摘要:

There is considerable variation in the composition of primary and secondary dentine. In general, secondary deposits, regardless of type, contain less calcium, phosphorous, and collagenous matrix per unit volume when compared to primary dentine. Fluoride levels show the reverse tendency. These observations suggest a more open, porotic structure for secondary deposits.

ISSN:0008-6568    

DOI:10.1159/000261146

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Labial surfaces of 64 bovine incisors (8 teeth/treatment) were subjected to 1-min treatment with (1) 500 ppm Sr, (2) 0.5% I2 plus 1 % KI solution, (3) F varnish treatment (Duraphat®) for 24 h, or (4) combined treatments. The treated teeth were incubated under an artificial Streptococcus sobrinus plaque for 10 days. The ‘oral fluid’ with maleate buffer (pH 5.8) partially saturated with Ca3(PO4)2 and with or without 3.3% sucrose or sucrose plus 25 ppm F, was replaced by a mixture containing thioglycolate broth and the buffer for 4 h daily. This was done in an attempt to maintain the viability of the plaque as it was not renewed. Analysis of the Ca and inorganic P in the ñuid phase taken after the 1st and the 10th day of incubation indicated that complete protection was obtained with F varnishing plus 25 ppm F in the fluid, with added sucrose. The Sr plus F treatment was more protective than F or Sr alone. The iodine treatment was slightly protective when combined with F varnishing. The results of the enamel surface and subsurface F and Sr as well as measurements of surface microhardness also indicated the highest protective effect with the double-F treatment and a marked protection provided by the Sr plus F treatment. The efficacy of the double-F treatment was partly explained by the prevention of a fall in ‘plaque’ pH and partly by the release of bacterial inorganic P in the extracellular fluid. The present caries model is versatile in quantification of changes in numerous parameters (14 parameters measured) involved in the caries-like process and its i

ISSN:0008-6568    

DOI:10.1159/000261147

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Streptococcus mutans is known to be one of the most cariogenic oral microorganisms. Recently, organisms classified as S. mutans have been shown to be genotypically heterogeneous and to form at least six separate species. In this study, differences in acid production between the mutans streptococci and Streptococcus sanguis were investigated at pH values from 5.0 to 7.0. While all of the species investigated were able to produce acids, Streptococcus sobrinus was found to be significantly more acidogenic than the others. S. sobrinus was capable of sustained acid production at pH levels below 6.0, while acid production by other species ceased or was strongly inhibited. These results indicate that S. sobrinus deserves more attention as a potentially cariogenic microorganism.

ISSN:0008-6568    

DOI:10.1159/000261148

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Effects of zinc and/or fluoride on growth, glycolysis and survival of Streptococcus mutans GS-5 were examined in vitro. Zinc inhibited growth and glycolysis, and enhanced the antimetabolic activity of fluoride. Zinc alone had little effect on cell survival. During cell growth without pH control a protection from cell death was mediated by fluoride, which appeared to be caused by a higher final pH in the culture medium. When cell death was observed under controlled pH conditions in a lactate-acetate buffer at pH 6.5, 5.0 or 4.0, fluoride was bactericidal only at pH 4.0. However, the combination of zinc plus fluoride was strongly bactericidal at all pH values that were tested.

ISSN:0008-6568    

DOI:10.1159/000261149

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Female Sprague-Dawley rats were divided into three groups. All three groups were given the same solid diet (with 1.6 ppm F). Group I was given deionized water, group II drank water with 5 ppm fluoride added, and group III had 50 ppm fluoride added. All females were mated with the same male. The pups were sacrificed at 28 days, and the mandibles were removed and cleaned. Three-dimensional representations of the occlusal surfaces of the 1st and 2nd mandibular molars were reproduced via computer-digitized images using stereophotogrammetry. Fissure depths and widths were measured, and ‘volumes’ of the fissures were computed. The fissure widths, depths, and volumes were compared statistically using unpaired t tests between groups (p < 0.05). There were significant differences in fissure depth between groups I and II and between groups I and III. For fissure volumes, significant differences were found between groups I and III. The width of the fissure and the overall tooth size were not significantly different between fluoride-treated groups. Standardization showed a reproducibility to within ± 40 mm with the stereophotogrammetric me

