Interactions between fluoride and plaque in the remineralization of enamel caries-like lesions.

The effect of fluoride and plaque, separately and together on the remineralization of early artificial caries lesions was studied in a group of volunteers in a double-blind randomized study design. Artificial caries lesions produced in slabs of human enamel were mounted buccally in silver bands cemented bilaterally to the mandibular first molar teeth. Volunteers wore the bands for two 2-week periods, rinsing daily with either a placebo or a 500 ppm fluoride mouthrinse. Plaque accumulation was encouraged by placing Dacron gauze over one of each pair of slabs. Sections were cut from the lesions and analyzed by microradiography followed by microdensitometry and image analysis. Microdensitometric data revealed that non-significant increases in mineralization had occurred in all of the test groups. However, the image analysis results indicated that significant remineralization had occurred in lesions after 2 weeks on the fluoride rinse regimen, with no significant remineralization in lesions exposed to the placebo. The presence or absence of plaque over the lesions had no effect on the amount of remineralization induced on the fluoride rinse regimen.     

General anaesthesia: practical recommendations and recent advances.

General anaesthesia has become, thanks to recently developed drugs, monitoring devices and delivery systems, a very well tolerated method of making the great surgical opportunities of the last few years available to all ages of patient. With a balanced and rational use of drug profiles, general anaesthesia allows even frail and very ill patients a margin of tolerability inconceivable just a few years ago. For the vast majority of patients, the risk from the general anaesthetic technique is so small it can be considered negligible. However, the majority of general anaesthetic drugs are both highly potent and very toxic, with many of the volatile agents still having a therapeutic ratio of about 4:1. The anaesthetic staff have to continually upgrade their skills and knowledge to ensure that harm does not result. It is, however, reasonable to offer some practical guidelines from the current literature on when to choose a general anaesthetic technique, either alone or with a regional local anaesthetic method, and when to avoid loss of consciousness. The complications expected from the use of general anaesthesia are reviewed, and the basis for these complications investigated. The currently available drugs and their place in anaesthetic practice are also assessed. Recent developments in the area of total intravenous anaesthesia and monitoring for potential awareness using bispectral analysis suggest that this technique should now be included in the choice of anaesthetic. Recommendations are made on both the selection of the technique, and the appropriate agents for a given group of patients.