Plaque Microflora Research Articles

Oral microflora in betel-chewing adults of the Karen tribe in Thailand

Objective To study a possible influence of betel chewing on the composition of the oral microflora in plaque and saliva and on oral health parameters as well as a possible betel effect on oral bacteria in vitro. Material and methods Thirty-two adults (16 betel chewers and 16 non-betel-chewing controls) of the Karen Hill tribe in Thailand were investigated. Saliva samples and 2 pooled supragingival plaque samples were taken from each individual for microbial analysis with culture and 4 subgingival samples for analysis with the DNA–DNA hybridization method against 12 periodontitis associated bacterial species. Caries (DMFS), plaque (PlI%) and bleeding on probing (% BoP) was registered as well as number of sites with >5 mm probing pocket depth (PPD). Water extract of the betel ( areca chatechu) nut was tested for its antimicrobial effect in vitro against 10 oral bacterial species with the agar diffusion method. Results An antimicrobial effect of betel nut water extract was found on the oral microorganisms in vitro. The levels of mutans streptococci and lactobacilli in saliva were low or absent in both chewers and controls. The prevalence of the periodontitis associated bacteria was >90%. Betel chewers had significantly lower levels of some bacteria in subgingival plaque ( Prevotella intermedia p < 0.001) than non-chewers. This study population was low in missing teeth (mean 0.7 and 0.3), caries decay (DS 2.1 vs 1.6), and number of deep pockets (mean 1.9 vs 1.3). Great variation in oral hygiene (PlI and BoP) between the subjects was seen. Conclusions An antimicrobial effect of the betel nut was found in vitro and with a possible effect also in vivo however it did not seem to influence clinical parameters such as plaque index, caries prevalence (DMFS), bleeding on probing and number of deep pockets.

Effect of a single-use toothbrush on plaque microflora

To study and compare the microbial flora of dental plaque after the use of a self-contaminated toothbrush and that of a single-use toothbrush. The study group included 40 young volunteers from Yenepoya Dental College, who were free from any systemic or oral disease. In these subjects, plaque samples were collected after 1 month use of a self-contaminated toothbrush. Each subject was given a set of 30 new toothbrushes and a toothpaste tube and instructed to use one toothbrush everyday and discard it after use. The plaque samples were collected on a weekly interval and cultured on Mitis Salivarius agar. The colonies were identified and speciated and their count was recorded. Streptococcus mitis, S. mutans, S. sanguis, S. milleri and Candida were recovered from the samples. A highly significant decrease in their numbers was found after the use of a single-use toothbrush (P value 0.001). As a contaminated toothbrush can reintroduce microorganisms into the oral cavity, it may be a sound practice to change the toothbrush as frequently as possible.

Antibacterial Activity and Anti-Biofilm Effect of Chitosan against Strains of Streptococcus Mutans Isolated in Dental Plaque

Streptococcus mutans is the major cause of dental plaque and is often associated with biofilm formation. The aim of this study is to evaluate the activity of a hydrosoluble derivative of chitosan against S. mutans biofilms in vitro and in vivo. Strains of S. mutans were isolated from the dental plaque of 84 patients enrolled in the study. The antibacterial activity of chitosan was determined by broth microdilutions. The effect of chitosan at different concentrations and exposure times on S. mutans biofilms at different phases of development was assessed by a clinical study using the classical "4-day plaque regrowth" experiment in adult volunteers. The MIC values of chitosan were between 0.5 and 2 g/L. Compared to distilled water, the chitosan solution significantly decreased the vitality of plaque microflora (p<or=0.05). Chlorhexidine, used as a positive control, reduced vitality even further. The results showed that S. mutans in the adhesion phase (4 h) was completely inhibited by chitosan at any concentration (0.1, 0.2, 0.5XMIC) or exposure time investigated (1, 15, 30, 60 min), while S. mutans at successive stages of accumulation (12-24 h) was inhibited only by higher concentrations and longer exposure times. These data confirm the effective action of chitosan against S. mutans biofilms.

