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PubMed1991

Fluoride and mutans streptococci in plaque grown on glass ionomer and composite.

The aim of this study was to compare the levels of fluoride and mutans streptococci in plaque grown on glass ionomer (Ketac-Fil) and composite (Silar) restorations in vivo. From tunnels left under the brackets bonded either with glass ionomer or composite, 14-day-old plaque samples were collected 14, 28, and 42 days after bonding. For glass ionomer the mean counts of mutans streptococci in plaque were 0.5 x 10(3), 6.7 x 10(3), and 8.8 x 10(3) CFU at the first, second, and third collection, respectively, whereas for composite restorations the corresponding values were 32.1 x 10(3), 14.6 x 10(3), and 120.6 x 10(3) CFU. For glass ionomer the mean concentrations of fluoride were 19,985, 5,788, and 5,019 ppm at first, second, and third collections of 14-day-old plaque samples, respectively, whereas for composite restorations the mean concentrations of fluoride were about 200 ppm throughout the study. The results show that the fluoride level in plaque growing on glass ionomer is much higher than that on composite restorations which seems to affect the level of mutans streptococci in dental plaque.

Acrylic Resins↗

PubMed1992

Effects of tung oil on salivary viscosity and extent and incidence of dental caries in rats.

Increased salivary viscosity may be associated with an increase in dental caries. In order to examine this relationship, the caries level in rats was monitored following gastric intubation with tung oil which has been shown to significantly increase salivary viscosity. Tung oil intubation over an 8-week period significantly increased the salivary viscosity in rats as compared with deoinized water and corn oil intubation. The total number of carious lesions was significantly increased (p less than 0.05) in the tung oil intubated rats as compared with the two other groups. This increase in carious lesions was primarily associated with the smooth surfaces of the teeth. There was also a significant increase (p less than 0.05) in the extent of enamel and dentin involvement of the tung oil intubated rats as compared with the other two groups. Histologic examination of the submandibular glands revealed an increase in the amount of glycoprotein material in the convoluted granular tubules of the tung oil intubated rats as compared with the deionized water and corn oil intubated animals. Collectively, these results suggest that tung oil intubation is correlated with both increased salivary viscosity and increased smooth-surface dental caries, suggesting that the viscosity may be related to dental caries progression.

Animals↗

PubMed1993

Microbiological validation of assessments of caries activity during cavity preparation.

The operative management of primary and secondary caries assumes that all discoloured tissue at the enamel-dentine junction (EDJ) represents active disease and this is removed to arrest the carious process. This study aims to establish clinical criteria to differentiate between active and arrested caries at the EDJ using microbiological assessment of dentine samples to verify its clinical status. Radiographs were available for posterior teeth. Cavities (n = 205) were prepared under rubber dam. After gaining access, areas of the EDJ were chosen and assessments made of consistency (soft, medium, hard), colour (dark brown, mid-brown, pale) and moisture content (wet, dry). Dentine was removed by using a No. 3 round burr and placed in 1 ml of bacteriological culture broth. This sampling procedure was repeated at the same site once during cavity preparation and again when the cavity was judged as fully prepared. Samples were vortexed, diluted and cultured to give viable counts of the total anaerobic microflora, mutans streptococci and lactobacilli; viable counts were expressed as log10 (CFU per sample +1). Results showed no significant differences between the microflora of primary and secondary caries. The number of bacteria recovered diminished significantly as cavities were completed. Initial samples from soft and wet lesions harboured significantly more bacteria, lactobacilli and mutans streptococci than samples from medium, hard or dry lesions. Lesions visible on radiographs harboured more bacteria, including lactobacilli and mutans streptococci, while dentine colour was not discriminatory.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

The effect of glass-ionomer cement on carious dentine: an in vivo study.

The effect of a glass-ionomer cement sealant on carious dentine was investigated clinically and bacteriologically. The study group consisted of 24 molar teeth, with small clinical visible occlusal dentine lesions, in 13 children (aged 7-18 years). Twenty of these molars were filled and sealed with a glass-ionomer cement (Fuji Ionomer Type III) and 4 with a resin sealant (Delton). From each molar, two dentine samples were collected aseptically with a time interval of 7 months. The first sample was taken after opening the lesion just beneath the dentino-enamel junction before application of the filling material (sample A), and the second beneath the removed filling material (sample B) 7 months later. Before collecting sample B the sealant was clinically evaluated and impressions were prepared in order to (re)evaluate the sealants later by scanning electron microscopy (SEM). After taking the second sample, the remaining fissures were opened to a standard depth, the caries which was still present was removed, and a composite resin restoration was applied. In all teeth, more glass-ionomer cement material was found by SEM compared to the clinical evaluation. In both the glass-ionomer- and the resin sealant-treated group, the median value of the total number of microorganisms (CFU) on blood agar was 100 times smaller in the B sample. Microorganisms were found in 90% of the B samples in the group treated with glass-ionomer cement; hard dentine was also found in 45% of the B samples from this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces↗

PubMed1993

Dental caries and cariogenic factors in pre-school urban Icelandic children.

