Correlations of oral bacterial arginine and urea catabolism with caries experience

Background/aim: Alkali generation by oral bacteria plays a key role in plaque pH homeostasis and may be a major impediment to the development of dental caries. To determine if the capacity of oral samples to produce ammonia from arginine or urea was related to caries experience, the arginine deiminase system (ADS) and urease activity in saliva and dental plaque samples were measured in 45 adult subjects. Methods: The subjects were divided into three groups according to caries status; 13 caries‐free (CF) individuals (decayed, missing, and filled teeth = 0); 21 caries‐active (CA) individuals (decayed teeth ≥ 4); and 11 caries‐experienced (CE) individuals (decayed teeth = 0; missing and filled teeth > 0). Real‐time polymerase chain reaction was used to quantify the proportion of certain acid‐ or alkali‐producing organisms in the samples. Results: The amount of ammonia generated from the test substrates by plaque samples was generally higher than that produced by salivary samples in all groups. Significantly higher levels of salivary ADS activity and plaque urease activity were observed in CF subjects compared to CA subjects (P = 0.0004 and P = 0.014, respectively). The proportions of Streptococcus mutans from saliva and dental plaque of CA subjects were significantly higher than those from the CF group (P = 0.0153 and P = 0.0009, respectively). In the CA group, there was an inverse relationship between urease activity and the levels of S. mutans (P < 0.0001). Conclusion: This study supports the theory that increased caries risk is associated with reduced alkali‐generating capacity of the bacteria colonizing the oral cavity; providing compelling evidence to further our understanding of oral alkali‐generation in health and disease.     

Effect of mechanical and chemical plaque control measures on oral microflora in schoolchildren

Abstract The incidence of S. sanguis, S. salivarius, S. mutans, total streptococci and lactobacilli was examined in highly caries active 13–14-year-old schoolchildren participating in a prophylactic program. After 1 year of trial, professional toothcleaning once every second week markedly reduced the frequency of gingivitis and the caries increment. Bimonthly topical applications of a 0.5 % chlorhexidine gel with or without subsequent rinsing with 2% MFP had no effect on plaque score and gingivitis but tended to reduce the caries activity. No significant changes were found in the groups with regard to the salivary number of total streptococci and S. sanguis. A reduction of the population of S. salivarius, S. mutans and lactobacilli was observed in the chlorhexidine group. In the group where chlorhexidine was combined with MFP, only S. mutans was reduced.     

人体口腔微生物组群与牙菌斑生物膜

牙菌斑是由多种微生物组成的生物膜结构,口腔微生物之间的相互作用可以影响牙菌斑生物膜的性质、形成、毒力,以及微生物在生物膜结构中的定位和定植。生物膜内细菌之间存在的信号传导对生物膜的形成及其毒力具有影响。本文重点介绍人体口腔微生物组群与牙菌斑生物膜关系的最新研究进展。     

The effect of disaggregated nano-hydroxyapatite on oral biofilm in vitro

ObjectiveAgglomeration is a common problem facing the preparation and application of nanomaterials, and whether nano-hydroxyapatite (nano HA) can modulate oral microecology left to be unclear. In this study, nano HA was disaggregated by sodium hexametaphosphate (SHMP) and ultrasonic cavitation to observe whether agglomeration would affect its effect on oral bacterial biofilm.MethodsDynamic light scattering (DLS) and scanning electronic microscope (SEM) were used to observe the treatment solutions. Single-species biofilms and multi-species biofilms were treated with 10% nano HA, 10% disaggregated nano HA, 10% micro hydroxyapatite (micro HA) and deionized water (DDW) for 30 min and analyzed via MTT assay, lactic acid measurement, SEM and confocal laser scanning microscope (CLSM). Real-time polymerase chain reaction was performed to analyze the biofilm composition.ResultsUltrasonic cavitation combined with SHMP could significantly reduce the degree of agglomeration of nano HA. Disaggregated nano HA could inhibit bacterial growth and reduce the ability of bacterial biofilm to produce lactic acid and extracellular polysaccharides. There was no significant difference on composition of multi-species biofilms between nano HA and disaggregated nano HA.SignificanceThe disaggregated nano-hydroxyapatite could inhibit the metabolism and acid production of oral bacterial biofilm, but did not significantly affect the composition of multi-species biofilms.     

