Spectral characteristics of caries autofluorescence obtained from different locations and caries severities

Dental caries usually occurs at interproximal and occlusal surfaces. The purpose of the present study was to determine if characteristic spectral factors extracted from autofluorescence (AF) spectra are informative regarding caries detection and the determination of caries stage as compared with DIAGNOdent results. AF spectra were obtained from caries lesions of different severities at two locations using a 405 nm laser. Three spectral factors, that is, spectral slope at 550 to 600 nm, spectral area under the curve at 500 to 590 nm and two‐peak ratio between 625 and 667 nm, were extracted. The values of three spectral factors linearly decreased as caries progressed. According to micro‐CT images, conventional visual and tactile inspections of lesions under or overestimated (25%‐65%) caries states, and brown or thickly stained layer on interproximal or occlusal surfaces, respectively, caused misclassifications of caries stage. Of the spectral factors examined, spectral slope and area under curve for interproximal and occlusal surfaces, respectively, were found to be significantly related to caries stage and showed least data overlap. For interproximal and occlusal surfaces, DIAGNOdent readings of different stages overlapped considerably though their mean values were significantly different regardless of stage.      

Inhibitory effect of zingiber officinale towards Streptococcus mutans virulence and caries development: in vitro and in vivo studies

Background

Streptococcus mutans is known as a key causative agent of dental caries. It metabolizes dietary carbohydrate to produce acids which reduce the environmental pH leading to tooth demineralization. The ability of this bacterium to tolerate acids coupled with acid production, allows its effective colonization in the oral cavity leading to the establishment of highly cariogenic plaque. For this reason, S. mutans is the only bacterium found in significantly higher numbers than other bacteria in the dental plaque. The aim of this study was to evaluate the effect of crude extract and methanolic fraction of Z. officinale against S. mutans virulence properties.

Results

We investigated in vitro and in vivo activity of crude extract and methanolic fraction at sub- MIC levels against cariogenic properties of S. mutans. We found that these extracts strongly inhibited a variety of virulence properties which are critical for its pathogenesis. The biofilm formation in S. mutans was found to be reduced during critical growth phases. Furthermore, the glucan synthesis and adherence was also found to be inhibited. Nevertheless, the insoluble glucan synthesis and sucrose dependent adherence were apparently more reduced as compared to soluble glucan synthesis and sucrose- independent adherence. Biofilm architecture inspected with the help of confocal and scanning electron microscopy, showed dispersion of cells in the treated group as compared to the control. The Quantitative Real Time PCR (qRT-PCR) data had shown the down regulation of the virulence genes, which is believed to be one of the major reasons responsible for the observed reduction in the virulence properties. The incredible reduction of caries development was found in treated group of rats as compared to the untreated group which further validate our in vitro data.

Conclusion

The whole study concludes a prospective role of crude extract and methanolic fraction of Z. officinale in targeting complete array of cariogenic properties of S. mutans, thus reducing its pathogenesis. Hence, it may be strongly proposed as a putative anti- cariogenic agent.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-014-0320-5) contains supplementary material, which is available to authorized users.     

The Structure of M-Gtfi,An Inhibitor of Glucosyltransferase from S. Mutans,And Its Inhibitory Relationship with Other Sulfate Ester-Containing Inhibitors

Abstract

M-GTFI, an inhibitor of glucosyltransferase from S. mutans was produced by Micromonospora narashinoensis strain No. 731. The isolation procedure for M-GTFI was improved and established for spectro-scopic analyses, and some properties of the inhibitor were investigated. The structure of M-GTFI was shown to be trisodium [2-sulphonato-9-undecenyll-oxacyclotriacont-3-en-2-one, 16, 18-his sulp-honate. The chemical structure of M-GTFI was therefore similar to that of izumenolide which is a β-lactamase inhibitor containing sulfate ester groups in its molecule.

The inhibitory characteristics of M-GTFI were parallel to that of other inhibitory compounds containing sulphate esters but the spectrum of activity was wider.     

From the mouths of babes: Dental caries in infants and children and the intensification of agriculture in mainland Southeast Asia

Many bioarchaeological studies have established a link between increased dental caries prevalence and the intensification of agriculture. However, research in Southeast Asia challenges the global application of this theory. Although often overlooked, dental health of infants and children can provide a sensitive source of information concerning health and subsistence change. This article investigates the prevalence and location of caries in the dentition of infants and children (less than 15 years of age) from eight prehistoric mainland Southeast Asian sites collectively spanning the Neolithic to late Iron Age, during which time rice agriculture became an increasingly important subsistence mode. Caries prevalence varied among the sites but there was no correlation with chronological change. The absence of evidence of a decline in dental health over time can be attributed to the relative noncariogenicity of rice and retention of broad‐spectrum subsistence strategies. No differences in caries type indicating differences in dental health were found between the sites, apart from the Iron Age site of Muang Sema. There was a higher prevalence of caries in the deciduous dentition than the permanent dentition, likely due to a cariogenic weaning diet and the higher sensitivity of deciduous teeth to decay. The level of caries in the permanent dentition suggests an increased reliance on less cariogenic foods during childhood, including rice. The absence of a temporal decline in dental health of infants and children strengthens the argument that the relationship between caries and agricultural intensification in Southeast Asia was more complex than the general model suggests. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.     

