Dental Biofilm Research Articles

The effect of bovine trypsin on dental biofilm dispersion: an in vitro study.

To investigate the degradation effect of bovine trypsin on multispecies biofilm of caries-related bacteria and provide an experimental foundation for the prevention of dental caries. Standard strains of S. mutans, S. sanguis, S. gordonii, and L. acidophilus were co-cultured to form 24h, 48h, and 72h biofilms. The experimental groups were treated with bovine trypsin for 30s, 1min, and 3min. Morphological observation and quantitative analysis of extracellular polymeric substances (EPS), live bacteria, and dead bacteria were conducted using the confocal laser scanning microscope (CLSM). The morphological changes of EPS and bacteria were also observed using a scanning electron microscope (SEM). When biofilm was treated for 1 min, the minimal inhibitory concentration (MIC) of bovine trypsin to reduce EPS was 0.5mg/mL in 24h and 48h biofilms, and the MIC of bovine trypsin was 2.5mg/mL in 72h biofilms (P < 0.05). When biofilm was treated for 3min, the MIC of bovine trypsin to reduce EPS was 0.25mg/mL in 24h and 48h biofilms, the MIC of bovine trypsin was 1mg/mL in 72h biofilm (P < 0.05). The ratio of live-to-dead bacteria in the treatment group was significantly lower than blank group in 24h, 48h, and 72h multispecies biofilms (P < 0.05). Bovine trypsin can destroy multispecies biofilm structure, disperse biofilm and bacteria flora, and reduce the EPS and bacterial biomass in vitro, which are positively correlated with the application time and concentration.

Subgingival Use of Air-Polishing Powders: Status of Knowledge: A Systematic Review.

Effective subgingival biofilm removal is crucial for achieving positive and stable outcomes in periodontal therapy, forming an indispensable part of any periodontal treatment approach. The development of air-polishing tools has emerged as a promising alternative to hand and ultrasonic scalers for dental biofilm removal. The objective of this systematic review was to assess existing literature regarding the subgingival use of various types of air-polishing powders, as an effective method of subgingival biofilm control. For this, 55 articles on this subjected were sourced from searched databases and subjected to an evaluation process of their contained information, which was subsequently structured and compiled into this manuscript. The existing literature acknowledges that good subgingival biofilm control is essential for the success of periodontal therapy, including through subgingival air-polishing, as an adjunctive procedure. This approach has the potential to enhance patient comfort during and after subgingival mechanical plaque removal, thereby mitigating damage to periodontal structures. Consequently, it may lead to improved healing capabilities within the periodontal tissues and the formation of a more stable reparative gingival junctional epithelium.

Hub genes and pathways related to caries-free dental biofilm: clinical metatranscriptomic study.

This study aimed to evaluate the microbial functional profile of biofilms related to caries-free (CF, n = 6) and caries-arrested (CI, n = 3) compared to caries-active (CA, n = 5) individuals. A metatranscriptomic was performed in supragingival biofilm from different clinical conditions related to caries or health. Total RNA was extracted and cDNAs were obtained and sequenced (Illumina HiSeq3000). Trimmed data (SortMeRNA) were submitted to the SqueezeMeta pipeline in the co-assembly mode for functional analysis and further differential gene expression analysis (DESeq2) and weighted gene co-expression network analysis (WCGNA) to explore and identify gene modules related to these clinical conditions. A total of 5303 genes were found in the metatranscriptomic analysis. A co-expression network identified the most relevant modules strongly related to specific caries status. Correlation coefficients were calculated between the eigengene modules and the clinical conditions (CA, CI, and CF) discriminating multiple modules. CA and CI showed weak correlation coefficient strength across the modules, while the CF condition presented a very strong positive correlation coefficient (r = 0.9, p value = 4 × 10-9). Pearson's test was applied to further analyze the module membership and gene significance in CF conditions, and the most relevant were HSPA1s-K03283, Epr- K13277, and SLC1A-K05613. Gene Ontology (GO) shows important bioprocesses, such as two-component system, fructose and mannose metabolism, pentose and glucuronate interconversions, and flagellar assembly (p-adjust < 0.05). The ability to use different carbohydrates, integrate multiple signals, swarm, and bacteriocin production are significant metabolic advantages in the oral environment related to CF. A distinct functional health profile could be found in CF, where co-occurring genes can act in different pathways at the same time. Genes HSPA1s, Epr, and SLC1A may be appointed as potential biomarkers for caries-free biofilms. Potential biomarkers for caries-free biofilms could contribute to the knowledge of caries prevention and control.