Deletion of gtfC of Streptococcus mutans has no influence on the composition of a mixed-species in vitro biofilm model of supragingival plaque

Glucosyltransferases from Streptococcus mutans are thought to play an important role in bacterial adherence to the tooth surface. The goal of the present study was to determine the effect of the deletion of the gtfC gene, which encodes a glucosyltransferase that catalyses primarily the formation of insoluble glucan (mutan), on colonization of S. mutans in a mixed-species biofilm model of supragingival plaque. A gtfC deletion mutant of S. mutans UA159 grew poorly in biofilms on a polystyrene surface in Todd–Hewitt medium containing sucrose, but biofilm formation in the semi-defined fluid universal medium (FUM) was not affected. The S. mutans gtfC mutant colonized with the same efficiency as the wild-type strain when grown together with five other species in a mixed-species biofilm on hydroxyapatite in a mixture of FUM and saliva with pulses of sucrose and showed the same ability to demineralize enamel in vitro . Colonization of mutant and wild-type strains was also equal in an association experiment in specific-pathogen-free rats. However, the gtfC mutant gave rise to more dentinal fissure lesions and smooth surface caries than the wild-type strain; this could be caused by a change in diffusion properties as a result of to the lack of mutan.     

Effect of arginine on the growth and biofilm formation of oral bacteria

BackgroundAlkali production via arginine deiminase system (ADS) of oral bacteria plays a significant role in oral ecology, pH homeostasis and inhibition of dental caries. ADS activity in dental plaque varies greatly between individuals, which may profoundly affect their susceptibility to caries.ObjectiveTo investigate the effect of arginine on the growth and biofilm formation of oral bacteria.Methods and resultsPolymicrobial dental biofilms derived from saliva were formed in a high-throughput active attachment biofilm model and l-arginine (Arg) was shown to reduce the colony forming units (CFU) counts of such biofilms grown for various periods or biofilms derived from saliva of subjects with different caries status. Arg hardly disturbed bacterial growth of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus gordonii in BHI medium, but only inhibited biofilm formation of S. mutans. Scanning electron microscope (SEM) showed S. mutans biofilms harboured fewer cells grown with Arg than that without Arg, even in the initial 2 h and 8 h phase. Confocal laser scanning microscope (CLSM) images of poly-microbial dental and S. mutans biofilms revealed the biofilms grown with Arg had lower exopolysaccharide (EPS)/bacteria ratios than those without Arg (P = 0.004, 0.002, respectively). Arg could significantly reduce the production of water-insoluble EPS in S. mutans biofilms (P < 0.001); however, quantitative real-time PCR (qRT-PCR) did not show significantly influence in gene expression of gtfB, gtfC or gtfD (P = 0.32, 0.06, 0.44 respectively).ConclusionsArg could reduce the biomass of poly-microbial dental biofilms and S. mutans biofilms, which may be due to the impact of Arg on water-insoluble EPS. Considering the contribution to pH homeostasis in dental biofilms, Arg may serve as an important agent keeping oral biofilms healthy thus prevent dental caries.     

Efficacy of red propolis hydro-alcoholic extract in controlling Streptococcus mutans biofilm build-up and dental enamel demineralization

