A mathematical model of the influence of salivary urea on the pH of fasted dental plaque and on the changes occurring during a cariogenic challenge.
Urea diffusing from saliva into dental plaque is converted to ammonia and carbon dioxide by bacterial ureases. The influence of normal salivary urea levels on the pH of fasted plaque and on the depth and duration of a Stephan curve is uncertain. A numerical model which simulates a cariogenic challen...
| Publicado en: | Caries Research Vol. 32; no. 1; pp. 70 - 75 |
|---|---|
| Autores principales: | , |
| Formato: | research Journal Article |
| Publicado: |
Karger AG
Jan/Feb1998
|
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=50308526&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 50308526 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 00086568 DEU jtl: Caries Research issn: 00086568 maglogo: N pubinfo: dt: Jan/Feb1998 vid: 32 iid: 1 pid: 2485 pub: Karger AG artinfo: ui: 50308526 50308526 NLM9438574 50308526 10.1159/000016432 NLM9438574 50308526 ppf: 70 ppct: 5 formats: tig: atl: A mathematical model of the influence of salivary urea on the pH of fasted dental plaque and on the changes occurring during a cariogenic challenge. aug: au: Dibdin, G. H. Dawes, C. affil: MRC Dental Group, The Dental School, Bristol, UK sug: subj: Dietary Sucrose Pharmacodynamics Dental Caries Physiopathology Saliva Metabolism Cariogenic Agents Pharmacodynamics Urea Metabolism Models, Biological Dental Plaque Physiopathology Forecasting Urease Metabolism Dietary Sucrose Administration and Dosage Diffusion Hydrogen-Ion Concentration Saliva Physiology Cariogenic Agents Administration and Dosage Bacteria Electrochemistry Human Phosphates Pharmacodynamics Carbonates Pharmacodynamics Buffers Fasting Carbon Dioxide Metabolism Dental Plaque Metabolism Chewing Gum Ammonia Pharmacodynamics Ammonia Metabolism Dental Deposits Metabolism Ions Protons Dental Deposits Physiopathology Lactates Pharmacodynamics Dental Caries Metabolism Acids Metabolism Acetic Acid Pharmacodynamics Validation Studies Comparative Studies Evaluation Research Multicenter Studies ab: Urea diffusing from saliva into dental plaque is converted to ammonia and carbon dioxide by bacterial ureases. The influence of normal salivary urea levels on the pH of fasted plaque and on the depth and duration of a Stephan curve is uncertain. A numerical model which simulates a cariogenic challenge (a 10% sucrose rinse alone or one followed by use of chewing-gum with or without sugar) was modified to include salivary urea levels from 0 to 30 mmol/l. It incorporated: site-dependent exchange between bulk saliva and plaque surfaces via a salivary film; sugar and urea diffusion into plaque; pH-dependent rates of acid formation and urea breakdown; diffusion and dissociation of end-products and other buffers (acetate, lactate, phosphate, ammonia and carbonate); diffusion of protons and other ions; equilibration with fixed and mobile buffers; and charge-coupling between ionic flows. The Km (2.12 mmol/l) and Vmax (0.11 micromol urea/min/mg dry weight) values for urease activity and the pH dependence of Vmax were taken from the literature. From the results, it is predicted that urea concentrations normally present in saliva (3-5 mmol/l) will increase the pH at the base of a 0.5-mm-thick fasted plaque by up to 1 pH unit, and raise the pH minimum after a sucrose rinse or sugar-containing chewing-gum by at least half a pH unit. The results suggest that plaque cariogenicity may be inversely related to salivary urea concentrations, not only when the latter are elevated because of disease, but even when they are in the normal range. pubtype: Academic Journal doctype: research Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
|---|