AIM To examine the effect of condensation pressure on surface hardness, microstructure and compressive strength of mineral trioxide aggregate (MTA). METHODOLOGY White ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN, USA) was mixed and packed into cylindrical polycarbonate tubes. Six groups each of 10 specimens were subjected to pressures of 0.06, 0.44, 1.68, 3.22, 4.46 and 8.88 MPa respe...

OBJECTIVE The aim of this study was to evaluate the degree of conversion and hardness of different composite resins, photo-activated for 40 s with two different light guide tips, fiber optic and polymer. METHODS Five specimens were made for each group evaluated. The percentage of unreacted carbon double bonds (% C═C) was determined from the ratio of absorbance intensities of aliphatic C═C (pe...

Effects of the electrical flame off (EFO) parameters on the hardness and work hardening properties of Cu free air balls (FABs) are reported and compared to those of Au. Cu FABs were characterised using an online deformability method that measures the insitu deformability of the Cu FAB and by traditional off-line Vickers microhardness testing of cross-sectioned samples. The online deformability ...

Achieving extreme hardness in the newly synthetic steel formed by converting from initial amorphous state to subse-quent crystalline structure –named as devitrification process- was studied in this research work. Results of TEM observa-tions and XRD tests showed that crystallized microstructure were made up four different nano-scale phases i.e., α-Fe, Fe 36 Cr12 Mo10 , Fe 3 C and Fe3 B. More, V...

OBJECTIVES The aim of this study was to evaluate surface roughness and hardness of a nanofiller GIC, a resin-modified GIC, three conventional GICs, and a silver-reinforced GIC. METHODS For each material, 11 spcecimens were prepared and then stored in distilled water at 37 °C for 24 h. The surface roughness of 5 specimens was measured using a surface profilometer before polishing and after pol...

OBJECTIVE To evaluate the effect of disinfectants and distilled water on the micro-hardness of heat cure acrylic resins. METHODS The case-control study was conducted at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, and Nadirshaw Edulji Dinshaw University of Engineering and Technology, Karachi, from April to October 2011. Specimens were fabricate...

In the present study, the solution and ageing treatments behavior of Mg-RE-Zr-Zn alloy (Elektron21) and its nano-AlN reinforced nanocomposites have been evaluated. The properties of the thermal-treated materials were investigated in terms of Vickers hardness, the area fraction of precipitates, microstructure and phase composition. The solution treatments were performed by treating at 520 °C, 55...

OBJECTIVE The aim of this study is to evaluate if the cytotoxic effects of the Surefil SDR flow, bulk fill flowable composite resin and three conventional flowable materials (Venus Diamond Flow, Filtex Supreme XTE Flowable and Enamel plus HRi Flow) correlated with the conversion degree (DC); hardness and depth of cure are also assessed. MATERIALS AND METHODS Disks of each materials--cured usi...

It is attempted to augment a coating resin with a bleaching effect to provide both short- and long-term whitening effects. Base resin containing sodium percarbonate (SPC) effectively bleached bovine teeth discolored by the Maillard reaction. SPC did not reduce Vickers hardness, but hardness in the hybrid material increased. The shear bonding strength of SPC-containing resin was low. No inflamma...