The use of mineral trioxide aggregate in endodontics - status report

Mineral trioxide aggregate (MTA) is a clinical product comprising a mixture of Portland cement and bismuth oxide which is currently used as a root−filling material in dentistry. It has good biological compatibility, is capable of promoting both osteogenesis and cementogensis, and is finding increasing use in endodontic therapy. It is dimensionally stable, and provides an acceptable and durable seal for endodontically treated teeth. This article reviews the chemistry and applications of MTA, and highlights the fact that very little is currently known about the hydration chemistry, phase evolution and stability of this cement in physiological environments. However, biological effects of MTA have been well documented and are considered in detail. The article concludes that this material is a useful addition to the range of materials available for clinical application in endodontics.

An integrated study (geochemistry, stable oxygen and carbon isotopes, nannofossils, planktonic foraminifera, inoceramid bivalves, ammonites and crinoids) of the Waxahachie Dam Spillway section, north Texas: a possible boundary stratotype for the base of the Campanian Stage

The spillway of Lake Waxahachie, Ellis County (Texas), exposes a > 17 m section of the Hutchins Member of the Austin Chalk Group, un-conformably overlain by Taylor Clay. The Austin sequence was regarded as a potential Global Stratotype Section for the base of the Campanian Stage at the 1995 Brussels meeting on Cretaceous Stage boundaries, with the last occurrence of the crinoid Marsupites testudinarius (von Schlotheim, 1820) as the potential boundary marker. An integrated study of the geochemistry, stable carbon and oxgen isotopes, nannofossils, planktonic foraminifera, inoceramid bivalves, ammonites and crinoids of this section place the last occurrence of M. testudinarius in a matrix of eighteen ancillary biostratigraphic markers, while the boundary can also be recognised on the basis of a delta C-13 excursion that can, in principle, be detected globally in marine sediments. A new forma of the crinoid Marsupites testudinarius is introduced. The Waxahachie section fulfils sufficient geological criteria as to be an excellent candidate GSSP for the base of the Campanian Stage, if problems of ownership and access to the section can be resolved.