Original research reportA critique of bond strength measurements
Abstract
The lack of consistent values for dentine bond strengths in shear or in tension from what are superficially identical experimental procedures has led to ambiguities in the interpretation of the data. These variations in bond strength are usually considered to be related to different adhesive procedures. However so far little attention has been paid to the detail of the test procedures used. In this study the sensitivity of bond strengths to changes in testing conditions has been calculated using finite element stress analysis. It is shown that tensile and shear bond strengths are highly dependent on the geometry of the test arrangement and the materials involved. It is concluded that the concept of ‘average stress’ for the measurement of bond strength does not stand up to close examination. The measurement does not provide a material property as its value is dependent on local conditions and the actual stresses have little relationship to the average stress value. This demonstrates that there is a need for the standardization of test procedures for the measurement of bond strengths so that a universally valid comparison between different bonding agents can be performed.
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Cited by (463)
In vitro and practical guide for the analysis of bond strength to ceramics
2023, Ceramics InternationalThe purpose of this study was to characterize different test designs applied for analysis of the bond strength between ceramic and resin cement. One lithium disilicate (LD, IPS Emax CAD®, Ivoclar) and one zirconia (YZ, Ceramill, Amann-Girrbach) ceramic were used for specimens’ preparation (n = 10) according to the proposed test: Microtensile, Tensile, Microshear, Shear, Micropush-out, Push-out, and Interfacial Fracture Toughness. A resin cement (Multilink Automix dualcure, Ivoclar) was used to bond the ceramic to the substrate (composite resin, Tetric N-Ceram, Ivoclar) selected according to the test design. During preparation and testing of the specimens, the time required, amount of material and level of difficulty were assessed. Bond strength data were analyzed using one-way ANOVA and Tukey test (P < 0.05). The homogeneity and magnitude of the bond strength values were verified by calculating the Weibull modulus. Failure mode was analyzed by stereomicroscope for all tests. Microshear resulted in the highest (LD: 41.00 ± 14.96 MPa; YZ: 48.95 ± 6.64 MPa) and Interfacial Fracture Toughness in the lowest (LD: 3.54 ± 0.94 MPa; YZ: 4.10 ± 1.65 MPa) bond strength values, regardless of the ceramic. The analysis of the mode of failure showed 100% adhesive failure for Microtensile and Micropush-out samples for both, LD and YZ. Interfacial Fracture Toughness samples of LD also presented 100% adhesive failure. Most of the samples presented mixed failure modes, and only Tensile and Push-out tests presented cohesive failure in the resin cement layer. Overall, the test design affected bond strength results. Weibull modulus indicated that a smaller sample size may be adequate for the analysis of bond strength to ceramic materials. Microtensile test was classified as the most difficult test in terms of preparing the specimen and performing the test.
