Oral ulceration (Part 1).

Ulceration is probably the oral mucosal condition seen most frequently by general dental practitioners. It is almost always painful and therefore sufferers are prompt to seek advice. An important exception to this generalisation is the occurrence of oral squamous cell carcinoma, which is often painless in its early stages. Definitive diagnosis, which requires mucosal biopsy, is mandatory for any persistent area of oral ulceration.

Droplet Sizes Emitted from Demonstration Electric Toothbrushes.

The COVID-19 pandemic has drawn attention to microbial transmission risk via aerosols in dental practice. Demonstration electric toothbrushes are used intra-orally for education. The aim of this investigation was to measure the size of droplets emitted by the brush head of two demonstration oscillating-rotating electric toothbrushes. Measurement of droplet production and size was recorded in vitro using three methods: (1) Malvern Spraytec (LASER particle size measurement device with detectable particle size of 0.1-2500 µm) and brushes mounted on a 3D-printed, two-shell form-fit fixture with a supply of tap water; (2) a DustTrak aerosol measurement device and toothpaste slurry, with brushing simulated in the oral cavity of a phantom head; (3) high-speed visualization in a simulated-use situation in the oral cavity of a phantom head, with individual evaluation of tap water, water with detergent, 70% ethanol, glycerin and toothpaste slurry. Both brushes showed the size of emitted droplets was consistently between 200 and 1200 µm, categorized as splatter (dental aerosols are <50 µm diameter). No significant incremental aerosol-sized matter was detected during toothbrush operation. The high-speed video visualization confirmed only splatter-sized droplets during operation. These findings indicate that oscillating-rotating toothbrushes do not produce aerosol-sized particles during simulated use.

Molecular community profiling of the bacterial microbiota associated with denture-related stomatitis.

Denture-associated stomatitis (DS) affects over two-thirds of denture-wearers. DS presents as erythema of the palatal mucosa in areas where denture-surface associated polymicrobial biofilms containing the fungus Candida albicans exist. The contribution of the oral bacterial microbiota toward the infection is unknown. Therefore, this study characterised the bacterial microbiota of sites within the oral cavity to identify potential associations with occurrence of DS. Denture-wearing patients were recruited (denture stomatitis (DS) n = 8; non-denture stomatitis (NoDS) n = 11) and the oral bacterial microbiota of the tongue, palate and denture-fitting surface was characterised using next-generation sequencing. Operational taxonomic units (OTUs) were identified to bacterial genera and species, and presence/absence and relative abundances were examined. A significant (P = 0.007) decrease in the number of OTUs and thus, diversity of the microbiota was observed in tongue samples of DS patients (vs non-DS). The microbiota of denture-fitting surfaces and palatal mucosae were similar. Large differences in the abundance of bacterial genera and species were observed at each sample site, and unique presence/absence of bacteria was noted. Presence/absence and relative abundance of specific bacteria associated with DS warrants further in vitro and in vivo evaluation, particularly as our previous work has shown C. albicans virulence factor modulation by oral bacteria.

Denture-associated biofilm infection in three-dimensional oral mucosal tissue models.

PURPOSE: In vitro analyses of virulence, pathogenicity and associated host cell responses are important components in the study of biofilm infections. The Candida-related infection, denture-associated oral candidosis, affects up to 60 % of denture wearers and manifests as inflammation of palatal tissues contacting the denture-fitting surface. Commercially available three-dimensional tissue models can be used to study infection, but their use is limited for many academic research institutions, primarily because of the substantial purchase costs. The aim of this study was to develop and evaluate the use of in vitro tissue models to assess infections by biofilms on acrylic surfaces through tissue damage and Candida albicans virulence gene expression. METHODOLOGY: In vitro models were compared against commercially available tissue equivalents (keratinocyte-only, SkinEthic; full-thickness, MatTek Corporation). An in vitro keratinocyte-only tissue was produced using a cancer-derived cell line, TR146, and a full-thickness model incorporating primary fibroblasts and immortalised normal oral keratinocytes was also generated. The in vitro full-thickness tissues incorporated keratinocytes and fibroblasts, and have potential for future further development and analysis. RESULTS: Following polymicrobial infection with biofilms on acrylic surfaces, both in-house developed models were shown to provide equivalent results to the SkinEthic and MatTek models in terms of tissue damage: a significant (P<0.05) increase in LDH activity for mixed species biofilms compared to uninfected control, and no significant difference (P>0.05) in the expression of most C. albicans virulence genes when comparing tissue models of the same type. CONCLUSION: Our results confirm the feasibility and suitability of using these alternative in vitro tissue models for such analyses.

