Development of an in vitro denture plaque biofilm to model denture malodour

This study aimed to develop an in vitro denture plaque biofilm to model denture malodour. No previous studies have attempted to characterize the malodour associated with dentures and the effect of Candida spp. (main aetiological agent of denture-related stomatitis) on malodour. Pooled denture plaque microcosms and 'model' denture plaque biofilms (pooled saliva supplemented with additional microbial species) with and without addition of candida were grown aerobically at 37 °C for up to 13 days in a constant depth film fermenter (CDFF) on denture acrylic discs. Sample discs were removed, rinsed in sterile water and placed in phosphate buffered saline (PBS). The discs were vortex mixed to remove the biofilms, diluted in PBS and plated in duplicate onto general and selective media. The composition and stability of the biofilms over time were assessed. CDFF-grown microcosms and 'model' denture plaque biofilms were relatively stable in composition, with streptococci remaining the dominant microbial group. Model denture plaque biofilms were comparable in composition to denture plaque microcosms. This model system has the potential for evaluation of agents that might affect these parameters such as denture cleansers and other oral hygiene treatments

Raising awareness of antimicrobial resistance among the general public in the UK: the role of public engagement activities

In response to the accepted risk of emerging antimicrobial resistance, many organizations and institutions have developed and delivered events and activities designed to raise awareness of the issue and to change the behaviour of the intended audience. However, few of these events for a general public audience are documented or able to be sourced by those who might wish to repeat, adapt or modify, particularly those events that are successful. ‘Insider knowledge’ appears to be the best search tool. Moreover, evaluation of the success or impact of the event is rarely published. It would be useful if there were a ‘hub’ where descriptions of such activities could be deposited, enabling the building of a significant resource with real academic value

Potential pathogenic aspects of denture plaque

Oral health status declines with age and as a result the need for removable prostheses increases. Oral health is a reflection of one's general health, affecting the ability of an individual to eat and speak, and contributes significantly to a sense of confidence and well-being. Currently, there are 15 million denture wearers in the UK, representing a significant consumer base and a special healthcare consideration. The microbiology of denture plaque has received little attention in comparison with dental plaque, yet it differs in location and composition. Denture plaque and poor denture hygiene is associated with stomatitis (Candida infection), may also serve as a reservoir of potentially infectious pathogens, and may contribute to oral malodour and to caries and periodontitis in people who have remaining natural teeth. Oral bacteria have been implicated in bacterial endocarditis, aspiration pneumonia, gastrointestinal infection and chronic obstructive pulmonary disease, among others, and dentures offer a reservoir for microorganisms associated with these infections. An effective oral hygiene regimen is important to control denture plaque biofilm and contributes to the control of associated oral and systemic diseases

Evaluating student perception of learning using a virtual reality experience of altitude sickness

Virtual simulation offers the benefit of putting the user within the learned content; offering interactive lessons where experiential learning improves the rate at which we understand new concepts (So et al., 2019; Angel-Urdinola et al., 2021). As educators, we aim to provide learners with ‘real world’ scenarios whilst allowing learners to fail in safe and controlled simulated environments. Evidence supporting simulation learning appears in medical and nursing literature, little is known of student perception of simulation learning in basic science, or building confidence in application of threshold concepts beyond laboratory environments associated with basic sciences. It is unknown as to whether simulation learning is effective in promoting confidence in threshold concepts compared with lecture learning. This study was approved by the Science and Engineering Research Ethics Committee, Manchester Metropolitan University. “Exercise and Environmental Physiology”, is a level 5, 30 credit unit as part of BSc (Hons) Human Physiology. Students were administered an anonymous survey after a 2-hour lecture session on altitude physiology and 1-hour Computer automatic virtual environment (CAVE) simulation. Student confidence in identifying the signs and symptoms of altitude sickness and word association of students feelings in identifying signs and symptoms of altitude sickness was assessed. After CAVE simulation, students were surveyed on their perception of the experience and whether it added to the learning experience. Students rated from “Strongly Disagree”, “Disagree”, “Neither Agree nor Disagree”, “Agree” or “Strongly Agree”. Word associations were 9 options and/or free text. Differences between student confidence identifying signs and symptoms and word association of perception toward identifying signs and symptoms were assessed using χ2 goodness of fit (SPSS 28, IBM). After CAVE simulation, 80% (n=10) “Strongly Agree” and 20% “Agree” with being able to identify signs and symptoms of altitude sickness, compared with 0% “Strongly Agree” and 71% “Agree” after lecture (n=7) (p<0.001). Words associated with the lecture activity when compared with CAVE simulation were different (Figure 2; p<0.001). 100% “Strongly Agree”/“Agree” they enjoyed CAVE simulation, felt it helped improve knowledge and skills in addition to lecture, was engaging and would recommend to others for applying knowledge to real-world scenarios. 90% “Strongly Agree”/ “Agree” that the CAVE simulation covered what they expected, met learning needs, was appropriate to aid learning, was a high standard, easy to follow, gained new knowledge and learned how to apply knowledge to real-world scenarios. 80% “Strongly Agree”/“Agree” that it exceeded expectations. Some respondents however responded with themes of “Pressure”, “Stressed” and neutrally in learning efficacy, suggesting some felt this environment is not conducive to confidence and learning. Despite this, those students did still respond with agreement to gaining/applying knowledge and understanding threshold concepts. The CAVE environment presents an exciting and innovative way for educators in basic science to expose students to real-world scenarios in a safe, controlled environment and simultaneously meet threshold concepts of learning. Some caution however is advised in creating experiences where all students feel able to participate and to not exceed stress thresholds where learning may no longer take place (Vogel & Schwabe, 2016)