AETIOLOGICAL CHARACTERISTICS OF DENTAL IMPLANT FAILURE

Dental implant placement is a predictable and widely used procedure in modern dentistry. Nevertheless, several factors can negatively affect the functioning and duration of implant restoration. Considering the significant data supporting the role of the microbial factor in the development of tissue inflammation around the prosthesis, the purpose of this review was to investigate the etiological structure of implant loss from a microbiological point of view. Materials and methods. We conducted a comprehensive content analysis of scientific publications available in the PubMed/MEDLINE and Google Scholar databases. Results and discussion. Six groups of microorganisms are known as potential contributor to the dental biofilm. These groups are designated by a specific color – yellow, green, purple, orange and red. The orange and red groups include pathogens of periodontal inflammation, and also play a significant role in the development of peri-implant (PI) inflammation. Implants and teeth share histopathological and ecological similarities, thus, we can suggest that the microbial communities around these structures are similar. In the studies, the composition of the PI-associated complex of microorganisms including Porphyromonas gingivalis, Porphyromonas endodontalis, Tannerella forsythia, Filifactor alocis, Fretibacterium fastidiosum, Desulfobulbus spp. and Treponema lecithinolyticum was decsribed. It has been reported that the PI microbiome is specific to the site where an implant is placed, and the microbial composition of the biofilm of the contralateral healthy sites is more similar to the spectrum of healthy prostheses, including other subjects, than those from the same oral cavity. We can suggest that the changes in the implant microbiocenosis are dynamic. Several studies have shown the long-term consequences of dental implant restoration that can include the modification of the microbiome consisting in the progressive increase of P. gingivalis, T. forsythia, A. actinomycetemcomitans and Prevotella intermedia within 3-6 months following the procedure of implant placement. There is also an opinion about the peculiarities of the biofilm microbiota of the peri-implant tissues in case of early and late loss of the dental prosthesis. Bacteria are an important component of the microbiocenosis in any ecological niche, but the role of archaea is often overlooked. Methanogenic archaea, and Methanobrevibacter oralis are components of the normal oral microbiome, but their considerable prevalence may also be associated with peri-implant tissue inflammation. Conclusions. We have elucidated the complex nature of microbial communities within peri-implant sites and established an association between peri-implant diseases and the dysbiosis of subgingival microbial communities. Our study underscores the pivotal role of microbiota in peri-implant diseases.

The Role of Probiotic in Oral Biofilm

Dental plaque, a biofilm composed of various bacterial colonies, exists on the tooth surface. The balance of the surrounding environment is disrupted through a change in the composition of the bacterial community when homestasis of dental plaque is disrupted. Probiotics refers to microorganisms that confer health benefits to hosts when administered in adequate amounts. Probiotics can release bioactive substances that can inhibit the growth and biofilm formation of pathogenic microorganisms such as Streptococcus mutans. Probiotics ability to integrate into dental biofilm is not yet clarified. The aim of this trial was to detect probiotic bacteria from probiotics in dental biofilm and saliva during and after intake. The article was conducted of PubMed database and were limited to period January 2019 to November 2023 with combination of the following keywords: “role” and “probiotic” and “oral” and “biofilm”. The results obtained were 41 articles found at the beginning of the search in pubmed databases, and the 7 full text articles were selected for further review and discussion The potential inhibitory activity probiotic strains on the growth of S. mutans were Lactococcus lactis, L. salivarius, Lactobacillus fermentum, Lactobacillus casei, Lactobacillus plantarum, and Lactobacillus reuteri. The other probiotic, W. cibaria and B. lactis HN019 are a beneficial oral probiotic that improves oral health. The mechanism of action of probiotics in oral health is an imbalance in the composition of the microbiota, known as dysbiosis. This dysbiosis is associated with increased permeability and disruption of the epithelial barrier, leading to inflammation and chronic inflammatory pathologies.

