Educational technology in the teaching of dentistry: the importance of objectives

A description of educational technology is given and the importance of establishing clear teaching-learning objectives is related to curriculum, evaluation and teaching methods.

The effect of 1,4-diaminobutanone on the stability of ornithine decarboxylase from Aspergillus nidulans

1,4-Diaminobutanone, a competitive inhibitor of ornithine decarboxylase in Aspergillus nidulans, is able to increase the half-life of this enzyme and thus stimulate an increase in its activity in vivo. It also protects ornithine decarboxylase against proteolysis by chymotrypsin in vitro.

A comparison of two methods of demonstrating an exercise in dental technology

A comparison between conventional and live television methods of demonstrating an exercise in dental technology was carried out and indicated that they were equally effective as judged by grading of students' work. Students' comments suggested that the television method was received less favourably. Their comments form a basis for discussion regarding the use of material recorded on cassette or cartridge with immediate replay facilities rather than television demonstrations in real time.

A comparison of the casting ability of precious and nonprecious alloys for porcelain veneering

The alloys tested varied with respect to their castability. This variability is related to density. Problems caused by low density may be solved by increasing the casting force. For all parameters measured in the laboratory, Thermocraft, a precious alloy, proved to be the most satisfactory- Wiron S, a nonprecious alloy, was comparable to Degudent Universal, a gold alloy. The application of Wiron S as a successful gold substitute should, therefore, be further investigated clinically. Equipment, investment, and casting techniques, all designed for the casting of gold alloys, were also used for the nonprecious alloys. These are standard facilities readily available in clinical practice. Modifications or technical improvement to these factors may result in more successful application to the other nonprecious alloys.

Family response to loss of a child by sudden infant death syndrome

Nineteen families were interviewed after their loss of an infant by sudden infant death syndrome. Their bereavement responses are described. The outcome after 13 months is studied in terms of resumption of normal living, and health changes. The parents' perceptions of intervention are discussed, and recommendations are made about how best to help such families.

Some aspects of non-precious metal alloys for ceramic restorations

Comment is made regarding the cost, related to working properties, of non-precious metal alloys compared to precious metal alloys for ceramics and their possible potential for the production of allergic response.

Polyamine and ornithine metabolism during the germination of conidia of Aspergillus nidulans

1. The activities of ornithine decarboxylase, S-adenosylmethionine decarboxylase and ornithine-2-oxoglutarate aminotransferase were studied during the first 24 h of conidial germination in Aspergillus nidulans. 2. Increases (over 100-fold) in the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase occurred during the emergence of the germ-tube and before the doubling of DNA and this was followed by a sharp fall in the activities of both enzymes by 16h. 3. The increase in ornithine decarboxylase could be largely suppressed if 0.6 mM-putrescine was added to the growth medium. 4. Low concentrations of cycloheximide, which delayed germination by 2h, caused a corresponding delay in the changes in ornithine decarboxylase activity. 5. Ornithine-2-oxoglutarate aminotransferase activity increased steadily during the first 24h of germination. 6. Ornithine or arginine in the growth medium induced higher activity of ornithine-2-oxoglutarate aminotransferase, but did not affect ornithine decarboxylase activity. 7. The significance of these enzyme changes during germination is discussed.

Heat treatment of cast restorations

A survey of commercial dental laboratories in Brisbane indicates that hardening heat treatment of cast restorations, while not always prescribed by the dentist, is performed in most dental laboratories.

The properties of four dental cements

Tests on 4 cements showed no significant difference in the retentive property of zinc phosphate and polycarboxylate cements but significant differences existed between these and two zinc oxide eugenol (modified) materials. Polycarboxylate cement was the only material which fractured partially or wholly within the cement film and the zinc oxide eugenol modifications mostly adhered to the inlay.

Smoking and pregnancy

Smoking is associated with decreased fertility in both males and females, an increased abortion rate, lowered birth weight, an increased still birth rate and probably an increased neonatal death rate. There is also a reduced incidence of maternal hypertension (although the babies are at even greater risk), an increased incidence of ante-partum haemorrhage, impaired brain development and possible teratogenic effects. These effects can be reversed if the mother gives up smoking in pregnancy.

Prolongation of allografts in animals with a new agent: tilorone

Tilorone, a synthetic amino-alkoxyflorenone, has been demonstrated to prolong allografts in rats and dogs. Tilorone, in combination with low dose non-specific immunosuppression, appears to have an additive effect. Tilorone's mechanism of action is unclear at this time but may involve a combination of specific T lymphocyte depletion and interferon induction.

Comparison of impact strength of joints made with four dental cements

Tests on 4 cements showed the impact strength of joints between gold and tooth structure varied somewhat with the surface roughness and cementing force. Polycarboxylate provided stronger joints although the results were variable. Little difference was found between zinc phosphate, zinc oxide-eugenol with polymethyl methacrylate, and zinc oxide-eugenol with ortho ethoxybenzoic acid.

Retention with specific and mechanical adhesive lutes

Attention is drawn to some of the fundamental differences between retention afforded by specifically adhesive and mechanically adhesive lutes. Terms are defined and conclusions drawn regarding the present status and potential of polyacrylate cements.