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PubMedDate not supplied

Antibacterial effect of chlorhexidine on bacteria adsorbed onto experimental dental plaque.

The most common method used to examine the antibacterial effect of antiplaque agents is the minimal inhibitory concentration (MIC) method, which is tested on bacteria in suspensions. Examining the antibacterial effect on bacteria adsorbed onto dental surfaces models is not as popular, although it is clear that such models reflect the conditions in the oral cavity far more accurately than the conventional MIC method. The antibacterial effect of chlorhexidine (CHX) on bacteria adsorbed onto experimental dental plaque model was investigated. Hydroxyapatite beads were coated with human saliva. Next, cell-free fructosyltransferase (FTF) and glucosyltransferase (GTF) were adsorbed onto the beads, and sucrose was added to allow the synthesis of polysaccharide by the surface-bound enzymes. Following adsorption of Streptococcus sobrinus to the experimental dental plaque (EDP), the EDP was exposed to CHX at concentrations between 0.008 to 0.0002% at pH values of 5.5, 6.5, and 7.5. After 150 min incubation, growth of the adsorbed bacteria was measured by their incorporation of 3H-uridine or 3H-thymidine. Comparison of bacterial growth on the EDP with that in suspension showed that the surface-bound bacteria were less sensitive to CHX than were the bacteria in suspension. At all tested CHX concentrations, the antibacterial effect was independent of pH. In addition, under our experimental conditions, the use of 3H-uridine as an indicator of bacterial viability proved to be more sensitive than 3H-thymidine. The antibacterial effect of an agent in a model closely mimicking the tooth surface should generate results that are more relevant to the in vivo conditions than are conventional methods, thus bearing significant information concerning clinical applications of CHX.

Adult↗

PubMed1998

In vitro assessment of the antimicrobial activity of a local sustained release device containing amine fluoride for the treatment of oral infectious diseases.

Dental caries and periodontal diseases are chronic infectious diseases caused by oral bacteria. Local sustained release delivery systems extend the time in which the drug is present in the oral cavity, thus enhancing its therapeutic potential while reducing its side effects. Amine-fluorides (AmF) are known anticaries agents and have recently been found to have an antibacterial effect against periodontal pathogens and caries-associated bacteria. The purpose of this in vitro study was to assess the antimicrobial activity of a local sustained release device (LSRD) containing AmF on Streptococcus sobrinus 6715. LSRD was prepared from an ethylcellulose matrix containing AmF. Release kinetics of AmF from the LSRD was measured simultaneously with its antimicrobial activity. The organic amine and the fluoride were released in different kinetics profiles: The fluoride was released faster than the organic amine. The antimicrobial activity of AmF was measured on planktonic bacteria in solution and on bacteria as part of experimental dental plaque. During a 10-day period, the concentration of the released AmF was above its MIC and no bacterial growth was observed. Bacterial counts in the dental plaque were reduced by 1 to 2 log units. Hence, the LSRD containing AmF has the potential to serve as a medicament in prevention and treatment of dental caries and periodontal diseases.

Anti-Infective Agents, Local↗

PubMedDate not supplied

Rapid and constant detection of HIV antibody response in saliva of HIV-infected patients; selective distribution of anti-HIV activity in the IgG isotype.

Anti-HIV antibodies can be specifically detected with a sensitivity and a specificity of 100% in the saliva of all HIV-infected patients. A saliva collection device facilitates the sampling procedure, and if a rapid test is used, the diagnosis of infection can be established in as little as 10 min. The analysis of a group of CDC stage IV AIDS patients showed a decrease in lactoferrin (produced by the oral mucosa) in comparison with HIV-negative controls, associated with an increase in albumin (filtering from plasma), indicating an alteration of the mucosal barrier. The salivary anti-HIV-gp160 activity was largely carried by the IgG isotype whereas the salivary antibacterial activity (anti-Streptococcus sobrinus; anti-LPS from Escherichia coli) remained located in the IgA isotype as usually observed with all infectious agents. Salivary IgG carried a specific anti-gp160 activity 25-fold higher than that of serum IgG. Thus, significant local synthesis of specific IgG by oral mucosa was revealed as a characteristic of HIV infection.