ObjectiveThe efficacy of a red propolis hydro-alcoholic extract (RP) in controlling Streptococcus mutans biofilm colonization was evaluated. The effect of RP on dental demineralization was also investigated.MethodsChemical composition was determined by High Performance Liquid Chromatography (HPLC). Minimum Inhibitory and Bactericidal Concentration (MIC and MBC, respectively) were investigated against Streptococcus mutans (ATCC 25175). The cytotoxic potential of 3% RP in oral fibroblasts was observed after 1 and 3 min. Bovine dental enamel blocks (N = 24) were used for S. mutans biofilm formation (48 h), simulating ‘feast or famine’ episodes. Blocks/biofilms were exposed 2×/day, for 3 days, to a cariogenic challenge with sucrose 10% (5 min) and treated (1 min) with: 0.85% saline solution (negative control), 0.12% Chlorhexidine (CHX, positive control for biofilm colonization), 0.05% Sodium Fluoride (NaF, positive control to avoid demineralization) and 3% RP. Biofilms were assessed for viability (CFU/mL), and to observe the concentration of soluble and insoluble extracellular polysaccharides (SEPS and IEPS). Dental demineralization was assessed by the percentage of surface hardness loss (%SHL) and through polarized light microscopy (PLM).ResultsThe RP presented 4.0 pH and ºBrix = 4.8. The p-coumaric acid (17.2 μg/mL) and luteolin (15.23 μg/mL) were the largest contents of phenolic acids and flavonoids, respectively. MIC and MBC of RP were 293 μg/mL and 1172 μg/mL, respectively. The 3% RP showed 43% of viably cells after 1 min. Lower number (p < 0.05) of viable bacteria (CFU/mL) was observed after CHX (1.8 × 10⁵) followed by RP (1.8 × 10⁷) treatments. The lowest concentration (μg/CFU) of SEPS (12.6) and IEPS (25.9) was observed in CHX (p < 0.05) followed by RP (17.1 and 54.3), and both differed from the negative control (34.4 and 63.9) (p < 0.05). Considering the %SHL, all groups differed statistically (p < 0.05) from the negative control (46.6%); but NaF (13.9%), CHX (20.1%) and RP (20.7%) did not differ among them (p > 0.05). After all treatments, suggestive areas of caries lesions were observed by PLM, which were lower for CHX and NaF.ConclusionThe 3% RP reduced S. mutans colonization, decreased concentration of extracellular polysaccharides and reduced dental enamel demineralization.     

牙菌斑生物膜模型的研究进展

牙菌斑生物膜是龋病和牙周病的主要致病因素,也是目前口腔微生物学和生态学研究的热点.研究者们建立了多种模型以研究菌斑生物膜的发生机制和发生过程.龈上菌斑和龈下菌斑的生存环境及其内的微生物群有明显差异,故模型系统也各不相同.龈上菌斑易于收集且其生存环境易于模拟,目前已有多种体内和体外模型被用于龈上菌斑生物膜的研究,而龈下菌斑生物膜模型的研究相对较少.本文就牙菌斑生物膜模型的最新研究进展作一综述.     

Non‐oral bifidobacteria and the aciduric microbiota of the denture plaque biofilm

The microbiota of the denture plaque biofilm colonizing the fitting surface of dentures in edentulous subjects with healthy palates (n = 20) and in edentulous subjects with denture stomatitis (n = 20) was studied. The numbers of bacteria colonizing the dentures of healthy subjects was significantly less than the numbers colonizing the dentures of stomatitis subjects. The proportions and frequency of isolation of mutans streptococci, lactobacilli, bifidobacteria and yeasts were significantly (P < 0.05) greater in the subjects with denture stomatitis. The proportions of these organisms in the denture plaque biofilm of the subjects with denture stomatitis were similar to those found in carious lesions, indicating that the site is a low pH environment. The predominant bifidobacterial species in the mouths of dentate subjects is Bifidobacterium dentium but in the edentulous subjects wearing dentures B. dentium was isolated from only one of the 20 subjects with denture stomatitis and from none of the 20 subjects with healthy palates. Instead, Bifidobacterium breve, Bifidobacterium scardovii and Bifidobacterium longum subsp. longum were isolated. Only a single non‐oral bifidobacterial species was isolated from each individual and repetitive extragenic palindromic‐ and BOX‐polymerase chain reaction typing methods indicated that the same genotypes were shared between subjects. Using deferred antagonism spot plate assays, interspecies inhibition was demonstrated between oral isolates of B. dentium, B. breve, B. scardovii and B. longum subsp. longum. Here we have shown that bifidobacteria and caries‐associated microbiota are present in denture plaque at levels similar to those of carious lesions and B. dentium cannot be maintained in an edentulous mouth.     

多胺对细菌生物膜作用的多样性

生物膜的形成和分散受多种因素调控,阻断生物膜的形成及促进生物膜的解离分散是目前的研究热点和前沿方向。近年来的研究表明,多胺这一在原核和真核生物中广泛存在的物质同样在细菌生物膜的形成和分散过程中起到了非常重要的作用,本文就多胺对细菌生物膜相关作用的研究作一综述。     

