摘要:

Epidemiologic studies and caries experiments with animals have suggested that caries susceptibility of teeth decreases with age. Observations on the changes in the dental tissues and their environment with age have pointed out that a process commonly referred to as ‘posteruptive maturation’ of the dental enamel may be responsible. To test this assumption 10 unerupted third molars and 56 erupted human premolar teeth of various posteruptive ages were subjected for 130 days to an acid gel for caries-like lesion formation in vitro. Sections of the teeth were examined with polarized light and ‘contour maps’ were drawn with the approximate porosity of the lesions. The results were: unerupted = 833 μm (± 261); erupted of posteruptive age 0–3 years = 561 μm (± 150), 4–10 years = 470 μm (± 136), 11–30 years = 459 μm (± 192) and over 30 years = 297 μm (± 89). These findings show a decrease in the susceptibility of enamel to artificial caries with increasing age, which was especially marked at and shortly after eruption. This may be explained by a completion of mineralization of the outer enamel at about eruption, by a maturation process of the outer enamel posteruptively and by a reduction in the permeability of enamel occurring through to old age. The fluoride content of the mid-coronal buccal surface enamel under study was found to decrease posteruptively with age, therefore not accounting for the deceasin

ISSN:0008-6568    

DOI:10.1159/000261371

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

An in vitro demineralization model has been developed and used to examine the effect of various fluoride treatments on early enamel demineralization. The effect of fluoride treatments on the calcium demineralization rate of enamel was studied by analyzing the amount of calcium which demineralized from teeth into solution when the teeth were exposed to weak acid solutions. Continuous (72 h total) exposure of enamel to very low levels of fluoride, 0.014 ppm, was observed to have a protective effect against demineralization, as was intermittent exposure to higher levels of fluoride delivered from solution and from dentifrices for shorter periods of time (40 min total). This work suggests that the residual salivary fluoride concentrations reported to be reached by water fluoridation (0.016 ppm) or brushing with a fluoride-containing dentifrice (0.014 ppm) give a level of fluoride in saliva which may give some protection to the dental enamel from demineralization.

ISSN:0008-6568    

DOI:10.1159/000261372

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Two successive acid etch biopsies were performed on the permanent maxillary right central incisors of two age-groups of children resident in an urban area in Belgium. Lead was determined in the biopsy solutions and the concentrations were related to etch depths which were calculated from the calcium and phosphorus concentrations in the biopsy solutions. The mean lead concentration of the first enamel biopsy layer was five times higher than in the second biopsy layer. A strong relation was observed between the two biopsies. It was shown that calibration of the lead values with respect to etch depths and Ca/P ratios was desirable and that a robust regression analysis approach was needed instead of classic least-squares regression analysis. However, the second biopsy provided more reliable lead estimates. In this study no increase in lead concentration in surface enamel could be demonstrated with age. Therefore, it was concluded that for these children the presence of lead in surface enamel had to be attributed primarily to preeruptive uptake.

ISSN:0008-6568    

DOI:10.1159/000261373

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The effect of 2-O-stearoyl glycerol-1,3-bisphosphate (Glydip) on caries lesion formation in root surfaces of sound human third molars was investigated in vitro. For this purpose parts of the root surfaces were treated with Glydip. Adjacent parts of the surfaces were not treated and served as control. Lesions were obtained by demineralization with an acetate buffer of pH 5.0. It was found that Glydip had no inhibiting effect on the rate of lesion formation. Additionally, pretreatments were performed with lauryl sulphate, a chloroform-methanol mixture, an aqueous solution of sodium hypochlorite, and coUagenase prior to the treatment with Glydip to enhance the accessibility of the tissue for Glydip. None of these pretreatments or combinations of them revealed an inhibiting effect of Glydip on the rate of caries lesion formation. This result is in contrast to the effect of Glydip on the demineralization of enamel.

ISSN:0008-6568    

DOI:10.1159/000261374

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

This investigation comprised two studies evaluating the effects of an acidic calcium phosphate solution (CPS) on fluoride uptake in the enamel, glycolysis of dental plaque, the incidence of dental caries and urinary fluoride concentrations of rats wearing an intraoral fluoride-releasing device (IFRD). In the first study, CPS-fluoride treatment preceded the cariogenic challenge. In the second study, the cariogenic challenge preceded the treatments. In the first study, CPS treatments increased the ability of enamel to bind fluoride. However, the enamel-bound fluoride exerted a negligible effect on plaque glycolysis as measured by the pH decrease after sucrose challenge. In the second study CPS augmented the caries inhibition for both the sulcal-morsal and buccallingual surfaces. In both studies the IFRD significantly restricted the development of carious enamel on the sulcal-morsal surfaces and caused elevated concentrations of fluoride in the urine independent of CPS treatments.

