objectives: micromechanical retention of resin cements to alloys is an important factor affecting the longevity of metal base restorations. this study aimed to compare the bond strength and etching pattern of a newly introduced experimental etchant gel namely nano met etch with those of conventional surface treatment techniques for nickel-chrome (ni-cr) and high noble alloys.  materials and met...

o bjectives: the purpose of this study was to evaluate the effect of salivary ph on the shear bond strength (sbs) of orthodontic brackets to tooth surface. materials and methods: eighty intact premolars were randomly divided into four groups of 20.  after bonding a bracket on each tooth, the groups one to four were stored in artificial saliva at a ph of 3.8, 4.8, 5.8, and 6.8, respectively for ...

introduction: the aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and erbium-doped yttrium aluminum garnet (er:yag) laser. methods: thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. specimens were ground to expose superficial...

The mechanisms which lead to shear failure of longitudinally reinforced concrete beams are complex and often misunderstood. In this paper, a combination of a special closed loop test technique and machine vision are applied to tests on two reinforced concrete beams failing in shear: one made of normal strength concrete and the second of high strength concrete. To control the progression of the ...

background: casein phosphopeptide-amorphous calcium phosphate (cpp-acp) is applied for remineralization of early caries lesions or tooth sensitivity conditions and may affect subsequent resin bonding. this in vitro study investigated the effect of cpp-acp on the shear bond strength of dental adhesives to enamel. materials and methods: sixty extracted human molar teeth were selected and randomly...

background: dental surfaces prepared with different er:yag laser distance may have different characteristics compared with those prepared with conventional instruments. the aim of this study was to investigate the effect of er:yag laser irradiation distance from enamel and dentin surfaces on the shear bond strength of composite with self-etch and etch and rinse bonding systems compared with con...

In this study, carbon nano fibers (CNFs) were mixed into epoxy resin through a magnetic stirrer and again mixed using ultra sonicator. Using hand layup technique, biaxial braided fiber composites were prepared with unfilled, 0.2, 0.5 and 1 wt% CNF. Tensile test and shear test was performed to identify the tensile strength and shear strength of the composites. Fractured surface of the tensile sp...

The properties of barnacle adhesive on silicone surfaces were studied by AFM indentation, imaging, and other tests and compared to the barnacle shear adhesion strength. A multilayered structure of barnacle adhesive plaque is proposed based on layered modulus regions measured by AFM indentation. The fracture of barnacles from PDMS surfaces was found to include both interfacial and cohesive failu...

pits, quarries, and on construction sites. The prediction of the penetration rate of drilling machines is very important for cost estimation and planning of rock excavation projects. Many researchers have investigated percussive drilling theoretically or experimentally and correlated the penetration rate with various rock properties. Protodyakonov (1962) developed drop tests and described the c...