Relationship between cariogenic bacteria and molar incisor hypomineralization in Brazilian schoolchildren.

Teeth with defects in their structure, such as the ones affected by molar-incisor hypomineralization (MIH), are more susceptible to carious lesions. Caries is a complex and multifactorial disease highly prevalent in childhood. The present research evaluated the relationship between the stages of MIH and cariogenic bacteria in children. After examining 566 schoolchildren, four groups of 10 children each were formed: healthy (G1), mild MIH (G2 and G3), and severe MIH + caries (G4). Dental biofilm was assessed to quantify Streptococcus mutans (SM) and Lactobacillus spp. (LB) using real-time polymerase chain reaction (RT-PCR). LB counting in biofilm samples of healthy children (G1) and those with mild MIH characterized by white opacities (G2) were not significantly different. The same happened when the ones with yellow opacities (G3) were compared with severe MIH + caries (G4) (P>0.05). The post hoc Tukey test proved that G4 had greater levels of SM and LB when compared with G2 (P<0.05); however, the control group did not diverge from the others considering SM (P>0.05). Increased LB enhanced the severity of MIH [rate ratio (RR): 7.706; P=0.035]. LB was influenced by different degrees of MIH and the presence of caries and could guide clinical decisions and patients' recommendations to prevent carious lesions in MIH children.

Recombinant Prevotella melaninogenica α-1,3 glucanase and Capnocytophaga ochracea α-1,6 glucanase as enzymatic tools for in vitro degradation of S. mutans biofilms.

Dental biofilms represent a serious oral health problem playing a key role in the development of caries and other oral diseases. In the present work, we cloned and expressed in E. coli two glucanases, Prevotella melaninogenica mutanase (PmGH87) and Capnocytophaga ochracea dextranase (CoGH66), and characterized them biochemically and biophysically. Their three-dimensional structures were elucidated and discussed. Furthermore, we tested the capacity of the enzymes to hydrolyze mutan and dextran to prevent formation of Streptococcus mutans biofilms, as well as to degrade pre- formed biofilms in low and abundant sugar conditions. The percentage of residual biofilm was calculated for each treatment group in relation to the control, as well as the degree of synergism. Our results suggest that both PmGH87 and CoGH66 are capable of inhibiting biofilm formation grown under limited or abundant sucrose conditions. Degradation of pre-formed biofilms experiments reveal a time-dependent effect for the treatment with each enzyme alone. In addition, a synergistic and dose-dependent effects of the combined enzymatic treatment with the enzymes were observed. For instance, the highest biomass degradation was 95.5% after 30min treatment for the biofilm grown in low sucrose concentration, and 93.8% after 2h treatment for the biofilm grown in sugar abundant condition. Strong synergistic effects were observed, with calculated degree of synergism of 5.54 and 3.18, respectively and their structural basis was discussed. Jointly, these data can pave the ground for the development of biomedical applications of the enzymes for controlling growth and promoting degradation of established oral biofilms.

Evaluation of compressive strength, surface microhardness, solubility and antimicrobial effect of glass ionomer dental cement reinforced with silver doped carbon nanotube fillers