Acquired Immunodeficiency Syndrome↗

PubMed2001

Induction and 3D reconstruction of caries-like lesions in an experimental dental plaque biofilm model.

The aim of this study was to examine an in vitro dental plaque model for volumetric assessment and 3D reconstruction of experimentally bacterial induced caries-like lesions. Twenty-three extracted, impacted human molars were coated with a varnish leaving a 3 x 3 mm window on the smooth surface. The teeth were coated with human saliva and Streptococcus sobrinus 6715 adhered onto the enamel via a sucrose dependent mechanism. The coated teeth were incubated for 1, 7, 14 and 28 days. At the end of each incubation period microhardness was measured on three sectioned teeth of each incubation period at the enamel surface and at 450 and 750 microm depth perpendicular to the enamel surface. The enamel surface was investigated by scanning electron microscopy (SEM) prior to embedding and serial sectioning of 12 other teeth. The serial sections were studied with polarization light microscopy to investigate subsurface demineralization. The outlines of the caries-like lesions were then traced consecutively on transparencies, digitized and three-dimensionally reconstructed to demonstrate the expansion of the lesion into enamel for volumetric assessment. Microhardness was significantly reduced on the enamel surface after 7, 14 and 28 days incubation. The SEM investigation showed a surface demineralization with dissolution of the prism cores after 28 days incubation. Polarization light microscopy demonstrated caries-like lesions with an irregular expansion into enamel. The results demonstrate that the described method produces caries-like lesions which can be used for further experimental studies regarding demineralization and remineralization processes.

Biofilms↗

PubMed1998

Effects of continuous glucocorticoid infusion on the progression of dentinal caries in growing rats.

This study was undertaken to test the effects of a low dose of continuous glucocorticoid infusion on the rate of progression of dentinal caries in molars of young rats. Forty-seven rats were inoculated in the mouth with Streptococcus sobrinus and fed ad libitum a cariogenic diet and 10% sweetened water. After 10 days of caries initiation ten animals were killed to serve as a reference group. In the rest of the animals the cortisone or placebo pellet was implanted subcutaneously in the back of the neck. The daily release of cortisone was 0.42 mg per rat. Sweetened water was changed to pure water, and the diet was the same cariogenic diet. After 6 weeks of medication the areas of dentinal caries were quantified planimetrically. Schiff's staining was used to classify caries. Although cortisone medication slightly increased the number of carious lesions, statistical significance was not reached. However, compared with the placebo group, the rats receiving cortisone medication showed significantly increased dentinal caries progression and severity of lesions. This study suggests that glucocorticoids with a cariogenic diet reduce the intrinsic modulation or response of the odontoblasts to caries attack.

Animals↗

PubMed1998

Comparison of dentin apposition and dentinal caries progression in the mandibular and maxillary molars of the rat.

To show that the rate and the rate of reduction of dentin apposition are about the same in mandibular and maxillary molars, 23 Sprague-Dawley rat pups were randomized into 2 groups on the day of birth. During lactation half of their dams received a standard rodent diet; the other half, a diet containing 41% sucrose. At the age of 3 weeks the pups were weaned, weighed, given an intraperitoneal injection of oxytetracycline hydrochloride, and inoculated with oral Streptococcus sobrinus. During the experiment the pups received the same diet as their dams during lactation. After 5 weeks the pups were decapitated, their jaws sectioned sagittally, the first and second molars photographed, and the areas of dentin apposition and dentinal caries measured planimetrically. The area of dentin formation was about the same in maxilla and mandible in the first molars, but slightly smaller in the mandibular second molars of the control group. The sucrose diet reduced dentin apposition significantly in both jaws, although the areas were significantly smaller in the mandibles than in the maxillae. Caries did not affect the rate of dentin apposition. The areas of caries lesions were smaller in the maxillary molars of both diet groups. The results show that the hypothesis of equal rate of dentin apposition in mandible and maxilla was not valid because the reduction, caused by sucrose, was more prominent in mandibular molars for unknown reasons. The reduction of dentin apposition was reflected as acceleration of caries progression among the diet groups and the jaws. It was concluded that the response of the pulpodentinal complex to sucrose and dentinal caries during the primary dentinogenesis cannot be seen as a formation of reactionary or reparative dentin, as with adult rats.

