[Alumina reinforced porcelain jacket crown].
Aluminum oxides provide one of the most useful sources of high-strength and high-modulus crystals. New types of high alumina content glasses may replace feldspathic porcelains. Esthetics compare favorably.
Research in dental practice: a 'SWOT' analysis.
Most dental treatment, in most countries, is carried out in general dental practice. There is therefore a potential wealth of research material, although clinical evaluations have generally been carried out on hospital-based patients. Many types of research, such as clinical evaluations and assessments of new materials, may be appropriate to dental practice. Principal problems are that dental practices are established to treat patients efficiently and to provide an income for the staff of the practice. Time spent on research therefore cannot be used for patient treatment, so there are cost implications. Critics of practice-based research have commented on the lack of calibration of operative diagnoses and other variables; however, this variability is the stuff of dental practice, the real-world situation. Many of the difficulties in carrying out research in dental practice may be overcome. For the enlightened, it may be possible to turn observations based on the volume of treatment carried out in practice into robust, clinically related and relevant research projects based in the real world of dental practice.
Mechanical Properties and Chemical Reactivity in Mullite—Glass Systems
Mullite-glass systems were studied by vacuum hot-pressing sized mullite crystal particles with known glass compositions. During the hot-pressing at relatively low temperatures, significant chemical reactivity was observed between mullite and a soda borosilicate glass. This reaction led to the precipitation of a silica-rich crystalline phase in the glass matrix and to a change in the mullite structure as evidenced by the X-ray diffraction pattern. Wetting studies at elevated temperatures indicated an interfacial chemical reaction. The modulus of rupture increased when the second crystalline phase was present. Increased volume fraction of the crystalline phase and development of a stronger interfacial bond between mullite and glass may be the primary factors responsible for the increase in mechanical strength.