On the possibility of estimating the fracture toughness of enamel.

Objectives: There are many works that have attempted to estimate the fracture toughness of enamel by indentation techniques using equations whose success in determining the actual value of fracture toughness, rely on a particular three-dimensional pattern consisting of cracks growing from the edges of the indentation. Recently, an alternative methodology based on an energetic approach has been developed to estimate the fracture toughness of coatings by depth sensing indentation that is not less affected by the cracks pattern generated. In this work, the energetic approach to indentation fracture toughness of bovine enamel is presented and compared with those toughness values obtained using the traditional expressions reported in the literature.

Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives.

The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers' instructions.

Early hardness of self-adhesive resin cements cured under indirect resin composite restorations.

Purpose: To determine the influence of curing mode on the surface hardness of seven resin cements used to lute indirect composite restorations.

Materials And Methods: Seven commercial dual-curing resin cements were tested: two were total-etch (RelyX ARC [3M ESPE, St. Paul, MN, USA] and Variolink II [Ivoclar Vivadent, Schaan, Liechtenstein]); one was self-etch (Multilink Automix [Ivoclar Vivadent]), and four were self-adhesive (RelyX Unicem [3M ESPE], Maxcem Elite [Kerr Corp.

Mechanical characterization of sclerotic occlusal dentin by nanoindentation and nanoscratch.

Purpose: To evaluate the mechanical properties of occlusal wear lesions identified as sclerotic.

Methods: Nanoindentation and nanoscratch techniques have been applied to determine elastic modulus (E), hardness (H) and wear resistance of different types of sclerotic dentin. Nanoscratch testing was applied to evaluate the tribological behavior.

Mechanical characterization of resin cements used for luting fiber posts by nanoindentation.

Objectives: To evaluate the mechanical behavior of resin cements used for luting fiber post. The influence of the curing mode is analysed.

Methods: Nanoindentation techniques have been applied to determine hardness and Young's modulus of disc-shaped specimens of three types of cements: chemical- , photo- and dual-cured, provided by Ivoclar-Vivadent.