Antibiotic Guardians: the Role of the Dental Profession.

The increasing emergence of antibiotic resistance is a major international public health problem. As a consequence, it is essential that steps are taken to conserve the effectiveness of existing antimicrobial agents. Consumption of antibiotics is the prime contributor to the development of resistance. General dental practitioners write almost 1 out of 10 prescriptions for antibiotics in primary care within the UK and therefore the prudent prescribing of antibiotics in dentistry has never been more vital. This paper outlines the impact of antimicrobial resistance on modern healthcare, describes the current use of antibiotics in general dental practice, and recommends pragmatic ways in which dental practitioners can evaluate and optimize their prescribing. Clinical relevance: Dental professionals have a responsibility to both their patients and the wider community to prescribe antibiotics appropriately.

Community analysis of dental plaque and endotracheal tube biofilms from mechanically ventilated patients.

PURPOSE: Mechanically ventilated patients are at risk for developing ventilator-associated pneumonia, and it has been reported that dental plaque provides a reservoir of respiratory pathogens that may aspirate to the lungs and endotracheal tube (ETT) biofilms. For the first time, metataxonomics was used to simultaneously characterize the microbiome of dental plaque, ETTs, and non-directed bronchial lavages (NBLs) in mechanically ventilated patients to determine similarities in respective microbial communities and therefore likely associations. MATERIAL AND METHODS: Bacterial 16S rRNA gene sequences from 34 samples of dental plaque, NBLs, and ETTs from 12 adult mechanically ventilated patients were analyzed. RESULTS: No significant differences in the microbial communities of these samples were evident. Detected bacteria were primarily oral species (e.g., Fusobacterium nucleatum, Streptococcus salivarius, Prevotella melaninogenica) with respiratory pathogens (Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcuspneumoniae, and Haemophilus influenzae) also in high abundance. CONCLUSION: The high similarity between the microbiomes of dental plaque, NBLs, and ETTs suggests that the oral cavity is indeed an important site involved in microbial aspiration to the lower airway and ETT. As such, maintenance of good oral hygiene is likely to be highly important in limiting aspiration of bacteria in this vulnerable patient group.

Respiratory pathogen colonization of dental plaque, the lower airways, and endotracheal tube biofilms during mechanical ventilation.

PURPOSE: In mechanically ventilated patients, the endotracheal tube is an essential interface between the patient and ventilator, but inadvertently, it also facilitates the development of ventilator-associated pneumonia (VAP) by subverting pulmonary host defenses. A number of investigations suggest that bacteria colonizing the oral cavity may be important in the etiology of VAP. The present study evaluated microbial changes that occurred in dental plaque and lower airways of 107 critically ill mechanically ventilated patients. MATERIALS AND METHODS: Dental plaque and lower airways fluid was collected during the course of mechanical ventilation, with additional samples of dental plaque obtained during the entirety of patients' hospital stay. RESULTS: A "microbial shift" occurred in dental plaque, with colonization by potential VAP pathogens, namely, Staphylococcus aureus and Pseudomonas aeruginosa in 35 patients. Post-extubation analyses revealed that 70% and 55% of patients whose dental plaque included S aureus and P aeruginosa, respectively, reverted back to having a predominantly normal oral microbiota. Respiratory pathogens were also isolated from the lower airways and within the endotracheal tube biofilms. CONCLUSIONS: To the best of our knowledge, this is the largest study to date exploring oral microbial changes during both mechanical ventilation and after recovery from critical illness. Based on these findings, it was apparent that during mechanical ventilation, dental plaque represents a source of potential VAP pathogens.

Comparison of foam swabs and toothbrushes as oral hygiene interventions in mechanically ventilated patients: a randomised split mouth study.

