ISSN:0008-6568    

DOI:10.1159/000261625

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

The aim of the present study was to determine fluoride profiles in mature unerupted enamel following removal of the surface organic material. Thirty teeth were randomly allocated into three groups. The surface organic material (Nasmyth’s membrane) was left intact in group I; it was removed by tooth-brushing in group II, and in group III the surface organic layer was removed along with subsurface organic material by deproteinizing. Each tooth was then sectioned into halves and a standardized biopsy area was created. Initially alkali-soluble fluoride was extracted with 1M KOH followed by acid etch analysis to measure the remaining fluoride. No difference was seen in the alkali-soluble fluoride levels but residual fluoride concentrations were significantly reduced (p < 0.05) after deproteinizing but not after toothbrushing. It would appear that a substantial amount of fluoride (∼ 25%) in mature enamel from unerupted teeth can be removed by a deproteinizing agent, which may suggest an association of this fluoride with subsurface organic mater

ISSN:0008-6568    

DOI:10.1159/000261626

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Composite restorations are prone to develop secondary caries if a gap exists between tissue and restoration. The aim of this article was to quantify the effects of a fluoridating and non-F composite on secondary dentine caries in vitro as a function of time. The mineral loss in dentine was assessed in an artificial gap of 200 μm width at the composite/dentine interface; the samples were demineralised in a carboxymethylcellulose gel (pH = 5, 37 °C) for 8 weeks. Once a week the mineral content of the samples was determined using non-destructive wavelength-independent microradiography (WIM). After 8 weeks transversal microradiography (TMR) was done on the samples to investigate the mineral distribution of the dentine lesions. The WIM results show that the fluoride-releasing composite decreased the dentine demineralisation statistically significantly with respect of the non-F control by approximately 45%. The mineral loss values are found to be strictly proportional to time; the demineralisation reduction is expected to continue over extended periods of clinical relevance. The TMR results show that the fluoridating composite reduced the mineral loss values significantly with respect to the non-F control by approximately 55%, but had a negligible effect on the lesion depth values. This study indicates that WIM is an accurate and reliable technique to measure in vitro secondary dentine caries next to a composite restoration as a function of tim

ISSN:0008-6568    

DOI:10.1159/000261627

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Streptococcus downeii MFe28 maintains a transmembrane pH gradient at low extracellular pH values using energy from glucose metabolism. The metabolic activity was measured in saturating glucose solutions using a pH-stat, and results were expressed as rates of titratable acid production at defined pH values. The tolerance to acid shock was studied in terms of the ability of cells to resume acid production at pH 8.0 following short-term exposure to low-pH environments. The results with control cells showed an optimum rate of acid production at pH 8.0. The activity extended to pH 4.5 with a half-maximal rate at pH 5.4. Addition of carbonyl cyanide-m-chlorophenylhydrazone, potassium laurate, or potassium fluoride inhibited acid production at lower but not at higher pH values. Inhibition by carbonyl cyanide-m-chlorophenylhydrazone and fluoride was found to be fully reversible at pH 8.0 when compared to control cells. In contrast, laurate inhibited irreversibly at pH values of 6.0 and below. The acid tolerance of S. downeii was severely compromised by laurate, and this action could be useful in dental caries control.

ISSN:0008-6568    

DOI:10.1159/000261628

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Salivary glands and their secretions play key roles in the prevention of dental diseases. The antibacterial and physicochemical properties of saliva are compromised in chronic malnutrition. The present study has examined the possibility that some malnutrition-induced changes in salivary gland function are potentially capable of promoting growth and metabolic activities of pathogenic oral microorganisms. Compared to well-fed controls, rats fed a 3% protein diet for 18 days showed a significant reduction (p < 0.001) in the submandibular gland arginase (L-arginine amidinohydrolase, EC 3.5.3.1) activity. Associated with the latter finding was a marked increase (+85%) in the glandular level of free arginine, this basic amino acid accounting for 12.2% of the total essential amino acids as compared with a figure of only 4.6% for the controls. The total free amino acid pool in whole saliva was relatively unaffected by malnutrition, but the levels of the basic amino acids arginine and histidine were marginally increased. Many oral bacterial species, some of which are dominant plaque microorganisms, utilize the arginine deiminase (EC 3.5.3.6) pathway. Thus, increased availability of free arginine from salivary glands offers a plausible explanation for the frequently reported observation of differential overgrowth of several potentially pathogenic microorganisms including some mutans streptococci in protein-deficient laboratory animals and may well apply to similar findings in malnourished populations in Third World countries.

ISSN:0008-6568    

DOI:10.1159/000261629

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

A series of rat caries experiments was carried out to test the relative cariogenic potential and to identify the major cariogenic elements of 22 popular snack foods. Parameters that were measured included rat caries, number of cariogenic bacteria in plaque, salivary parameters including flow rate, buffering capacity, total protein, lysozyme and amylase content, and composition of test foods including protein, fat, phosphorus, calcium, fluoride, galactose, glucose, total reducing sugar, sucrose, and starch. Many interesting relationships were observed between food components, numbers of plaque bacteria, salivary components, and specific types of carious lesions. Protein, fat, and phosphorus in foods were all associated with inhibition of both sulcal and bucco-lingual (smooth-surface) caries. Food fluoride was associated with inhibition of buccolingual caries, whereas calcium was related to inhibition of sulcal caries. Glucose, reducing sugar, and sucrose in foods were all related to promotion of both sulcal and smooth-surface caries. The numbers of Streptococcus sobrinus in plaque were associated with promotion of smooth-surface caries only, whereas lactobacilli, non-mutans bacteria, and total viable flora were related to promotion of both smooth-surface and sulcal caries. The salivary flow rate was associated with inhibition of both buccolingual and sulcal caries. Salivary buffering capacity (at pH 7) and salivary lysozyme delivery were associated with inhibition of number and severity of sulcal caries, while the salivary amylase content was related to the promotion of the number of sulcal lesions.