Animals↗

PubMed2006

Preparation and antimicrobial activity of gelatin microparticles containing propolis against oral pathogens.

Gelatin microparticles containing propolis ethanolic extractive solution were prepared by spray-drying technique. Particles with regular morphology, mean diameter ranging of 2.27 microm to 2.48 microm, and good entrapment efficiency for propolis were obtained. The in vitro antimicrobial activity of microparticles was evaluated against microorganisms of oral importance (Enterococcus faecalis, Streptococcus salivarius, Streptococcus sanguinis, Streptococcus mitis, Streptococcus mutans, Streptococcus sobrinus, Candida albicans, and Lactobacillus casei). The utilized techniques were diffusion in agar and determination of minimum inhibitory concentration. The choice of the method to evaluate the antimicrobial activity of microparticles showed be very important. The microparticles displayed activity against all tested strains of similar way to the propolis, showing greater activity against the strains of E. salivarius, S. sanguinis, S. mitis, and C. albicans.

Anti-Infective Agents↗

PubMed1997

High-level ability of secretory IgA to block HIV type 1 transcytosis: contrasting secretory IgA and IgG responses to glycoprotein 160.

The IgG and secretory IgA (S-IgA) responses to the HIV-1 envelope (gp160 antigen) were analyzed in the colostrum (Col) and in the cervicovaginal fluid (CVF) of HIV-l-infected women. We show IgG antibodies (Abs) to the recombinant gp160 to be predominant as compared with the corresponding S-IgA isotype. The low level of the S-IgA response cannot be related to a general disturbance of the mucosal-associated Iymphoid tissue (MALT) because the level of a current Ab to a caries-associated antigen from Streptococcus sobrinus was in the normal range in these secretions. The major subclass of IgA to gp160 was of the alpha1 isotype both in Col and in CVF. However, the specific activities of S-IgA1 and S-IgA2 were different when expressed as the ratio of the anti-gp160 related to total Ig of each subclass. Indeed, the specific activity of the S-IgA2 was predominant over S-IgA1 in the Col, whereas the reciprocal results were found in CVF, showing a subcompartmentalization of these secretions. The ability of S-IgA and IgG to block one of the pathways involved in the HIV-1 penetration across mucosa, i.e., transcytosis through epithelial cells, was evaluated using a functional in vitro assay. Both S-IgA and IgG Abs impaired virus transcytosis, irrespective of the level of antigp160 specific activities. However, specific S-IgA was more efficient than IgG. These features suggest that mucosal specific S-IgA to HIV-1 could be relevant in decreasing infectivity of HIV-1 in corporal fluids.

Adult↗

PubMed2006

In vitro assessment of antimicrobial peptides as potential agents against several oral bacteria.

BACKGROUND: Antimicrobial peptides are components of the innate immunity that play an important role in systemic and oral health. OBJECTIVES: The antibacterial activity of the amphibian-derived K4 -S4(1-15)a antimicrobial peptide was tested against oral pathogens associated with caries and periodontitis and compared with the activities of the human-derived antimicrobial peptides LL-37 and dhvar4a. METHODS: Growth inhibition of planktonic bacteria was tested using standard microdilution assays. Live/Dead staining followed by confocal scanning laser microscopy (CSLM) was used to determine the bactericidal effect of K4 -S4(1-15)a on Streptococcus mutans attached to a glass surface or grown as biofilm. RESULTS: The cariogenic species S. mutans, Streptococcus sobrinus, Lactobacillus paracasei and Actinomyces viscosus were resistant to LL-37 found in the oral cavity. Porphyromonas gingivalis was the species most resistant to the three tested peptides. K4 -S4(1-15)a demonstrated the highest activity against the tested planktonic bacteria. In addition, K4 -S4(1-15)a was bactericidal to surface-attached S. mutans as well as to S. mutans biofilms grown in vitro. However, surface attachment increased S. mutans resistance to the antimicrobial peptide. CONCLUSIONS: Our results support growing evidence suggesting the use of antimicrobial peptides for prevention and treatment of oral disease.

