Mineral trioxide aggregate (MTA) is composed of Portland cement, with 4:1 addition of bismuth oxide added so that the material can be detected on a radiograph. The cement is made up of calcium, silicon and aluminium. The main constituent phases are tricalcium and dicalcium silicate and tricalcium aluminate. There are two commercial forms of MTA, namely the grey and the white. The difference between the grey and the white materials is the presence of iron in the grey material, which makes up the phase tetracalcium alumino-ferrite. This phase is absent in white MTA. Hydration of MTA occurs in two stages. The initial reaction between tricalcium aluminate and water in the presence of calcium sulphate results in the production of ettringite. Tricalcium and dicalcium silicate react with water to produce calcium silicate hydrate and calcium hydroxide, which is leached out of the cement with time.

Mineral trioxide aggregate (MTA) has been widely used for different reparative procedures in endodontics. The extensive use of this cement for pulp capping, apexifications, apical surgeries, and revascularization is related to its ability to induce tissue repair and to stimulate mineralization. Several research studies have tested modifications in the composition of MTA-based cements in order to enhance their clinical performance. Novel formulations have been introduced in the market with the aim of increasing flowability. Important properties such as appropriate radiopacity and setting time, color stability, alkaline pH, release of calcium ions, and biocompatibility have to be considered in these new formulations. The latest research studies on the physical, chemical, and biological properties of tricalcium silicate-based cements are discussed in this critical review.

Portland cement is used in the building industry to make concrete. It is hydraulic and thus it develops its properties well in the presence of moisture. The oral environment is inherently wet, however, all dental materials need a dry field for optimal performance. A mixture of Portland cement and bismuth oxide was developed and marketed as mineral trioxide aggregate (MTA). The first formulation was gray in color followed by a white version and eventually by various similar materials, which are all composed of a tricalcium silicate‐based cement and radiopacifier. The MTA was originally suggested for particular clinical uses, such as root‐end filling and perforation repair, where maintenance of a dry field is difficult. The suggested uses were extended to apexification and dressing over pulpotomies, pulp capping and also as a sealer cement. The multipurpose use of MTA necessitated the development of improved formulations where material additives were included to the original cement/radiopacifier formulation. These additives supposedly enhance the material's properties and improve its function. Furthermore, the original Portland cement formulation was replaced with tricalcium silicate to avoid the inclusion of an aluminum phase and eliminate the inclusion of trace elements. The bismuth oxide was also replaced with alternative radiopacifiers. The multifaceted use of MTA allows the material to come into contact with different oral environmental conditions, including blood, saliva, tissue fluids, dental restorative materials, tooth structure and even air. These different conditions affect the properties and setting of the material. Future developments should further investigate the material's interactions and strive to create materials which are suited to a specific use.

Properties of materials affect results of antimicrobial testing, but this may not directly reflect the antimicrobial potential of the material in question. Careful choice of methodology and interpretation of results is important.

This preliminary study suggests that metal-based removable prostheses leach trace metal ions in saliva. Nickel-chromium-based dentures exhibit an etched appearance unrelated to GERD.