Efficacy of oral chlorhexidine in critical care

In their review of airway hygiene, Jelic and colleagues highlighted that colonization or infection of the upper airway precedes the development of ventilator-associated pneumonia [1]. Although the effects of chlorhexidine on reducing pneumonia were discussed, there was no mention of the possible contribution of physical plaque removal, in particular tooth brushing, which is often performed either infrequently or inadequately in mechanically ventilated patients [1]. Such removal is important because in critically ill patients the normal microflora of dental plaque becomes rapidly colonized by potential pathogens, and this biofilm serves as a reservoir for the subsequent development of ventilator-associated pneumonia [2,3]. Physical removal of dental plaque is essential for the optimal benefit of chlorhexidine since its primary action is inhibition of plaque formation. Whilst chlorhexidine kills both Gram-negative bacteria and Gram-positive bacteria by damaging their cell wall, its antiplaque activity is superior to other antiseptics with greater antibacterial activity. This superior activity occurs because chlorhexidine is absorbed onto oral surfaces and is released over a long period of time. This property, known as substantivity, explains why chlorhexidine is excellent at inhibiting plaque formation in a clean mouth but is otherwise of limited efficacy [4]. It is also not generally appreciated that if toothpaste is used prior to chlorhexidine then it must be thoroughly removed to prevent formation of inactive low-solubility salts [5]. Oral chlorhexidine is widely used in critical care practice and has been the subject of many investigations in mechanically ventilated patients. These studies unfortunately do not address the essential need for mechanical cleaning prior to chlorhexidine use and therefore potentially underestimate the benefit of this agent in reducing ventilator-associated pneumonia.

Denture Plaque Microflora in Geriatric Inpatients and Maxillary Defect Patients

Purpose: The purpose of this study was to investigate denture plaque microflora of geriatric inpatients and maxillary defect patients from the standpoint of infection control in the elderly.Methods: Denture plaque was collected from 80 elderly subjects who were categorized into 3 groups: group A, 21 healthy complete denture wearers; group B, 49 complete denture wearers residing at a geriatric hospital; and group C, 10 complete denture wearers with maxillary defects. The microflora was investigated by counting the total number of microorganisms, including streptococci, staphylococci, and Candida spp.Results: The colony-forming unit (CFUs) count and incidence, particularly those of Candida spp., were significantly higher in group B (P<0.01). The CFUs of staphylococci were significantly higher in group C (P<0.01), and methicillin-resistant Staphylococcus aureus (MRSA) was observed in all Staphylococcus-positive patients. The CFUs of Candida spp. were significantly correlated to those of staphylococci (P<0.01).Conclusion: A high CFU count of Candida spp. and staphylococci (including MRSA) are characteristic of the microflora in geriatric inpatients and maxillary defect patients, respectively. This study supports the hypothesis that dentures might serve as potential reservoirs of organisms causing systemic infections.

The role of sucrose in cariogenic dental biofilm formation--new insight.

Dental caries is a biofilm-dependent oral disease, and fermentable dietary carbohydrates are the key environmental factors involved in its initiation and development. However, among the carbohydrates, sucrose is considered the most cariogenic, because, in addition to being fermented by oral bacteria, it is a substrate for the synthesis of extracellular (EPS) and intracellular (IPS) polysaccharides. Therefore, while the low pH environment triggers the shift of the resident plaque microflora to a more cariogenic one, EPS promote changes in the composition of the biofilms' matrix. Furthermore, it has recently been shown that the biofilm formed in the presence of sucrose presents low concentrations of Ca, P(i), and F, which are critical ions involved in de- and remineralization of enamel and dentin in the oral environment. Thus, the aim of this review is to explore the broad role of sucrose in the cariogenicity of biofilms, and to present a new insight into its influence on the pathogenesis of dental caries.

Effect of Withdrawal of Fluoride-Containing Toothpaste on the Interproximal Plaque Microflora

To compare the effects of fluoride-containing and fluoride-free toothpaste on plaque microflora, 15 subjects were enrolled in a double-blind crossover trial. All subjects used a fluoride toothpaste for 7 days before the trial started. Then, 4 interproximal sites per subject were professionally cleaned and subjects used one of the toothpastes for 5 days. On the 5th day plaque was collected from 2 sites, 12 and 6 h after toothpaste use. There was no difference between the groups in the numbers or proportions of aciduric bacteria (recovered at pH 4.8 or 5.2), or of yeasts, neisseriae, lactobacilli or streptococci (total or individual species, including Streptococcus mutans). However, the numbers and proportions of Gram-positive pleomorphic rods, primarily Actinomyces naeslundii, increased in 6-hour samples from subjects using fluoride toothpaste. The data suggest that the anti-caries effect of fluoride toothpaste is not mediated primarily through effects on the plaque microflora, although effects on plaque physiology could be important.

