[Chemical composition of Mineral Trioxide Aggregates [MTA]: a review of literatures]

In 1993, Mineral Trioxide Aggregates [MTA], a grey-colored material was introduced to dentistry. A similar product in white-color was also produced later. The aim of this study was to review the literature in order to compare the chemical composition of these two different types of MTA. Over 600 articles have been published about the properties of MTA, 33 of which were about chemical and 28 were on its physical properties. In addition, about 80 articles have been published on similarities and differences between MTA and Portland Cements [PC]. This article reviews the history of MTA's manufacturing, its introduction to market, its patent, its commercial brands, and its similarities with PC. We also reviewed size of powder particle, setting form, and also hydration reaction of MTA. Mainly consisting of CaO and SiO2, MTAs and PC have similar compositions. MTA also contains Bi2O3 as an opacifier. The main difference in chemical composition of white MTA and PC with grey MTA is that the latter contains less amount of some minor elements specifically FeO. White MTA has finer particles and crystals compared to the grey one. No phosphate does exist in MTA composition, but during the hydration, this material is able to release calcium and hydroxyl ions which, in reaction to exogenous phosphate, results in hydroxyapatite formation. Both MTA and PC are hydrophilic cements. Regarding the biocompatibility of these materials, MTA is considered suitable for clinical applications; while no permission exists for clinical use of PC

comparative study between mineral trioxide aggregate and calcium hydroxide as pulp capping agents in dog's teeth

This study was carried out in order to compare mineral trioxide aggregate [MTA] and dycal in dog's teeth as pulp capping agents. After general and local anesthesia forty-two teeth of three dogs were used. In each tooth a class V cavity was prepared and the pulp was exposed using No.1 round bur. Then the exposed area was capped using either MTA or calcium hydroxide and the rest of the cavity was restored by amalgam. Radiographic image was taken before the procedure and after 4, 8, and 12 weeks. The animals were sacrificed at 4, 8, and 12 weeks and the teeth were prepared for H and E staining. The pulps of the teeth were evaluated for inflammation, necrosis, and formation and thickness of calcified bridge. Histologic data were analyzed by Kruskal Wallis, x [2], Cochran, and Friedman tests. Histopathologic results showed that in four weeks, MTA had significant differences with calcium hydroxide in the presence and thickness of calcified bridge [P=0.046] as well as inflammation [P= 0.014] and hyperemia [P=0.014]. Eight weeks MTA specimens showed significant difference in thickness of calcified bridge [P=0.008]. Twelve weeks after pulp capping, the amount of necrosis and chronic inflammation were higher in dycal specimens; however, there was no significant difference between two experimental groups. Radiographic evaluation did not show any periapical lesion, internal and external resorption, or widening of periodontal ligament in none of the teeth at all time intervals. Based on the result of this study, MTA showed to be a more reliable material as pulp capping agent in comparison with calcium hydroxide