Zingerone marginally impacts dental caries-causing oral bacteria biofilm formation

To examine the spatial distribution of dead and vital bacteria in the early formation of native dental biofilm. An experimental dental biofilm model in the oral cavity was established by enamel slabs and the spatial distribution of dead and vital bacteria in the early colonization of native dental biofilm on the enamel surface was observed by in situ real-time and dynamic observations and optical sections utilizing confocal laser scanning microscope (CLSM) and live and dead bacterial fluorescence staining technique. At the initial stage of dental biofilm formation, the structure was sparse and the percentage of dead cells reached 70% - 80% at the inner layers. In the middle layers the structure became denser than in the inner layers, which was mainly composed of vital cells (40% - 70%), and void-like structures were surrounded by vital bacteria. In the outer layers, the structure was sparse and vital cells occupied 20% - 40%. Native dental biofilms showed an uneven spatial distribution of vital and dead microorganisms. The percentage of vital microorganisms was lower adjacent to the enamel surface, increased in the z-axis towards the central parts, and decreased again towards the outer layers. The dead bacteria is an integral component in the early formation of native dental biofilm. Bacteria in the biofilms increased with time forming abundant channels.

Prevention of gingivitis is largely governed by limiting the development of oral dental plaque and biofilm formation. It is also broadly acknowledged that accumulation of microorganisms are of pivotal importance in the initiation and progression of gingivitis and associated oral diseases (Socransky, Haffajee, 2005). We propose that krill enzymes (Krillase®) as they disintegrate cell surface structures and diminish bacterial adhesion to be a novel and innovative method for prevention of gingivitis. Krillase® is isolated from the digestive tract of Antarctic krill (Euphausia superba), a shrimp like animal constituting an enormous biomass in the Antarctic convergence. The harsch ecological situation in the Antarctica implies that krill has an exceptionally effective digestive apparatus containing a co-operative multi-enzyme system involving both endoand exopeptidases. Moreover, these enzymes have much lower activation energies than those of mammalian enzymes ensuring fast and highly efficient breakdown of diverse biological substrates (Hellgren et al, 1999). The objective for the development of Krillase® has been to maintain the natural composition of krill enzymes intact throughout the purification process. Krillase® is defined as a mixture of acidic endopeptidases (trypsinand chymotrypsin-like enzymes) and exopeptidases (carboxypeptidase A and B). The final product (chewing gum) is well characterized with respect to stability, enzyme activity, uniformity and biocompability. Data from toxicology, pharmacology, preresp clinical studies give evidence for a broad safety profile. Krill enzymes, due to their unique synergistic action, have been proven to exert both quantitative and qualitative effects on dental plaque/biofilm as well as on bacterial adherence to teeth surfaces. This leads to significant decrease in plaque accumulation and reduction in occurrence of gingivitis and caries pathogenesis (Hellgren, 2009). In summary, Krillase® constitutes an important future alternative to a variety of other more toxic chemicals presently marketed for oral use including bisguanid, triclosan, aminoalcohols.

Nanocomplexes of carboxymethyl chitosan/amorphous calcium phosphate reduce oral bacteria adherence and biofilm formation on human enamel surface

Oral cavity is inhabited by more than 25,000 different bacterial phylotypes; some of them cause systemic infections in addition to dental and periodontal diseases. Emergence of multiple antibiotic resistance among these bacteria necessitates the development of alternative antimicrobial agents that are safe, stable, and relatively economic. This review focuses on the significance of metal oxide nanoparticles, especially zinc oxide and titanium dioxide nanoparticles as supplementary antimicrobials for controlling oral infections and biofilm formation. Indeed, the ZnO NPs and TiO2 NPs have exhibited significant antimicrobial activity against oral bacteria at concentrations which is not toxic in in vivo toxicity assays. These nanoparticles are being produced at an industrial scale for use in a variety of commercial products including food products. Thus, the application of ZnO and TiO2 NPs as nanoantibiotics for the development of mouthwashes, dental pastes, and other oral hygiene materials is envisaged. It is also suggested that these NPs could serve as healthier, innocuous, and effective alternative for controlling both the dental biofilms and oral planktonic bacteria with lesser side effects and antibiotic resistance.