Caries prevalence and several caries-related factors were measured in 158 pre-school children in Reykjavík, initially aged 4 years and followed longitudinally for 2 years. The mean dmfs at 4 years was 3.3 and rose to 5.8 at 6 years although 34% remained caries-free throughout the study. Caries was very unevenly distributed. Children with dmfs > or = 5 at 4 years were significantly more likely to have caries in their permanent dentition at 6 years than those with a lower caries score at 4 years. Almost all children carried Streptococcus mutans but only 58% carried lactobacilli at 4 years. Lactobacilli declined in numbers at 5 and 6 years as the number of open carious lesions decreased but the mean count of S. mutans remained fairly static (> 10(5) cfu/ml). There were strong associations between high counts of S. mutans or lactobacilli and caries. Salivary parameters were not as strongly associated with caries although a low salivary pH and low salivary flow rate were significantly associated with high caries scores. The misuse of sugar as determined by dietary questionnaire was strongly associated with a high caries score and low caries prevalence was found in those children that took fluoride tablets regularly.

Buffers↗

PubMed1994

A comparison of primary root caries lesions classified according to colour.

Three hundred and ninety-five primary root caries lesions in 117 patients were included in this study. Each lesion was clinically characterised (colour, dimensions, distance from gingival margin and texture) and a sample of infected or altered dentine was taken using a standardised sampling procedure. The relationships between the colour and the microflora, texture, physical dimensions and distance from the gingival margin of the lesions were investigated. Lesions in each colour group (light brown, yellow, dark brown and black) were identified in each texture category (soft, leathery and hard), except for black lesions which were recorded as only soft or leathery. Black soft and black leathery lesions had a significantly greater area and harboured more lactobacilli than all other types of lesions while black leathery lesions also harboured significantly more yeasts. There were no significant differences in the number of bacteria or mutans streptococci isolated from soft or leathery lesions irrespective of lesion colour. Overall, these data indicate that the colour of primary root caries lesions is not a reliable indicator of primary root caries activity. Assessment of the clinical severity of primary root caries lesions requires consideration of lesion texture and the distance of the lesion from the gingival margin rather than the colour of the lesion.

Actinomyces↗

PubMed1994

Residual effects of fluoride on a severe cariogenic challenge in rats.

The influence of temporary dietary restriction with and without fluoridated drinking water on the progression of caries was studied in 60 desalivated Sprague-Dawley rats. Dietary restriction alone had little effect on caries progression when the challenge was interrupted and then resumed, in contrast to the effects of dietary restriction plus fluoride. Animals subjected to gavage plus fluoride in the drinking water for 11 days developed significantly less severe lesions on their lingual surfaces than did any of the other groups. No significant differences were observed in the microbial flora of the animals at the end of the study. The results show that temporary dietary restriction alone has little permanent effect on caries progression and that fluoride administered even for a short time in the absence of cariogenic challenge has a statistically significant, but probably less than optimum, protective effect against a subsequent caries challenge.

Animals↗

PubMed1995

Adherence of microorganisms to rat salivary pellicles.

Numerous studies, using models to mimic the formation of the acquired pellicle, have concentrated on human saliva-coated hydroxyapatite; in contrast, although the rat is frequently used as an animal model, the information concerning the formation of pellicles from rat saliva is sparse. We compared the ability of Streptococcus and Actinomyces species to adhere to hydroxyapatite coated by rat saliva (rsHA) and human saliva (sHA). We also explored the influence of glucan synthesized in situ on the adherence of organisms. We show that each strain of organism has a distinct binding pattern, which was essentially the same with surfaces coated with either rat or human saliva. Dissolved rsHA beads revealed a major protein band (35-49 kD), identified as glutamine/glutamic-acid-rich protein; acidic proline-rich protein (31-45 kD and alpha-amylase (66 kD) were also identified. Overall, these in vitro data strongly suggest that the principles of bacterial adhesion to rsHA are similar to those observed with sHA.