Anti-Bacterial Agents↗

PubMed2001

In vitro evaluation of the antimicrobial activity of a castor oil-based irrigant.

The antimicrobial activity of irrigating solutions--Endoquil (castor oil detergent), 2% chlorhexidine gluconate solution, and 0.5% NaOCl solution-was evaluated against gram-positive cocci (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecalis, Staphylococcus epidermidis, Streptococcus mutans, and Streptococcus sobrinus), gram-negative rods (Escherichia coli and Pseudomonas aeruginosa), and the yeast Candida albicans. Activity was evaluated using the two-layer agar diffusion technique. The base layer was obtained by pouring 10.0 ml of Muller Hinton Medium or 10.0 ml of Brain Heart Infusion agar in a Petri dish. After solidification a 5.0 ml seed layer of Muller Hinton Medium or Brain Heart Infusion agar with inoculum (106/ml) was added. Absorbent paper disks (6.0 mm in diameter) immersed in the solutions were placed at equidistant points. Plates were maintained at room temperature for 2 h for prediffusion of the solutions and incubated at 37 degrees C for 24 h. The candle jar system was used for the Brain Heart Infusion agar plates. All tests were performed in duplicate. After incubation the medium was optimized with 0.05 g% triphenyltetrazolium chlorate gel and inhibition halos were measured. All bacterial strains were inhibited by 2.0% chlorhexidine gluconate. Endoquil was effective against gram-positive microorganisms, and 0.5% NaOCl was effective only against S. aureus.

Anti-Infective Agents, Local↗

PubMed1994

Effect of fluoride on the rate of dentin apposition and caries progression in young and old Wistar rats.

The effect of fluoride in drinking water on the progression of dentinal caries and dentin apposition was studied separately in young and old Wistar rats. The animals were inoculated with Streptococcus sobrinus and fed ad libitum on a 43% sucrose diet and distilled water supplemented with 0, 1, or 19 ppm fluoride. After a 7-wk (young) or 13-wk (adult) cariogenic challenge, the areas of dentinal caries and dentin apposition were quantified after tetracycline staining. Fluoride in the drinking water reduced the progression of dentinal caries and the speed of dentin formation in the young animals but only the progression of dental caries in the adult ones. Both the progression of carious lesions in the dentin and the rate of dentin apposition were 10 times faster during primary dentinogenesis.

Aging↗

PubMed2002

Expression and characterization of streptococcal rgp genes required for rhamnan synthesis in Escherichia coli.

Six genes (rgpA through rgpF) that were involved in assembling the rhamnose-glucose polysaccharide (RGP) in Streptococcus mutans were previously identified (Y. Yamashita, Y. Tsukioka, K. Tomihisa, Y. Nakano, and T. Koga, J. Bacteriol. 180:5803-5807, 1998). The group-specific antigens of Lancefield group A, C, and E streptococci and the polysaccharide antigen of Streptococcus sobrinus have the same rhamnan backbone as the RGP of S. mutans. Escherichia coli harboring plasmid pRGP1 containing all six rgp genes did not synthesize complete RGP. However, E. coli carrying a plasmid with all of the rgp genes except for rgpE synthesized the rhamnan backbone of RGP without glucose side chains, suggesting that in addition to rgpE, another gene is required for glucose side-chain formation. Synthesis of the rhamnan backbone in E. coli required the initiation of transfer of N-acetylglucosamine to a lipid carrier and the expression of the rgpC and rgpD genes encoding the putative ABC transporter specific for RGP. The similarities in RGP synthesis between E. coli and S. mutans suggest common pathways for rhamnan synthesis. Therefore, we evaluated the rhamnosyl polymerization process in E. coli by high-resolution sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the lipooligosaccharide (LOS). An E. coli transformant harboring rgpA produced the LOS modified by the addition of a single rhamnose residue. Furthermore, the rgpA, rgpB, and rgpF genes of pRGP1 were independently mutated by an internal deletion, and the LOS chemotypes of their transformants were examined. The transformant with an rgpA deletion showed the same LOS profile as E. coli without a plasmid. The transformant with an rgpB deletion showed the same LOS profile as E. coli harboring rgpA alone. The transformant with an rgpF deletion showed the LOS band with the most retarded migration. On the basis of these results, we speculated that RgpA, RgpB, and RgpF, in that order, function in rhamnan polymerization.