BackgroundConventional glass ionomer cements (GICs) are currently the most widely used dental cements due to their chemical bonding into tooth structure, release of fluoride, and ease of manipulation and usage. One of their drawbacks is their low mechanical properties and high solubility. Carbon nanotubes (CNTs) could be utilized in dentistry due to their several potential applications. CNTs can be used as fillers to reinforce polymers or other materials. Additionally, silver (Ag) nanoparticles are highly effective at preventing dental biofilm and enhancing mechanical properties.ObjectivesThe aim of the present in vitro study is to evaluate the compressive strength, surface microhardness, solubility, and antimicrobial effect of the conventional GIC reinforced with manual blending of 0.01 wt.% Ag doped CNT fillers.MethodsThe control group was prepared by mixing dental GIC powder with their liquid. The innovatively reinforced dental GIC group was prepared by incorporating 0.01 wt.% Ag doped CNT fillers into the GIC powder prior to liquid mixing. Chemical characterization was performed by XRF. While, physical characterization was done by measuring film thickness and initial setting time.The compressive strength, surface microhardness, solubility, and antimicrobial effect against Streptococcus mutans bacteria using an agar diffusion test were measured. The data was statistically analyzed using independent sample t-tests to compare mean values of compressive strength, surface microhardness, solubility, and antimicrobial activity (p ≤ 0.05).ResultsThe results revealed that innovative reinforced GIC with 0.01 wt.% Ag doped CNT fillers showed higher mean compressive strength, surface microhardness, and antimicrobial effect values than the conventional GIC control group; there was no significant difference between different groups in relation to the solubility test (P ≤ 0.05).ConclusionThe innovatively reinforced GIC with 0.01 wt.% Ag doped CNT fillers had the opportunity to be used as an alternative to conventional GIC dental cements.

A Review of Bacterial Colonization on Dental Implants With Various Hygiene Instruments.

Peri-implant diseases can still develop despite oral hygiene practices being maintained. Consequently, regular debridement must be carried out to ensure the implant is sustained. This review evaluated bacterial colonization on implants following the use of different hygiene instruments. A literature search was conducted in PubMed, ScienceDirect, and Scopus databases for articles published from 2012 to 2022. A total of 19 full-text papers were selected. The number of bacteria colonized was most commonly evaluated with a scanning electron microscope (SEM) or by colony-forming unit (CFU) counts, crystal violet assays, plaque index, probing depth, bleeding on probing, turbidity test, and live-dead assays. Rubber cup polishing with an abrasive paste showed a significantly greater reduction in biofilm formation compared with air abrasion with glycine powder, while the air abrasion treatment was found to be more efficient than piezoelectric, carbon, and stainless steel scalers. Surface treatment with Er, Cr: YSGG laser, and Er: YAG laser resulted in statistically significant superior dental biofilm removal compared with titanium curettes and photodynamic therapy. Air abrasion, plastic curette, titanium curette, and ultrasonic scaler showed no significant differences in bacterial colonization, but air abrasion and plastic curette were safer for zirconia implant decontamination. Furthermore, the titanium brush showed better results in decontaminating the implant surface than the Er: YAG laser. Although no single instrument or method could be considered as offering a gold standard in treating peri-implant diseases, the use of air abrasion with glycine powder, laser therapies, rubber cup polishing with an abrasive paste, and a titanium brush had high levels of cleaning efficacy and acceptance by patients.

Effectiveness of Mouthwashes in Managing Oral Diseases and Conditions: Do They Have a Role?

Antimicrobial mouthwashes are considered to reduce dental plaque biofilm and thus the potential to prevent plaque-induced oral diseases, particularly periodontal diseases. The effectiveness of mouthwashes relates to this antiplaque role, as well as, their tooth-whitening potential and ability to mask/mange malodour (halitosis). There is also a growing interest in the use of mouthwashes as an adjunctive measure in post surgical and post-dental care, while the COVID-19 pandemic has given a new lease of life to mouthwashes as an oral antispetic that may be useful in reducing the oral viral load. The mode of action of mouthwashes varies, depending on their active ingredients, concentrations, and mode and frequency of use, as does their potential effectiveness. This article aims to provide a narrative overview of the evidence of the effectiveness of the most widely used mouthwashes in managing oral diseases, oral conditions, and adjunctive care roles.

Synergistic metabolism of salivary MUC5B in oral commensal bacteria during early biofilm formation.

