This study compared the abrasion resistance of direct composite resins cured by light-emitting diodes (LED) and halogen light-curing units. Twenty specimens (12 mm in diameter; 1.0 mm thick) of each composite resin [TPH (Dentsply); Definite (Degussa); Charisma (Heraus Kulzer)] were prepared using a polytetrafluoroethylene matrix. Ten specimens per material were cured with the LED source and 10 ...

A study was conducted to determine whether the mandibles of the detrito-/bryophagous groundhopper Tetrix tenuicornis are subject to mechanical wear as a result of feeding, as is the case for grasshoppers that feed on silica-rich grasses. Abrasion was evaluated by measuring the length and width of the 3rd incisor and length of the 4th incisor in adults of different ages collected under natural c...

This study evaluated the effect of air-particle abrasion protocols on the biaxial flexural strength, surface characteristics and phase transformation of zirconia after cyclic loading. Disc-shaped zirconia specimens (Ø: 15mm, thickness: 1.2mm) (N=32) were submitted to one of the air-particle abrasion protocols (n=8 per group): (a) 50μm Al2O3 particles, (b) 110μm Al2O3 particles coated with silic...

BACKGROUND Screw-rod constructs have been widely used to correct spinal deformities, but the effects of different screw-rod systems on anti-rotational torque have not been determined. This study aimed to analyze the biomechanical effect of different rod-screw constructs on anti-rotational torque. METHODS Three conventional spinal screw-rod systems (Legacy, RF-F-10 and USSII) were used to test...

Introduction Aeolian abrasion is the dominant rock weathering mechanism on Mars. Ventifacts, defined as rocks whose shapes or textures have been modified by windblown particles, are the manifestation of this weathering mechanism and are found on Earth and Mars. Studies of ventifacts and related features at the well-traversed Spirit Mars Exploration Rover (MER) landing site provides insight into...

Introduction: Low resistance of composite resins to abrasion is a primary concern in the application of these materials for posterior restorations which are prone to high occlusal loads. This study compared the wear resistance of three types of composites. Methods: In this laboratory experiment, five specimens of each of the three types of composites (z250, Heliomolar, Opallis) were prepared...