Functional Implication of the Hydrolysis of Platelet Endothelial Cell Adhesion Molecule 1 (CD31) by Gingipains ofPorphyromonas gingivalisfor the Pathology of Periodontal Disease

Periodontitis is a response of highly vascularized tissues to the adjacent microflora of dental plaque. Progressive disease has been related to consortia of anaerobic bacteria, with the gram-negative organism Porphyromonas gingivalis particularly implicated. The gingipains, comprising a group of cysteine proteinases and associated hemagglutinin domains, are major virulence determinants of this organism. As vascular expression of leukocyte adhesion molecules is a critical determinant of tissue response to microbial challenge, the objective of this study was to determine the capacity of gingipains to modulate the expression and function of these receptors. Given the potential multifunctional role of platelet endothelial cell adhesion molecule 1 (PECAM-1) in the vasculature, the effect of gingipains on PECAM-1 expression by endothelial cells was examined. Activated gingipains preferentially down-regulated PECAM-1 expression on endothelial cells compared with vascular cell adhesion molecule 1 and endothelial-leukocyte adhesion molecule 1, but the reduction in PECAM-1 expression was completely inhibited in the presence of the cysteine proteinase inhibitor TLCK (Nalpha-p-tosyl-l-lysine chloromethyl ketone). Endothelial monolayers treated with activated gingipains demonstrated progressive intercellular gap formation that correlated with reduced intercellular junctional PECAM-1 expression as determined by Western blotting and immunofluorescence microscopy. This was accompanied by enhanced transfer of both albumin and neutrophils across the monolayer. The results suggest that degradation of PECAM-1 by gingipains contributes to increased vascular permeability and neutrophil flux at disease sites.

Levels of mutans streptococci and lactobacilli in plaque on aged restorations of an ion-releasing and a universal hybrid composite resin

The purpose of this in vivo study was to evaluate the cariogenic microflora of plaque on aged restorations of a hydroxyl, fluoride, and calcium ion-releasing composite resin (IRCR) (Ariston pHc), and to compare it intra-individually with a universal hybrid composite resin and enamel. Each of 19 subjects received one proximal restoration of the IRCR, one proximal universal hybrid composite resin restoration (CR) and each subject had one non-filled proximal enamel control surface to make intra-individual comparisons possible. To avoid peak ion releases from the materials, aged restorations were studied. Plaque was collected from 57 surfaces using sterile applicator tips. Samples were cultured to determine the numbers of mutans streptococci, lactobacilli, and total microorganisms. The relative numbers for mutans streptococci (% of total bacteria) were: IRCR 0.59%, CR 0.40%, enamel 0.22%. Two outliers were found in the IRCR group. Excluding these outliers resulted in a relative number of 0.33%. Lactobacilli were detected in the plaque from only 9 surfaces and at very low relative proportions for all three surfaces: 0.01%. The enamel surfaces showed the lowest relative numbers of mutans streptococci and lactobacilli, but the differences were not significant. It can be concluded that the ion release of the IRCR did not influence the growth of cariogenic microorganisms in dental plaque.

Subgingival plaque microbiota in Saudi Arabians after use of miswak chewing stick and toothbrush

The chewing stick, the miswak, is used in many developing countries as the traditional means for oral hygiene. It is prepared from the roots, twigs and stem of Salvadora persica or other alternative local plants. To compare the effects of the chewing stick miswak (from S. persica) and toothbrush on subgingival plaque microflora among Saudi Arabian individuals. Further, to investigate whether components extracted from S. persica may interfere with the subgingival plaque micro-organisms. Fifteen healthy Saudi Arabian male volunteers aged 21-36 years were included in a single-blind, randomized cross-over study. The participants were taught how to use each device properly. Plaque sampling for DNA test was performed at the baseline, 1 week after professional tooth cleaning, and after 3 weeks of either miswak or toothbrush use. Identification and quantification of microbial species were performed by the checkerboard method, using whole genomic, digoxigenin-labelled DNA probes. Inhibition zones around miswak were examined on agar plates with Actinobacillus actinomycetemcomitans and the leukotoxicity of this bacterium was analyzed in a bioassay with macrophages+/-extracts of miswak. Miswak and toothbrushing had a similar influence on the levels of the subgingival microbiota. However, A. actinomycetemcomitans was significantly more reduced by miswak (p<0.05) than by toothbrushing. These results were supported by our in vitro results which, indicated that extracts from S. persica might interfere with the growth and leukotoxicity of A. actinomycetemcomitans. In contrast to toothbrush use, miswak use significantly reduced the amount of A. actinomycetemcomitans in the subgingival plaque.