与窝沟龋有关的优势耐酸菌构成的分析

目的　分析不同患龋状态窝沟中的优势耐酸菌构成,了解其在龋病发病中的作用。方法　第一年轻恒磨 牙窝沟新发早期龋儿童10名,2年无龋儿童10名。取新发龋窝沟处菌斑和同口正常第一恒磨牙窝沟菌斑及无龋 儿童第一恒磨牙窝沟菌斑,用平皿培养法分析菌群构成;用最可能数法(MPN)分离优势耐酸菌;API 20 Strep试剂盒 鉴定链球菌。结果　变形链球菌是无龋组窝沟的优势耐酸菌,且中性条件下检出较多;血链球菌是新龋组正常窝 沟和新龋窝沟处的优势耐酸菌;革兰阳性杆菌在酸性条件下占总检出菌比例(82%)显著高于中性条件下(61%)。 结论　菌斑生态构成非常复杂,在各个生态阶段,菌群组成不同。菌斑内局部pH值伴随菌群构成的变化推动着龋 病过程。     

牙菌斑生物膜研究模型的进展

口腔微生物群落是典型的生物膜,牙菌斑生物膜是多种菌属组成的三维结构,黏附在牙齿表面,具有生物膜结构和微生物生理学的功能。牙菌斑生物膜是龋病和牙周病的主要致病因素,已有多种生物膜模型用于研究龋病的病因、预防和治疗的研究。这些龋病生物膜模型有助于研究者用一种可控、简化的方式来预测龋病的临床进展结果。目前,研究龋病微生物的模型有体外单菌种生物膜模型和多菌种生物膜模型。本文将从研究龋病的生物膜体外模型建立做一综述。     

原位菌斑生物膜的一种完整获得方法和结构研究

目的:通过对一种方法获得原位牙菌斑生物膜的结构分析,证明这种方法的可行性。方法:选择安装有局部可摘义齿的志愿者在基托表面粘贴塑料片的方法,在塑料片上可获得1、4、24h牙菌斑生物膜,并用激光共聚焦扫描显微镜进行结构的观察和分析。结果:牙菌斑生物膜的细菌、基质清楚可见,1、4、24h菌斑生物膜的平均厚度分别是(21.41±0.03)μm,(34.03±0.02)μm,(58.53±0.03)μm。结论:这种方法获取的菌斑生物膜结构完整、简便可行,是一种很好的获取原位牙菌斑生物膜的方法,可为进一步的实验提供平台。     

The effect of supragingival plaque control on the subgingival microflora

The effect of plaque control on the apical microflora of deep periodontal pockets was studied. 8 subjects exhibiting signs of chronic periodontitis were chosen for the study, each subject having at least one pocket greater than 6 mm. These subjects were placed on a plaque control programme consisting of 3 visits, during which oral hygiene instructions were given. On two visits, the teeth of these subjects were scaled and polished. Bacteriological samples from the apex of a deep pockets from each subject were collected before the commencement of the plaque control programme and again at 8 and 16 weeks after the last scale and polish. No significant difference in the microbial flora was observed before and after plaque control, but marked fluctuation in bacterial composition was noted at the 3 samplings. It was concluded that supragingival plaque reduction was not sufficient to produce significant changes in the subgingival plaque composition of deep periodontal pockets.     

The effect of dental restorative materials on dental biofilm

To investigate the arrangement of biofilms formed in vivo, volunteers wore splints with slabs of six different dental materials inserted to collect smooth surface plaque. After 5 d of undisturbed plaque accumulation, the specimens were vital stained and analyzed by the confocal laser scanning microscopy (CLSM) to evaluate the percentage of vital biofilm microflora (VF percentage). Further parameters were the area of the specimens covered by plaque (surface coating; SC, %) and the height of the biofilms (BH, pm). The metals amalgam and gold, the compomer, as well as the glass-ionomer cement harboured an almost entirely dead biofilm (VF <8%). Resin composite led to vitality values between 4 and 21%, while a very thin biofilm on ceramic revealed the highest vitality values (34-86%). SC varied from 6% on glass-ionomer cement to 100% on amalgam. BH reached its highest value on amalgam and gold of 17 and 11 microm, respectively, while heights of between 1 and 6 microm were found on the ceramic, resin composite, compomer and the glass-ionomer cement. Within their limits, the present findings indicate that amalgam, gold, compomer and glass-ionomer cement exert an influence against the adhering biofilm. No general relationship could be established between the different parameters VF percentage, SC percentage and BH (microm).     

