Do the Microshear Test Variables Affect the Bond Strength Values?

Abstract

Little is known about the effect of specimen preparation and testing protocols on the micro-shear bond strength (μSBS) results. To evaluate whether variations in polyethylene rod use affect (μSBS)). Human dentin disks were randomly distributed into six groups (n = 5): polyethylene tube (3 levels) and adhesive system (2 levels). In Group 1, polyethylene tubes filled with polymerized composite) were placed on adhesive covered surfaces. Tubes were removed 24 h after water storage, leaving the rods only. In Group 2, the same procedure was performed; however, tubes were kept in place during testing. In Group 3, composite rods without tubes were placed on adhesive covered dentin. In all groups, adhesives were photoactivated after positioning filled tubes/rods on adhesive covered surfaces. Specimens were tested under shear mode and the data subjected to a two-way ANOVA and Tukey's tests. Groups 1 and 2 resulted in statistically similar mean μSBS (P > 0.05); however, a greater number of pretest failures were observed for Group 1. Higher μSBS values were detected for Group 3, irrespective of adhesive system used (P < 0.05). Removing the polyethylene tube before composite rod is placed on dentin affects μSBS values.

Influence of the addition of chlorhexidine diacetate on bond strength of a high-viscosity glass ionomer cement to sound and artificial caries-affected dentin

“…Low bond strength values may have occurred because before the mechanical test, the plastic matrix used for fabrication of the test specimens was removed with the aid of a scalpel blade, and the pressure exerted for cutting may have been transferred to the cylinder of material, forming cracks in it, and also cause some level of stress at the bond interface, thus interfering in the real bond strength 25 . Maintaining the plastic matrix would be an alternative, however, it is resilient and capable of absorbing stress during the test.…”

Evaluation of the micro-shear bond strength of four adhesive systems to dentin with and without adhesive area limitation

“…Compared to the macro-shear bond strength test, the μ-SBS test is more advantageous; it has fewer internal defects as well as more homogeneous stress distributions at the interface due to the use of smaller specimen [10]. In addition, the μ-SBS test does not require an additional specimen trimming process after the bonding procedure, which conserves the integrity of the specimens and avoids pre-testing failures [11]. However, due to the unrestricted adhesive area, the traditional μ-SBS test technique still does not produce precise data.…”

Influência de tratamento dentinário com EDTA sobre a resistência de união de sistemas adesivos autocondicionantes

“…A mensuração da resistência de união é um dos métodos mais comuns para a avaliação das propriedades adesivas dos materiais restauradores. Vários métodos mecânicos -tais como tensão, flexão, ensaios de corte, cisalhamento e microtração -são usados para avaliar a união ao substrato dental 21 . O teste de microcisalhamento tem sido rotineiramente aplicado 22,23 e, diferentemente do teste de microtração, não há necessidade de se realizarem cortes dos espécimes, tornando-o mais simples e fácil de ser realizado 8 .…”