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Results for “Shear Strength”

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At least 163 records · Page 9Linked to original sources

PubMed2000

The effect of zinc oxide-eugenol on the shear bond strength of a commonly used bonding system.

It has been claimed that eugenol has a detrimental effect on resin composites and dentin bonding systems. The aim of the present study was to examine whether zinc oxide-eugenol (ZOE) cement would reduce the efficacy of a bonding system. Human third molars were selected for the study, and cylindrical posts of a resin composite (Z100) were bonded vertically to a standardized flat dentinal surface, prepared on the buccal surface of the teeth and treated with Scotchbond Multi-Purpose. The tooth surfaces involved were either freshly cut, or had been exposed to ZOE cement for 6 days, with and without a subsequent thorough cleansing with ethanol. The bond strength in shear was measured after 24 hours. The results showed that ZOE cement had no negative effect on the bond strength of the resin composite (Z100) to dentin when this bonding system was used. The mean shear bond value for the specimens covered with ZOE cement for 6 days was 28.1 MPa. For specimens covered with ZOE cement and cleansed with 96% ethanol, the mean shear bond value was 23.5 MPa. The corresponding value for the controls was 19.0 MPa. These findings suggested that eugenol-containing temporary filling materials may be used safely prior to inserting resin based restorative materials, when Scotchbond Multi-Purpose is employed as the bonding agent.

Composite Resins↗

PubMed1991

Shear bond strength of silicoated bonded orthodontic attachments.

The shear bond strength of bonded orthodontic attachments, coated with a silicon oxide layer to enhance adhesion, was tested and compared to that of untreated attachments. Twenty buttons for direct bonding (test group) were "silicoated" and bonded to surgically removed, unerupted human third molars, using "Right-On" adhesive. The control group consisted of 20 similar teeth to which untreated buttons were bonded. Half of the specimens in each group were then thermocycled to stress the bonds. Shear strength was tested with the use of the Instron Universal testing machine. The mean shear bond strength of the silicoated attachments was found to be higher than that of the untreated attachments. This was a highly significant finding (p less than 0.005). The bond strength after thermocycling decreased in both the test and control groups, although this decrease was only significant at the level p less than 0.01. The results obtained from this study indicate that silicoating of orthodontic attachments prior to bonding significantly increases their shear bond strength to dental enamel.

Dental Bonding↗

PubMed1991

Shear bond strength of Scotchbond in vivo.

The shear bond strengths of Scotchbond, HEMA/Scotchbond, and Scotchbond 2 were measured in vivo in dog canine and molar enamel and dentin. Dentin bond strengths were compared in superficial, middle, and deep dentin. The acid-etched enamel bond strengths of the three bonding systems ranged from 10 to 11 MPa and were not statistically different. Scotchbond/Silux bonds to superficial and middle cuspid and molar dentin were 3 MPa and were not statistically different. HEMA-treated dentin did not consistently improve Scotchbond strengths to either tooth type at any dentin depth. Deep dentin from either tooth type yielded significantly lower bond strengths. Scotchbond 2/Silux shear bond strengths were significantly higher (6-8 MPa) in superficial and middle cuspid dentin but were not different from Scotchbond bonds made to deep cuspid dentin or to any depth of molar dentin. The observation that molar bond strengths are lower than those made to cuspid dentin indicates that there are important substrate differences between teeth as well as within dentin as a function of depth. The dog model may be useful for the screening of new dentin bonding systems prior to clinical trials.

Animals↗

PubMed1994

Effect of surface treatments and storage methods on the shear bond strength between composite/glass-ionomer cement laminate.

The shear bond strengths between a visible light cure posterior composite and different surface treatments of glass-ionomer Cement were estimated in the dry and wet conditions. A total number of 60 specimens were used in the present investigation. The specimens were divided into 6 equal groups (10 specimens each). Each group was divided into two equal subgroups, in order to study the effect of the storage condition on the shear bond strength for each group. It was found that group (V), where saline coupling agent was applied to the non-etched glass-ionomer cement surface, followed by the application of bonding agent, demonstrated the maximum shear bond strength (10.87 mm/m2). On the other hand, group (II) where composite resin was packed directly on the etched glass-ionomer surface displayed the minimum shear bond (1.93 Mn/M2). Moreover, the wet storage of the different groups elicited a varying percentage of reduction in the shear bond strength values.

Analysis of Variance↗

PubMed2005

Shear bond strength of Resilon to a methacrylate-based root canal sealer.