Adsorption↗

PubMed1997

Influence of iron alone or with fluoride on caries development in desalivated and intact rats.

Sugar is used as a vehicle for iron fortification in communities where anemia is prevalent. The purpose of the present study was to investigate the relationship between caries experience and iron concentration in sugar fed to rats subjected to a severe cariogenic challenge. Desalivated and intact animals were assigned to 4 different diet subgroups, 3 receiving iron sucrose (350, 175 and 88 ppm Fe) and a control group. The influence of iron sugar combined with 10 ppm F in drinking water was explored in an additional study. Iron reduces the incidence of smooth-surface carries in desalivated rats at concentrations as low as 88 ppm Fe. In addition, a combination of iron and fluoride reduced the incidence of dental caries in our rats.

Anemia, Iron-Deficiency↗

PubMed2004

Single-molecule imaging of the dynamic interactions between macromolecules.

In recent years, the development of single-molecule detection techniques has allowed the dynamic properties of biomolecules, which are normally obscured in conventional ensemble measurements, to be measured. One of these single-molecule detection techniques allows the measurement of dissociation and association events of individual molecules to be measured. This technique is based on the unique premise that the mobility between molecules that are bound and the mobility between those that are free in solution are different. The binding of ATP at the beginning and its dissociation at the end of the hydrolysis reaction were detected at the single-molecule level in real time. In this study, we extended this technique to image the dynamic interactions between large biomolecules (protein/protein and protein/polysaccharide). The binding and dissociation of fluorescently labeled macromolecules to partner molecules fixed on a glass surface were visualized by total internal reflection fluorescence microscopy. The dynamic interactions between the proteins in two energy conversion systems, that is, signaling proteins and enzyme molecules moving on dextran, have been measured. In these systems, the dynamic interactions were sensitive to the factors determining the chemical reactions. Thus, the dynamic interactions monitored in the single-molecule measurements provided useful information to further the understanding of the underlying mechanisms of energy conversion systems.

Adenosine Triphosphate↗

PubMed1991

In vitro acidogenic potential and mutans streptococci of human smooth-surface plaque associated with initial caries lesions and sound enamel.

Samples of human dental plaque were pooled from several "white spot" smooth tooth surface areas as well as from several clinically-sound tooth surface areas in each of 12 caries-positive college students. Each of the two samples from each subject was used for the determination of: (1) pH-lowering potential in vitro involving dispersed plaque suspensions, excess glucose supply, and a 60-minute test, and (2) the proportions of mutans streptococci and lactobacilli. When all subjects were considered, plaques from "white spot" areas, as compared with samples from sound surface areas, were characterized by significantly higher proportions of mutans streptococci, a lower starting ("resting") pH, a faster rate of pH drop between pH 6.0 and 5.0, and a lower minimum pH of the suspension; the lactobacillus proportions were generally very low in both types of plaques. For individual subjects, however, the proportions of mutans streptococci in plaque associated with "white spot" areas showed a wide range (0.001-10.0%), and samples with high as well as low levels of these micro-organisms could exhibit a high rate of pH drop and a low pH minimum. This suggests that, besides mutans streptococci and lactobacilli, other bacteria capable of acidogenesis at a low pH may contribute to the high pH-lowering potential exhibited by many plaques.

Acids↗

PubMed1991

Mutans streptococci and non-mutans streptococci acidogenic at low pH, and in vitro acidogenic potential of dental plaque in two different areas of the human dentition.

Samples of human dental plaque were obtained from sound tooth surfaces in the lower anterior and upper posterior areas of each of 11 subjects with various degrees of caries experience. Both types of plaque were compared for: (1) their pH-lowering potential [pH at 10 and 60 min after sugar addition and the pH drop between 0 and 10 min (delta pH)] with an in vitro method involving dispersed plaque suspensions and excess glucose supply; (2) the proportions of mutans streptococci; and (3) the distribution of the predominant non-mutans streptococci according to their final pH in glucose broth. Compared with plaque from the lower anterior area, plaque from the upper posterior area exhibited a significantly higher pH-lowering potential, i.e., a lower pH at 10 and 60 min and a greater delta pH and significantly higher levels of mutans streptococci. The final pH values for the non-mutans streptococci exhibited a wide range from about 4.4 to over 5.0. The proportions of such organisms designated as capable of acidogenesis at low pH (final pH less than 4.6), whether expressed as a percentage of the total non-mutans streptococci or of the total plaque flora, were significantly increased in plaque from the upper posterior area. The proportions of non-mutans streptococci capable of acidogenesis at low pH in plaque from the upper posterior area were also significantly increased, with decreasing pH values at 10 and 60 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗

PubMed1993

A microbiological study of primary root-caries lesions with different treatment needs.

