxide and propolis intracanal medicaments on the push-out bond strength of a resin-based endodontic sealer to the root canal dentin: An in vitro study

Introduction: The aim of this study was to evaluate the effects of calcium hydroxide [Ca(OH)2] and propolis intracanal medicaments on the push-out bond strength of a resin-based sealer (AH Plus) to root dentin. Materials and Methods: After chemomechanical instrumentation using ProTaper rotary system, three groups of root canal specimens were prepared: 10 root canals were left untreated as controls (G1), 10 received Ca(OH)2intracanal medicament (G2), and another 10 received propolis intracanal medicament (G3). Canals were obturated with AH Plus and gutta-percha. After bond strength evaluation using push-out test, data was analyzed using 2- way ANOVA and Tukey post hoc tests (P = 0.05). Results: At coronal and middle thirds, there were no significant differences in bond strength among the three groups (P > 0.05). At apical third, G3 was significantly superior to G2 and G1 (P < 0.05), but there was no significant difference between G2 and G1 (P > 0.05). Conclusion: The use of propolis as an intracanal dressing material, with AH Plus used as the sealer in endodontic therapy was shown to have better sealer-dentin interfacial bond strength.

Evaluation of Shear Bond Strength of Feldspathic CAD/CAM Ceramic with Dentin using 2 Bonding Agents and 2 Surface Treatments- An Invitro Study.

All ceramics are the material of choice for aesthetic tooth replacements. The success of all ceramic restoration depends on the bond between the ceramic and the tooth surface hence this study was done to evaluate the shear bond strength of Feldspathic CAD/CAM ceramic with <5% hydrofluoric acid and hydrofluoric acid combined with silane coupling agent. To evaluate the shear bond strength of Feldspathic CAD/CAM ceramic with Dentin using bonding agents Prime & Bond NT, XenoIII and surface treatments <5% hydrofluric acid, hydrofluric acid combined with silane coupling agent. Forty cylinders with 6mm diameter and 5mm height were milled from CEREC Blocs through CAD/CAM technology. Cerec blocks were bonded to etch freshly extracted tooth surface using a self etch and total etch bonding agent. The samples were divided into 4 groups. Group A1-Ceramic cylinders were treated with < 5% HF and bonded using Prime & Bond NT and Variolink II. Group A2- treated with < 5% HF and silane coupling agent and bonded same as group A1. Group B1- treated with < 5% HF and bonded using Xeno III and Variolink II. Group B2- treated with < 5% HF and silane coupling agent, and bonded same as Group A3. The shear bond strength was evaluated after 24 hours by Storing in distilled water in Instron 3385 universal testing machine with 10-KN force. Statistical analysis was done using student's t-test and Lavene's test. The p-value <0.05 shows significant difference in bond strength between A1 and A2 & B1and B2. The application of a silane coupling agent to the ceramic surface after etching with hydrofluoric acid increased the adhesion strength with both bonding agents. Student's t-test revealed a significant effect of silanization.

Influence of air abrasion and sonic technique on microtensile bond strength of one-step self-etch adhesive on human dentin.

The purpose of this in vitro study was to evaluate the microtensile bond strength of one-step self-etch adhesive to human dentin surface modified with air abrasion and sonic technique and to assess the morphological characteristics of the pretreated dentin surface. The occlusal enamel was removed to obtain a flat dentin surface for thirty-six human molar teeth. The teeth were randomly divided into three experimental groups (n = 12 per group), according to the pretreatment of the dentin: (1) control group, (2) air abrasion group, and (3) sonic preparation group. Microtensile bond strength test was performed on a universal testing machine. Two specimens from each experimental group were subjected to SEM examination. There was no statistically significant difference in bond strength between the three experimental groups (P > 0.05). Mean microtensile bond strength (MPa) values were 35.3 ± 12.8 for control group, 35.8 ± 13.5 for air abrasion group, and 37.7 ± 12.0 for sonic preparation group. The use of air abrasion and sonic preparation with one-step self-etch adhesive does not appear to enhance or impair microtensile bond strength in dentin.

The effect of chlorhexidine on the push-out bond strength of calcium-enriched mixture cement.