AIM: To evaluate the adhesive strength of Resilon to Next root canal sealant (Heraeus-Kulzer), a methacrylate-based root canal sealer, using a modified microshear bond testing design. METHODOLOGY: Flat Resilon surfaces of different roughnesses (smooth surface and surface roughness equivalent to 320-grit and 180-grit) were prepared by compression moulding for bonding to the sealer and compared with a composite control. The shear strength data were statistically analysed using Kruskal-Wallis one-way anova on ranks and Dunn's multiple comparison tests (alpha = 0.05). After shear testing, fractured specimens were examined using a field emission-scanning electron microscope for detailed analysis of the failure modes. RESULTS: The composite control exhibited significantly higher mean shear strength (7.62 MPa) that was 4.4-4.7 times those of the Resilon groups (1.64-1.74 MPa; P < 0.001). Increasing the surface roughness of the Resilon surface did not contribute to further improvement in shear bond strength for this methacrylate-based sealer (P > 0.05). Failure modes in the composite control were cohesive and mixed failures, while those in the Resilon groups were predominantly adhesive failures, with a small percentage of mixed failures. Ultrastructural evidence of phase separation of polymeric components could be identified in Resilon. Both intact, non deformed and plastically deformed Resilon surfaces could be observed in specimens that exhibited adhesive failures. CONCLUSION: The low shear strength of Resilon to a methacrylate-based sealer compared with a composite control suggests that the amount of dimethacrylate incorporated in this filled, polycaprolactone-based thermoplastic composite may not yet be optimized for effective chemical coupling to methacrylate resins.

Analysis of Variance↗

PubMed2002

Halogen versus high-intensity light-curing of uncoated and pre-coated brackets: a shear bond strength study.

AIM: To evaluate the shear bond strengths of adhesive pre-coated brackets (APC) and conventional uncoated brackets (Victory) cured with two different light-curing units: a conventional halogen light (Visilux 2) and a micro-xenon light (Aurys). SETTING: Ex vivo study MATERIALS AND METHODS: Sixty freshly extracted bovine permanent mandibular incisors were randomly assigned to one of four groups, each group consisting of 15 specimens. Two groups (one for each type of bracket) were exposed to the halogen light for 20 seconds and used as controls. The remaining two groups were cured with the micro-xenon light for 2 seconds. After 24 hours, all samples were tested in a shear mode on an Instron Machine. Analysis was by two-way ANOVA with Scheffé's test for comparisons, Kaplan-Meier survival estimates, and Cox model. The Chi-square (chi(2)) test was used to determine significant differences in the ARI scores. RESULTS: The mean shear bond strength of the uncoated brackets cured with Visilux 2 was significantly higher than those of all the other groups tested. Both groups cured with Visilux 2 produced significantly higher mean shear bond strengths than those of the corresponding groups cured with Aurys. No statistically significant differences were found between the two groups cured with Aurys. CONCLUSIONS: Compared to halogen light-curing, the micro-xenon light enables the clinician to reduce significantly the curing time of both APC and uncoated brackets, and although significantly lower, their shear bond strengths may be clinically acceptable.

Analysis of Variance↗

PubMed1992

Moist versus dry dentin: its effect on shear bond strength.

This study compared the shear bond strengths of dentin bonding systems applied to air dried and blot (moist) dried dentin. Five systems with primers possessing hydrophilic properties were evaluated. Three contained acetone. All Bond, Amalgambond, Mirage Bond and Tenure all produced significant statistical improvement in shear bond strength values when applied to moistened dentin. Mirage Bond values quadrupled. Bond strength values with Gluma were compromised by the presence of moisture. It was concluded that acetone probably facilitated deeper and more complete penetration of resin into dentin to enhance micro-mechanical retention. Amalgambond, while free of acetone is strongly hydrophilic and is known to form substantial mechanical bonding through the formation of a resin rich superficial layer of dentin (hybridization). Gluma while hydrophilic does not appear to possess the same behavioral characteristics embodied in the other systems as evidenced from lack of a bond to moist dentin.

Acetone↗

PubMedDate not supplied

Influence of different etchants and etching times on shear bond strength.