A new adhesion concept based on a dual surface modification for resin Ti adhesion
2023, International Journal of Adhesion and AdhesivesThe objective of this resin Ti adhesion study was to compare and contrast the effect of two novel dual surface modification methods on the surface morphology, changes in surface chemistry and to evaluate their enclosed mold micro-shear bond strength variation on artificial ageing. A total amount of 168 c.p. grade 2 titanium specimens were first manually polished, then 24 of them were randomly selected as control specimens. To study the effect of dual surface modification (silicatization followed by etching), 72 polished titanium specimens were silicatized (Rocatec™ Plus, 3M ESPE, 110 μm silica-coated alumina powder) according to the manufacturer’s protocol and then 36 of the silicatized specimens were etched with a blend of HNO3–HCl at 60 °C for 2 mins. The reversed dual surface modification (etching followed by silicatization) was done for the remaining 72 titanium specimens. They were first etched with a blend of HNO3–HCl at 60 °C for 2 mins, and then 36 of the etched specimens were silicatized with the same protocol as mentioned above. As a final treatment one third of all differently modified sample groups were silanized by Monobond™ Plus (Ivoclar Vivadent), and the other third with an experimental silane primer blend, 1.0 vol% 3-acryloxypropyltrimethoxysilane + 0.3 vol% 1,2-bis-(triethoxysilyl)ethane. One third of each sample groups was left without silanization. SEM, EDX, XPS, AFM, and surface roughness profilometry were conducted to study the effects of different surface modifications. Two enclosed mold resin stubs were bonded on each surface treated titanium specimens to evaluate the enclosed mold micro-shear bond strength. The specimens were artificially aged for 1 day, 1 week, 4 weeks, and 8 weeks, followed by adhesion strength testing and failure mode analyses. SpeedCem™ (Ivoclar Vivadent) was used as resin cement. The highest surface roughness was detected on the titanium specimens, silicatized and followed by etching with and without silanization (group E), while the lowest surface roughness was observed in two groups, silanized polished titanium (group A, control) and etched polished titanium with and without silanization (group C). The surface roughness of titanium only silicatized (group B) and specimens silicatized after etching (group D) exhibited similar surface roughness, higher than groups A and C, but lower than group E. These results were supported by the SEM images and AFM analysis. The EDX and EM-μSBS analyses pointed out that specimens which had higher [Si] and [Al], exhibited higher EM-μSBS values. The highest EM-μSBS values were observed in Ti specimens which were silicatized only or those which were silicatized after etching, i.e., groups B and D. Adhesive and mixed mode of fractures were observed in the specimens after EM-μSBS tests. A novel approach of silicatized titanium surface after etching might prevent the removal of embedded SiO2 and Al2O3, allowing the formation of a durable chemical bond with a silane blend.
Adhesion of veneering porcelain to cobalt-chromium dental alloys processed with casting, milling, and additive manufacturing methods: A systematic review and meta-analysis
2022, Journal of Prosthetic DentistrySelective laser melting (SLM) additive manufacturing (AM) technologies provide an alternative to conventional casting and milling procedures in fabricating metal-ceramic dental prostheses. However, the quality of porcelain bond strength to the SLM AM cobalt-chromium (Co-Cr) metal framework of a dental restoration is unclear.
The purpose of this systematic review and meta-analysis was to identify in vitro studies that reported the porcelain bond strength to SLM AM Co-Cr dental metal alloys and compare the porcelain bond strength values to cast, milled, and additively manufactured Co-Cr dental alloys.
An electronic systematic review was performed in different databases: MEDLINE/PubMed, EMBASE, World of Science, Cochrane, and Scopus. A manual search was also conducted. Studies that reported the porcelain bond strength to SLM Co-Cr metal alloys and in the English language were included. Two investigators evaluated the quality assessment of the studies by applying the JBI critical appraisal checklist for quasi-experimental studies (nonrandomized experimental studies). A third investigator was consulted to resolve lack of consensus. Two subgroups were created based on the test used, 3-point bend and shear bond strength tests. The porcelain bond strength of cast, milled, and AM Co-Cr dental alloys were compared. The I2 statistic and its associated P value were used to assess the heterogeneity between studies. The Eger test was used for determining significance of the funnel pots.
A total of 216 studies were collected from the electronic and manual searches. After independently evaluating the titles and abstracts by the reviewers, 26 articles were identified. Three of these were excluded after full-text revision. The porcelain bond strength comparison between the cast and AM alloys for the 3-point bend subgroup revealed a significant result for overall effect (P<.001) favoring the SLM method with considerable heterogeneity (I2=83%, P<.001). Furthermore, the porcelain bond strength comparison between cast and milled alloys for the shear bond strength subgroup revealed a significant test for overall effect (P=.04) favoring milled procedures with a nonsignificant unimportant heterogeneity (I2= 0%, P<.47) and for the 3-point bend subgroup (P<.001) favoring milled specimens with a significant considerable heterogeneity (I2=79%, P<.001).
The metal manufacturing method had no effect on the porcelain bond strength to Co-Cr dental metal alloys.
