Monobacterial and mixed bacterial plaques of Streptococcus mutans and Veillonella alcalescens in an artificial mouth: development, metabolism, and effect on human dental enamel.

To gain greater understanding of the role of Streptococcus mutans and Veillonella in the caries process, studies of both aerobically and anaerobically grown plaques of S. mutans C67-1 and V. alcalescens V-1 on human enamel slabs were carried out in an artificial mouth. Plaque development, acid production, and demineralization were measured. Early plaque development of monobacterial and mixed bacterial plaques started from randomly adhering cells on day 1 to confluent multilayered microcolonies on day 4. Differences were observed in viable cell counts, total cell mass, and in acid production. In most cases CFU, DNA and acid production were higher in the mixed bacterial plaque, especially in the anaerobic mixed plaque. Lactic acid was the predominant acid in all cases following the supply of sucrose to the plaque. No decisive role could be found for acetic, formic, and propionic acid. No inhibition of demineralization was observed in the enamel slabs inoculated with both aerobic and anaerobic mixed plaques. Demineralization ranged from the more classical picture of lesion development in the aerobic monobacterial plaque-treated samples to an aggressive etching of the enamel surface in the anaerobically mixed treated slabs.

A new apparatus for continuous cultivation of bacterial plaque on solid surfaces and human dental enamel.

A new apparatus for the continuous cultivation of mono and mixed bacterial plaque on solid surfaces is described. The features are: easy preparation and handling; freedom from technical problems and microbial contamination; self-sufficient for periods of up to 56 d; 12 samples are taken simultaneously; programmable supply inlet. Experiments were performed with Streptococcus mutans C 67-1 for mono bacterial inoculation and in combination with Veillonella alcalescens V-1 for mixed bacterial inoculations. The results showed that the controlled conditions and versatility of the apparatus make possible the study of plaque-development and lesion production on a time-dependent basis. It is concluded that the apparatus is suitable for a wide range of dental and non-dental applications.

[Characteristics of evaluating nursing home residents in the Netherlands; a rating instrument]. / De samenhang in de validiteitskenmerken van de verpleeghuisbewoners in Nederland; een meetinstrument.

This article describes the way in which an instrument has been developed to measure the need for help of patients in the nursing homes of the Netherlands. The instrument is an important variable in the so-called Basic Research into the cost structure of the Dutch nursing homes (in Dutch BKV). The need for help is expressed as an index ('help-index') per patient. The index is based on the strong hierarchical relations between a number of patient-variables: washing, clothing, feeding, toileting, transferring (in and out of bed, walking, standing, wheelchair-activities), continence (urine and/or faeces) and contact function (speech). The 'help-indices' of the individual patients of a specific nursing home can be summarized in the average 'help-index' of that nursing home. The averages of the individual nursing homes differ to a great extent. The average 'help-index' per nursing home is considered to be of great importance as an independent variable with respect to staff per 100 beds and costs (total or per patient day) in the nursing homes. The latter is the subject of further research.