Are dental diseases examples of ecological catastrophes?

Dental diseases are among the most prevalent and costly diseases affecting industrialized societies, and yet are highly preventable. The microflora of dental plaque biofilms from diseased sites is distinct from that found in health, although the putative pathogens can often be detected in low numbers at normal sites. In dental caries, there is a shift towards community dominance by acidogenic and acid-tolerant Gram-positive bacteria (e.g. mutans streptococci and lactobacilli) at the expense of the acid-sensitive species associated with sound enamel. In contrast, the numbers and proportions of obligately anaerobic bacteria, including Gram-negative proteolytic species, increase in periodontal diseases. Modelling studies using defined consortia of oral bacteria grown in planktonic and biofilm systems have been undertaken to identify environmental factors responsible for driving these deleterious shifts in the plaque microflora. Repeated conditions of low pH (rather than sugar availability per se) selected for mutans streptococci and lactobacilli, while the introduction of novel host proteins and glycoproteins (as occurs during the inflammatory response to plaque), and the concomitant rise in local pH, enriched for Gram-negative anaerobic and asaccharolytic species. These studies emphasized (a). significant properties of dental plaque as both a biofilm and a microbial community, and (b). the dynamic relationship existing between the environment and the composition of the oral microflora. This research resulted in a novel hypothesis (the 'ecological plaque hypothesis') to better describe the relationship between plaque bacteria and the host in health and disease. Implicit in this hypothesis is the concept that disease can be prevented not only by directly inhibiting the putative pathogens, but also by interfering with the environmental factors driving the selection and enrichment of these bacteria. Thus, a more holistic approach can be taken in disease control and management strategies.

Effects of fixed orthodontic appliance on the microflora of dental plaque

This study was undertaken to elucidate the effect of fixed orthodontic appliance on the microbial composition of dental plaque and to detect any difference between the isolated microflora from different teeth before and during treatment. Twenty subjects (15 females and 5 males) between (12) and (23) years of age, participated in this study. From each subject, four swabs were collected; two in the anterior region (upper and lower central incisors) and two in the posterior region (upper and lower first molars). Bacterial examinations were performed before the beginning of the treatment and (4-6) weeks after placement of orthodontic appliances, so (160) swabs were collected. The composition of dental plaque determined was under light microscope. The statistical analysis was performed and the results showed a variety of microorganisms from supra-gingival plaque samples in pre-and during treatment fixed orthodontic patient. Changes during treatment consisted of an increase in the Peptpcocci,Klebsiella,α- Streptococci, Pseudomonas and Escherichia coli in certain locations. Conversely, a decrease in the Peptostreptococci,Bacteroids,Veillonella, Staphylococci,Streptococcus mutans, Klebsella, Candida, Lactobacilli and Propeniobacterium in different locations, whereas other microorganisms and some of the above-mentioned microorganisms in certain locations showed insignificant differences. The comparison of microflora between different teeth indicated that the molars presented a significantly more microorganisms than incisors did specially in pre-treatment, whereas the upper incisor in both pre-and during treatment presented more microorganisms than lower incisor; while the lower molar exhibited more microorganisms than the upper molar particularly during treatment.

Colonization of denture plaque by respiratory pathogens in dependent elderly.

