Mechanical behavior of M-Wire and conventional NiTi wire used to manufacture rotary endodontic instruments.

OBJECTIVE: Comparison of physical and mechanical properties of one conventional and a new NiTi wire, which had received an additional thermomechanical treatment. METHODS: Specimens of both conventional (NiTi) and the new type of wire, called M-Wire (MW), were subjected to tensile and three-point bending tests, Vickers microhardness measurements, and to rotating-bending fatigue tests at a strain-controlled level of 6%. Fracture surfaces were observed by scanning electron microscopy and the non-deformed microstructures by transmission electron microscopy. RESULTS: The thermomechanical treatment applied to produce the M-Wire apparently increased the tensile strength and Vickers microhardness of the material, but its apparent Young modulus was smaller than that of conventionally treated NiTi. The three-point bending tests showed a higher flexibility for MW which also exhibited a significantly higher number of cycles to failure. SIGNIFICANCE: M-Wire presented mechanical properties that can render endodontic instruments more flexible and fatigue resistant than those made with conventionally processed NiTi wires.

Effect of commercial ethanol propolis extract on the in vitro growth of Candida albicans collected from HIV-seropositive and HIV-seronegative Brazilian patients with oral candidiasis.

The present study assessed the susceptibility of Candida albicans strains, collected from HIV-positive patients with oral candidiasis, to a commercial 20% ethanol propolis extract (EPE) and compare it to the inhibitory action of the standardized antifungal agents nystatin (NYS), clotrimazole (CL), econazole (EC), and fluconazole (FL). Twelve C. albicans strains collected from HIV-positive patients with oral candidiasis were tested. The inhibition zones were measured with a pachimeter and the results are reported as means and standard deviation (M +/- SD). Data were analyzed statistically by the non-parametric Kruskal-Wallis test. EPE inhibited all the C. albicans strained tested. No significant difference was observed between the results obtained with NYS and EPE, while significant differences were observed between EPE and other antifungals. The C. albicans strains tested showed resistance to the remaining antifungal agents. The propolis extract used in this study inhibited the in vitro growth of C. albicans collected from HIV-seropositive Brazilian patients, creating/forming inhibition zones like those ones formed by NYS. This fact suggests that commercial EPE could be an alternative medicine in the treatment of candidiasis from HIV-positive patients. However, in vivo studies of the effect of EPE are needed to determine its possible effects on the oral mucosa.