The aim of this in vitro study was to evaluate the effect of 2% chlorhexidine (CHX) on the push-out bond strength (BS) of calcium-enriched mixture (CEM) cement. Root-dentin slices from 60 single-rooted human teeth with the lumen diameter of 1.3 mm were used. The samples were randomly divided into 4 groups (n=15), and their lumens were filled with CEM cement mixed with either its specific provided liquid (groups 1 and 3) or 2% CHX (groups 2 and 4). The specimens were incubated at 37(°)C for 3 days (groups 1 and 2) and 21 days (groups 3 and 4). The push-out BS were measured using a universal testing machine. The slices were examined under a light microscope at 40× magnification to determine the nature of bond failure. The data were analyzed using the two-way ANOVA. For subgroup analysis the student t-test was applied. The level of significance was set at 0.05. After three days, there was no significant difference between groups 1 and 2 (P=0.892). In the 21-day specimens the BS in group 3 (CEM) was significantly greater than group 4 (CEM+CHX) (P=0.009). There was no significant difference in BS between 3 and 21-day samples in groups 2 and 4 (CEM+CHX) (P=0.44). However, the mean BS after 21 days was significantly greater compared to 3-day samples in groups 1 and 3 (P=0.015). The bond failure in all groups was predominantly of cohesive type. Mixing of CEM with 2% CHX had an adverse effect the bond strength of this cement.

Resin cement to indirect composite resin bonding: effect of various surface treatments.

Debonding at the composite-adhesive interface is a major problem for indirect composite restorations. The aim of this study was to evaluate the bond strength (BS) of an indirect composite resin after various surface treatments (air-abrasion with Al2O3, phosphoric acid-etchig and different applications of NdYAG laser irradiations). Fifty composite disks were subjected to secondary curing to complete polymerization and randomly divided into five experimental groups (n = 10) including Group 1, untreated (control); Group 2, phosphoric acid-etched; Group 3, air-abrasion with Al2 O3 ; Group 4, Nd:YAG laser irradiated with non-contact and Group 5, Nd:YAG laser irradiated with contact. They were then bonded to resin cement and shear BS was determined in a universal testing device at a crosshead speed of 1 mm/min. One way analysis of variance (ANOVA) and Tukey post-hoc tests were used to analyze the BS values. The highest BS value was observed in Group 4 and followed by Group 3. Tukey test showed that there was no statistical difference between Group1, 2 and 5. Furthermore, differences in BSs between Group 4 and the other groups except Group 3 were significant (p < 0.05) and also there were significant differences in BSs between Group 3 to 1 and Group 3 to 2 (p < 0.05). This study reveals that air-abrasion with Al2 O3 and Nd:YAG laser irradiation with non-contact provided a significant increase in BS between indirect composite and resin cement.

In vitro shear bond strength of two self-adhesive resin cements to zirconia

Statement of problemAlthough the use of anatomic-contour zirconia restorations has expanded in the recent past, disagreement still exists as to reliable cementation techniques and materials. PurposeThe purpose of this in vitro study was to compare the immediate and artificially aged shear bond strength of 2 commercially available self-adhesive resin cements to zirconia: one with silica coating and silanation as a zirconia surface treatment and the other contained a phosphate monomer, which eliminated the need for a separate primer. Material and methodsSixty composite resin rods (2.5 mm in diameter and 3 mm in length) were fabricated from a nano-optimized composite resin by using a polypropylene mold, then light polymerized with a light-emitting diode. zirconia plates (10×10×4mm) were sectioned from an yttrium-stabilized zirconia puck, sintered, and then mounted in autopolymerizing acrylic resin custom tray material. Composite resin rods were cemented to the zirconia plates with 2 different cements. The surface treatment of zirconia followed the manufacturers’ instructions for each cement. The specimens were tested for shear bond strength at 3 aging conditions: immediate, after 24 hours of moist storage, and after 30 days of moist storage with 10000 thermocycles. Specimens were loaded to failure in a universal testing machine, and the data were analyzed with 2-way ANOVA (α=.05). Weibull parameters (modulus and characteristic strength) also were calculated for each group. ResultsTwo-way ANOVA revealed that only the aging condition significantly affected the bond strength to zirconia. The cement and the interaction of the cement and aging did not significantly affect the shear bond strength to zirconia. The highest bond strength for both cements was achieved at 24 hours, whereas the lowest bond strength values were recorded in the immediate groups. ConclusionsNo significant differences in bond strength to zirconia were observed between a cement with a silane priming step and an methacryloxydecyl dihydrogen phosphate-containing cement without a separate primer. Aging had a significant effect on the shear bond strength of the 2 self-adhesive resin cements to zirconia.

Silica coating of zirconia by silicon nitride hydrolysis on adhesion promotion of resin to zirconia.