Recently, there has been a resurgence of interest in the interactions between oral conditions and a number of prevalent systemic diseases. The morbidity and mortality of the dependent elderly that result from aspiration pneumonia have been recognized as a major geriatric health problem. The purpose of this study was to gain more information on the microflora of plaque on dentures and to assess the existence of oral infectious pathogens potentially causing the respiratory disease in the dependent elderly. The denture bacterial flora of 50 dependent elderly were examined to identify microorganisms by the culture method. 18 species of microorganisms were detected in denture plaque in this study. A variety of pathogens with the potential to cause respiratory infection pathogens colonized on the dentures of dependent elderly. The results of the present study revealed that bacteria that commonly cause respiratory infection colonized on the dentures of dependent elderly, suggesting that denture plaque may function as a reservoir of potential respiratory pathogens to facilitate colonization on the oropharynx.

A microbiological study of Papillon-Lefévre syndrome in two patients

Aim—To analyse the microflora of subgingival plaque from patients with Papillon-Lefévre syndrome (PLS), which is a very rare disease characterised by palmar-plantar hyperkeratosis with precocious periodontal destruction. Methods—Bacterial isolates were...

A pilot study of confocal laser scanning microscopy for the assessment of undisturbed dental plaque vitality and topography

Confocal microscopy and vital fluorescence techniques were combined for the first time to investigate ex vivo human dental plaque. The vital fluorescence technique used discriminates vital from dead cells, while confocal laser scanning microscopy allows the optical sectioning of undisturbed biofilms leaving the samples intact during analysis. The concomitant use of both methods made an examination of the three-dimensional architecture of dental plaque possible. The topography of plaque biofilms that were allowed to accumulate in situ on glass and enamel was recorded. The distribution of plaque microflora vitality as well as its accumulation varied according to plaque age. A plaque thickness of up to 8, 35 and 45 μm was estimated ex vivo on enamel after 1, 2 and 3 days, respectively. Young and sparse plaque biofilms consisted mainly of dead material. Vital bacteria were observed on top of this dead layers.

Chemical agents for the control of plaque and plaque microflora: an overview.

This presentation provides an overview of the technologies available for the chemical control of plaque. It is generally accepted that the formation of dental plaque at the interfaces of tooth/gingiva is one of the major causes of gingival inflammation and dental caries. Several therapeutic approaches have been used to control dental plaque and supragingival infections. These include fluoride preparations such as stannous fluoride, oxygenating agents, anti-attachment agents, and cationic and non-cationic antibacterial agents. Among the fluoride preparations, stable stannous fluoride pastes and gels have been shown to reduce supragingival plaque, gingivitis, hypersensitivity and caries. The effect of the oxygenating agents on the supragingival plaque has been equivocal, but recent data indicate that a stable agent which provides sustained active oxygen release is effective in controlling plaque. A polymer, PVPA, which reduced attachment of bacteria to teeth was shown to significantly reduce plaque formation in humans. A new generation of antibacterials includes non-ionics such as triclosan, which in combination with a special polymer delivery system, has been shown to reduce plaque, gingivitis, supragingival calculus and dental caries in long-term studies conducted around the world. Unlike the first generation of agents, the triclosan/copolymer/sodium fluoride system is effective in long-term clinicals and does not cause staining of teeth, increase in calculus, or disturbance in the oral microbial ecology.

Variations in the predominant cultivable microflora of dental plaque at defined subsites on approximal tooth surfaces in children

The distribution and composition of the resident microflora were determined in approximal gingival margin plaque from 21 premolars extracted from schoolchildren (mean age 12.0 ± 1.8 yr). Indigo carmine (5% w/v) was used to visualize plaque to facilitate sampling. About 1 mm 2 of plaque was removed from sites away from (A), to the side of (S), and below (B) the contact area. Plaque samples were dispersed, serially diluted, and cultured on selective and non-selective agar media. An average of seven to nine species was found at each subsite. Streptococcus and Actinomyces were subdivided on the basis of a range of biochemical tests. The predominant Actinomyces and streptococcal species at most subsites were A. naeslundii and Strep. mitis biovar I. A. naeslundii and A. odontolyticus were isolated more often at subsite B (90.5 and 57.1%, respectively), and A. israelii at subsite S (66.7%). Strep. mitis I and Strep. sanguis were found more frequently at subsite S (76.2 and 66.7%, respectively), whereas Strep. mutans, Strep. sobrinus, Strep. gordonii and Veillonella spp. were recovered most commonly from subsite B (85.7, 33.3, 38.1 and 76.2%, respectively). The isolation frequencies of Strep. mutans and Strep. sobrinus were significantly higher at subsite B (A < B, p < 0.01 and p > 0.05, respectively), Veillonella spp. were significantly higher at subsites B and S (A < B, p > 0.01; B > S, p < 0.05), while Neisseria spp. were most common at subsite A (A > B, p < 0.03). IgA1 protease-producing species were found at each subsite, but they formed only a small proportion of the total Streptococcus population. This study has shown that local variations were evident at different subsites, both with respect to species prevalence and to proportions of each species within each subsite. The population shifts in gingival margin plaque appear to relate to the location of plaque in relation to the most caries-prone site below the contact area B.

