Linked Life Data

9602287

Source:http://linkedlifedata.com/resource/pubmed/id/9602287

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-8-25
pubmed:abstractText
The aim was to examine factors that potentially control the resting pH, defined as the pH unaffected by meals, of microcosm dental plaques and Streptococcus mutans biofilms under standard conditions, and to examine the effect of supplying urea at concentrations found intraorally. Microcosm plaques were cultured from plaque bacteria-enriched saliva in an 'artificial mouth' with a continuous supply of a medium including 0.25% mucin [Basal Medium Mucin, (BMM), 3.6 ml/hr per plaque] and a periodic supply of sucrose. The steady-state resting pH was 6.4 (range +/- 0.1) in BMM containing no urea and supplied at the standard flowrate. This is a robust property of the ecosystem. In one experiment with a replicated (n = 9) set of measurements, the resting pH was approx. pH 6.3, 6.4, 6.7 and 7.3 with 0, 1, 5 and 20 mmol/l urea in the BMM. The magnitude of sucrose- and urea-induced pH responses was unaffected by elevating the resting pH to produce parallel pH curves. The sucrose-induced pH curves were analogous to those classically reported by Stephan that showed an association between caries activity and increasingly acidic plaque pH responses to glucose. Stopping the BMM flow caused a pH rise, indicating continuing net alkali generation from BMM components in the absence of a fluid flow. Step. mutans monoculture biofilms had an acidic resting pH of 5.0 to 5.3, which increased to 6.8 following an adventitious superinfection by Bacillus cereus. It was concluded that the resting pH in plaque results from a delicate balance between alkali and acid generation, which is in turn dependent both on the bacterial composition of the plaque and on the supply of substrates and buffers from, and metabolite clearance into, flowing oral fluid. In vivo the resting pH will vary with site-specific changing saliva flows. Urea continuously supplied at concentrations normal for saliva and gingival crevicular fluid can raise the resting pH of microcosm plaque by an amount tat in vivo would probably be significant in reducing dental caries.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
D
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0003-9969
pubmed:author
pubmed:issnType
Print
pubmed:volume
43
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
93-102
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Factors affecting the resting pH of in vitro human microcosm dental plaque and Streptococcus mutans biofilms.
pubmed:affiliation
Department of Pathology, Wellington School of Medicine, Otago University, New Zealand.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't