In this study, the effect of silica coating on zirconia by silicon nitride hydrolysis in resin zirconia bonding was investigated. The silica coated zirconia samples were prepared in silicon nitride dispersion at 90 °C under different immersion times followed by a thermal treatment at 1400 °C. Four test groups were prepared: 1) zirconia samples treated by sandblasting, 2) zirconia samples treated by immersion in silicon nitride dispersion for 6 h, 3) zirconia samples treated by immersion in silicon nitride dispersion for 24 h and 4) zirconia samples treated by immersion in silicon nitride dispersion for 48 h. The coatings were characterized by SEM, EDX, XRD and Raman. The resin zirconia bond strengths of the four test groups were evaluated under three storage conditions: dry storage, water storage in deionized water at 37 °C for 30 days and thermo-cycling for 6000 cycles between 5.0 and 55.0 °C. Surface morphology and composition of zirconia were changed after surface treatments. Phase transformation was observed for zirconia surface by sandblasting treatment but was not observed for zirconia surface treated with silicon nitride hydrolysis. Significant differences in bond strengths were found under different surface treatments (p<0.001) and under three storage conditions (p<0.005). The highest bond strength values were obtained by sandblasting treatment.

Effect of simplified ethanol-wet bonding on microtensile bond strengths of dentin adhesive agents with different solvents

Background/purposeAvailable knowledge about the effect of solvent-type etch-and-rinse adhesives on dentin bond strengths achieved with ethanol-wet bonding is limited. Therefore, this study was conducted to determine 24-hour bond strengths of etch-and-rinse adhesives with different solvents to acid-etched dentin saturated with either water-wet bonding or ethanol-wet-bonding techniques. Materials and methodsSixteen bovine incisors were divided into the following four groups based on the bonding techniques and adhesives used: Group I, water-wet bonding + Single Bond 2 (water/ethanol-based adhesive); Group II, water-wet bonding + Prime & Bond NT (acetone-based adhesive); Group III, ethanol-wet bonding + Single Bond 2 (water/ethanol-based adhesive); and Group IV, ethanol-wet bonding + Prime & Bond NT (acetone-based adhesive). After etching and rinsing, dentin surfaces were either left moist with water or immersed in ethanol. Following adhesive application and composite buildups, bonded teeth were sectioned into resin–dentin sticks for microtensile bond strength testing, which was conducted after storing the sticks in water for 24 hours. Data were analyzed by two-way analysis of variance and Tukey test (P = 0.05). ResultsMean bond strength values (MPa) and standard deviations at 24 hours were as follows: Group I, 34.41 (12.6); Group II, 41.62 (11.8); Group III, 43.52 (13.8); and Group IV, 41.68 (9.1). No significant difference in bond strength was observed between different bonding techniques for both adhesives (P > 0.05). ConclusionSimplified ethanol-wet bonding exhibited similar 24-hour bond strength mean values for both ethanol/water-based and acetone-based etch-and-rinse adhesives. Therefore, solvent content may not interfere with bond strength to ethanol-saturated dentin.

Effects of surface treatment and artificial aging on the shear bond strength of orthodontic brackets bonded to four different provisional restorations

To evaluate the combined effects of material type, surface treatment, and thermocycling on the bond strength of orthodontic brackets to materials used for the fabrication of provisional crowns. Four materials were included in this study (ProTemp, Trim Plus, Trim II, and Superpont C+B). Sixty cylindrical specimens (1 × 3 cm) were prepared from each material and equally divided into three groups. The first group was ground with silica carbide paper, the second was polished with pumice, and the last group was sandblasted with 50-µm aluminum oxide particles. Stainless-steel maxillary central incisor brackets (Victory Series, 3M) were bonded to the provisional material specimens with Transbond XT light-cured composite resin, and half of the specimens from each group were thermocycled 500 times in 5°C and 55°C water baths. Then the brackets were debonded with shear testing, and the results were statistically analyzed by three-way analysis of variance and Tukey's multiple-comparison tests at α = 0.05. Adhesive Remnant Index (ARI) was also identified. Before and after thermocycling, ProTemp materials showed the highest shear bond strength with orthodontic brackets (10.3 and 13.1 MPa, respectively). The statistical analysis indicated an interaction among the three independent variables (P < .05) and statistically significant differences in bond strength among provisional materials (P < .001), surface treatments (P < .001), and thermocycling (P < .05). According to the ARI, most groups demonstrated adhesive failure. The provisional material type, surface treatment, and artificial aging have a significant effect on bond strength. Sandblasting treatment exerts a beneficial effect on shear bond strength.

Adhesion between glass fiber posts and resin cement: evaluation of bond strength after various pre-treatments

Purpose. To evaluate surface roughness and bond strength of glass fiber posts to a resin cement after various surface treatments. Materials and methods. Sixty individually formed glass fiber posts with a diameter of 1.5 mm and a length of 20 mm were used for this study. They were randomly assigned to six groups of pre-treatment (n = 10/group): Group C, untreated (control); Group SB, sandblasted; Group SC, silica coated; Group HF, hydrofluoric acid-etched; Group N, Nd:YAG laser irradiated; Group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. The posts were then bonded to resin cement and tensile bond strengths were determined in a universal testing machine. For statistical analysis, two-way ANOVA and post-hoc comparison tests (α = 0.05) were performed. Results. The highest bond strength value was observed in group HF, followed by group SC. There was a statistically significant difference in bond strength between group C and groups HF, SC and E (p < 0.001, p = 0.002 and p = 0.041, respectively). Posts of group SB and group N showed the highest surface roughness. Conclusions. The findings of the present study reveal that hydrofluoric acid-etching, silica coating and Er:YAG laser irradiation provided a significant increase in bond strength between glass fiber posts and resin cement.