INTRODUCTION: During critical illness, dental plaque may serve as a reservoir of respiratory pathogens. This study compared the effectiveness of toothbrushing with a small-headed toothbrush or a foam-headed swab in mechanically ventilated patients. METHODS: This was a randomised, assessor-blinded, split-mouth trial, performed at a single critical care unit. Adult, orally intubated patients with >20 teeth, where >24 hours of mechanical ventilation was expected were included. Teeth were cleaned 12-hourly using a foam swab or toothbrush (each randomly assigned to one side of the mouth). Cleaning efficacy was based on plaque scores, gingival index and microbial plaque counts. RESULTS: High initial plaque (mean=2.1 (SD 0.45)) and gingival (mean=2.0 (SD 0.54)) scores were recorded for 21 patients. A significant reduction compared with initial plaque index occurred using both toothbrushes (mean change=-1.26, 95% CI -1.57 to -0.95; p<0.001) and foam swabs (mean change=-1.28, 95% CI -1.54 to -1.01; p<0.001). There was significant reduction in gingival index over time using toothbrushes (mean change=-0.92; 95% CI -1.19 to -0.64; p<0.001) and foam swabs (mean change=-0.85; 95% CI -1.10 to -0.61; p<0.001). Differences between cleaning methods were not statistically significant (p=0.12 for change in gingival index; p=0.24 for change in plaque index). There was no significant change in bacterial dental plaque counts between toothbrushing (mean change 3.7×104 colony-forming units (CFUs); minimum to maximum (-2.5×1010 CFUs, 8.7×107 CFUs)) and foam swabs (mean change 9×104 CFUs; minimum to maximum (-3.1×1010 CFUs, 3.0×107 CFUs)). CONCLUSIONS: Patients admitted to adult intensive care had poor oral health, which improved after brushing with a toothbrush or foam swab. Both interventions were equally effective at removing plaque and reducing gingival inflammation. TRIAL REGISTRATION NUMBER: NCT01154257; Pre-results.

Microbial profiling of dental plaque from mechanically ventilated patients.

Micro-organisms isolated from the oral cavity may translocate to the lower airways during mechanical ventilation (MV) leading to ventilator-associated pneumonia (VAP). Changes within the dental plaque microbiome during MV have been documented previously, primarily using culture-based techniques. The aim of this study was to use community profiling by high throughput sequencing to comprehensively analyse suggested microbial changes within dental plaque during MV. Bacterial 16S rDNA gene sequences were obtained from 38 samples of dental plaque sampled from 13 mechanically ventilated patients and sequenced using the Illumina platform. Sequences were processed using Mothur, applying a 97% gene similarity cut-off for bacterial species level identifications. A significant 'microbial shift' occurred in the microbial community of dental plaque during MV for nine out of 13 patients. Following extubation, or removal of the endotracheal tube that facilitates ventilation, sampling revealed a decrease in the relative abundance of potential respiratory pathogens and a compositional change towards a more predominantly (in terms of abundance) oral microbiota including Prevotella spp., and streptococci. The results highlight the need to better understand microbial shifts in the oral microbiome in the development of strategies to reduce VAP, and may have implications for the development of other forms of pneumonia such as community-acquired infection.

Interactions of Candida albicans with host epithelial surfaces.

Candida albicans is an opportunistic, fungal pathogen of humans that frequently causes superficial infections of oral and vaginal mucosal surfaces of debilitated and susceptible individuals. The organism is however, commonly encountered as a commensal in healthy individuals where it is a component of the normal microflora. The key determinant in the type of relationship that Candida has with its host is how it interacts with the epithelial surface it colonises. A delicate balance clearly exists between the potentially damaging effects of Candida virulence factors and the nature of the immune response elicited by the host. Frequently, it is changes in host factors that lead to Candida seemingly changing from a commensal to pathogenic existence. However, given the often reported heterogeneity in morphological and biochemical factors that exist between Candida species and indeed strains of C. albicans, it may also be the fact that colonising strains differ in the way they exploit resources to allow persistence at mucosal surfaces and as a consequence this too may affect the way Candida interacts with epithelial cells. The aim of this review is to provide an overview of some of the possible interactions that may occur between C. albicans and host epithelial surfaces that may in turn dictate whether Candida removal, its commensal persistence or infection follows.

Antimicrobial resistance and virulence traits of Enterococcus faecalis from primary endodontic infections.

OBJECTIVES: To determine the phenotypic and molecular characteristics of Enterococcus faecalis recovered from primary endodontic infections in Brazilian patients. METHODS: Twenty isolates of E. faecalis recovered from 43 Brazilian patients with primary endodontic infections were identified by biochemical profiling (API20Strep) and 16S rDNA sequencing. Antimicrobial susceptibility was ascertained by agar dilution, using the recommended protocol of the Clinical and Laboratory Standards Institute (CLSI). PCR with validated primers was used to detect genes associated with antibiotic resistance and specific virulence factors. RESULTS: All isolates were deemed susceptible to penicillin G, erythromycin and vancomycin. However, nine isolates had a minimum inhibitory concentration of 4µg/mL to vancomycin (the resistance breakpoint). Fourteen isolates (70% of isolates) were also resistant to tetracycline with MICs of >64µg/mL. PCR products for tetracycline resistance genes were detected in test isolates, while erythromycin and vancomycin resistance genes were not evident. Gelatinase, aggregation substance and enteroccocal surface protein genes were detected in 20, 18 and 12 isolates, respectively. CONCLUSIONS: Endodontic E. faecalis isolates exhibit high level of resistance to tetracycline, an antibiotic that has use in local treatment of dental infections. This opens up a much-needed debate on the role and efficacy of this antibiotic for oral infections. Furthermore, these isolates were shown to possess genes that could contribute to pathogenicity in the pulp cavity.