Bacterial metabolism in oral biofilms is comprised of complex networks of nutritional chains and biochemical regulations. These processes involve both intraspecies and interspecies networks as well as interactions with components from host saliva, gingival crevicular fluid, and dietary intake. In a previous paper, a large salivary glycoprotein, mucin MUC5B, was suggested to promote a dental health-related phenotype in the oral type strain of Streptococcus gordonii DL1, by regulating bacterial adhesion and protein expression. In this study, nuclear magnetic resonance-based metabolomics was used to examine the effects on the metabolic output of monospecies compared to dual species early biofilms of two clinical strains of oral commensal bacteria, S. gordonii and Actinomyces naeslundii, in the presence of MUC5B. The presence of S. gordonii increased colonization of A. naeslundii on salivary MUC5B, and both commensals were able to utilize MUC5B as a sole nutrient source during early biofilm formation. The metabolomes suggested that the bacteria were able to release mucin carbohydrates from oligosaccharide side chains as well as amino acids from the protein core. Synergistic effects were also seen in the dual species biofilm metabolome compared to the monospecies, indicating that A. naeslundii and S. gordonii cooperated in the degradation of salivary MUC5B. A better understanding of bacterial interactions and salivary-mediated regulation of early dental biofilm activity is meaningful for understanding oral biofilm physiology and may contribute to the development of future prevention strategies for biofilm-induced oral disease.IMPORTANCEThe study of bacterial interactions and salivary-mediated regulation of early dental biofilm activity is of interest for understanding oral microbial adaptation to environmental cues and biofilm maturation. Findings in oral commensals can prove useful from the perspectives of both oral and systemic health of the host, as well as the understanding of general microbial biofilm physiology. The knowledge may provide a basis for the development of prognostic biomarkers, or development of new treatment strategies, related to oral health and disease and possibly also to other biofilm-induced conditions. The study is also an important step toward developing the methodology for similar studies in other species and/or growth conditions.

Changes in Dental Biofilm Proteins' Secondary Structure in Groups of People with Different Cariogenic Situations in the Oral Cavity and Using Medications by Means of Synchrotron FTIR-Microspectroscopy.

This work unveils the idea that the cariogenic status of the oral cavity (the presence of active caries lesions) can be predicted via a lineshape analysis of the infrared spectral signatures of the secondary structure of proteins in dental biofilms. These spectral signatures that work as natural markers also show strong sensitivity to the application in patients of a so-called modulator-a medicinal agent (a pelleted mineral complex with calcium glycerophosphate). For the first time, according to our knowledge, in terms of deconvolution of the complete spectral profile of the amide I and amide II bands, significant intra- and intergroup differences were determined in the secondary structure of proteins in the dental biofilm of patients with a healthy oral cavity and with a carious pathology. This allowed to conduct a mathematical assessment of the spectral shifts in proteins' secondary structure in connection with the cariogenic situation in the oral cavity and with an external modulation. It was shown that only for the component parallel β-strands in the amide profile of the biofilm, a statistically significant (p < 0.05) change in its percentage weight (composition) was registered in a cariogenic situation (presence of active caries lesions). Note that no significant differences were detected in a normal situation (control) and in the presence of a carious pathology before and after the application of the modulator. The change in the frequency and percentage weight of parallel β-strands in the spectra of dental biofilms proved to be the result of the presence of cariogenic mutans streptococci in the film as well as of the products of their metabolism-glucan polymers. We foresee that the results presented here can inherently provide the basis for the infrared spectral diagnosis of changes (shifts) in the oral microbiome driven by the development of the carious process in the oral cavity as well as for the choice of optimal therapeutic treatments of caries based on microbiome-directed prevention measures.

Dextranase enzyme and Enterococcus faecium probiotic have anti-biofilm effects by reducing the count of bacteria in dental plaque in the oral cavity of dogs.

