Cariogenic potential of lactosylfructoside as determined by acidogenicity of oral streptococci in vitro and human dental plaque in situ

Developments in dental plaque pH modelling

OBJECTIVES

The objectives of this review were to give a comprehensive account of the methods used to determine dental plaque pH over the last 50 years, to review how these methods have been used in dental cariology research and to give an update as to how dental plaque pH studies might be developed in the future.

DATA

Published, referred papers and abstracts of conference proceedings in the literature were reviewed.

SOURCES

A comprehensive search of the electronic databases PubMed and Medline, was undertaken. In addition, a hand search of the Index Denticus was done to identify relevant citations before 1966.

STUDY SELECTION

Relevant published literature in peer-reviewed publications was reviewed. No additional inclusion criteria were applied.

CONCLUSIONS

This comprehensive review gives an account of the background to, history of, relative merits and demerits of, applications of and future of dental plaque pH technologies.

Acid diffusion through extracellular polysaccharides produced by various mutants of Streptococcus mutans

Mutants of Streptococcus mutans V403, constructed by allelic exchange and altered in their capacity to produce enzymes involved in the production of extracellular polysaccharides from sucrose, were used to study the role of glucans and fructans in the diffusion of ions through cell concentrates. A 4.0mm diameter, 0.75 mm deep diffusion chamber with an ion-sensitive field-effect transistor electrode positioned at the base was used to monitor the diffusion of hydronium ions from a sodium lactate buffer using cell concentrates prepared from bacteria grown in various concentrations of sucrose and glucose. The wild-type strain V403 produced at least seven times as much water-insoluble glucan (ISG) from sucrose as mutants deficient in various combinations of glucosyltransferase B (GTF B), GTF C, GTF D and fructosyltransferase. The fastest diffusion of hydronium ions occurred with sucrose-grown cell concentrates of strain V403, and the time of diffusion to the bottom of the chamber was approximately 2.3 times longer when this strain was grown in glucose. The speed of diffusion with glucose-grown V403 was similar to that obtained with each of the mutants. When cells of strain V403 grown in sucrose and glucose were mixed, increases in diffusion speed were found to be directly related to the proportion of sucrose-grown cells. The mixing of ISG with several strains of S. mutans revealed that increases in diffusion speed were directly related to the quantity of ISG added.