Samples of altered or carious dentin for microbiological culture were obtained from 301 primary root-caries lesions in 59 patients by means of a standardized sampling procedure. This involved the cleansing of each root surface of extraneous supragingival plaque by means of a hand-held toothbrush and distilled water and the collection of the sample with a sterile dental excavator passed through the entire vertical dimension of each lesion. The total number of colony-forming units (cfu) in each sample and the numbers of mutans streptococci (primarily Streptococcus mutans), lactobacilli, yeasts, and Gram-positive pleomorphic rods (GPPR) were determined. Individual bacterial counts were expressed as log10 (cfu per sample), as a percentage of the total number of bacteria per sample, and as a frequency of isolation from lesions with different clinical diagnostic criteria. Clinical measurements of each lesion were made for color, texture, position relative to the gingival margin, and treatment need. Lesions classified as soft yielded significantly more bacteria, mutans streptococci, lactobacilli, and GPPR than leathery lesions, which yielded more bacteria than hard lesions. Lesions were classified into 5 treatment categories: soft and restore, leathery and restore, leathery and debride of caries; leathery and treat therapeutically; and hard no treatment. The total numbers of bacteria, mutans streptococci, lactobacilli, GPPR, and yeasts decreased significantly with decreasing treatment need. The frequency of isolation of mutans streptococci, lactobacilli, and yeasts was significantly greater from lesions requiring restoration and from lesions situated within 1 mm of the gingival margin. We suggest that the majority of root caries is initiated adjacent to the gingival margin.

Actinomyces↗

PubMed1994

Definition of a fundamental repeating unit in streptococcal glucosyltransferase glucan-binding regions and related sequences.

The C-termini of the glucosyltransferases (Gtfs) of oral streptococci are responsible for glucan binding. These glucan-binding domains (GBDs) are composed of a series of repeated sequences that have been classified into four different classes (A-D) by virtue of sequence similarity and which, by inference, have been suggested to be of functional importance. In contrast, we propose that repeat sequences evolve in response to selection for an increase in the number of copies of a particular domain through multiple duplication events occurring at different times. According to this hypothesis, repeats should possess various degrees of similarity, especially if only key residues are of functional importance. Analysis of the GBDs of the Gtfs indicated that a common fundamental repeat, designated the "YG" repeat, could be discerned within the "A", "B", "C", and "D" repeats. Similar elements were also conserved in the ligand-binding repeats of the Clostridium difficile toxins and the lysins and the PspA protein of Streptococcus pneumoniae, suggesting that similar selective pressures had also been imposed on these sequences. Analysis of the "YG" repeats present in the GtfJ and GtfK of Streptococcus salivarius indicated that some of the "YG" repeats in the GBDs of these proteins had arisen as a result of duplication events involving a series of three sequential "YG" repeats.

Amino Acid Sequence↗

PubMed1995

Marginal ditching and staining as a predictor of secondary caries around amalgam restorations: a clinical and microbiological study.

Caries at the margins of restorations is difficult to diagnose. In particular, the relevance of both marginal ditching and staining around amalgam restorations is unclear. This clinical study questions the relevance of marginal ditching and color change to the level of infection of the dentin beneath the margins of amalgam restorations. Clinically visible sites (330) on the tooth/restoration margin were selected on 175 teeth. The enamel adjacent to each site was noted as stained (a grey discoloration) or stain-free. One hundred and seventy-eight sites were clinically intact, 83 sites had narrow ditches (< 0.4 mm), and at 49 sites, wide ditches were present (> 0.4 mm). Twenty sites with frankly carious lesions were also included. Plaque was sampled at the tooth-restoration margin, and the dentin was sampled at the enamel-dentin junction below each site. Samples were vortexed, diluted, and cultured for total anaerobic counts, mutans streptococci, lactobacilli, and yeasts. Plaque samples showed that margins with wide ditches (> 0.4 mm) harbored significantly more bacteria, mutans streptococci, and lactobacilli than did clinically intact margins and margins with narrow ditches. There were no significant differences in the degree of infection of the dentin beneath clinically intact restorations and those with narrow ditches, but samples associated with wide ditches and carious lesions yielded significantly more bacteria, mutans streptococci, and lactobacilli. The color of the enamel adjacent to the sample site was irrelevant to the level of infection of the dentin beneath the filling margin, provided a frankly carious lesion was not present.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1996

The inhibiting effect of aqueous Azadirachta indica (Neem) extract upon bacterial properties influencing in vitro plaque formation.