Periodontal disease is a common clinical complication and has a negative impact on the quality of life and the welfare of companion dogs. Periodontal disease occurs when pathogenic bacteria are accumulated in the gingival sulcus, which favors biofilm formation. The oral health of dogs can be significantly compromised by dental plaque accumulation. Thus, this investigation demonstrates the effect of Enterococcus faecium probiotic, dextranase enzyme, and their combination on dental biofilm in the oral cavity of dogs. The 30 dogs were referred to Polyclinic with no oral ulcers, severe periodontitis, and internal diseases. Dextranase enzyme, E faecium probiotic, and their combination were administered in the oral cavity of dogs. Microbiological samples were obtained from tooth surfaces and gums before and after intervention with the substances. Bacterial colonies were enumerated by using a colony counter. Also, Porphyromonas gingivalis hmuY gene expression was evaluated by reverse transcription quantitative real-time PCR analysis. The total colony count of the bacterial culture indicated that the dextranase enzyme, E faecium probiotic, and their combination significantly reduced the total bacteria count in the oral cavity. Moreover, in the reverse transcription quantitative real-time PCR analysis it was observed that using the combination of E faecium probiotic and dextranase enzyme decreases the hmuY gene expression of P gingivalis bacteria. The results clearly indicated that the dextranase enzyme and E faecium probiotic could be used as preventive agents to reduce oral biofilm in dogs. Furthermore, no side effects were observed while using these substances.

Synergistic Antibiofilm Action of Cinnamomum verum and Brazilian Green Propolis Hydroethanolic Extracts against Multidrug-Resistant Strains of Acinetobacter baumannii and Pseudomonas aeruginosa and Their Biocompatibility on Human Keratinocytes.

The accumulated dental biofilm can be a source of oral bacteria that are aspirated into the lower respiratory tract causing ventilator-associated pneumonia in hospitalized patients. The aim of this study was to evaluate the synergistic antibiofilm action of the produced and phytochemically characterized extracts of Cinnamomum verum and Brazilian green propolis (BGP) hydroethanolic extracts against multidrug-resistant clinical strains of Acinetobacter baumannii and Pseudomonas aeruginosa, in addition to their biocompatibility on human keratinocyte cell lines (HaCaT). For this, High-performance liquid chromatography analysis of the plant extracts was performed; then the minimum inhibitory and minimum bactericidal concentrations of the extracts were determined; and antibiofilm activity was evaluated with MTT assay to prevent biofilm formation and to reduce the mature biofilms. The cytotoxicity of the extracts was verified using the MTT colorimetric test, evaluating the cellular enzymatic activity. The data were analyzed with one-way ANOVA and Tukey's tests as well as Kruskal-Wallis and Dunn's tests, considering a significance level of 5%. It was possible to identify the cinnamic aldehyde in C. verum and p-coumaric, caffeic, and caffeoylquinic acids as well as flavonoids such as kaempferol and kaempferide and Artepillin-C in BGP. The combined extracts were effective in preventing biofilm formation and reducing the mature biofilms of A. baumannii and P. aeruginosa. Moreover, both extracts were biocompatible in different concentrations. Therefore, C. verum and BGP hydroethanolic extracts have bactericidal and antibiofilm action against multidrug resistant strains of A. baumannii and P. aeruginosa. In addition, the combined extracts were capable of expressively inhibiting the formation of A. baumannii and P. aeruginosa biofilms (prophylactic effect) acting similarly to 0.12% chlorhexidine gluconate.

An In Vitro Evaluation of the Antibacterial Efficacy of Solanum xanthocarpum Extracts on Bacteria From Dental Plaque Biofilm.

The focus of research has recently shifted toward developing herbal-based medicines due to the emerging bacterial resistance and side effects of antibiotics. Solanum xanthocarpum (Sx) is a medicinal plant with potent pharmacological properties. This study aimed to evaluate the antibacterial activity of its crude extracts on bacteria isolated from dental plaque in patients with gingivitis. Aqueous, ethyl acetate, hexane, chloroform, and ethanolic extracts were prepared from Sx. Dental plaque samples were collected from patients with plaque-induced gingivitis. Disk diffusion assay was performed to determine the antibacterial activity of the extracts at concentrations of 25 mg/ml, 50 mg/ml, and 75 mg/ml with ampicillin 200 mg/ml as a positive control. The minimum inhibitory concentration (MIC) of the aqueous extract was also evaluated by broth dilution test against bacteria isolated from dental plaque biofilm. The antibacterial activity was estimated by measuring the zones of inhibition through the disc diffusion method. The Kruskal Wallis with Dunn post hoc test performed for intergroup comparison between the various extracts showed a statistically significant difference in inhibition of bacterial growth between 25 mg/ml and 75 mg/ml concentrations. There was no significant difference between the 75 mg/ml Sx concentration and the positive control. In addition, the MIC was elucidated to be 0.625 g/ml, at which there was maximum inhibition of bacterial growth. The Sx extract exhibited antibacterial activity against periodontal pathogens. Thus, it can be concluded that optimum concentrations of Sx could be used in therapeutic strategies to prevent and manage periodontal diseases.