Comparison of shear bond strength of metal orthodontic brackets bonded to a CAD/CAM prosthetic provisional material after the use of a self-adhesive resin cement versus a light adhesive paste and different surface conditioning protocols: An in vitro study
2022, International OrthodonticsAdult orthodontic treatment has been increasingly popular, and brackets may need to be bonded to provisional crowns, including CAD/CAM crowns. The use of self-adhesive resin cement or light adhesive paste have been suggested with different surface conditioning protocols to improve the adhesion to CAD/CAM PMMA provisional crowns. Objective To determine and compare the in vitro shear bond strength (SBS) of metal brackets bonded to a provisional prosthetic CAD/CAM material after the use of different adhesive cements and surface conditioning protocols.
One hundred twenty Telio® CAD specimens were manufactured in 12 groups (n = 10). Each specimen was bonded to a metal bracket and divided according to adhesive technique (3M™Transbond™ XT Light Cure Paste or 3M™RelyX™ U200) surface treatment (macroretentions) and the use of silane. Half of the specimens were thermocycled (5000 cycles, 5 °C/55 °C water baths). The SBS test was carried out using a shear bond strength tester, and the type of adhesive failure was determined by means of the adhesive remnant index. The data were analysed with the Mann–Whitney test (α = 0.05).
Statistically significant differences (P < 0.001) in SBS were found among the groups. The group with macroretentions, silane, and not thermocycled was the one that obtained the highest average value (17.31 ± 4.89 MPa). The lowest average value was the group without macroretentions, without silane, and thermocycled (3.4 ± 3.37 MPa).
The shear bond strength of brackets to provisional prosthetic CAD/CAM materials depended on the type of adhesive, surface treatment, and aging by thermocycling.
A split-Chevron-Notched-Beam sandwich specimen for fracture toughness testing of bonded interfaces
2022, Journal of the Mechanical Behavior of Biomedical MaterialsThe realization that the use of strength tests as a means to probe the bonding performance of adhesive systems to dental restorative materials suffers from inherent drawbacks has shifted efforts towards devising viable and valid fracture toughness test for that purpose. Here we introduce a new procedure to produce split-Chevron-Notched-Beam specimens that need not undergo sawing or notching after bonding, thus sparing the interface from pre-stresses. We evaluate the formal geometric factor considering the influence of the use of different materials having different elastic properties, and show that the results obtained fall within reasonable ranges measured by other established compliance calibrated methods. We demonstrate the application of this new approach for dentin-luting composite and zirconia-luting composite interfaces for different adhesive systems and pre-treatment procedures in order to probe the sensitivity of the method to different bond qualities.
Dynamic characterization of hybrid composite based on flax/E-glass epoxy composite plates
2022, Materials Today: ProceedingsThe fundamental investigation on the dynamic characterization of Flax/E-glass hybrid composite plates was done and the mathematical model was developed for Flax/E-glass hybrid composite using Finite element method. In this experimental set up vaccum bagging process was implemented in order to fabricate prototypes of Flax/Epoxy, E-glass/Epoxy, Flax/E-glass epoxy hybrid composites and to conduct experimental investigation on dynamic properties. The first order shear deformation plate theory was used in this study for developing the mathematical model. Modal analysis was done on each composite plate for three times and average was taken between the values obtained to minimize the error. By this natural frequency of Flax/Epoxy, E-glass/Epoxy and Flax/E-glass epoxy hybrid composite and natural frequencies were found out experimentally by modal testing. The effect of natural frequencies on composite material, with respect to boundary condition, ply angle and aspect ratio were studied and the experimental results were validated with respect to mathematical modeling Mode Shapes with effect of natural frequencies on composite material, ply angle, aspect ratio, boundary conditions were studied, for all laminates and it was found that for all laminates CCCC boundary condition has high natural frequencies compared to other models. Hence it was observed that experimental results obtained through modal testing were very close to the Matlab results.