摘要:

The fluoride ion activities of two NaF dentrifrices have been determined in undiluted samples, in samples diluted in 6 ml water or saliva, and in saliva-dentifrice slurries after 2 min brushing. The activity potentials were compared with the activities of NaF standards. The fluoride ion concentration of each dentifrice was determined when 0.1 g dentifrice was dissolved in 5 ml water and 20 ml buffer. The activities in diluted samples were about twice the activities in in vivo samples. The fluoride ion activity in saliva before fluoride application was below 0.06 ppm and rose to about 1 ppm half an hour after fluoride application.

ISSN:0008-6568    

DOI:10.1159/000259747

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Hydroxyapatite was exposed to solutions of monofluorophosphate (MFP) at pH 5 and pH 7, for periods up to 48 h, and fluoride (F––) and F as MFP were measured in solution and solid. The exposed solid was dissolved in 0.5 m HC104 at 2 °C and F–– measured immediately, and after hydrolysis had been completed 24 h later, employing a fluoride electrode. Solutions were analyzed in a similar manner. Solution F–– (3% of total F) decreased rapidly and then gradually increased to concentrations above the original level. Solution MFP decreased continuously, the rate decreasing with time. The corresponding deposition of F on the solid was in the forms of both F–– and MFP. The fraction of deposited F–– increased with increased time of exposure while the fraction of F as MFP decreased. MFP was removed more readily by washing than F––. MFP in MFP exposed apatite decreased while forming F–– under humid conditions, but remained constant under dry conditions. Only small amounts of F were deposited from MFP in intact enamel. MFP retained in the mouth after a MFP rinse was subjected to rapid hydrolysis. The findings showed that the uptake of F from MFP was greater at pH 5 than at pH 7 and that MFP is hydrolyzed by two mechanisms, one operating at the solid solution interface of the apatite and the other in saliva and/or plaque. It is concluded that the caries-reducing effect of MFP is due to F–

ISSN:0008-6568    

DOI:10.1159/000259748

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Disc electrophoresis studies of the in vitro adsorption on hydroxyapatite (HA) of human salivary supernatant proteins confirmed a preferential uptake of 4 electrophoretically homogeneous proteins, 3 of which derived predominantly from the parotid secretion. Amino acid analysis of the adsorbed complex also inferred a parotid secretion origin, indicated by its high proline content. Following column iso-electric focusing of the salivary proteins, fractions were examined for their amino acid composition. One electrophoretically homogeneous protein was characterised by a high proline content and high pi (c. 9) and shown to be adsorbed by HA. Another salivary protein component (pi, c. 7) was similarly adsorbed by HA. Both proteins were shown by disc electrophoresis to be co-incident in position with 2 of the 3 parotid secretion proteins specifically adsorbed by HA. It is postulated that these parotid proteins might contribute to the in vivo formation of the first formed integumental structures acquired post-eruptively by the tooth enamel surfaces.

ISSN:0008-6568    

DOI:10.1159/000259749

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Fresh sublingual gland tissue from Macaco irus monkey was minced and incubated at 37 °C for 72 h in a synthetic medium supplemented with radioactively labelled L-leucine, D-glucose, or both. The secreted proteins were separated by isoelectric focussing from the culture medium (LKB 8101 column, ampholines pH 3–10). The radioactive incorporation was determined by scintillation counting of the dialyzed fractions. Five labelled sublingual protein fractions were found, with isoelectric points of about 3.0, 4.7, 6.0, 7.5, and 10.0. The most consistent fractions were No. 1, 2, and 5. The acidic fraction (pI 3) was identified as a virus-haemagglutination-inhibiting glycoprotein (HI) containing sialic acid, previously isolated from human saliva. A molecular weight of about 600,000 was found by ultra-centrifugation after further purification of this fraction. The largest protein fraction (pI 4.7) homogeneous as judged by disc electrophoresis, was also of glycoprotein character, with amino acid and amino sugar patterns similar to the HI glycoprotein. Carbohydrate analysis, however, indicated only fucose, not sialic acid, as the terminal carbohydrate. The alkaline fraction (pI 10.0) showed a different amino acid content and contained only small amounts of amino sugars. The possibility of finding the pI 4.7 glycoprotein fraction in other salivary glands is discuss

ISSN:0008-6568    

DOI:10.1159/000259750

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

A comparison of the histology of enamel caries as observed by the optical microscope and the scanning electron microscope is reported. Preferential demineralisation of the prism cores commencing at their necks and involving ultimately the entire core is demonstrated. In addition to the prism sheaths it is observed that the striae of Retzius may also sometimes show resistance to demineralisation. From a comparison of the zones of enamel caries as observed optically with the SEM results it seems likely that some remineralisation occurs in the dark zone. In relation to the role of the organic matrix in the dissolution of the enamel, however, no assessment is possible since, at the present time, this matrix cannot be observed in the SEM.

ISSN:0008-6568    

DOI:10.1159/000259751

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Six premolar teeth, from patients aged11 to 15 years, were used in a study of peritubular and intertubular dentin in the crown and root. Anelectron microprobe with an associated scanning electron microscope was used to determine simultaneously the concentrations, in weight %, of calcium, phosphorus and magnesium, using a beam size of approximately 0.25 μm diameter. Coronal peritubular dentin was hypermineralized (total of Ca: P and Mg) by up to 9% by weight though usually this was between 2 and 4 %. Radical peritubular dentin was either hypo- or isomineralized in these young teeth when compared to the intertubular dentin. In most teeth the coronal dentin was more highly mineralized than the radicular dentin in both peritubular and intertubular area. Analysis of the data showed that there was a significantly greater variability of calcification in the peritubular dentin. These results are discussed particularly in relation to the microradiographic data which are available on dentin

ISSN:0008-6568    

DOI:10.1159/000259752

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Path difference measurements were recorded in sound and carious enamel both before and after treatment with dimethyl-formamide, xylol and the enzyme pronase. It would appear that significant changes are produced after such treatment. Imbibition experiments with water and Thoulet’s solution show that the enamel becomes more accessible to imbibition fluids without necessarily being demineralized. Quantitative work in histopathologic studies is, therefore, influenced to a significant degree. Imbibition with Thoulet’s solutions having refractive indices higher than 1.623 indicate that the intrinsic birefringence of enamel apatite is higher than has been generally presu

ISSN:0008-6568    

DOI:10.1159/000259753

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

When enamel is exposed to dilute lactic acid in vitro the surface of the tissue is rapidly etched, unlike that seen in caries. Experiments have been carried out to see whether enamel surface deposits, produced by bacteria in vitro, could modify simple acid attack on the tissue. Results show that by growing deposits of dextran-producing strains of Streptococcus sanguis and Streptococcus mutans on the surface of teeth prior to exposure to buffered lactic acid, the pattern of acid attack can be modified. Control teeth show demineralization of the outer surface layer after the formation of the ‘plaque-like’ deposits. Removal of the microbial deposit and exposure to buffered lactic acid results in loss of surface tissue and subsequent cavitation. However, after exposure of experimental teeth, having surface deposits, to buffered lactic acid in vitro lesions are produced that demonstrate well-mineralized surface zones superficial to demineralized subsurface regions. Quantitative imbibition studies have demonstrated that the initially demineralized surfaces produced by ‘plaque’ formation show an increase in mineral content after subsequent lesion formation. Attempts have been made to produce similar effects with other micro-organisms and also to alter the effects produced by treating the microbial deposits with the enzyme dextranase prior to acid e

ISSN:0008-6568    

DOI:10.1159/000259754

出版商:S. Karger AG    

年代:1971

数据来源: Karger