This study compared the shear bond strength to enamel of Scotchbond Multi-Purpose Dental Adhesive System's bonding resin following etching of enamel with 10% maleic, 1.6% oxalic, 10% phosphoric, and 35% phosphoric acids for 15, 30, and 60 seconds. Three hundred and sixty human molar teeth were used to create 12 groups of 30 enamel specimens per group (n = 30). Flattened enamel surfaces were treated with the different etchants for the time periods indicated, the surfaces primed, and adhesive resin applied according to the manufacturer's recommendations. The specimens were completed with Silux Plus resin and subjected to 1000 thermocycles (5-55 degrees C) followed by shear stress in an Instron Testing Machine to failure within a 24-hour period. A two-way ANOVA revealed significant differences for shear bond strength values by type of etchant (10% phosphoric, 35% phosphoric > 10% maleic > 1.6% oxalic acid) (P < 0.005) and by length of application time (P < 0.005). The interaction term for these two treatments was statistically significant (P < 0.005).

Acid Etching, Dental↗

PubMed1996

Bonding of amalgam to dentine: microleakage and shear bond strength evaluation.

This study investigates the shear bond strengths (SBS) of different products used for bonding amalgam to dentine and the marginal seal provided by these materials. The SBS test was carried out by bonding cylinders of Dispersalloy amalgam to human dentine with an intermediate layer of Amalgambond Plus, All-Bond 2, Imperva Bond/Dual or Scotch Bond Multi-Purpose was first placed. Thereafter the samples were tested to failure in the shear mode. For the microleakage test, standardized class V cavities were prepared in human molars with one cavo margin abutting enamel and another dentine/cementum. Amalgam was condensed into the cavities, pretreated with one of the products mentioned above. In addition two further groups were prepared. One receiving treatment with Polyvar varnish and the other remained untreated as the control. Microleakage was assessed with a reflecting light microscope using I.S.O. criteria and the fracture sites and marginal gaps were examined in a scanning electron microscope. Results indicate that All-Bond 2 and Amalgambond Plus induced similar SBS and Scotchbond Multi-Purpose the weakest. At both enamel and dentine/cementum junctions resin bonding agents reduced microleakage. However, this reduction was greater at the enamel interface than at the other. Varnish allowed the greatest amount of marginal leakage and leakage was similar to the untreated control. Amalgam bonding agents are more effective at preventing marginal leakage at the enamel margin than at the dentine/cementum margin. Cavity varnish is not effective in preventing microleakage around amalgam restorations. There is a correlation between shear bond strength and marginal leakage. Materials giving the highest shear bond strength also exhibited the least marginal leakage. All-Bond 2, Amalgambond Plus and Imperva Bond/Dual are recommended to improve the seal around amalgam restorations.

Dental Amalgam↗

PubMed1995

Evaluating the effect of glove coating on the shear bond strength of porcelain laminate veneers.

Gloves have become a standard tool in dentistry due to infection control concerns. But the starch powder with which many of these gloves are coated may contaminate surfaces on contact, creating potential problems during adhesive procedures such as the placement of porcelain veneers. The authors studied the powder's effect on the strength of the shear bond of etched porcelain to etched human tooth enamel and compared it to the effect of a powder-free polymer glove coating. While the starch coating led to a statistically significant decrease in shear bond strength, the powder-free coating produced no significant decrease in strength.

Acid Etching, Dental↗

PubMed1999

Effect of surface conditioning on the shear bond strength of compomers to human primary and permanent enamel.

PURPOSE: To compare the bond strength of two polyacid-modified composite resins (Compomer) to primary and permanent enamel with and without acid-etching and to test for a possible relationship between the determined shear strength values and area of cohesive failure within the materials on the bonding interface. MATERIALS AND METHODS: Two compomer materials (Dyract and Compoglass) with their respective one-bottle primer/adhesive agents (Prime & Bond 2.0 and Syntac Single Component) were investigated. The parameters tested were shear strength and area of cohesive type of failure after debonding of specimens with respect to the total area of the bonding interface. RESULTS: Mean bond strength to primary enamel ranged from 4.09 MPa (Compoglass) to 5.6 MPa (Dyract), while in permanent enamel the mean values were between 12.3 MPa (Compoglass) and 14.3 MPa (Dyract), when pretreatment was made with bonding agents only. Generally, acid-etching prior to pretreatment improved adhesion significantly (6.0 MPa and 8.1 MPa in primary enamel and 16.0 MPa and 19.4 MPa in permanent enamel for Compoglass and Dyract, respectively). Over one-half of the variation in the values for cohesive failure area was explained by its linear relationship with shear bond strength.

Acid Etching, Dental↗

PubMed2004

The effect of variation in mesh-base design on the shear bond strength of orthodontic brackets.