Background: The function of Acyl homoserine Lactone (AHL) as a communication system in oral biofilm formation by oral microorganisms is essential. A complete understanding of the role of AHL in oral microflora leads to new strategies for controlling biofilms and promoting oral health. The relationship between AHL and oral biofilm formation is not fully understood. Closing this knowledge gap leads to a better understanding of how oral AHL influences the microbiota and enables the development of more effective oral healthcare strategies. Objective: To summarise the connection between AHL and oral biofilm formation, including the mechanisms involved and the impact of Quorum sensing (QS) on oral and dental health. Methods: The authors performed a comprehensive literature review utilising Google Scholar and PubMed to investigate the association between the AHL and the development of biofilms by oral microflora. Result: The research included a comprehensive overview of the existing knowledge regarding the interplay between AHL signalling and the formation of oral biofilms. Conclusion: The AHL quorum sensing system plays a fundamental function in developing and organising oral biofilms, which contribute to oral and dental diseases such as gum disease and dental caries.

α-Amylase-binding streptococci (ABS) are a heterogeneous group of commensal oral bacterial species that comprise a significant proportion of dental plaque microfloras. Salivary α-amylase, one of the most abundant proteins in human saliva, binds to the surface of these bacteria via specific surface-exposed α-amylase-binding proteins. The functional significance of α-amylase-binding proteins in oral colonization by streptococci is important for understanding how salivary components influence oral biofilm formation by these important dental plaque species. This review summarizes the results of an extensive series of studies that have sought to define the molecular basis for α-amylase binding to the surface of the bacterium as well as the biological significance of this phenomenon in dental plaque biofilm formation.

A wide range of bacterial species are harbored in the oral cavity, with the resulting complex network of interactions between the microbiome and host contributing to physiological as well as pathological conditions at both local and systemic levels. Bacterial communities inhabit the oral cavity as primary niches in a symbiotic manner and form dental biofilm in a stepwise process. However, excessive formation of biofilm in combination with a corresponding deregulated immune response leads to intra-oral diseases, such as dental caries, gingivitis, and periodontitis. Moreover, oral commensal bacteria, which are classified as so-called “pathobionts” according to a now widely accepted terminology, were recently shown to be present in extra-oral lesions with distinct bacterial species found to be involved in the onset of various pathophysiological conditions, including cancer, atherosclerosis, chronic infective endocarditis, and rheumatoid arthritis. The present review focuses on oral pathobionts as commensal and healthy members of oral biofilms that can turn into initiators of disease. We will shed light on the processes involved in dental biofilm formation and also provide an overview of the interactions of P. gingivalis, as one of the most prominent oral pathobionts, with host cells, including epithelial cells, phagocytes, and dental stem cells present in dental tissues. Notably, a previously unknown interaction of P. gingivalis bacteria with human stem cells that has impact on human immune response is discussed. In addition to this very specific interaction, the present review summarizes current knowledge regarding the immunomodulatory effect of P. gingivalis and other oral pathobionts, members of the oral microbiome, that pave the way for systemic and chronic diseases, thereby showing a link between periodontitis and rheumatoid arthritis.

Background/Objectives: The formation of oral biofilms in periodontal pockets and around dental implants with induction of periodontitis or peri-implantitis is an increasing problem in dental health. The intelligent design of a biofilm makes the bacteria embedded in the biofilm matrix highly tolerant to antiseptic therapy, often resulting in tooth or implant loss. The question therefore arises as to which mouthwashes have eradication potential against oral biofilm. Methods: A human oral biofilm model was developed based on donated blood plasma combined with buffy coats, inoculated with oral pathogenic bacterial species found in periodontal disease (Actinomyces naeslundii, Fusobacterium nucleatum, Streptococcus mitis, and Porphyromonas gingivalis). Over a span of 7 days, we tested different mouth rinsing and antiseptic solutions (Chlorhexidine, Listerine®, NaOCl, Octenisept®, and Octenident®) covering the matured biofilm with 24 h renewal. Phosphate-buffered saline (PBS) was used as a control. Bacterial growth patterns were detected via quantitative polymerase chain reaction (qPCR) after 2, 4, and 7 days of treatment. Results: While all groups showed initial bacterial reduction, the control group demonstrated strong regrowth from day 2 to 4. Listerine showed a near-significant trend toward bacterial suppression. Additionally, strain-specific efficacy was observed, with Octenisept® being most effective against Streptococcus mitis, Octenident® and NaOCl showing superior suppression of Actinomyces naeslundii, and Listerine® outperforming other solutions in reducing Fusobacterium nucleatum. Donor-specific, individual variability further influenced treatment outcomes, with distinct trends in bacterial suppression and regrowth observed across donors. Conclusions: These findings underscore the complexity of biofilm-associated infections and highlight the importance of targeted therapeutic approaches for managing bacterial biofilms. In this experiment, the donor-specific outcomes of the antimicrobial effects of the solutions may indicate that genetic predisposition/tolerance to oral infections appears to play a critical role in the control of oral biofilms.