Co-occurrence of periodontal lesions and dental wear in incisor and masticatory teeth in two sheep flocks in Brazil.

Periodontitis and tooth wear are multifactorial diseases with distinct etiopathogenesis that affect the health, feed efficiency and welfare of sheep. This study evaluated the co-occurrence of tooth wear and periodontal lesions in 129 ewes from two Brazilian flocks, clinically classified the lesions and presence of dental calculus, and identified potential pathogens in the dental biofilm of 63 ewes by polymerase chain reaction. Of the 129 ewes included in the study, 75 presented periodontal lesions, while all animals presented tooth wear and dental calculus. Of the animals with periodontal lesions, 16.2% had lesions in incisor teeth and 52.7% in masticatory teeth. Regarding excessive tooth wear, 38.6% had severe wear on the incisor teeth and 89.1% on the masticatory teeth. Ewes older than 36 months had a higher frequency of periodontal lesions in incisor teeth (p<0.001) and a greater amount of dental calculus (p < 0.001), but there was no association between tooth wear and animal age. Fusobacterium nucleatum, Tannerella forsythia and Fusobacterium necrophorum predominated in periodontal lesions. This study is limited by the small sample size and lackof diagnostic imaging to assess periodontal disease. The co-occurrence of periodontal lesions and excessive dental wear involving both the incisor and masticatory teeth suggests that although the two diseases have different aetiologies, they likely have common risk factors.

Determinants of Microscale pH in In Situ-Grown Dental Biofilms.

Dental biofilm pH is the most important determinant of virulence for the development of caries lesions. Confocal microscopy-based pH ratiometry allows monitoring biofilm pH with high spatial resolution. Experiments performed on simplified biofilm models under static conditions identified steep pH gradients as well as localized acidogenic foci that promote enamel demineralization. The present work used pH ratiometry to perform a comprehensive analysis of the effect of whole saliva flow on the microscale pH in complex, in situ-grown 48-h and 96-h biofilms (n = 54) from 9 healthy participants. pH was monitored in 12 areas at the biofilm bottom and top, and saliva flow with film thicknesses corresponding to those in the oral cavity was provided by an additively manufactured microfluidic flow cell. Biofilm pH was correlated to the bacterial composition, as determined by 16S rRNA gene sequencing. Biofilm acidogenicity varied considerably between participants and individual biofilms but also between different areas inside one biofilm, with pH gradients of up to 2 units. pH drops were more pronounced in 96-h than in 48-h biofilms (P = 0.0121) and virtually unaffected by unstimulated saliva flow (0.8 mm/min). Stimulated flow (8 mm/min) raised average biofilm pH to near-neutral values but it did not equilibrate vertical and horizontal pH gradients in the biofilms. pH was significantly lower at the biofilm base than at the top (P < 0.0001) and lower downstream than upstream (P = 0.0046), due to an accumulation of acids along the flow path. pH drops were positively correlated with biofilm thickness and negatively with the thickness of the saliva film covering the biofilm. Bacterial community composition was significantly different between biofilms with strong and weak pH responses but not their species richness. The present experimental study demonstrates that stimulated saliva flow, saliva film thickness, biofilm age, biofilm thickness, and bacterial composition are important modulators of microscale pH in dental biofilms.