Acetylglucosamine↗

PubMed1999

Litter effects on caries in rats and implications for experimental design.

The purpose of this study was to obtain quantitative estimates of litter effects on caries development in rats and to examine the implications for design of rat caries experiments. Twelve female Sprague-Dawley rats, aged 60 days, were bred with 4 male rats. Nine of the 12 dams had litters in close proximity. The litters were culled to 10 pups. One pup from each litter was placed with each of the other dams for nursing, leaving 2 pups from each litter with the birth dam. This design allowed the litter effect to be separated into a prenatal component, reflecting the shared genetic makeup and in utero environment of littermates, and a postnatal component reflecting a shared environment from shortly after birth to weaning. Pups were infected with Streptococcus sobrinus and fed Diet 2000 and 10% (w/v) sucrose water for 5 weeks. There was no significant evidence of a postnatal litter effect for smooth surface caries (p = 0.37) or sulcal caries (p = 0.43). The prenatal litter effect was significant for both smooth surface caries and sulcal caries (p<0. 01). When litter effects are present, the statistical power of caries studies is improved if animals from the same litter are divided evenly among experimental groups. In addition, if litter effects are present but not allowed for in data analysis, incorrect statistical inferences may be drawn. Based on our results and other reports of litter effects, we recommend planning for litter effects in the design and analysis of rat caries studies.

Animals↗

PubMedDate not supplied

The effect of chronic clonidine administration on salivary glands and caries in the rat.

Clonidine is a widely prescribed, centrally acting antihypertensive with proposed pharmacologic mechanisms of stimulation of central postsynaptic alpha(2)-adrenergic receptors and agonist activity at presynaptic alpha(2)-adrenergic receptors, interfering with peripheral regulation of norepinephrine and acetylcholine release. Both of these mechanisms are capable of adversely influencing salivary output and composition, potentially leaving an individual with increased caries risk. The purpose of the present study was to determine the effect of chronic administration of clonidine on saliva, salivary glands, and caries in rats. Sprague-Dawley rat pups were infected with Streptococcus sobrinus, given Diet 2000 and 10% sucrose water ad libitum, and either desalivated, or treated with clonidine HCl (125 or 250 microg/kg administered daily for 28 days by means of osmotic minipumps), or assigned as controls. There were no statistical differences in stimulated parotid or submandibular gland salivary output or sublingual gland weights among the groups. The weight of the submandibular glands as a percent of total body weight was significantly decreased in animals that received clonidine when compared with controls. Sulcal caries scores in both clonidine groups and smooth surface caries scores in the high clonidine group were increased when compared with control animals. Positive control animals (desalivated) had significantly higher caries scores than all other groups. These data show that chronic administration of clonidine significantly decreases submandibular gland weight and increases susceptibility to dental caries.

Animals↗

PubMed1995

Investigation of the effects of aluminum mouthrinses on rat dental caries and plaque.

The effects of topically applied mouthrinses containing AlCl3, or AlK(SO4)2 on dental caries and plaque were investigated in a rat model. For comparison, NaF and a two-step treatment of AlCl3 and NaF were also tested. Six groups of 20 weanling rats were inoculated with Streptococcus sobrinus 6715 and provided a caries-inducing diet and distilled water ad libitum. Test agents were topically applied twice daily 5 days per week at a concentration of 0.037 mol/l in a mouthrinse vehicle and were compared with a vehicle control rinse and a distilled water control. After 10 weeks none of the treatments reduced plaque amounts relative to the controls. The AlCl3 and AlK(SO4)2 rinses significantly reduced both smooth-surface and sulcal caries by approximately 40%. The cariostatic activity of the aluminum rinses was equivalent to an equimolar NaF mouthrinse on smooth surface lesions, but was statistically less than NaF on sulcal caries. The two-step treatment with AlCl3 and NaF indicated numerically additive effects, but the results were not statistically better than with NaF alone. Dentine caries progression paralleled the enamel caries prevalence results. No deaths, toxicologic effects, or inhibition of growth rates were observed in any treatment group. This study confirmed that topically applied solutions of aluminum salts inhibited caries formation in the rat caries model and showed that the cariostatic activity of aluminum was maintained in a compatible mouthrinse vehicle.