ISSN:0008-6568    

DOI:10.1159/000261375

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The effects of trehalulose, a structural isomer of sucrose, and a syrup (TP syrup) rich in trehalulose and palatinose on caries development were examined in specific pathogen-free Sprague-Dawley rats. Streptococcus mutans MT8148R and Streptococcus sobrinus 6715 fermented the syrup which resulted in acid production, while both strains were found not to utilize trehalulose. Furthermore, trehalulose did not serve as a substrate for glucosyltransferases of these mutans streptococci to synthesize water-insoluble glucan, and it inhibited the sucrose-dependent adherence of mutans streptococci to a glass surface. Although trehalulose induced no significant dental caries in specific pathogen-free rats infected with either MT8148R or 6715, TP syrup was found to induce significant but low dental caries. Furthermore, replacement of the dietary sucrose content with trehalulose resulted in a significant reduction of caries development in rats infected with strain 6715.

ISSN:0008-6568    

DOI:10.1159/000261376

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

There is a growing population who suffer from hyposalivation. These patients frequently sip liquids to alleviate their discomfort. Milk appears to have many of the physical properties of a good saliva substitute. Desalivated rats given 2% milk or lactose-reduced milk remained essentially caries-free. In contrast, animals given sucrose or lactose to drink developed caries. In addition, animals given sucrose or lactose harbored significantly higher populations of Streptococcus sobrinus than did other groups. Results showed that milk and lactose-reduced milk can be used safely by hyposalivatory patients as a saliva substitute.

ISSN:0008-6568    

DOI:10.1159/000261377

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

In a recent clinical trial of sodium monofluorophosphate dentifrices, oral rinsing habits were found to influence dental caries. Thus an oral fluoride clearance study has been undertaken which was designed to test a possible mechanism for the observed effects. Eight subjects brushed with one of the trial dentifrices and then rinsed using 1 of 8 procedures of varying thoroughness. The salivary fluoride concentration measured 5 min after dentifrice application decreased significantly with increasing rinse volume, rinse duration, and rinse frequency (p < 0.01, analysis of variance). The area under the clearance curve determined over a further 3 h was significantly higher (300%; p < 0.01) following use of the least thorough rinsing procedure (5 ml × 2 s once) as compared with the corresponding area under the clearance curve following the most thorough procedure (20 ml × 10 s twice). These findings indicate that rinsing habits may play an important role in the oral retention of fluoride from dentifrices which may, in turn, affect their clinical efficac

ISSN:0008-6568    

DOI:10.1159/000261378

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

This study describes the effects of varnishes containing 0, 25, 33 and 40% chlorhexidine diacetate on mutans streptococci in human approximal dental plaque. The chlorhexidine release from the varnishes was determined in vitro. Eleven subjects participated in the clinical experiment, each with at least five approximal areas harboring high levels of mutans streptococci. The approximal areas in each of the individuals were randomly assigned to five experimental groups, in each of which one of the varnishes was tested; 40% chlorhexidine varnish was tested in two experimental groups. The varnish treatment consisted of a single application of a small amount of varnish onto the selected approximal areas. From one of the sites receiving the 40% chlorhexidine varnish, all visible varnish was removed 15 min after application. The volunteers were asked to leave the varnish on the remaining treated sites and not to brush their teeth for 8 h. All chlorhexidine varnishes strongly suppressed mutans streptococci until 4 months after the varnish application. The extent of the suppression depended upon the concentration of chlorhexidine in the varnish, 40% chlorhexidine varnish giving the greatest suppression of mutans streptococci. No significant difference was found between the numbers of mutans streptococci from sites where the 40% varnish was removed after 15 min and sites where the 40% chlorhexidine varnish was left. The results suggested that 40% chlorhexidine varnish can be used successfully for the long-term suppression of mutans streptococci. A contact time of the varnish with the tooth surface of only 15 min is sufficient to achieve this long-term suppression.

ISSN:0008-6568    

DOI:10.1159/000261379

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The purpose of this in vitro study was to test the accuracy and the reproducibility of diagnostic and treatment decisions of fissure caries with and without explorer. 34 dentists were asked to diagnose 61 teeth and decide upon possible treatment. The teeth were then histologically prepared and diagnosed. The agreement between histological and clinical diagnoses was assessed. The results showed no difference in diagnostic accuracy between explorer and visual technique only. Sensitivity (62%) and specificity (84%) showed that the dentists were more likely not to treat decayed teeth than to restore sound teeth. The percentage ‘correctly diagnosed teeth’ was approximately 42%. As there was an inherent possibility of a correct diagnosis by chance, this value had to be corrected to 23% (kappa statistics). The percentage of ‘clinically’ correct treatment decisions, however, was 73%. The reproducibility test gave kappa values of 0.47 for diagnostic and 0.44 for treatment decisions. It was concluded that the use of an explorer does not improve the validity of the diagnosis of fissure caries when compared to that of a visual inspectio

ISSN:0008-6568    

DOI:10.1159/000261380

出版商:S. Karger AG    

年代:1991

数据来源: Karger