Lipopolysaccharide-induced M2 to M1 macrophage transformation for IL-12p70 production is blocked by Candida albicans mediated up-regulation of EBI3 expression.

Macrophages are heterogeneous cell populations that are present in all tissues. Macrophages can be divided into classically activated inflammatory macrophages (M1) and alternatively activated anti-inflammatory macrophages (M2). It has been generally accepted that M1 macrophages are polarised in an inflammatory environment to produce pro-inflammatory cytokines, whilst M2 macrophages are involved in anti-inflammation and aid tissue repair in wound healing. Bacterial endotoxin (lipopolysaccharide; LPS) is a potent factor in infection, which induces M1 macrophages resulting in higher levels of iNOS, TNFα and IL-12p70 which dictate inflammatory T cell responses. M2 macrophages can be transformed into M1 macrophages following LPS stimulation to promote inflammation. Candida albicans is a commensal fungal microorganism, which has been suggested to induce immune tolerance; however, the mechanism of C. albicans-induced immune tolerance has not been investigated in detail. IL-35 is a recently identified anti-inflammatory cytokine which is a heterodimeric protein consisting of the Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35. IL-35 shares the protein subunit p35, with IL-12p70. IL-12p70 is the most potent cytokine to induce Th1 responses during inflammation. In this study, we demonstrate that heat-killed C. albicans (HKC) strongly suppressed LPS-induced IL-12p70 production in M2 macrophages. Candida albicans induced a high level of EBI3 expression in M2 macrophages, which served as a mechanism for IL-12p70 suppression by competitive binding of the common protein subunit (p35) of IL-35 and IL-12p70. To demonstrate that EBI3 expression had the ability to block IL-12p70 production intracellularly, a Chinese Hamster Ovary (CHO) cell line with biscistronic expression of IL-12p40 and p35 was constructed, followed by ectopic over-expression of EBI3. The over-expression of EBI3 in the IL-12p70 producing cell line effectively suppressed IL-12p70 production. IL-35 secretion was also detected in the cell line, with suppressed IL-12p70 production by immune-precipitation Western blotting. However, this secretion was not evident in M2 macrophages following stimulation by HKC. This can be explained by the constitutive expression of IL-35 receptors (gp130 and IL-12Rß2) in M2 macrophages for cytokine consumption. Our results have indicated that C. albicans can suppress host inflammatory responses in mucosal skin by suppressing LPS-induced IL-12p70 production. Lower IL-12p70 production may avoid an unnecessary Th1 response in order to retain immune tolerance, which may be one of the mechanisms by which C. albicans achieves a successful commensal lifestyle without having a detrimental effect on the host's health.

Role of bacterial lipopolysaccharide in enhancing host immune response to Candida albicans.

Human infections involving yeast of the genus Candida often occur in the presence of bacteria, and, as such, it is important to understand how these bacteria influence innate host immunity towards Candida. Dectin-1 is a cell receptor of macrophages for Candida albicans recognition. The aim of this study was to examine dectin-1 expression by monocytes after stimulation with bacterial lipopolysaccharide (LPS), followed by heat-killed C. albicans (HKC). Freshly isolated human peripheral blood monocytes (PBMCs) and human monocytes cell line (THP-1) cells expressed low levels of dectin-1. Stimulation with LPS and GM-CSF/IL-4 was found to increase dectin-1 expression in both CD14(+) human PBMC and THP-1 cells. Enhanced dectin-1 expression resulted in increased phagocytosis of Candida. When THP-1 cells were challenged only with HKC, detectable levels of IL-23 were not evident. However, challenge by LPS followed by varying concentrations of HKC resulted in increased IL-23 expression by THP-1 cells in HKC dose-dependent manner. Increased expression of IL-17 by PBMC also occurred after stimulation with Candida and LPS. In conclusion, bacterial LPS induces an enhanced immune response to Candida by immune cells, and this occurs through increasing dectin-1 expression.

'Hubble-bubble leads to trouble'--waterpipe smoking and oral health.