Biological Properties and Antimicrobial Potential of Cocoa and Its Effects on Systemic and Oral Health.

Cocoa is considered a functional food because it is a natural source of macro- and micronutrients. Thus, cocoa is rich in vitamins, minerals, fiber, fatty acids, methylxanthines and flavonoids. In addition to favoring the metabolism of lipids and carbohydrates, the bioactive components of cocoa can have an antioxidant, anti-inflammatory and antimicrobial effect, providing numerous benefits for health. This literature review presents an overview of the effects of cocoa, fruit of the Theobroma cacao tree, on systemic and oral health. Several studies report that cocoa intake may contribute to the prevention of cardiovascular, neurodegenerative, immunological, inflammatory, metabolic and bone diseases, in addition to reducing the risk of vascular alterations and cognitive dysfunctions. On oral health, in vitro studies have shown that cocoa extract exerted an inhibitory effect on the growth, adherence and metabolism of cariogenic and periodontopathogenic bacteria, also inhibiting acid production, glycosyltransferase enzyme activity and the synthesis of insoluble polysaccharides. Additionally, administration of cocoa extract reduced biofilm accumulation and caries development in animals infected with cariogenic species. Clinical studies also reported that the use of mouthwashes containing cocoa extract reduced Streptococcus mutans counts in saliva and dental biofilm formation. In short, these studies highlight the nutritional value of cocoa, considering its clinical applicability, stability and economic accessibility.

Efficient Removal of Dental Plaque Biofilm from Training Typodont Teeth via Water Flosser.

Plaque biofilms play critical roles in the development of dental caries. Mechanical plaque control methods are considered to be most effective for plaque removal, such as brushing teeth or using flosser. Recently, water flosser has been paid much attention. Here, we tested the ability of a water flosser to remove the adhered sucrose and the dental plaque biofilms formed by Streptococcus mutans, Streptococcus sanguinis, and Actinobacillus viscosus. We found that the residual sucrose concentration was 3.54 mg/mL in the control group, 1.75 mg/mL in the syringe group (simulating the ordinary mouthwash), and 0 mg/mL in water flosser group. In addition, the residual bacterial concentration was 3.6 × 108 CFU/mL in the control group, 1.6 × 107 CFU/mL in the syringe group, and only 5.5 × 105 CFU/mL in the water flosser group. In summary, water flosser is effective for cleaning the teeth, which may have significant potential in preventing dental caries and maintaining oral health.

Evaluation of a protocol to assess a novel artificial biofilm equivalent for dentures-A prospective clinical pilot study.

This pilot study aimed to carry out preliminary tests of the removability of an artificial biofilm equivalent (ABE) and to verify the reproducibility of the ABE testing protocol for a planned main study. There is a lack of data to develop suitable artificial biofilm substitutes, which may be helpful to perform denture hygiene education and to carry out in vitro examinations of oral hygiene products. This single-group, prospective, longitudinal, interventional pilot study was conducted in Dresden (Germany) from February until December 2020. Participants were recruited who wore fully functional upper complete dentures. Denture biofilm was grown on acrylic specimens by wearing dentures for 12 h and 36 h using intraoral appliances. Acrylic specimens were coated with ABEs of three compositions: chitosan (ChS) 0.3 g, methylcellulose (MC) 1.7 g; ChS 0.2 g, MC 1.8 g; ChS 0.1 g, MC 1.9 g (labelled 1.7MC, 1.8MC and 1.9MC, respectively). All specimens underwent standardised mechanical brushing. The percentages of remaining biofilm (POB) were measured. Thirty-one participants were prescreened, and eight (26%) were included. The appliances were well tolerated, and biofilm was collected. ABE was prepared and brushed as planned. Three and six brushing strokes were needed to remove 12-h and 36-h natural denture biofilm, respectively. Correspondingly, three brushing strokes were needed to remove 1.9MC ABE and six brushing strokes to remove 1.8MC and 1.7MC ABE. A reproducibility of ABE removal was indicated. The removability of ABE and the ABE testing protocol were feasible and reproducible for conducting the future main study.