Effect of accelerated aging on the bonding performance of fluoridated adhesive resins

The purpose of this study was to investigate the dentin bond durability of a one-step, fluoride-containing, glass ionomer-based adhesive system, Reactmer Bond (RB), and that of a two-step, fluoride-containing, self-etch adhesive system, Clearfil Protect Bond (CPB). Enamel was removed from the occlusal surfaces of teeth, and flat dentin surfaces were entirely covered with a composite resin following the application of an adhesive material (n=10). After specimens were sectioned into rectangular sticks of 0.87 ± 0.03 mm(2), the sticks were randomly assigned into two accelerated aging time period groups: 1 week or 1 year. Microtensile bond strengths were determined. Bond strength of RB increased significantly after 1 year (1 week=27.80 ± 10.57 MPa versus 1 year=36.93 ± 14.38 MPa) (p<0.05). In contrast, there was no significant difference in bond strength between the two time periods for CPB (1 week=51.74 ± 17.8 MPa versus 1 year=56.03 ± 18.85 MPa) (p>0.05). Both fluoride-containing adhesives seemed to demonstrate reliable bonding performance after 1 year of accelerated aging in water.

An in vitro Evaluation of Shear Bond Strength of Adhesive Precoated Brackets

Newer materials have been introduced in the field of ortho­ dontics to improve clinical efficacy as well as to simplify the tech nique. In an effort to reduce the time and steps to bond ortho dontic attachments, adhesive precoated (APC) brackets were introduced. In this study, an attempt is made to evaluate the shear bond strength (SBS) and debonding behavior of APC brackets compared with uncoated ceramic brackets. A total of 60 human premolar teeth were divided into two groups of 30 each, bonded with APC ceramic brackets and uncoated ceramic brackets. Group I bonded with APC brackets as pres­ cribed by the manufacturers and group II was bonded with con ventional bonding using Turbobond. After bonding, sthe samples were kept in distilled water at 37°C for 24 hours and a universal testing mechine was used to apply an occlusal shear force at a speed of 0.5 mm/min. The shear bond strength of the groups was compared using Student t­test and the debonding behavior were compared using Mann­Whitney’s U test. Mean shear bond strength and standard deviation of the groups were group I ­ 9.09 ± 2.5 MPa and group II ­ 12.95 ± 2.81 MPa. There were significant differences in bond strength observed between the two groups. The debonding behavior showed an adhesive remnant index score of 0.90 ± 0.08 for group I and 1.10 ± 0.04 for group II, which indicates there is significant difference between each other. When considering the values required for optimum bond strength, APC brackets in this study showed adequate bond strength and could be used for routine clinical use.

Push-out bond strength of a self-adhesive resin cement used as endodontic sealer.

ObjectivesThe aim of the present study was to investigate the bond strength of RelyX Unicem (3M) to root canal dentin when used as an endodontic sealer.Materials and MethodsSamples of 24 single-rooted teeth were prepared with Gates Glidden drills and K3 files. After that, the roots were randomly assigned to three experimental groups (n = 8) according to the filling material, (1) AH Plus (Dentsply De Trey GmbH)/Gutta-Percha cone; (2) Epiphany SE (Pentron)/Resilon cone; (3) RelyX Unicem/Gutta-Percha cone. All roots were filled using a single cone technique associated to vertical condensation. After the filling procedures, each tooth was prepared for a push-out bond strenght test by cutting 1 mm-thick root slices. Loading was performed on a universal testing machine at a speed of 0.5 mm/min. One-way analysis of variance and Tukey test for multiple comparisons were used to compare the results among the experimental groups.ResultsEpiphany SE/Resilon showed significantly lower push-out bond strength than both AH Plus/Gutta-Percha and RelyX Unicem/Gutta-Percha (p < 0.05). There was no significant difference in bond strength between AH Plus/Gutta-Percha and RelyX Unicem/Gutta-Percha (p > 0.05).ConclusionsUnder the present in vitro conditions, bond strength to root dentin promoted by RelyX Unicem was similar to AH Plus. Epiphany SE/Resilon resulted in lower bond strength values when compared to both materials.