老人病院入院患者の口腔状態とデンチャープラークの細菌構成について 第１報 予備調査結果

Dental treatment must meet the needs of the rapidly increasing elderly people in Japan. In addition, geriatric inpatients also increased with the increase of elderly people. Investigation was carried out to determine the oral condition and microflora in denture plaque of elderly patients in two geriatric hospitals and Tokushima Dental Hospital. The difference between healthy patients and geriatric inpatients was. discussed. The results of the preliminary survey were as follows:1. Inpatients in a geriatric hospital were more elderly, and the frequency of edentulous patients was fairly high. The prognosis of the denture was poor because of high frequencies of low residual ridge and oral diskinesia.2. Denture plaque of geriatric inpatients had the following characteristics compared to that of healthy elderly patients.1) Numbers of total bacteria, Streptococci, Candida, and Staphylococci in isolated denture plaque of the geriatric inpatients were larger than those of healthy patients.2) Linear relationships between numbers of total bacteria and Streptococci and between numbers of Candida and Staphylococci were found.3) The frequency of MRSA in the geriatric inpatients was higher than in the healthy patients.4) Numbers of total bacteria and Streptococci in denture plaque obtained in the inpatients with heart disease and cerebrovascular accident were much larger than those in the inpatients without these diseases.

A 6‐month home‐usage trial of 0.1% and 0.2% delmopinol mouthwashes (II). Effects on the plaque microflora

The effects of 0.1% and 0.2% delmopinol mouthwashes on supragingival plaque flora were investigated in a 6-month home-use study. 141 subjects were studied from whom plaque was collected at baseline, 12, 24, and 36 weeks. Overall, there were no consistent effects on microscopic or total counts. However, there was a significant reduction in the proportion of dextran-producing streptococci in the active groups compared to the control group throughout treatment. There was no colonisation by Candida or Gram-negative aerobic bacilli in the active groups nor was there any decrease in susceptibility to delmopinol. Delmopinol appears to mediate its anti-plaque effect without causing a major shift in bacterial populations, although dextran-producing bacteria appear to be affected, which may have relevance to this agent's mode of action.

Occurrence of Certain Bacterial Species and Morphotypes in Juvenile Periodontitis in Chile

The occurrence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, Fusobacterium nucleatum, Campylobacter rectus, Capnocytophaga species, and certain bacterial morphotypes was determined in 18 affected and 18 unaffected sites in 10 localized juvenile periodontitis (LJP) patients, and in 10 affected and 10 unaffected sites in 5 generalized juvenile periodontitis (GJP) patients. The subgingival proportion of the 7 bacterial species was determined by selective and nonselective culturing. The results showed that when considering the pure prevalence of bacteria ( > 0%) there were significant differences (P < 0.05) in the subgingival plaque microflora of the affected sites versus those of the unaffected sites for P. gingivalis, A. actinomycetemcomitans, P. intermedia, E. corrodens, C. rectus, and F. nucleatum in LJP, and for P. gingivalis, P. intermedia, and F. nucleatum in GJP. The mean proportions of cocci, motile rods and spirochetes were also significantly different (P < 0.05) in affected sites compared to unaffected sites. Capnocytophaga sp, F. nucleatum, P. intermedia, and E. corrodens were found in more than 75% of affected sites in LJP. When taking the approach that an organism, to be associated with periodontal disease, has to be detected above a certain minimum threshold, the results indicated that bacteria most frequently associated with LJP and GJP in Chile are P. gingivalis (66% of LJP and 80% of GJP affected sites), and A. actinomycetemcomitans (44% of LJP and 50% in GJP affected sites). Different bacterial species may be judged to be important in the disease process depending upon whether a pure bacterial prevalence, or a prevalence above a certain detection level, is considered.