Alum Compounds↗

PubMed1997

Fluoride and pilocarpine reduce the risk of caries produced by chronic clomipramine treatment in rats.

The effects of chronic clomipramine treatment on the incidence of caries in the rat and their prevention by fluoride and pilocarpine were investigated. One hundred and twenty male Wistar rats were divided into six groups, five experimental groups, one control group and treated with 50 mg/kg/day of clomipramine, 10 ppm fluoride in drinking water, and 5 mg/kg/day of pilocarpine. All animals were infected with Streptococcus sobrinus 6715 and fed a cariogenic diet ad libitum for 42 days. Water and food consumption, weight gain, salivary flow rate, amylase activity, protein and fluoride concentration in saliva, and caries scores were determined in all animals. Whereas clomipramine significantly increased the fluoride and protein concentration in saliva, pilocarpine only decreased fluoride concentration. Animals treated with clomipramine developed 40% more sulcal caries than nontreated animals. Administration of fluoride (10 ppm) in drinking water and chronic oral administration of pilocarpine prevented the increased risk of developing caries associated with chronic treatment with clomipramine.

Administration, Oral↗

PubMed1988

The effects of different levels of dietary sucrose on root caries subsequent to gingivectomy in conventional rats infected with Actinomyces viscosus M-100.

Three groups of weanling, Sprague-Dawley-derived rats were inoculated with Actinomyces viscosus M-100 and fed powdered diet containing either 67%, 5%, or 0% confectioner's sugar. Two further groups were fed diet containing 5% confectioner's sugar and inoculated with Streptococcus sobrinus 6715 or S. sobrinus 6715 plus A. viscosus M-100. The most coronal 1 mm of gingiva was removed from maxillary and mandibular right molar quadrants (gingivectomy), and the animals re-inoculated following gingivectomy. The animals were killed 64 days following gingivectomy, and the lingual surface of mandibular first molar roots was measured for exposed root-surface area and root caries. In the groups of rats infected with A. viscosus M-100, root caries area was significantly greater in the group fed diet containing 67% confectioner's sugar. Sucrose level did not significantly affect the amount of exposed lingual first molar root area regardless of whether the tooth had been subjected to a gingivectomy. In the groups of rats receiving diet containing 5% confectioner's sugar, there were no significant differences in root caries area or exposed root-surface area, regardless of the infection status of the animals. In the rat model presented here, a high level of dietary sucrose was a necessary condition for the initiation of root caries in the absence of other readily fermentable carbohydrates.

Actinomyces↗

PubMed1994

Polydimethylsiloxane as a tooth surface-bound carrier of triclosan: a new concept in chemical plaque inhibition.

Polydimethylsiloxane (silicone oil) has an extremely low surface tension: It spreads over solid surfaces and forms a tenacious film which is hydrophobic and water-repellent. It is known that this liquid binds to hydroxyapatite and to dental enamel and changes the properties of these solids. It has been suggested that silicone oil may be applied to teeth and serve as a reservoir of lipid-soluble antibacterial substances which presumably will be slowly released into saliva due to their low solubility in water. The present paper reviews recent papers where this hypothesis is tested in vitro and in vivo. It was first shown that test tubes treated with the combination silicone oil and the lipid-soluble agent triclosan acquired a layer which inhibited bacterial growth in a culture of Streptococcus sobrinus (OMZ 176) which was grown in sucrose. Both growth in the medium and polysaccharide adsorption to the glass wall were inhibited. Silicone oil alone inhibited polysaccharide adsorption to some degree, whereas the growth in the medium was not affected. In a similar clinical plaque-inhibition study, topical application of silicone oil/triclosan to the teeth of a test panel showed marked plaque inhibition, particularly giving an increased number of teeth with scores of 0 (no plaque). In a study where silicone oil and triclosan were incorporated into a toothpaste, improved gingival health was observed after a period of one month. It is concluded that the use of silicone oil/triclosan in the manner described above represents a new principle in preventive dentistry. The results obtained seem to warrant further experiments with this combination.

Adolescent↗