ISSN:0008-6568    

DOI:10.1159/000261630

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

In this study, the null hypothesis was tested that topical application of standard buffer solutions, pH 7.00 and pH 4.01, to 4-day-old plaque deposits accumulated in situ causes the plaque to attain the pH values of the buffer solutions applied. Following a 4-day abstention from all oral hygiene procedures, the plaque pH of four interdental sites in each of 5 volunteers was measured at resting state and following topical applications of buffers pH 7 and pH 4. Later the same day plaque pH was measured following rinses with the buffers. Topical application of buffer pH 7 caused a plaque pH increase from a mean value of 6.40 to 6.59 within 30 s while buffer pH 4 caused plaque pH to drop to a mean value of 5.11. Rinsing with buffers caused plaque pH to increase to 6.50 (buffer pH7) and to drop to 4.92 (buffer pH4). Statistical analysis of the results led to rejection of the null hypothesis. The results thus indicated that the validity of the in situ approach of calibration of plaque-covered indwelling electrodes may be questioned.

ISSN:0008-6568    

DOI:10.1159/000261631

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

This study reports the interexaminer agreement of three pairs of evaluators of salivary dip slide tests for mutans streptococci and lactobacilli. 717 Carie-screen® SM and Bactotest® LB dip slides were available for assessment by 2 dentists and 1 dental hygienist. A single calibration session was held prior to the onset of the study. Each dip slide was read once by each examiner independently. Among the three pairs of examiners Pearson R values ranged from 0.84 to 0.90 for Cariescreen and from 0.78 to 0.87 for Bactotest. Kappa statistic values ranged from 0.56 to 0.61 for Cariescreen and from 0.70 to 0.74 for Bactotest. The range of agreement was from 72.2 to 76.9% for Cariescreen and from 86.4 to 88.3% for Bactotest. The majority of disagreements were of one category in magnitude, though there were a few disagreements of greater magnitude. This study found moderately strong agreement among the three examiners; it suggests that multiple examiners of dip slide tests carefully calibrated initially and periodically to ensure a high level of agreemen

ISSN:0008-6568    

DOI:10.1159/000261632

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

The study consisted of eight experiments, divided into three series, aimed at investigating the effect on the salivary fluoride (F) concentration of three post-brushing regimes: (1) rinsing once or twice with water, (2) rinsing either with a slurry of the toothpaste foam and water or with an 0.05% NaF solution, or a single NaF mouthrinse with no prior brushing, and (3) chewing and drinking (‘eating’) for 2 min. Brushing was done with 1.5 g of an 0.32% NaF dentifrice. The concentration of F in whole saliva was determined in 15 subjects at various time points up to 45 min after completing each experimental procedure. Results showed that the initial (0 min post-brushing) F concentration in saliva decreased about 1-2 times after a single, and 4-5 times after a double post-brushing water-rinse, as compared with no rinsing at all (p < 0.001). Brushing followed by a mouthrinse with an 0.05% NaF solution elevated the F concentration more than brushing alone (p < 0.001). Rinsing with the slurry of toothpaste foam and water gave only a somewhat (but not significantly) lower concentration of F in saliva than just rinsing with the 0.05 % NaF solution. Eating immediatly after brushing reduced the salivary F level about 12-15 times (p < 0.001) compared with brushing alone. The conclusions from this study are therefore: (1) that both rinsing with water and eating immediately after toothbrushing accelerates the rate of F elimination in saliva, and (2) that mouthrinsing either with an 0.05% NaF solution or with the toothpaste foam-water slurry after brushing elevates the concentration of F in saliva for a prolonged period of time as compared with toothbrushing followed by a single or a double water-ri

ISSN:0008-6568    

DOI:10.1159/000261633

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

For 548 children aged 4-16 years, mean ( ± SD) age 10.3 ± 2.7 at visit 1, the dental status was recorded at four consecutive 6-monthly visits. Simultaneously oral hygiene was scored according to a modified patient hygiene performance (PHP) index after application of disclosing solution and before the dental examination. The following cariogenic changes could be observed: initiation (white spot formation), progression (cavitation), stabilisation and regression (disappearance of a white spot). The PHP score was examined in relation to these changes in smooth surfaces, as well as in fissures. For fissures when oral hygiene worsened, stabilisation of a white spot increased significantly. Also, regression of a white spot into sound enamel increased with poor oral hygiene, but the significance was only marginal. White spots turning into cavities, however, did not change with poor oral hygiene. It was speculated that under low oral hygiene conditions the remaining plaque of children receiving intensive fluoride treatment can bind fluoride to the fissure surfaces, thereby promoting enamel maturation concomitant with stabilisation and regression of white spots which in an earlier study were also found to be dependent on posteruptive ag

ISSN:0008-6568    

DOI:10.1159/000261634

出版商:S. Karger AG    

年代:1994

数据来源: Karger