ISSN:0008-6568    

DOI:10.1159/000261150

出版商:S. Karger AG    

年代:1989

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261151

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Dentine subjected to an in vivo demineralization challenge by plaque looses substantial amounts of mineral and is expected to change its ultrastructure. Results are presented of a combined microradiography and scanning electron microscopy (SEM) study on in vivo demineralized human dentine. The tissue was first demineralized in vivo under plaque for 3 weeks and subsequently analyzed by microradiography and SEM. In 6 participants dentine was positioned in a full prosthesis just under M2 in such a way that the outer surface of the tissue was 1.5 mm lower than the surface of the prosthesis; plaque accumulation takes place in the recessed area. A special technique allows SEM observations (at a given distance from the outer surface) on broken thin sections of demineralized dentine with a mineral content determined by microradiography. The results show that the ultrastructure of the dentine changes during severe demineralization. The main ultrastructural features are, however, still largely intact, even if half of the mineral originally present has been lost. In dentine with a mineral content of about 25 vol%, the dentinal tubules are enlarged by about 30%. In vivo demineralized dentine looses mineral in substantial amounts both from intertubular and from peritubular regions.

ISSN:0008-6568    

DOI:10.1159/000261152

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The effects of chewing Parafilm® and cheese following sucrose rinsing on human dental plaque pH and plaque fluid organic and amino acid concentrations were investigated. Immediate increases in plaque pH were observed following chewing with concomitant decreases in lactate and acetate concentrations and increases in the concentration of formate and many amino acids. Chewing with cheese when compared with Parafilm resulted in significantly higher (p < 0.05) plaque fluid concentrations of most amino acids, although significant decreases (p < 0.05) in phosphate, succinate, and acetate concentrations were observed. However, no significant difference in the levels of formate, lactate, and propionate were found between the two chewing treatments

ISSN:0008-6568    

DOI:10.1159/000261153

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The levels of salivary Streptococcus mutans and lactobacilli and caries experience were studied in 113 teenagers and 163 adults. The study population consisted of 82 mother-child and 73 father-child pairs. The number of decayed, missing, and filled tooth surfaces (DMFS) was eightfold higher in adults than in teenagers (56.4 ± 22.8 vs. 7.3 ± 6.7). The percentage distribution of the level of salivary S. mutans and lactobacilli was approximately the same in both groups. The mean number of DMFS increased with increasing levels of salivary S. mutans and lactobacilli, the correlation being highly significant both in teenagers and adults. There was a significant correlation of the DMFS indices in the mother-child pairs (r = 0.364), but the correlation was not significant in the father-child pairs (r = 0.138). The salivary level of S. mutans was higher in the children of mothers with high DMFS values compared to the children of mothers with low DMFS value

ISSN:0008-6568    

DOI:10.1159/000261154

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

A study was conducted amongst 1,131 randomly selected persons aged 15–65 years in a rural area of Kenya, having minimal access to dental care. A relatively low prevalence of frank cavitation was found in the 15- to 24-year-old cohort, but in the older age groups over 80% were so affected. Caries in the youngest cohort was characterized by a predominance of enamel lesions. At the age of 25–34 years, however, involvement of pulpal tissues and loss of teeth due to caries was more common, and this age group exhibited the largest number of dentinal lesions. The 35- to 44-year-old cohort exhibited fewer enamel and dentinal lesions, but more pulpally involved lesions and more extracted teeth. In the group aged 45–54 years, enamel and dentinal lesions were less common, and at the age of 55–65 years, such lesions were less common in comparison to their occurrence in younger cohorts. The 55- to 65-year cohort could generally be characterized as having larger numbers of root surface lesions, lesions involving the pulp, and extracted teeth. Root surface lesions were principally associated with age over 35 years. In all age groups caries exhibited a skewed distribution, most of the lesions occurring in a minority of individuals. This study demonstrates that caries activity continues throughout life and is not a phenomenon confined to any one period

ISSN:0008-6568    

DOI:10.1159/000261155

出版商:S. Karger AG    

年代:1989

数据来源: Karger