Inhibition of Streptococcus mutans biofilm accumulation and development of dental caries in vivo by 7-epiclusianone and fluoride

7-Epiclusianone (7-epi), a novel naturally occurring compound isolated from Rheedia brasiliensis, effectively inhibits the synthesis of exopolymers and biofilm formation by Streptococcus mutans. In the present study, the ability of 7-epi, alone or in combination with fluoride (F), to disrupt biofilm development and pathogenicity of S. mutans in vivo was examined using a rodent model of dental caries. Treatment (twice-daily, 60s exposure) with 7-epi, alone or in combination with 125 ppm F, resulted in biofilms with less biomass and fewer insoluble glucans than did those treated with vehicle-control, and they also displayed significant cariostatic effects in vivo (p < 0.05). The combination 7-epi + 125 ppm F was as effective as 250 ppm F (positive-control) in reducing the development of both smooth- and sulcal-caries. No histopathological alterations were observed in the animals after the experimental period. The data show that 7-epiclusianone is a novel and effective antibiofilm/anticaries agent, which may enhance the cariostatic properties of fluoride.     

Characterization of biofilm formed by multidrug resistant Pseudomonas aeruginosa DC-17 isolated from dental caries

The present work reports with the screening of biofilm-producing bacteria from the dental caries. The dental pathogens showed resistance against various antibiotics and biofilm forming ability at various levels. Among the bacterial strain, Pseudomonas aeruginosa DC-17 showed enhanced biofilm production. Extracellular polymeric substance (EPS) was synthesized by the selected bacterial isolate considerably and contributed as the major component of biofilm. EPS composed of eDNA, proteins and lipids. The total protein content of the EPS was found to be 1.928 mg/mL and was the major component than carbohydrate and DNA. Carbohydrate content was 162.3 mg/L and DNA content of EPS was 4.95 μg/mL. These macromolecules interacted in the matrix to develop dynamic and specific interactions to signalling biofilm to differentiating various environments. Also, the isolated bacteria showed resistant against various commercially available antibiotics. The isolates showed more resistance against penicillin (98%) and were sensitive against amoxicillin. Among the factors, temperature, pH and sugar concentration influenced biofilm formation. Biofilm forming ability of the selected bacterial stain was tested at various pH values and alkaline pH was favoured for biofilm production. Biofilm production was found to be maximum at 40 °C and 8% sucrose enhanced biofilm formation. Biofilm formed by P. aeruginosa DC-17 was resistant against various tested antimicrobials and chemicals.     

苹果多酚作为微生态调节剂对窝沟致龋菌调节作用的研究

目的初步探讨苹果多酚作微生态调节剂抑制变形链球菌,扶持血链球菌生长的实验研究,为龋病的防治提供一定的依据。方法采用抑菌环实验观察苹果多酚对变形链球菌和血链球菌生长的影响,检测其对变形链球菌产酸的变化,并通过扫描电镜观察对变形链球菌在玻片粘附情况的影响。结果苹果多酚能够明显抑制变形链球菌的生长,阻止其对玻片的粘附,降低其产酸能力,但对血链球菌生长没有明显的抑制作用。对变形链球菌与血链球菌的影响比较差异有统计学意义。结论苹果多酚具有调整窝沟致龋菌的作用,进一步研究很可能是一良好的窝沟菌群的微生态调节剂。     

Development of species-specific primers for detection of Streptococcus mutans in mixed bacterial samples

Streptococcus mutans is the major microbial pathogen associated with dental caries in children. The objectives of this study were to design and evaluate species-specific primers for the identification of S. mutans. Validation of the best primer set, Sm479F/R, was performed using seven S. mutans reference strains, 48 ATCC non-S. mutans strains, 92 S. mutans clinical isolates, DNA samples of S. mutans-Streptococcus sobrinus or S. mutans-Streptococcus sanguinis, and mixed bacterial DNA of saliva samples from 33 18-month-old children. All of the S. mutans samples tested positive, and no PCR products were amplified from members of the other streptococci or nonstreptococci strains examined. The lowest detection level for PCR was 10(-2) ng of S. mutans DNA (c. 4.6 x 10(3) copies) in the test samples. The results of this study suggest that the Sm479F/R primer pair is highly specific and sensitive for identification of S. mutans in either purified or mixed DNA samples.     

Dental health indicators of hunter-gatherer adaptation and cultural change in Siberia's Cis-Baikal

This investigation of the Cis-Baikal dental record focuses on health and lifestyle reconstruction of the region's mid-Holocene foragers, with particular interest in an apparent fifth millennium BC biocultural hiatus. The four cemetery populations considered represent two distinct biological and cultural groups separated by an apparent 700-year hiatus: the late Mesolithic-early Neolithic Kitoi culture (6800-4900 BC) and the middle Neolithic-early Bronze Age Serovo-Glaskovo cultural complex (4200-1000 BC). Research focuses on the frequency and severity of seven dental health indicators: enamel hypoplasia, caries, alveolar defects, periodontitis, antemortem tooth loss, dental calculus, and dental attrition. Together, these seven indicators provide a basis not only for better understanding mid-Holocene lifeways in the Cis-Baikal but also for independently assessing the relative effectiveness of the different adaptive strategies employed by pre- and posthiatus peoples. Results reveal some discrepancies between the Kitoi and Serovo-Glaskovo, specifically in their relative vulnerability to physiological stress, providing evidence to support previous interpretations of their distinct adaptive regimes (namely the narrower resource base and decreased mobility of the former). Results also suggest that some of the differences observed among the four sites may reflect geographical or environmental factors rather than simply cultural ones. However, despite these distinctions, the overriding trend appears to be one of general continuity, social equality, and good health among all mid-Holocene occupants of the Cis-Baikal, pre- and posthiatus alike.