The present study was undertaken in response to a growing concern among clinicians about an increase in gingival recession among children and adolescents. Groups of 50 boys and 50 girls aged respectively 7, 12, and 17 yr were examined at Espoo Health Centre in 1983. Gingival recession was measured on the facial and lingual aspects of all permanent teeth. Whenever the gingival margin was located on root cementum, the distance from the gingival margin to the enamel border was measured to the nearest 0.5 mm. Recession was categorized as "slight" (0.5 or 1 mm) or "extensive" (1.5-3.5 mm). The prevalence of gingival recession was 5% at 7 yr, 39% at 12 yr, and 74% at 17 yr of age. More girls than boys had recession in the two youngest age groups. At 17 yr recession was equally common in both sexes and both "slight" and "extensive" recession was most often recorded on facial surfaces of first molars, premolars and canines. The alarmingly high prevalence of gingival recession at young age warrants further study of both the reasons and the consequences of early cementum exposure.
The usual metods for cellulose determinations, excepting those in which the material is decomposed by total hydrolysis, are principally methods for producing cellulose preparations. In these the non-cellulosic compounds are tried to be removed as thoroughly as possible without decomposing the cellulose. However, the preparations obtained still contain different non-cellulosic components for which corrections must be made. In the method proposed by the authors a crude cellulose preparation is produced by a relatively mild treatment, and corrections are made for crude lignin and pentosans. The main feature in producing the crude cellulose preparation is shaking the samples with 3N NaOH solution in pressure bottles in a boiling water bath. The method appears to give readable results for fodder materials. For woods the results are evidently too high, especially due to mannan in the crude cellulose.
Under normal circumstances in man and in farm animals no part of the alimentary tract is ever empty, and in every part there occurs a mixing of the contents so that no sharp boundary exists between the components of successive meals. Paloheimo (4) has shown that in rat in spite of the formation of strata in the stomach, the components of succeeding meals enter into the intestine more or less mixed.
The authors present a new method for the determination of the complex of vegetable cell wall substances. The sample is extracted with boiling 80 % ethanol, boiling absolute ethanol and cold water. The residue corrected for ash, protein, and, if necessary, for starch, gives the amount of cell wall substances. Determinations were made of the same samples of which Salo in this department, using quite a different principle, has determined the cell wall complex. She determined separately cellulose, neutral sugar hemicellulose, uronic acid hemicellulose, and lignin. Adding up these items Salo obtained the total of the cell wall substances. The results obtained with the new method are in most cases in agreement with the results of Salo (Table 1). The 80 % ethanol seems to be a very efficient solvent. In most cases more than 35 % of the dry matter of the sample was dissolved by it, while only about 0.3 % was dissolved in the succeeding extraction with absolute ethanol (Table 2). 1—12 % was dissolved by water. The new method is compared also with the earlier method of Paloheimo in which the sample is boiled in 0.05 N hydrochloric acid. It appeared that the results obtained with the latter procedure are considerably lower than those obtained with the new method. Evidently most plant materials contain cell wall substances which are extractable with a very weak acid treatment.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.