摘要:

Toothbrushing with and without dentifrice containing abrasive was performed on human enamel pieces attached to resin plates exposed to the oral cavities of 3 human subjects for 8 weeks. The effects on the ground enamel surfaces with engraved scratches were examined by scanning electron and scanning laser microscopy. Brushing with such a dentifrice caused smaller scratches to disappear, large scratches to expand and new microwear to appear; in some samples, prism structures were exposed. Under brushing without dentifrice, these scratches were protected by an organic pellicle with mineral deposits, and also the experimental surface was entirely covered with these membranous deposits. The results indicate that toothbrushing with no dentifrice but saliva induces an organic-mineral protective membrane on the enamel surface. The membrane may increase the enamel resistance to caries. On the other hand, the use of abrasive-containing dentifrice causes slight abrasion with microwear. This roughness may contribute to the formation of dental plaque.

ISSN:0008-6568    

DOI:10.1159/000261507

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The effectiveness of fluoridation has been documented by observational and interventional studies for over 50 years. Data are available from 113 studies in 23 countries. The modal reduction in DMFT values for primary teeth was 40-49% and 50-59% for permanent teeth. The pattern of caries now occurring in fluoride and low-fluoride areas in 15- to 16-year-old children illustrates the impact of water fluoridation on first and second molars. The secular changes in caries in Hartlepool, a natural fluoride area in the North East of England, shows only a modest change between 1949 and 1989. Information on the pre-eruptive effects of water fluoridation has been reviewed, suggesting that fluoridation should start at birth to provide optimal protection to primary teeth. At 15 years of age, the maximum DMFS reduction in a fluoridated area was due about half to the pre-eruptive and about half to the post-eruptive effect of fluoride.

ISSN:0008-6568    

DOI:10.1159/000261594

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The microradiographic mineral content and birefringence in water and Thou-let’s solution were measured at selected points in sections of caries-like lesions. Birefringence was not related to mineral content in sound superficial enamel immersed in Thoulet’s solution or in the lesion body immersed in water. For the surface layer of the lesion, birefringence in water could be used to obtain qualitative information about mineral content. For the lesion body, birefringence in Thoulet’s solution was linearly related to mineral content and can be used to estimate the latter with a standard error of about 7 vol%. The intrinsic birefringence for the lesion body was estimated as ––34.5 ( ± 2.3) · 10––4; This value may also be valid for other parts of the lesion. From consideration of ionic sizes, it is argued that Thoulet’s solution cannot necessarily penetrate all enamel pores accessible to water. It appeared that there is a progressive fall in the content of pores inaccessible to Thoulet’s solution in the surface layer of the lesion as deminer

ISSN:0008-6568    

DOI:10.1159/000261508

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The rehardening of surface-softened and surface-etched enamel was investigated in vitro and by intraoral exposure. Surface-softened enamel was obtained by treatment with 0.1 M acetic acid buffer solution (pH = 5.5) for 3 h. Surface-etched enamel was obtained by the acid etch procedure used in clinical situations (37% phosphoric acid gel, 30 s). The enamel lesions were treated in vitro, with calcifying solutions for 8 h or were carried for 48 h in an intraoral appliance. Changes at the enamel surfaces were investigated by surface micro-hardness measurements. Following the treatment with calcifying solutions a significantly greater indentation length was observed in surface-etched than in surface-softened enamel. No significant difference in indentation length between both types of enamel lesions was observed following intraoral exposure. It was concluded that the initial rate of rehardening between both types of enamel lesions is comparable. At his stage remineralization occurs in microspaces created in the slightly destroyed enamel structures. The influence of the etch pits on the indentation length becomes dominating when remineralization continues. An obliteration of etch pits was observed in enamel samples treated with the calcifying solution with the highest degree of saturation. It was suggested that freshly prepared highly supersaturated calcifying solutions can be used to enhance mineral appositions in accidental etch pits.

ISSN:0008-6568    

DOI:10.1159/000261509

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

An analysis of the literature evaluated the caries-protective effects of various methods of fluoridation. Salt fluoridation (250 or 350 mg F/kg) can be considered as equivalent to fluoridation of drinking water. Existing evidence suggests that milk fluoridation cannot be considered equivalent to fluoridation of either drinking water or salt because of problems of consistent delivery. Sugar, beverages (including tea) as well as fluoride-rich mineral waters are likely to be of only limited importance for caries prevention, but may be effective on an individual basis.

ISSN:0008-6568    

DOI:10.1159/000261597

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

A digital imaging analysis (DIA) procedure for recording and assessing erosive changes on teeth was developed and evaluated against an older subjective method. Results after exposure of rats’ teeth to various soft drinks showed that the DIA system was superior to the conventional method, with improved precision. The system provided a direct and highly sensitive means of quantifying the erosion of dental hard tissues by three different soft drinks, showing that it could be used to evaluate erosiveness and other dental damage. After 6 weeks’ exposure to soft drinks in the diet, the area of intact enamel on the lingual surface of the first mandibular molar averaged 47% on apple juice, 27% on still orange and 6% on carbonated orange. The greatest exposure of dentine (36%) was on the still orange drink. Eroded enamel accounted for 72.5% of the tooth surface on the carbonated dr

