INTRODUCTION The aim of this study was to evaluate the effects of bleaching gel using 35% hydrogen peroxide (HP), associated with red carmine pigment (RC), in the 3:1 or 1:1 ratio, on fracture resistance and dentin microhardness of endodontically treated teeth. MATERIALS AND METHODS A total of 40 lower incisors were endodontically treated and divided into four groups (n = 10), according to th...

The effect of 1%, 3% and 5% EGTA (ethylene glycol-bis-(beta-amino-ethyl ether) N,N,N',N'-tetra-acetic acid) on the microhardness of root dentin of the cervical third of human teeth was studied. Five newly extracted maxillary incisors were sectioned transversely at the cementoenamel junction, and the crowns were discarded. The roots were embedded in blocks of high-speed polymerized acrylic resin...

introduction: whitening toothpastes which have been accepted in populations may affect properties of enamel and restorative materials. the aim of this study was to compare the microhardness of human enamel and z250 microhybrid composite resin after brushing with two whitening toothpastes. materials and methods: in this experimental study of enamel specimens, forty five freshly extracted human i...

background: human endeavors to prevent dental caries have led to the use of different modalities and agents, the most commonly used of which is fluoridated dentifrice. an in situ study was carried out to evaluate the efficacy of fluoridated dentifrices in achieving remineralization of initial caries-like lesions using surface microhardness measurements and to study the qualitative changes by sc...

in this research a layer of ni-cu-p was deposited on 304 stainless steels by using gelatin and thiourea asadditives in a sulfate solution. in order to determine the properties of deposited layers, a microhardness testerwas used for microhardness measurement, x.r.d. for microstructural analysis, and a scanning electronmicroscope equipped with e.d.x. for determining morphology and analyzing the d...

background: although composite restorations are really valuable for esthetic zones, they have shown less longevity rather than amalgam restorations. since it may be related to the method used for curing the composite, postcuring could increase the degree of conversion and result in more long‑lasting composite restorations. this study was planned to evaluate the effect of two different postcurin...

  Objective: This study aimed to assess the destructive effects of citric acid, lactic acid and acetic acid produced from the fermentation of foods on primary teeth enamel.   Methods: This in vitro, experimental study was conducted on 24 sound primary teeth. The teeth were polished with a fine abrasive paper under running water. Tooth pieces measuring 3 × 4 × 3mm were cut out of the teeth and s...

Glasses with composition 10TeO2.15BaO.(75-x)B2O3.xNiO and 10TeO2.15BaO.(75-x)B2O3.xWO3 (where x= 0 to 1 mol% in steps of 0.2) have been prepared by using a conventional melt-quenching method. The amorphous nature of the samples was ascertained using X-ray diffractometry (XRD). Microhardness measurements were carried out using Zwick 3212 hardness tester fitted with a Vicker’s diamond pyramidal i...

Vickers microhardness tests were used to gauge the mechanical "competence" (ability to resist bending and failure) of cortical and trabecular bone along the humeri of three bird species. Hardness was greatest at the mid-length portion of the shaft. The mean hardness of trabeculae, where present, was between 78.7 and 90.9% of that of the adjacent cortical bone. The possible causes of this are br...

The mechanical properties (fracture strength, fracture toughness, and Vickers microhardness) of MgAl2O4 and x wt% ZrO2–MgAl2O4 (1 # x # 30) hot-pressed materials were measured at room temperature. Two kinds of materials, which were prepared from either ball-milled or attrited powders, were investigated. Compared with an unreinforced spinel, a twofold (or greater) increase in both strengthening ...