Derivatives from Saccharomyces cerevisiae yeast including yeast extracts and yeast cell walls are sustainable sources of valuable nutrients, including dietary fibers and proteins. Previous studies have shown that certain components from these yeast derivatives can inhibit the growth of harmful intestinal bacteria and promote the growth of beneficial bacteria. However, the effects of yeast derivatives on oral health have not yet been investigated. An in vitro oral biofilm model was employed to examine the impacts of yeast derivatives on the oral microbiota and their potential benefits for maintaining oral homeostasis. The model incorporated dental plaque donor material from both healthy and periodontitis diagnosed individuals. Biofilm formation, density, and microbial composition were quantified. Additionally, the production of short-chain fatty acids in the biofilm supernatants was measured. Yeast extracts had only minor effects on oral biofilm formation. In contrast, yeast cell wall derivatives, which are rich in polysaccharides such as beta-glucans and mannans, significantly reduced the density of the oral biofilms in vitro. This reduction in biofilm density was associated with an overall shift in the bacterial community composition, including an increase in beneficial bacteria and a decrease in the abundance of Tannerella forsythia, an important species involved in bacterial coaggregation and the development and maturation of the oral biofilm. Furthermore, the yeast cell wall derivatives decreased the production of short-chain fatty acids, including acetic and butyric acid. These findings were consistent across both healthy and periodontitis microbiomes. This study has demonstrated the potential of yeast cell wall derivatives to positively impact oral health by significantly reducing biofilm density, modulating the oral microbial composition, and decreasing the production of short-chain fatty acids. The observed effects highlight the promising applications of these yeast-based compounds as an approach to managing oral diseases. Further research is needed to fully elucidate the mechanisms of action and explore the clinical potential of yeast cell wall derivatives in promoting and maintaining oral health.

Context: Dental caries is an infectious disease resulting in destruction of tooth structure by acid-forming bacteria found in dental plaque and intraoral biofilms, which are made up of mixed-species microbial communities, and their uncontrolled outgrowth can lead to oral disease. Aims: To analyze new biological materials (papain, pectin, three plant extracts and their combinations), for prevention, control, and treatment of oral bacteria and biofilm in vitro and in vivo. Methods: Papain, citric pectin, extracts of Carya illinoinensis, Quercus rubra, and Smilax glyciphylla were applied. In vitro test was performed by means of the spectrophotometric assay and CFU evaluation after treatments application. In vivo tests were performed to evaluate the number of microorganisms presented in dental biofilm: before and 1.5 h after brushing with different treatments; after 10 days of brushing with various treatments in 10 groups of patients, signing an informed consent approved by the Institutional Ethics Committee of the Autonomous University of Coahuila. Results: In vitro, the plant extracts inhibited the growth of Streptococcus sp. as well as a mixture of microorganisms that form dental biofilms. Papain activity was inhibited by plant extracts. In vivo, brushing of teeth with selected plant extracts reduced the number of bacteria in the dental plaques. Conclusions: The extracts of Quercus rubra, Carya illinoinensis and Smilax glyciphylla and papain (with or without pectin) had an inhibitory effect on the dental biofilm formation. In vitro test demonstrated the bacteriostatic effect of plant extracts or their mixture.

The formation and composition of dental plaque biofilm in vivo are important factors which influence the development of gingivitis, caries and periodontitis. Studying dental plaque biofilm in in vitro models can cause an oversimplification of the real conditions in the oral cavity. In this study, bovine enamel slabs were fixed in an individual acrylic appliance in situ to quantify dental plaque formation and composition using multiplex fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy. Each of the five oligonucleotide probes used for FISH was specific for either eubacteria or one of four frequently isolated bacterial constituents belonging to early and late colonizers of tooth surfaces. The thickness of formed biofilm increased from 14.9+/-5.0 microm after 1 day to 49.3+/-11.6 microm after 7 days. Streptococcus spp. were predominant in 1-day-old dental plaque and decreased significantly after 7 days (P=0.0061). Compared to the first day, Fusobacterium nucleatum decreased after 2 days and increased significantly after 7 days (P=0.0006). The decreases of Actinomyces naeslundii content on day 2 and day 7 were significant (P=0.0028). Changes in Veillonella spp. were not significant during the study period (P >0.05). The results showed that an in vivo observation period of 7 days was required to detect significant changes in Streptococcus spp. and F. nucleatum. The multiplex FISH used is suitable for analysing the dynamics of four important bacterial constituents in the oral biofilm in epidemiological studies.