This study compared the shear bond strengths of two metallic orthodontic brackets, one with a single-mesh bracket base and the other with a double-mesh bracket base. The Transbond XT adhesive system was used to bond all brackets to the teeth. Two types of brackets were compared, ie, 20 Ovation metal bracket series, with a double-mesh base (Super-mesh) and an 81.50 gauge (0.126 inch), and 20 Victory series metal brackets that have a miniature single-mesh base. The teeth were bonded and debonded within half an hour from the initial bonding. The enamel surface was examined under 10x magnification to determine how much residual adhesive remained on the tooth. Student's t-test was used to compare the shear bond strength of the two groups. Chi-square test was used to compare the adhesive remnant index (ARI) scores for the two bracket types. The mean shear bond strength for the double-mesh brackets was 5.2 +/- 3.9 MPa and for the single-mesh brackets was 5.8 +/- 2.8 MPa. The t-test comparisons indicated that they were not significantly different from each other (P = .157). The ARI comparisons indicated that both bracket types had similar bracket failure modes and were not significantly different from each other (chi2 = 2.0, P = .5). These results indicated that single- and double-mesh bracket bases have comparable shear bond strength and bracket failure modes.

Chi-Square Distribution↗

PubMed1996

Effect of polymerization mode of a dual-cured resin cement on time-dependent shear bond strength to porcelain.

PURPOSE: To evaluate the shear bond strengths to porcelain and setting times of a dual-cured resin cement with light/chemical curing (dual) or chemical only curing versus time. MATERIALS AND METHODS: Variolink resin cement was bonded to specimens of etched, silanated porcelain. Groups of specimens were cured by dual cured or by chemical curing only. Shear bond strengths were recorded at 2, 3, 5, 60 minutes and 24 hours for dual cured and at 10, 20, 40, 50, 60 minutes and 24 hours for chemical-cured only after mixing. Kinetic-temperature profiles of dual and chemical curing modes of cement were calculated. RESULTS: Maximum bond strengths and time to attainment were 17.5 +/- 2.7 MPa at 60 minutes for chemical-cured and 26.1 +/- 2.3 MPa at 5 minutes for dual-cured. The peak in the kinetic-temperature setting profiles were 14.1 +/- 0.9 minutes for chemical curing and 52.2 +/- 5.2 seconds for dual curing. Dual curing provided significantly higher shear bond strengths versus chemical curing at both the 60-minute and 24-hour time periods.

Analysis of Variance↗

PubMed2006

Effect of polymerization mode of adhesive and cement on shear bond strength to dentin.

PURPOSE: To investigate the shear bond strength to dentin when two resin adhesive systems in light-cure, dual-cure, and auto-cure modes were used with three resin cements. This was done to determine the degree of compatibility that exists when resin products with different polymerization mechanisms are used together. METHODS: Three hundred non-carious human molars were divided into 30 test groups in which Prime & Bond NT and ScotchBond Multi-Purpose were used as adhesives with Calibra, Nexxus and Variolink cements to attach Rexillium III posts to flattened dentin surfaces. Debonding was achieved with an Instron testing machine and mean shear bond strengths were determined for each test group. The data were subjected to three-way ANOVA and post-hoc LSD testing to determine whether significant differences existed between the test groups. RESULTS: Bond strengths achieved were affected by the adhesive, the cement, and the cement curing mode. In general, the auto-cure application of the three cements demonstrated reduced shear bond strengths, both with respect to the different adhesives and their curing modes as well as compared to the dual-cure technique of the same cement. Additionally, Prime & Bond NT demonstrated considerably more variability than ScotchBond Multi-Purpose when used with both dual-cure and auto-cure varieties of the three cements. The bond strengths of resin cements depend on the curing mode of the cement and the adhesive. Unlike with direct light-cured resin composites, combining adhesive systems and dual-cured resin cements from different manufacturers may be contraindicated.

Adhesives↗

PubMed1995

The effect of tray material and surface condition on the shear bond strength of impression materials.

