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Biomedical subjects

E I Pearce

Publications and source records attributed to E I Pearce.

At least 73 records · Page 4Linked to original sources
PubMed1983

Increases in fluoride, calcium, and phosphate in dental plaque resulting from the use of a mineralizing mouthrinse containing urea and monofluorophosphate.

A mouthrinse used ten times over a four-day period increased the concentration of acid-extractable fluoride in immature plaque by 320%, calcium by 190%, and phosphate by 97%. Corresponding increases in mature plaque were smaller, yet significant. Diffusion of the ions from plaque was restricted, and hence a prolonged caries-inhibitory effect can be expected.

Calcium↗
PubMed1983

A microradiographic and chemical comparison of in vitro systems for the simulation of incipient caries in abraded bovine enamel.

An acetate buffer system, supersaturated with fluorapatite but not with hydroxyapatite, produced lesions in abraded bovine enamel which resembled human enamel caries lesions, both morphologically and in their F distribution. A gelatin-lactate system gave similar results when unpurified gelatin was used. Systems containing deionized gelatin, diphosphonate, or Ca and phosphate but no F, failed to produce caries-like lesions.

Animals↗
PubMed1981

Ion displacement following the adsorption of anionic macromolecules on hydroxyapatite.

Certain small anionic molecules displace phosphate ions from the hydroxyapatite crystal hydration layer on adsorption. This follows the interaction of negatively charged groups with calcium ions in the crystal surface. The present study examines ion-exchange processes occurring during the adsorption of anionic macromolecules and attempts to determine the role of coulombic forces in the process. Various natural and synthetic polyanionic substances were added to a buffered hydroxyapatite slurry and adsorption measured by solution depletion. Calcium and phosphate ion displacement or uptake by apatite was determined after accounting for polymer-bound ions. Carboxymethylcellulose and a polyacrylamide sample in which 54% of amide groups had been hydrolyzed to carboxyl were adsorbed in the lowest amounts, but both caused consistent rises in the bulk solution phosphate level. Crude bovine submaxillary mucin and a polyacrylamide sample in which 28% of amide groups had been hydrolyzed were adsorbed in greater amounts but caused little or no phosphate displacement. In no case was there a stoichiometric relation between carboxyl adsorbed and phosphate displaced. The polyacrylamide samples also displaced Ca ions into the bulk solution, whereas the other macromolecules caused a decrease in solution Ca concentration. These results provide some evidence for the operation of an ion-exchange mechanism in the adsorption of polyanions on hydroxyapatite but do not exclude the involvement of other mechanisms, especially in the case of salivary mucin.

Adsorption↗
PubMed1980

Stability of fluoride levels in surface layer of normal enamel during a 21-month fluoride mouthrinsing program.

A 21-month trial of the caries-preventive effect of a 0.2% NaF mouthrinse included monitoring changes in the concentration of F in normal enamel. Subsamples of 25 children were randomly selected from groups receiving either normal dental treatment (Control group); additional fortnightly professional prophylaxes (Test group); or prophylaxes plus fortnightly 2-min fluoride rinses (Test + F group). At the start of the trial the sound labial surface of tooth 24 (occasionally 23 or 22) was etched with 2 N HCL and the etchant analysed for F, Ca and phosphate. The contralateral tooth was sampled at the end of the trial. The caries increments (DFS) for the three groups over 21 months were Control, 2.88; Test, 2.51 and Test + F, 1.77, the last being significantly less than the others (P less than 0.05). The average sound enamel surface F concentrations were similar for the three groups at the start and the end of the trial. F parameter calculations showed that all differences were non-significant. Thus this factor could not explain the reduced caries increment due to F mouthrinsing. F biopsies for the purpose of predicting likely clinical effectiveness of neutral 0.2% NaF mouthrinsing will find little application in public health dentistry.

Adolescent↗