The purpose of this investigation was to examine the inhibitory effects of aqueous extracts derived from the bark-containing sticks (Neem stick) of Azadirachta indica upon bacterial aggregation, growth, adhesion to hydroxyapatite, and production of insoluble glucan, which may affect in vitro plaque formation. Neem stick extracts were screened for minimal bacterial growth inhibition (MIC) against a panel of streptococci by means of a broth dilution assay. Initial bacterial attachment was quantified by the measurement of the adhesion of 3H-labeled Streptococcus sanguis to saliva-conditioned synthetic hydroxyapatite. The effect of the Neem stick extract upon insoluble glucan synthesis was measured by the uptake of radiolabeled glucose from 14C-sucrose. Aggregating activity of the Neem stick extracts upon a panel of streptococci was also examined. No inhibition of bacterial growth was observed among the streptococcal strains tested in the presence of < or = 320 micrograms/mL of the Neem stick extract. The pre-treatment of S. sanguis with the Neem stick extract or the gallotannin-enriched extract from Melaphis chinensis at 250 micrograms/mL resulted in a significant inhibition of the bacterial adhesion to saliva-conditioned hydroxyapatite. Pre-treatment of saliva-conditioned hydroxyapatite with the Neem stick or gallotannin-rich extract prior to exposure to bacteria yielded significant reductions in bacterial adhesion. The Neem stick extract and the gallotannin-enriched extract from Melaphis chinensis inhibited insoluble glucan synthesis. Incubation of oral streptococci with the Neem stick extract resulted in a microscopically observable bacteria aggregation. These data suggest that Neem stick extract can reduce the ability of some streptococci to colonize tooth surfaces.

Alkaloids↗

PubMed1998

The activation and function of host matrix metalloproteinases in dentin matrix breakdown in caries lesions.

Matrix metalloproteinases (MMPs) are a family of enzymes which, in concert, are capable of degrading collagen. We investigated whether human MMPs could participate in the degradation of dentin organic matrix after demineralization. We performed Western blot analyses using MMP-specific antibodies to identify MMPs in human dental caries lesions. Enzymography and functional activity assays, with 125I-labeled gelatin as substrate or quantitating the degradation of type I collagen, were used to determine the activity of purified and salivary gelatinolytic (MMP-2 and MMP-9) and collagenolytic (MMP-8) enzymes with and without acid-activation in pHs relevant to caries. Respective analyses were done with caries-related bacteria. We performed electron microscope analyses to assess the degradative activity of sterilized salivary host MMPs on demineralized human dentin. Human MMP-2, MMP-8, and MMP-9 were identified in demineralized dentinal lesions. The latent purified forms of these enzymes were activated at low pH (4.5), followed by neutralization, mimicking the conditions during caries progression. Incubation of human saliva at low pH followed by neutralization resulted in a four-fold increase in the gelatinolytic activity. No gelatinolytic or collagenolytic activity was observed in bacterial samples. The activated enzymes in saliva degraded demineralized dentin organic matrix in vitro. These results demonstrate the pH-dependent activation mechanism of MMPs, which may have a distinct role in different physiological and pathological conditions. They further demonstrate that host MMPs, activated by bacterial acids, have a crucial role in the destruction of dentin by caries.

Bacterial Proteins↗

PubMed2002

The effect of a high-sucrose diet on dentin formation and dental caries in hyperinsulinemic rats.

A high-sucrose diet decreases dentin formation and its minerals, but the mechanisms behind the effect are largely unknown. We studied the combined and separate effects of sucrose and insulin on dentin formation and mineral metabolism in growing rats. At weaning, animals were randomized into 4 groups: control/sucrose diets both with and without external insulin (1 U/x 100 g body weight daily). After 4 weeks, we measured areas of dentin formation, numbers and areas of dentinal caries lesions, and serum and urine glucose, insulin, Ca, Na, K, and P. Exogenous insulin increased serum and urine insulin levels and decreased serum glucose level, but did not affect dentin formation or dentinal caries lesion formation or progression. A high-sucrose diet decreased dentin formation independently of insulin. The differences in serum and urine minerals between the groups were minor. The findings confirm that sucrose-diet-induced reduction in dentinogenesis is independent of insulin and loss of minerals in urine.

Analysis of Variance↗