This study compared the adhesive shear bond strength of three selected impression materials with that of thermoplastic and acrylic resin tray materials as a function of surface preparation. Polyether (Impregum), polyvinylsiloxane (Reprosil), and polysulfide (Permlastic) impression materials were evaluated on smooth, rough, and contaminated tray surfaces. Smooth surface samples were formed against glass and served as the control groups. Experimental groups consisted of samples contaminated with artificial saliva and rough surface samples that were abraded with 110 microns of Al203. A total of 126 samples were subdivided into 18 groups of seven specimens each. Each sample consisted of a 1 inch square, 3 mm thick mass of an impression material sandwiched between the prepared surfaces of a pair of resin plates. Each specimen was tested in a universal testing machine for adhesive shear bond strength. Data were analyzed with three-way analysis of variance and Scheffe's test. The results indicated that the thermoplastic resin material had better adhesive properties than the acrylic resin. For both tray materials mean adhesive shear bond strengths for Impregum and Reprosil were significantly greater than those of Permlastic. Tray surface contaminated with saliva decreased the adhesive shear strength at the tray adhesive impression interface.

Acrylic Resins↗

PubMedDate not supplied

Effect of air/water rinse versus water only and of five rinse times on resin-to-etched-enamel shear bond strength.

This study compared the shear bond strength of composite resin bonded to etched, flattened enamel that had been rinsed for 0, 1, 2, 3, 5 or 20 seconds with either a water stream or an air/water spray. One hundred seventy-six molars were separated into mandibular and maxillary groups, then divided equally into 11 groups of 16 teeth each. The facial enamel surfaces were ground flat and etched for 20 seconds with 37% phosphoric acid gel. In one group, the etching gel was dried but not rinsed. In five groups the gel was rinsed with a direct stream of water at 22 psi. In the remaining five groups the gel was rinsed with an air/water spray (air at 53 psi, water at 22 psi). One tooth from each group was removed for scanning electron microscopy evaluation, leaving 15 specimens in each group for shear bond testing. Teflon tape with a 3 mm in diameter window was placed over each etched area, a light-curing liquid resin was applied and polymerized for 10 seconds, and a cylinder of light-curing composite resin was polymerized over the window. Specimens were thermocycled from 5 to 50 degrees C for 500 cycles (30-second dwell time). After 30 days' hydration at room temperature, the teeth were mounted and the composite resin cylinders were loaded in shear to failure with an Instron machine at a cross-head speed of 5 mm/min. Mean load to failure was calculated for each group. Specimens that were not rinsed had significantly (P < 0.001) less bond strength (mean 0.53 MPa) than any of the rinsed specimens (mean 18.7 MPa).(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗

PubMed1999

Comparison of shear bond strength of three bonding agents with metal and ceramic brackets.

Shear bond strengths of a light-cured composite resin, a light-cured glass ionomer cement, and a light-cured compomer used with metal and ceramic brackets were compared, and ARI scores were evaluated. Ceramic brackets showed statistically higher shear bond strengths than metal brackets when bonded with all test materials (p<0.001). When used with metal brackets, the light-cured glass ionomer cement (LCGIC) and compomer materials demonstrated statistically lower shear bond strengths than the light-cured composite (p<0.01 and p<0.001, respectively). When used with ceramic brackets, LCGIC was found to have significantly lower shear bond strength than the composite material (p<0.001). Despite its relatively low shear bond strength, LCGIC demonstrated optimal bonding values (8.39+/-3.24 MPa) with ceramic brackets. Bond failures within the LCGIC groups occurred at the adhesive-tooth interface, whereas in the compomer and composite groups, failures were detected at the adhesive-bracket interface. In the metal bracket group, clinically acceptable shear bond strength was obtained only with the composite resin (7.06+/-1.65 MPa). Compomer and LCGIC demonstrated values well below the accepted standard for metal brackets (4.32+/-1.75 MPa and 4.45+/-1.06, respectively), while in the ceramic bracket group, values for composite and compomer were above the desired level (14.40+/-5.88 MPa and 12.31+/-6.09, respectively). LCGIC showed reasonably good bond strength with ceramic brackets, suggesting that this material may be considered suitable for use with ceramic brackets in clinical situations where moisture cannot be controlled.

Acrylic Resins↗

PubMed1992

Shear bond strength of a 4-META adhesive system.

This study evaluated the shear bond strength between amalgam and amalgam, amalgam and composite resin, and amalgam and dentin using a 4-META adhesive. Eighty samples were divided into four groups of 20 and were then divided into subgroups of 10 samples for thermocycling procedures. This study indicated that amalgam bonded to amalgam with a 4-META adhesive yielded bond strengths that were weaker than the shear strength of amalgam itself (p less than 0.05), and that thermocycling appeared to significantly weaken bond values (p less than 0.02).

Adhesives↗