Shear vs. Tensile Bond Strength of Resin Composite Bonded to Ceramic

Department of Restorative Dentistry, University of Sheffield, United Kingdom.
Journal of Dental Research (Impact Factor: 4.14). 10/1995; 74(9):1591-6. DOI: 10.1177/00220345950740091401
Source: PubMed


Since the mode of failure of resin composites bonded to ceramics has frequently been reported to be cohesive fracture of either ceramic or resin composite rather than separation at the adhesive interface, this study was designed to question the validity of shear bond strength tests. The reasons for such a failure mode are identified and an alternative tensile bond strength test evaluated. Three configurations (A, conventional; B, reversed; and C, all composite) of the cylinder-on-disc design were produced for shear bond strength testing. Two-dimensional finite element stress analysis (FEA) was carried out to determine qualitatively the stress distribution for the three configurations. A tensile bond strength test was designed and used to evaluate two ceramic repair systems, one using hydrofluoric acid (HF) and the other acidulated phosphate fluoride (APF). Results from the shear bond strength tests and FEA showed that this particular test has as its inherent feature the measurement of the strength of the base material rather than the strength of the adhesive interface. In the tensile test, failure invariably occurred in the adhesive layer, with HF and APF showing a similar ability to improve the bond of resin composite to ceramic. It is concluded that the tensile bond strength test is more appropriate for evaluating the adhesive capabilities of resin composites to ceramics.

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    • "Microtensile bond strength (μTBS) test was introduced in dentistry by Sano et al. [16] and was proven to be more appropriate than shear tests for evaluating the bonded joints. [17] The aging process prior to the μTBS test can be performed either by exposing the bonded block (block aging) [5] [7] or the sticks obtained from the bonded block (stick aging) to the aging media.[9] [18] [19] However, to date, the literature lacks studies comparing the effectiveness of the aging methods in these two experimental situations. "
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    ABSTRACT: The aim of the present study is to investigate the effect of aging type (thermocycling vs. water storage) and aged unit (block vs. stick) on the repair strength of resin composite to feldspathic porcelain in testing microtensile bond strength (μTBS). Ceramic specimens (N = 30) (10 × 5.7 × 4.5 mm3, Vita Mark II, Vita) were obtained from CAD–CAM blocks. One surface was etched with 10% HF and silanized. An adhesive was applied and resin composite blocks were constructed incrementally on the conditioned surface. The specimens were randomly divided into five groups (n = 6): Control (C): Non-aged; BTC: Blocks were thermocycled (5–55 °C, 6000 cycles); STC: Sticks were thermocycled; BS: Blocks aged in water storage (6 months) after themocycling; SS: Blocks aged in water storage (6 months) after thermocycling. After μTBS test, failure types were classified. Data (MPa) were statistically analyzed (1-way and Dunett and 2-way ANOVA, Tukey`s) (α = 0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m), and shape (0) values were calculated. Aging type (p = 0.009) and aged unit (p = 0.000) significantly affected the results. Interaction terms were also significant (p = 0.000). Considering the stick level, there was no significant difference between thermocycling (STC: 25.7 ± 2.3) and water storage (SS: 25.3 ± 3.8) (p > 0.05) but the results were significantly higher when blocks were thermocycled (BTC: 31.6 ± 2.9) (p < 0.05). Weibull modulus and characteristic strength was the highest in BTC (m = 4.2; σo: 34.4) among all other groups (m = 3–3.9; σo: 14.6–28.5). Adhesive failures were common and cohesive failures occurred in less than 5% in all groups. Aging protocol was detrimental on durability of repair strength of resin composite to feldspathic porcelain. Exposing the sticks to either thermocycling or water storage aging should be considered in in vitro studies.
    Full-text · Article · Nov 2015 · Journal of Adhesion Science and Technology
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    • "Such methods have been used to evaluate the effect of surface treatment or thermocycling of ceramic restorative materials [25] [26]; thermocycling has been used extensively to simulate aging of resin cement in an intra-oral environment [9] [27]. While relatively simple, such testing concepts are generally marred by large variations in the bond failure stress, the effect that may be attributed to the joint's sensitivity to geometric misalignments and the tendency for tensile stresses to concentrate at the bond terminus [28] [29]. An alternative means for assessing bond strength is the use of fracture mechanics. "
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    ABSTRACT: Objective. A major limiting factor for the widespread use of zirconia in prosthetic dentistry is its poor resin-cement bonding capabilities. We show that this deficiency can be overcome by infiltrating the zirconia cementation surface with glass. Current methods for assessing the fracture resistance of resin-ceramic bonds are marred by uneven stress distribution at the interface, which may result in erroneous interfacial fracture resistance values. We have applied a wedge-loaded double-cantilever-beam testing approach to accurately measure the interfacial fracture resistance of adhesively bonded zirconia-based restorative materials. Methods. The interfacial fracture energy GC was determined for adhesively bonded zirconia, graded zirconia and feldspathic ceramic bars. The bonding surfaces were subjected to sandblasting or acid etching treatments. Baseline GC was measured for bonded specimens subjected to 7 days hydration at 37 ◦C. Long-term GC was determined for specimens exposed to 20,000 thermal cycles between 5 and 55 ◦C followed by 2-month aging at 37 ◦C in water. The test data were interpreted with the aid of a 2D finite element fracture analysis. Results. The baseline and long-term GC for graded zirconia was 2–3 and 8 times greater than that for zirconia, respectively. More significantly, both the baseline and long-term GC of graded zirconia were similar to those for feldspathic ceramic. Significance. The interfacial fracture energy of feldspathic ceramic and graded zirconia was controlled by the fracture energy of the resin cement while that of zirconia by the interface. GC for the graded zirconia was as large as for feldspathic ceramic, making it an attractive material for use in dentistry.
    Full-text · Article · Sep 2015 · Dental Materials
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    • "Several studies have identified non-uniform stress distributions along bonded interfaces [45] [46] [47]. The nonuniform interfacial stress distribution generated for conventional tensile and shear bond strength tests initiate fractures from flaws at the interface or in the substrate in areas of high stress concentration [48]. "
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    ABSTRACT: Although several conventional surface treatments have been used on feldspathic ceramic, a few studies investigated the effects of the irradiation with Er: YAG laser using different parameters. The aim of this in vitro study was to evaluate the shear bond strength of a resin cement to feldspathic ceramic, after the application of different surface treatments, especially the irradiation with Er:YAG laser. Forty-two discs made of a feldspathic ceramic were divided into six groups (n = 7): G1: control group-10% hydrofluoric acid (HF), G2: Air abrasion with Al2O3 + HF; G3: Er: YAG laser with 500 mJ/4Hz, G4: Er: YAG laser with 500 mJ/4Hz: + HF; G5: Er: YAG laser with 400 mJ/6Hz and G6: Er:YAG laser with 400 mJ/6Hz + HF. After this, all the specimens were treated with silane, and then a resin cement cylinder was built on the treated ceramic surface. After 24 h at 37 °C, specimens were submitted to the shear bond strenght test and stereoscopic evaluation to determine the type of failure. The mean bond strength values (MPa) obtained were: G1-17.55, G2-18.80, G3-21.80, G4-12.62, G5-and 15.81 G6-11.59. After performing the ANOVA and Tukey's test, it was concluded that the group irradiated with Er:YAG laser at 500mJ/4Hz performed similarly to the groups that received the conventional treatments, such as hydrofluoric acid etching and the combination of air abrasion plus hydrofluoric acid, and was higher than the other groups irradiated with Er:YAG laser.
    Full-text · Article · Jun 2015 · Ceramica
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