龋病病因相关因素的激光扫描共聚焦显微镜研究

牙菌斑生物膜作为细菌生长的微环境,在龋病形成和发展中起重要作用;口腔环境中相关因素如口腔黏膜中钙离子含量等与龋病也有一定关系。利用新兴的激光扫描共聚焦显微镜对菌斑生物膜及其他相关因素进行研究,取得了一系列新的进展,本文就此领域的相关问题作一综述。     

The effect of a microbead dentifrice on microbial load in oral microenvironments

To cite this article:
Int J Dent Hygiene 9 , 2011; 136–142
DOI: 10.1111/j.1601‐5037.2010.00465.x
Sreenivasan PK, Haraszthy VI, Zambon JJ.The effect of a microbead dentifrice on microbial load in oral microenvironments. Abstract: Objectives: The human oral cavity contains several microenvironments or ecologic niches. While mechanical plaque control is well known to reduce the number of supragingival dental plaque bacteria, there is little data on antimicrobial effects in other oral ecologic niches. The present study examined the effects of mechanical plaque control using a microbead dentifrice on bacteria colonizing oral ecologic niches. Methods: Twenty‐two adults (aged 18–70 years) including nine generalized moderate chronic periodontitis subjects and 13 periodontally healthy subjects having average gingival indices ≥1 and plaque indices ≥1.5 completed a 1 week washout phase and refrained from oral hygiene the morning of baseline sample collection. Microbial samples from supragingival dental plaque, buccal mucosa, dorsal surface of the tongue and whole mixed saliva were obtained. Subjects brushed with a microbead dentifrice and, after 10 min, sampling was repeated. The number of anaerobic bacteria was determined by culture on non‐selective media and transformed to log₁₀ for statistical analyses. Results: Mechanical plaque control using the microbead dentifrice resulted in statistically significant reductions in bacterial numbers in each ecologic niche (P < 0.001). The greatest reduction in the number of viable bacteria occurred in samples taken from the buccal mucosa (97.22%) followed by a 95.22% reduction in supragingival plaque bacteria, a 94.51% reduction in the number of bacteria on the dorsal surface of the tongue and a 91.57% reduction in the number of bacteria in whole mixed saliva. Conclusions: Mechanical plaque control using a microbead dentifrice reduces microbial load in microenvironments throughout the human oral cavity.     

用激光共聚显微镜研究菌斑生物膜的结构

目的：研究菌斑生物膜的结构。方法：从牙齿表面获得完整的菌斑生物膜标本,运用激光共聚焦显微镜对其进行断层扫描和分析。结果：菌斑生物膜是由分布不均匀的细胞、基质和空隙构成的复杂结构。结论：应用激光共聚焦显微镜技术研究菌斑生物结构是一种可行的方法。     

Effects of 0.05% sodium hypochlorite oral rinse on supragingival biofilm and gingival inflammation

Objectives: This study aimed to evaluate the clinical effects of 0.05% sodium hypochlorite mouth rinse on supragingival biofilm and gingival inflammation. Methods: The study was performed as a controlled, randomised, investigator‐blinded, parallel group trial in 40 prison inmates. Following a preparatory period to obtain a plaque‐ and gingivitis‐free dentition, tooth‐brushing was substituted for 21 days by supervised twice daily rinsing with either 15 ml of fresh solution 0.05% sodium hypochlorite or 15 ml of distilled water. Clinical outcomes were assessed using the Quigley–Hein Plaque Index (QHPI), the Löe and Silness Gingival Index (L&SGI) and bleeding on probing. Adverse events were evaluated by questionnaire, visual examination and clinical photographs. Results: At day 21, the average QHPI score had increased to 3.82 in the water rinse group and 1.98 in the sodium hypochlorite rinse group. The average L&SGI score had increased to 2.1 in the water rinse group and 1.0 in the sodium hypochlorite rinse group, and the average percentage of sites that bled on probing had increased to 93.1% in the water rinse group and 56.7% in the sodium hypochlorite rinse group. Differences were statistically significant (P = 0.001). A brown extrinsic tooth stain along the gingival margin appeared in 100% of participants in the sodium hypochlorite rinse group and in 35.0% of participants in the water rinse group (P < 0.05). Conclusions: An oral rinse with 0.05% sodium hypochlorite resulted in significant reductions in supragingival biofilm accumulation and gingival inflammation. Dilute sodium hypochlorite may represent an efficacious, safe and affordable antimicrobial agent in the prevention and treatment of periodontal disease.