UNLABELLED: Waterpipes are used to smoke tobacco by more than 100 million people worldwide. Use is not restricted to any single racial, ethnic, or cultural group, and dentists are almost certain to encounter waterpipe users amongst their patients. This article describes what the practice involves and seeks to inform members of the dental team of the significantly detrimental impacts of waterpipe smoking on both general and oral health and how'hubble-bubble really can lead to trouble'. Advising patients on ceasing waterpipe use is also discussed. CLINICAL RELEVANCE: This paper explains what smoking a waterpipe involves, the associated misconceptions of safety amongst users and the dangers to health.

Education of healthcare professionals and the public.

In the winter of 2007-08 a new public-facing antimicrobial campaign was agreed by the Advisory Committee on Antimicrobial Resistance and Healthcare-Associated Infection (ARHAI) Education sub-Group (later divided into subgroups for professional and public education): it comprised posters with a positive message on how the public could help themselves when they had a cold. However, the poster campaign, used in isolation in England, did not improve antibiotic use; therefore, the Public Education sub-Group took forward educational approaches to change the behaviour of the public and health professionals. Professionals have been encouraged to give patients clear information about the likely duration of symptoms, self-care, and benefits and harms of antibiotics, reinforcing the public poster campaigns in surgeries, hospitals and pharmacies. Since 2008, campaigns have been launched in England to coincide with European Antibiotic Awareness Day (EAAD) on 18 November, using Department of Health and EAAD materials. Professional education has been facilitated by the 2008 National Institute for Health and Clinical Excellence respiratory tract infection delayed prescribing guidance for general practitioners. A toolkit of materials for medicines management teams, to facilitate good antimicrobial stewardship in primary care (ASPIC), is being taken forward by the Public Education sub-Group and professional societies. After advice from ARHAI, in 2009 the General Medical Council requested that all postgraduate deans and Royal Colleges ensure infection prevention and control and antimicrobial prescribing become standard practice implemented in all clinical settings, and that they are emphasized strongly in undergraduate and postgraduate medical training. ARHAI has also taken a keen interest in reviewing, advising and leading on a number of European Union initiatives dealing with professional education.

Real-time monitoring of the adherence of Streptococcus anginosus group bacteria to extracellular matrix decorin and biglycan proteoglycans in biofilm formation.

Members of the Streptococcus anginosus group (SAGs) are significant pathogens. However, their pathogenic mechanisms are incompletely understood. This study investigates the adherence of SAGs to the matrix proteoglycans decorin and biglycan of soft gingival and alveolar bone. Recombinant chondroitin 4-sulphate(C4S)-conjugated decorin and biglycan were synthesised using mammalian expression systems. C4S-conjugated decorin/biglycan and dermatan sulphate (DS) decorin/biglycan were isolated from ovine alveolar bone and gingival connective tissue, respectively. Using surface plasmon resonance, adherence of the SAGs S. anginosus, Streptococcus constellatus and Streptococcus intermedius to immobilised proteoglycan was assessed as a function of real-time biofilm formation. All isolates adhered to gingival proteoglycan, 59% percent of isolates adhered to alveolar proteoglycans, 70% to recombinant decorin and 76% to recombinant biglycan. Higher adherence was generally noted for S. constellatus and S. intermedius isolates. No differences in adherence were noted between commensal and pathogenic strains to decorin or biglycan. DS demonstrated greater adherence compared to C4S. Removal of the glycosaminoglycan chains with chondroitinase ABC resulted in no or minimal adherence for all isolates. These results suggest that SAGs bind to the extracellular matrix proteoglycans decorin and biglycan, with interaction mediated by the conjugated glycosaminoglycan chain.

The role of the IL-12 cytokine family in directing T-cell responses in oral candidosis.

Candida albicans is an opportunistic fungal pathogen that normally exists as a harmless commensal in humans. In instances where host debilitation occurs, Candida can cause a range of clinical infections, and whilst these are primarily superficial, effecting mucosal membranes, systemic infections can develop in severely immunocompromised individuals. The mechanism of host immunity during commensal carriage of C. albicans has been intensively studied. In this paper, we present the most recent information concerning host recognition of C. albicans leading to cytokine production and the subsequent T-cell responses generated in response to C. albicans. Particular focus is given to the role of the IL-12 cytokine family including IL-12, IL-23, IL-27, and IL-35, in host immunity to Candida. CD4(+) T-cells are considered crucial in the regulation of immunity and inflammation. In this regard, the role of Th1/2, helper cells, together with the recently identified Th17 and Treg cells in candidosis will be discussed. Understanding the detailed mechanisms that underlie host immunity to Candida not only will be of benefit in terms of the infections caused by this organism but could also be exploited in the development of therapeutic interventions for other diseases.