ISSN:0008-6568    

DOI:10.1159/000261510

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

While the clinical relevance of fluoride toothpastes per se is firmly established, the multifactorial processes involved in causation and prevention of caries render it difficult to define their exact role in an overall caries-preventive strategy. Therefore, an indirect pragmatic approach was chosen: the interpretation of secular trends in caries prevalence and other parameters is used to estimate the relative importance of this method of topical fluoride administration and to compare it with the contributions by other methods of prevention. All methods of caries prevention, with the exception of population-administered measures such as fluoridation of drinking water or domestic salt, can only work when applied regularly and conscientously. For this reason behavioural aspects such as compliance and the chances for widespread (if not universal) application have to be considered. There is indirect evidence that toothbrushing with fluoride toothpastes is a highly probable explanation for the decline of caries prevalence in developed countries since the 70s; moreover, toothbrushing, and the use of therapeutic dentrifices, is considered to meet spreading compliance because a ‘healthy mouth’ becomes more and more socially desirable in growing numbers of subpopulati

ISSN:0008-6568    

DOI:10.1159/000261598

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Mixed continuous cultures of Streptococcus species were obtained, using complex carbohydrate (mucin) as a source of nutrients, to study the ecological effects of oxygen and the lactoperoxidase system. S. mutans NCTC10449 was unable to grow as a pure culture on mucin, but attained a significant population size in the presence of S. oralis and S. sanguis strains. The cell densities of the anaerobic mixed cultures decreased when oxygen was supplied, and S. mutans was more suppressed by oxygen than were S. sanguis and S. oralis. However, the concentrations of hydrogen peroxide (30 μmol/l in the mixed culture of S. mutans with S. sanguis and 640 μmol/l in the culture with S. oralis) indicated a certain resistance of the organisms to hydrogen peroxide. Addition of lactoperoxidase and thiocyanate to the oxygen-supplied cultures had a differential effect on the streptococcal populations. While S. mutans was inhibited, and even disappeared in the culture with S. oralis, the growth of S. sanguis and S. oralis was unaffected. This latter observation was in accordance with the OSCN–– reductase activities of these organisms. When hydrogen peroxide was also added together with lactoperoxidase and thiocyanate, a further inhibition of S. mutans in the culture with S. sanguis was observed. Under these conditions, S. oralis was also inhibited, perhaps by the strong accumulation of OSCN––, exceeding the capacity of the OSCN–– reductase. The effects of lactoperoxidase on mixed cultures may reflect the situation in the mouth. Depending on the production of hydrogen peroxide in the environment, mutans streptococci would be inhibited by OSCN––, while populations of other streptococci would be much less affected by pero

ISSN:0008-6568    

DOI:10.1159/000261511

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Professionally applied topical fluoride should be used judiciously and is indicated only in patients with moderate or high caries activity. While the anticaries effectiveness of acidulated phosphate fluoride gels has been clinically documented, the 2% neutral NaF gel has not been adequately tested, and further clinical verification is needed. Daily use of a self-applied fluoride gel is recommended for patients undergoing orthodontic treatment or to those affected with xerostomia as a result of disease or head and neck radiation therapy. The dental profession and the public should be well informed on the proper use of clinically proven products to achieve optimum effectiveness and minimize the risk of fluoride ingestion.

ISSN:0008-6568    

DOI:10.1159/000261599

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Local passive immunization has been suggested as a method of preventing colonization of teeth by mutans streptococci. In this study we describe the effect of local application of monoclonal antibodies (Mabs) on the colonization of Streptococcus sobrinus. The rats, 37 days old, were divided in 4 groups: group 1 received Mab OMVU10 (Mab reactive with Antigen B of S. sobrinus, IgG2b), group 2 received Clone 24 (Mab reactive with lipid A of Escherichia coli, IgG2b), group 3 received uninoculated culture medium, and group 4 received phosphate-buffered saline (PBS). Mabs were applied 6 times on the surfaces of the molars and the labial surfaces of the incisors of the rats, on days 37, 40, 44, 46, 49 and 54 after birth. After the third application of Mabs, all rats were inoculated with S. sobrinus (day 45). Subsequently, the rats were fed a cariogenic diet containing 20% sucrose and 5% glucose. The rats were killed 34 days after inoculation and the maxillary molars were extracted and homogenized in order to determine the numbers of S. sobrinus. The proportions of S. sobrinus, expressed as a percentage of the total cultivable microflora, in rats which received OMVU10 (group 1) were 23.1 ± 14.8%, whereas in rats which received Clone 24, culture medium or PBS the levels were 34.5 ± 11.3%, 40.7 ± 14.9% and 36.7 ± 9.7%, respectively. Statistical analysis showed that the level of colonization of rats which received OMVU10 was significantly lower than that of rats which received Clone 24, culture medium or PBS (p < 0.001, p < 0,013 and p < 0.01, respectively). No statistical differences were found between the three control groups. It was concluded that local application of specific Mabs against Antigen B of S. sobrinus reduced the colonization level of implanted S. sobrinus compared to the control gro

ISSN:0008-6568    

DOI:10.1159/000261512

出版商:S. Karger AG    

年代:1993

数据来源: Karger