Biofilms are subjected to many environmental pressures that can influence community structure and physiology. In the oral cavity, and many other environments, biofilms are exposed to forces generated by fluid flow; however, our understanding of how oral biofilms respond to these forces remains limited. In this study, we developed a linear rocker model of fluid flow to study the impact of shear forces on Streptococcus gordonii and dental plaque-derived multispecies biofilms. We observed that as shear forces increased, S. gordonii biofilm biomass decreased. Reduced biomass was largely independent of overall bacterial growth. Transcriptome analysis of S. gordonii biofilms exposed to moderate levels of shear stress uncovered numerous genes with differential expression under shear. We also evaluated an ex vivo plaque biofilm exposed to fluid shear forces. Like S. gordonii, the plaque biofilm displayed decreased biomass as shear forces increased. Examination of plaque community composition revealed decreased diversity and compositional changes in the plaque biofilm exposed to shear. These studies help to elucidate the impact of fluid shear on oral bacteria and may be extended to other bacterial biofilm systems.

Fusobacterium nucleatum (F. nucleatum) is an integral component of supra- and subgingival biofilms, especially more prevalent in subgingival areas during both periodontal health and disease. In this review, we explore the physical, metabolic, and genetic interactions that influence the role of F. nucleatum in the formation of mixed oral biofilms. The role of F. nucleatum in antibiotic resistance in oral biofilms was discussed and some therapeutic strategies were proposed. PubMed, Scopus, Google Scholar, and the Web of Science were extensively searched for English-language reports. F. nucleatum-derived proteins such as RadD, Fap2, FomA, and CmpA are involved in direct interactions contributing to biofilm formation, while autoinducer-2 and putrescine are involved in metabolic interactions. Both groups are essential for the formation and persistence of oral biofilms. This study highlights the clinical relevance of targeted interactions of F. nucleatum in supra- and subgingival oral biofilms. By focusing on these interactions, researchers and clinicians can develop more effective strategies to prevent biofilm-related disease and reduce the spread of antibiotic resistance. Further research in this area is warranted to explore the potential therapeutic interventions that can be derived from understanding the interactions of F. nucleatum in oral biofilm dynamics.

Pathogenic oral biofilms are now recognized as a key virulence factor in many microorganisms that cause the heavy burden of oral infectious diseases. Recently, new investigations in the nanotechnology field have propelled the development of novel biomaterials and approaches to control bacterial biofilms, either independently or in combination with other substances such as drugs, bioactive molecules, and photosensitizers used in antimicrobial photodynamic therapy (aPDT) to target different cells. Moreover, nanoparticles (NPs) showed some interesting capacity to reverse microbial dysbiosis, which is a major problem in oral biofilm formation. This review provides a perspective on oral bacterial biofilms targeted with NP-mediated treatment approaches. The first section aims to investigate the effect of NPs targeting oral bacterial biofilms. The second part of this review focuses on the application of NPs in aPDT and drug delivery systems.

To evaluate the remineralizing efficacy of fluoride in early carious lesions using a novel microbial pH-cycling model that combines the chemical pH-cycling model with dental microcosm biofilms. Artificial carious lesions were formed in 48 bovine incisors. The chemical and microbial pH-cycling models were applied to 24 specimens, respectively; the latter was applied after formation of dental microcosm biofilms for 6days, based on the human saliva inoculation. The pH-cycling schedule was repeated for 12days. All specimens were evaluated for fluorescence loss (ΔF) using quantitative light-induced fluorescence-digital before and after the pH-cycling. Specimen biofilms were further analyzed for red/green values (R/G ratios) and colony-forming units (CFUs). One-way analysis of variance and Tukey's post hoc analysis were used to analyze change in fluorescence loss (ΔΔF) according to the pH-cycling model and treatment. When the chemical pH-cycling and microbial pH-cycling models were used, ΔΔF was 1.36 (p = 0.008) and 1.17 (p > 0.05) times higher, respectively, in the fluoride-treated group than that in the distilled water-treated group. In the microbial pH-cycling model, R/G ratios and CFU counts of biofilms were not significantly different between treatments (p > 0.05). No significant difference was observed in the remineralizing efficacy of fluoride according to the presence of dental biofilms covering early carious lesions. The remineralizing efficacy of fluoride could be overestimated in the absence of dental biofilms. Therefore, for accurate evaluation of the clinical value of remineralizing agents, dental biofilms should be included in in vitro tests.