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.

The collection and analysis of pre-evacuation times derived from evacuation trials and their application to evacuation modelling

This paper presents data relating to occupant pre-evacuation times from university and hospital outpatient facilities. Although the two occupancies are entirely different, they do employ relatively similar procedures: members of staff sweep areas to encourage individuals to evacuate.However the manner in which the dependent population reacts to these procedures is quite different. In the hospital case, the patients only evacuated once a member of the nursing staff had instructed them to do so, while in the university evacuation, the students were less dependent upon the actions of the staff, with over 50% of them evacuating with no prior prompting. In addition, the student pre-evacuation time was found to be dependent on their level of engagement in various activities.

Shear bond strengths of glass-ionomer cements to sound and to prepared carious dentine

The aim of this study was determine whether bonding of glass-ionomer cements to non-carious dentine differed from that to carious dentine. Five commercial cements were used, namely Fuji IX GP, Fuji IX capsulated, Fuji IX Fast capsulated (all GC, Japan), Ketac-Molar and Ketac-Molar Aplicap (both 3M-ESPE, Germany). Following conditioning of the substrate with 10% poly (acrylic acid) for 10 s, sets of 10 samples of the cements were bonded to prepared teeth that had been removed for orthodontic reasons. The teeth used had either sound dentine or sclerotic dentine. Shear bond strengths were determined following 24 h storage. For the auto-mixed cements, shear bond strength to sound dentine was found not to differ statistically from shear bond strength to sclerotic dentine whereas for hand-mixed cements, shear bond to sound dentine was found to be higher than to carious dentine (to at least p < 0.05). This shows that the chemical effects arising from interactions of glass-ionomer cements with the mineral phase of the tooth are the most important in developing strong bonds, at least in the shorter term.