Search results for "silica"
showing 10 items of 1092 documents
Analytical and mineralogical studies of ore and impurities from a chromite mineral using X-ray analysis, electrochemical and microscopy techniques
2007
A wide analytical study of South African chromite ore, material with high interest in ceramic industry, has been carried out. With this purpose, an accurate chemical identification and mineralogical characterization of the mineral and the gangue have been performed using X-ray fluorescence (XRF), voltammetry, X-ray diffraction (XRD), light microscopy (LM), and scanning electron microscopy (SEM/EDX). The elemental composition of the sample (ore and gangue) has been obtained by XRF. The voltammetric analysis has allowed to demonstrate that iron in the sample was as Fe(II). The main compound of the chromite ore was a spinel (magnesiochromite ferroan), identified by XRD from the sample, which c…
Traditional endodontic surgery versus modern technique: a 5-year controlled clinical trial.
2014
In this study, we compared outcomes of traditional apicoectomy versus modern apicoectomy, by means of a controlled clinical trial with a 5-year follow-up. The study investigated 938 teeth in 843 patients. On the basis of the procedure performed, the teeth were grouped in 3 groups. Differences between the groups were the method of osteotomy (type of instruments used), type of preparation of retrograde cavity (different apicoectomy angles and instruments used for root-end preparation), and root-end filling material used (gray mineral trioxide aggregate or silver amalgam). Outcome (tooth healing) was estimated after 1 and 5 years, postoperatively. Clinical success rates after 1 year were 67% (…
Osseous reaction to implantation of two endodontic cements : mineral trioxide aggregate (MTA) and calcium enriched mixture (CEM)
2012
Aim: The aim of the present in vivo study was to determine bone tissue reaction to calcium enriched mixture (CEM) and mineral trioxide aggregate (MTA) using a rat femur model. Study Design: Sixty-three rats were selected and randomly divided into three groups of 21 each [experimental groups (n=15), control (n=6)]. Implantation cavities were prepared in each femoral bone and randomly filled with the biomaterials only in the experimental groups. The animals in three groups were sacrificed 1, 4, and 8 weeks postoperatively. Histologic evaluations comprising inflammation severity and new bone formation were blindly made on H&E-stained decalcified 6-µm sections. Results: At 1, 4, and 8 weeks aft…
Biocompatibility of three new calcium silicate-based endodontic sealers on human periodontal ligament stem cells.
2016
Aim To evaluate the biocompatibility of three calcium silicate-based endodontic sealers, Bioroot BC Sealer (Septodont, Saint-Maur-des-Fosses, France), Endoseal MTA (EndoSeal, Maruchi, Seoul, Korea) and Nano-ceramic Sealer (B&L Biotech, Fairfax, VA, USA) (NCS), on human periodontal ligament stem cells (hPDLSCs). Methodology Human periodontal ligament stem cells were cultured in the presence of various endodontic sealer eluates for 24 h. Cell viability was determined using the MTT assay. Cell death and changes in phenotype induced by the set endodontic sealer eluates were evaluated through flow cytometry. Also, an in vitro scratch wound-healing model was used to determine their effects in cel…
Response of periodontium to mineral trioxide aggregate and Biodentine: a pilot histological study on humans.
2018
Background The aim of this study was to investigate for the first time the histological response of human periodontium to mineral trioxide aggregate (MTA) and Biodentine. Methods Six patients scheduled for implant full-arch rehabilitation were randomly assigned to one of the two test groups: MTA or Biodentine treatment. For each patient, two teeth scheduled for strategic extraction were randomly assigned either to the test or to the control treatment. A lateral perforation was drilled on the root and either repaired with MTA/Biodentine or filled with gutta-percha(control). Three months later, the teeth were extracted along with the coronal third of the alveolar bone and a portion of gingiva…
Effect of pH on compressive strength of some modification of mineral trioxide aggregate
2013
Objectives: Recently, it was shown that NanoMTA improved the setting time and promoted a better hydration process which prevents washout and the dislodgment of this novel biomaterial in comparison with WTMA. This study analyzed the compressive strength of ProRoot WMTA (Dentsply), a NanoWMTA (Kamal Asgar Research Center), and Bioaggregate (Innovative Bioceramix) after its exposure to a range of environmental pH conditions during hydration. Study Design: After mixing the cements under aseptic condition and based on the manufacturers' recommendations, the cements were condensed with moderate force using plugger into 9 × 6 mm split molds. Each type of cement was then randomly divided into three…
Assessment of the interaction of Portland cement-based materials with blood and tissue fluids using an animal model
2016
Portland cement used in the construction industry improves its properties when wet. Since most dental materials are used in a moist environment, Portland cement has been developed for use in dentistry. The first generation material is mineral trioxide aggregate (MTA), used in surgical procedures, thus in contact with blood. The aim of this study was to compare the setting of MTA in vitro and in vivo in contact with blood by subcutaneous implantation in rats. The tissue reaction to the material was also investigated. ProRoot MTA (Dentsply) was implanted in the subcutaneous tissues of Sprague-Dawley rats in opposite flanks and left in situ for 3 months. Furthermore the material was also store…
Effect of alkaline ph on sealing ability of white mineral trioxide aggregate
2011
Objectives: The aim of this study was to evaluate microleakage of white mineral trioxide aggregate (WMTA) after its exposure to a range of alkaline environments during hydration. Study Design: Seventy single-rooted teeth were divided into 4 experimental and 2 control groups. All the teeth were instrumented, and their apices were resected. Root-end cavities were filled with WMTA in the experimental groups. In the control groups, root-end cavities were not filled. Root-end fillings were exposed to alkaline environments with pH values of 7.4, 8.4, 9.4, or 10.4 for 3 days. Microleakage was evaluated by bovine serum albumin. Evaluations were carried out at 24-hour intervals for 80 days. Data wer…
Mineral trioxide aggregate in primary teeth pulpotomy. A systematic literature review
2009
Evidence-based dentistry is a critical evaluation, awareness of the available evidence to improve decision making about the care of individual patients and / or communities. Objective: To systematically analyze the available scientific literature on clinical and radiographic results of two materials used in pulpotomy in primary teeth: formocresol and mineral trioxide aggregate. Materials and methods: It was identified relevant publications through a search of electronic databases such as MEDLINE (Ovid) and The Cochrane Library. To be included in the review, studies had to define the material used in child patients with pulp exposure by caries or tooth-alveolar trauma. Results: Of the 21 art…
Study of two MTA cements
2014
Introduction: To determine and compare the pH, conductivity and calcium release of an experimental Portland cement (PE) consisting of trioxid mineral aggregate and a comercially available modified Portland cement (C.P.M.) after 1, 2, 3, 4, 8, 10, 15 and 30 days. Material and Methods: Cements were mixed following the manufacturer's instructions, with a powder: liquid ratio of 3:1. Each cement was placed in 12 PVC tubes 1 mm in diameter and 10 mm in length and allowed to set. Four empty tubes were used as negative controls. Tubes were submerged in plastic flasks containing 10 ml deionized water and stored at 37ºC and 100% humidity. After 1, 2, 3, 4, 8, 10, 15 and 30 days tubes were removed fr…