In vitro effect of acidulated phosphate fluoride gel on the surface of composites with different filler particles.
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Biomedical subjects
Publications and source records attributed to V Thompson.
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A laboratory study was conducted to determine effects of 1.23% APF gel on three composite resins. All composite resins immersed in APF gel lost significantly more weight than did their controls with significantly different weight losses among the APF-treated composites. Surfaces of all resins exposed to APF gel, as viewed in SEM's, exhibited degradation of filler particles.
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A prospective study was carried out to confirm the validity of a predictive index for patients at risk of developing deep vein thrombosis. The index, which correctly identified nine out of 10 patients and incorrectly identified seven out of 52 patients as being at risk, is based on five variable--namely, the euglobulin lysis time, serum concentration of fibrin-related antigen, age, percentage overweight for height, and presence of varicose veins. Thus a population of patients at particularly high risk of developing postoperative deep vein thrombosis may be identified preoperatively by means of this index, so that prophylaxis may be used more rationally.
Administration of prophylactic low-dose subcutaneous heparin to prevent postoperative deep vein thrombosis is expensive, entails treating many patients unnecessarily, and causes some side effects. By using a predictive index a population of patients who are at particularly high risk of developing postoperative deep vein thrombosis may be identified preoperatively. Prophylaxis was given only to these patients, resulting in an incidence of deep vein thrombosis of 3.8% compared with 16.1% in previous studies in which no specific prophylaxis was given. By limiting prophylaxis to the group of patients identified by the predictive index as being at high risk of developing postoperative deep vein thrombosis results may be obtained that are as good as those expected from treating the whole population. Thus many patients are saved from exposure to low-dose subcutaneous heparin.
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This is a study of the ventilatory functions of 1,805 normal Mexican-American, white, and black students of six public schools in Houston, Texas, with ages ranging from 7 to 20. A roll-seal piston type spirometer was used. The best performed forced vital capacity curve of each student was selected by the computer program from which the following measurements were extracted: FVC, FEV1, FEV1/FVC ratio, PEFR, and MMEF. Each student also had the peak expiratory flow rate measured by the Wright peak flowmeter to establish normal values with this instrument. Significant differences of lung volume and flow rate exist among the three races, and between male and female subjects. Prediction equations and prediction curves for each race and sex are presented. The results of the present study are compared with those of previously published works.
A study was undertaken to establish the normal values of peak expiratory flow rate using the WPFM in three ethnic groups. This report is based on the testing of 1,805 healthy students 7 to 20 years of age in the Houston public schools. Significant differences of WPFR are noted among the three races, and between boys and girls. Prediction equations and regression lines are presented for each sex/race group. The performance of the WPFM is compared with that of the spirometer.
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Most biologists beleive that recombination speeds response to selection for traits determined by polygenic loci. To test this hypothesis, sixteen Drosophila melanogaster populations were selected for positive phototaxis for twenty-one generations. In some populations, balancer chromosomes were used to suppress autosomal recombination, and in others the autosomes were free to recombine. Suppression of recombination had no effect on mean rate of response to selection, though it may have increased variability in the rate of response among replicate lines. Suppressed recombination lines did not shift selection response to the freely recombining X chromosomes, despite fairly large increased in X chromosome recombination. The results suggest that in populations of moderate size, sex does not accelerate short term response to selection.
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The purpose of this study was to determine by visual inspection and by scanning electron microscopy (SEM) whether commercially available, topical, acidulated phosphate fluoride (APF) and neutral sodium fluoride (NaF) agents cause surface roughening of five sealant materials: two unfilled resins, two filled resins, and one glass-ionomer material. In addition, the effect of treatment with 1.23% APF and sonification on weight of an unfilled and a filled sealant was compared to treatment with controls. Unfilled sealants exhibited no surface changes visually or on micrographs following any treatment. Filled sealants and the glass-ionomer sealant exhibited visually apparent changes depending on the treatment. SEM inspection of filled sealants with visually apparent changes showed loss of filler particles whereas the glass-ionomer sealant exhibited apparent destruction both of the matrix and the filler particle. No significant differences in weight were found between sonicated and unsonicated specimens. However, significant loss of weight was found with filled sealant specimens, but not unfilled sealant specimens, treated with 1.23% APF gel as compared with the specimens treated with water. The results of this in vitro study indicate that preventive therapies that combine use of topical fluorides and sealants may cause deterioration of filled sealants and glass-ionomer sealant material, but not unfilled sealants.
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