• International Journal of Oral Biology
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• v.46 no.1
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• pp.60-65
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• 2021

Dental health care workers (DHCW) are at a risk of occupational exposure to Helicobacter pylori from the aerosolized oral biofilms and saliva of patients. We designed this study to investigate the prevalence of H. pylori in the oral biofilms of a group of dental and non-dental undergraduates from Sri Lanka. After obtaining informed consent, oral biofilms were collected from 38 dental undergraduates (19 males and 19 females) undergoing clinical training and 33 non-dental undergraduates (14 males and 19 females). The participants were in the age range of 22-27 years and had healthy periodontium. Total DNA from the oral biofilms were extracted, and H. pylori DNA was detected using polymerase chain reaction (PCR) amplification of 16S rRNA gene of H. pylori using JW22-JW23 primers, and the results were confirmed using PCR amplification of H. pylori-urease specific HPU1-HPU2 primers. Out of 71 participants, 11 (28.95%) dental and 3 (9.09%) non-dental undergraduates had H. pylori in their oral biofilms indicating an overall prevalence rate of 19.72% (14/71). Thus, the prevalence of H. pylori in oral biofilms was significantly higher in dental undergraduates than in non-dental undergraduates (p < 0.05). An odds ratio of 4.07 indicated that dental undergraduates were four times more likely to harbor H. pylori in their oral biofilms than non-dental undergraduates. Foregoing data support the fact that there may be greater occupational risk of exposure to H. pylori for dental undergraduates during clinical training than that for non-dental undergraduates, warranting meticulous infection control practices during clinical dentistry.

• The korean journal of orthodontics
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• v.53 no.6
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• pp.345-357
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• 2023

Enamel demineralization represents the most prevalent complication arising from fixed orthodontic treatment. Its main etiology is the development of cariogenic biofilms formed around orthodontic appliances. Ordinarily, oral biofilms exist in a dynamic equilibrium with the host's defense mechanisms. However, the equilibrium can be disrupted by environmental changes, such as the introduction of a fixed orthodontic appliance, resulting in a shift in the biofilm's microbial composition from non-pathogenic to pathogenic. This alteration leads to an increased prevalence of cariogenic bacteria, notably mutans streptococci, within the biofilm. This article examines the relationships between oral biofilms and orthodontic appliances, with a particular focus on strategies for effectively managing oral biofilms to mitigate enamel demineralization around orthodontic appliances.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.556-560
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• 2009

Xanthorrhizol, a sesquiterpene isolated from Curcuma xanthorrhiza Roxb., was used to investigate its effect on reducing the saliva and multi-species oral biofilms consisting of Streptococcus mutans, Streptococcus sanguis, and Actinomyces viscosus by anti-biofilm and confocal laser scanning microscopy (CLSM) assays. Xanthorrhizol exhibited significant antibiofilm activity in the dose- and time-dependent manners. Exposure to 2 and $5{\mu}g/mL$ xanthorrhizol for 30 min remained <50% of saliva and multi-species biofilms formed for 24 hr. In addition, exposure to $10{\mu}g/mL$ xanthorrhizol for 30 min reduced 65 and 77% of 24 hr saliva and multi-species oral biofilms, respectively. CLSM results visually demonstrated that xanthorrhizol reduced bacterial viability in the saliva and multi-species oral biofilms. These results suggest that C. xanthorrhiza Roxb. containing xanthorrhizol with strong anti-biofilm activity can be employed as a plant source for oral care functional foods.

• Journal of Periodontal and Implant Science
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• v.44 no.2
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• pp.79-84
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• 2014

Purpose: While single-species biofilms have been studied extensively, we know notably little regarding multispecies biofilms and their interactions. The purpose of this study was to develop and evaluate an in vitro multispecies dental biofilm model that aimed to mimic the environment of chronic periodontitis. Methods: Streptococcus gordonii KN1, Fusobacterium nucleatum ATCC23726, Aggregatibacter actinomycetemcomitans ATCC33384, and Porphyromonas gingivalis ATCC33277 were used for this experiment. The biofilms were grown on 12-well plates with a round glass slip (12 mm in diameter) with a supply of fresh medium. Four different single-species biofilms and multispecies biofilms with the four bacterial strains listed above were prepared. The biofilms were examined with a confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM). The minimum inhibitory concentrations (MIC) for four different planktonic single-species and multispecies bacteria were determined. The MICs of doxycycline and chlorhexidine for four different single-species biofilms and a multispecies biofilm were also determined. Results: The CLSM and SEM examination revealed that the growth pattern of the multispecies biofilm was similar to those of single-species biofilms. However, the multispecies biofilm became thicker than the single-species biofilms, and networks between bacteria were formed. The MICs of doxycycline and chlorhexidine were higher in the biofilm state than in the planktonic bacteria. The MIC of doxycycline for the multispecies biofilm was higher than were those for the single-species biofilms of P. gingivalis, F. nucleatum, or A. actinomycetemcomitans. The MIC of chlorhexidine for the multispecies biofilm was higher than were those for the single-species biofilms of P. gingivalis or F. nucleatum. Conclusions: To mimic the natural dental biofilm, a multispecies biofilm composed of four bacterial species was grown. The 24-hour multispecies biofilm may be useful as a laboratory dental biofilm model system.

