摘要:

The development of a caries lesion is a dynamic process that includes frequently alternating periods of de- and remineralization, a process for which no in vitro models currently exists. The aim of this study was to develop a model which could repeatedly generate identical pH versus time curves over extended periods of time. To test the model demineralization studies on cementum/dentin were performed. Cementum/dentin blocks were repeatedly subjected to de- and remineralizing solutions delivered by a computerized pump system connected to a pH-meter and a recorder. pH versus time curves similar to those produced in plaque after carbohydrate intake were generated 18 times during 15 h followed by a remineralizing period of 9 h every day for 16 days. The intra-day and inter-day variation of the pH-cycling model were found to be low. The mineral change of the blocks was followed by 125I absorptiometry and the transmission through the blocks during the experimental period increased in average by 1.4 ± (SE) 0.18%. Microradiographic analysis of the transversal sections of the blocks confirmed the development of lesions resembling root caries

ISSN:0008-6568    

DOI:10.1159/000261228

出版商:S. Karger AG    

年代:1990

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261312

出版商:S. Karger AG    

年代:1990

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261313

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

This study was aimed at determining the amount of mineral removed from incipient enamel lesions during acid etching. The rationale being that fissures which are scheduled for sealing will often have undetected demineralized regions. Lesions were formed in bovine enamel specimens using either an acidified gelatine gel or a lactate buffer containing methane hydroxy diphosphonate. Different parts of each lesion were acid-etched either for a 1- or for a 2-min period in 36% H3PO4 or served as control. Mineral content profiles were recorded on thin sections using computerized microradiography to determine the mineral loss resulting from acid etching. The results show that during etching a layer at the outer surface is removed completely. The thickness of this layer was greater for lesions when compared with sound enamel and depended on the lesion characteristics (porosity and fluoride content). The amount of mineral removed from the deeper layers of the lesion was very small; and in the innermost part of the lesions the mineral profiles of the control and acid-etched areas coincide. These observations indicate that the effect of etching is essentially restricted to a thin outer layer, irrespective of the porosity of the underlying tissue. Although the thickness of the etched-off layer was different between the two types of lesions, these findings were made for both types studied. In practical terms this implies that etching of enamel lesions does not cause an excessive mineral loss throughout the lesion.

ISSN:0008-6568    

DOI:10.1159/000261229

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

In enamel fluoride uptake studies, the most frequently sampled site is the middle third of the buccal surface. Because different parts of the enamel surface vary in fluoride concentration, the present study investigated fluoride uptake at contrasting sites using two different topical agents. One was a neutral aqueous solution of sodium fluoride containing 2% w/w of fluoride, and the second was an aqueous solution of two amine fluorides containing 1% w/w of fluoride. The enamel of 10 pairs of clinically sound extracted human premolars was etched initially and after treatment with one of these agents on the cervical and middle thirds of the buccal surface and on the proximal surface, yielding the pre- and post-treatment fluoride concentrations of these sites at depths of 5 and 10 μm from the surface. Enamel treated with the amine F solution had significantly higher fluoride uptakes at all sites compared to the NaF-treated specimens. The differences in uptake from the two agents varied with site, being smallest for the buccal middle third enamel and greatest for the proximal enamel. It is suggested that these results relate to possibje differences in enamel maturation or to the presence of initial proximal caries, and the greater affinity of amine fluoride for porous enamel. The findings emphasise the importance of obtaining site-specific data in the study of fluoride in enamel

ISSN:0008-6568    

DOI:10.1159/000261230

出版商:S. Karger AG    

年代:1990

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261315

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Application of monocalcium phosphate monohydrate (MCPM) gel, which produces small amounts of dicalcium phosphate dihydrate in enamel, was previously shown to increase the enamel reactivity with fluoride (F). This study was conducted to determine whether the MCPM gel treatment is also effective in enhancing F uptake by root surfaces of human teeth. The results show that samples receiving daily treatments with MCPM gel for 10 min followed by immersion in a 1-ppm F solution for 5 days acquired a significantly greater amount of F compared to the controls which had the same exposure to the F solution. Because the F solution was undersaturated with respect to calcium fluoride (CaF2), the F incorporated into the root is apparently apatitic and not CaF2. This experimental treatment should be feasible in the clinical situation since only a short treatment time was required and delivery of the MCPM gel to specific sites was relatively easy.

ISSN:0008-6568    

DOI:10.1159/000261231

出版商:S. Karger AG    

年代:1990

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261316

出版商:S. Karger AG    

年代:1990

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261317

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

A method was developed to identify Streptococcus mutans in natural dental plaque by indirect immunofluorescence staining, using a high-titred polyclonal antiserum raised against a serotype c strain of S. mutans followed by an FITC conjugate. Specificity was determined by staining 45 representative strains of plaque organisms, which demonstrated minimal cross-reactions. In vitro incubation of S. mutans NCTC 10449 films with a human serum containing antibodies to S. mutans and the presence of extracellular polysaccharide did not inhibit staining. The staining method enabled 98% of the streptococci to be detected in mixtures of S. mutans NCTC 10449 and Lactobacillus casei NCTC 10302. S. mutans was detected at a ratio of 1:100,000 in mixtures of pure cultures. In plaque samples, S. mutans could be distinguished from other organisms, including an unidentified cross-reacting bacillus found in some gingival plaque samples. The results suggest that immunofluorescence is a fast, practical method for identifying specific bacteria in plaque and, therefore, could be of use in microbiological studies of caries.

ISSN:0008-6568    

DOI:10.1159/000261232

出版商:S. Karger AG    

年代:1990

数据来源: Karger