• Journal of Korean society of Dental Hygiene
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• v.23 no.4
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• pp.209-218
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• 2023

Objectives: To confirm the antibacterial effects of each mouth rinse on multiple oral biofilms in vitro. Methods: The antibacterial effects of different mouth rinses were examined by ATP and counted colony forming units (CFU). Preformed oral biofilms on saliva coated hydroxyapatite (sHA) disks were treated with essential oil and saline; then, the multiple oral biofilms were observed by Scanning electron microscope (SEM). RNA sequencing analysis was performed on total RNA isolated from old biofilms of P. intermedia ATCC 49046. Results: In the CFU measured result compared to controls, preformed multiple oral biofilms were reduced from a low of 39.0% to 95.7% (p<0.05). The size of bacterial cells changed after treatment with the essential oil, and some of the cells ruptured into small pieces of cell debris. Gene expression in P. intermedia ATCC 49046 significantly altered in RNA transcribed and protein translated genes after exposure to essential oil. Conclusions: Mouth rinse solutions with different ingredients had different antibacterial effects and may alter surface structure and gene expression as determined by RNA sequencing.

• Journal of Periodontal and Implant Science
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• v.47 no.4
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• pp.219-230
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• 2017

Purpose: The purpose of this study was to compare the characteristics of single- and dualspecies in vitro oral biofilms made by static and dynamic methods. Methods: Hydroxyapatite (HA) disks, 12.7 mm in diameter and 3 mm thick, were coated with processed saliva for 4 hours. The disks were divided into a static method group and a dynamic method group. The disks treated with a static method were cultured in 12-well plates, and the disks in the dynamic method group were cultured in a Center for Disease Control and Prevention (CDC) biofilm reactor for 72 hours. In the single- and dual-species biofilms, Fusobacterium nucleatum and Porphyromonas gingivalis were used, and the amount of adhering bacteria, proportions of species, and bacterial reduction of chlorhexidine were examined. Bacterial adhesion was examined with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Results: Compared with the biofilms made using the static method, the biofilms made using the dynamic method had significantly lower amounts of adhering and looser bacterial accumulation in SEM and CLSM images. The proportion of P. gingivalis was higher in the dynamic method group than in the static method group; however, the difference was not statistically significant. Furthermore, the biofilm thickness and bacterial reduction by chlorhexidine showed no significant differences between the 2 methods. Conclusions: When used to reproduce periodontal biofilms composed of F. nucleatum and P. gingivalis, the dynamic method (CDC biofilm reactor) formed looser biofilms containing fewer bacteria than the well plate. However, this difference did not influence the thickness of the biofilms or the activity of chlorhexidine. Therefore, both methods are useful for mimicking periodontitis-associated oral biofilms.

• International Journal of Oral Biology
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• v.35 no.4
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• pp.197-202
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• 2010

Most oral microorganisms exist as biofilms which initiate formation via the attachment of an early colonizer to host proteins on the tooth surface. Fusobacterium nucleatum act as a bridge between early and late colonizers. Dental biofilms eventually comprise dental pathogens such as Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia. To evaluate the effects of mutual interactions between oral bacteria on the growth of biofilms, periodontopathogens were co-cultured with a $0.4\;{\mu}m$ barrier. Streptococcus gordonii inhibited the growth of F. nucleatum and periodontopathogens. However, F. nucleatum, P. gingivalis and T. denticola activated the growth of other bacteria. A co-culture system of early and late colonizers could be a useful tool to further understand bacterial interactions during the development of dental biofilm.

• Journal of Korean Academy of Oral Health
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• v.43 no.3
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• pp.118-123
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• 2019

Objectives: The purpose of this study was to investigate changes in the composition of artificial cariogenic biofilms using a Streptococcus mutans biofilm model over a period of time. Methods: We analyzed the dry weight, colony forming unit (CFU) number, extracellular polysaccharide (EPS) biovolume, and acid production rate of S. mutans biofilms formed on saliva-coated hydroxyapatite discs after 26 h, 50 h, 74 h, 98 h, 171 h, and 195 h. In addition, we performed a laser scanning confocal fluorescence microscopy to determine the bacterial volume, EPS biovolume, and biofilm thickness. We calculated the biofilm density using dry weight and EPS biovolume. Results: Over a period of time, there was no change in the CFU number and acid production rate of S. mutans biofilms, but there was an increase in the dry weight and EPS biovolume of S. mutans biofilms. The bacterial volume, EPS biovolume, and biofilm thickness only increased in the 50-h-old biofilm; however, no change was observed in 50-195-h-old biofilms. In addition, an increase in the biofilm density was observed over time. Conclusions: These results suggest that the acid production ability of cariogenic biofilms does not change, but the biofilm density increases over time. However, due to scientific information, further research needs to be conducted in the field of dentistry to get further insights on the progression of cariogenic biofilms over time.

• Journal of Life Science
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• v.31 no.1
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• pp.100-108
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• 2021

In the oral cavity, there are hundreds of microbial species that exist as planktonic cells or are incorporated into biofilms. The accumulation and proliferation of pathogenic bacteria in the oral biofilm can lead to caries and periodontitis, which are typical oral diseases. The oral bacteria in the biofilm not only can resist environmental stress inside the oral cavity, but also have a 1,000 times higher resistance to antibiotics than planktonic cells by genes exchange through the interaction between cells in the oral biofilm. Therefore, if the formation of oral biofilm is suppressed or removed, oral diseases caused by bacterial infection can be more effectively prevented or treated. In particular, since oral biofilms have the characteristic of forming a biofilm by gathering several bacteria, quorum sensing, a signaling system between cells, can be a target for controlling the oral biofilm. In addition, a method of inhibiting biofilm formation by using arginine, an alkali-producing substrate of oral bacteria, is used to convert the distribution of oral microorganisms into an environment similar to that of healthy teeth or inhibit the secretion of glucosyltransferase by S. mutans to inhibit the formation of non-soluble glucans. It can be a target to control oral biofilm. This method of inhibiting or removing the oral biofilm formation rather than inducing the death of pathogenic bacteria in the oral cavity will be a new strategy that can selectively prevent or therapeutic avenues for oral diseases including dental caries.