Biofilm development by blastospores and hyphae of Candida albicans on abraded denture acrylic resin surfaces

© 2014 Editorial Council for the Journal of Prosthetic Dentistry. Statement of problem Candida albicans is a known etiologic agent of denture stomatitis. Candida hyphae exhibit the ability to respond directionally to environmental stimuli. This characteristic is thought to be important in the penetration of substrata such as resilient denture liners and host epithelium. It has been suggested that hyphal production also enhances adhesion and survival of Candida on host and denture surfaces. Surface roughness, in addition, can enhance adhesion where stronger interactions occur between cells and surface features of similar dimensions. Purpose The purpose of this study was to assess the development of hyphal and blastospore biofilms on abraded denture acrylic resin specimens and measure the ease of removal of these biofilms. Material and methods Biofilms were grown for 48 hours on abraded 1-cm2denture acrylic resin specimens from adhered hyphal phase C albicans or from adhered blastospores. Subsequently, all specimens were stained with Calcofluor White and examined with confocal scanning laser microscopy. Biofilms were removed by vortex mixing in sterile phosphate buffered saline solution. Removed cells were filtered (0.2-μm pore size). Filters were dried at 37°C for 24 hours for dry weight measurements. Any cells that remained on the acrylic resin specimens were stained with 0.03% acridine orange and examined with epifluorescence microscopy. Results Biofilms grown from both cell types contained all morphologic forms of C albicans. Although the underlying surface topography did not affect the amount of biofilm produced, biofilms grown from hyphal phase Candida were visibly thicker and had greater biomass (P<.05). These biofilms were less easily removed from the denture acrylic resin, especially in the case of rougher surfaces, evidenced by the higher numbers of retained cells (P≤.05). Conclusion The presence of hyphae in early Candida biofilms increased biofilm mass and resistance to removal. Increased surface roughness enhances retention of hyphae and yeast cells, and, therefore, will facilitate plaque regrowth. Therefore, minimization of denture abrasion during cleaning is desirable

Detection & characterisation of microoganisms in denture plaque

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The effect of free and encapsulated OIT on the biodeterioration of plasticised PVC during burial in soil for 20 months

The incorporation of silica or zeolite encapsulated biocide into plasticised poly vinyl chloride (pPVC) has been used to control biocide delivery rate. Previous in vitro studies have shown that free biocide leached from the plastic more rapidly than from encapsulated formulations. The aim of this study was to determine the long-term effects of free and encapsulated 2-n-octyl-4-isothiazolin-3-one (OIT) incorporation into PVC on properties of the plastic following burial for 20 months in microbially active soil. In general, fewer bacteria and fungi were isolated from samples containing OIT when compared with biocide-free controls. No patterns in fungal colony predominance or range were observed between the pPVC formulations. OIT-containing samples retained more plasticiser than the controls and hence underwent reduced biodegradation by microorganisms

Detection of bacterial populations in denture plaque using DGGE

Objectives: The aim of this study was to use the culture independent technique, Denaturing Gradient Gel Electrophoresis (DGGE) to characterise the bacterial populations in denture plaque and to investigate the differences in composition from sites seen to fluoresce in vivo under Quantitative Light-induced Fluorescence (QLF) conditions. Methods: In a clinical study 40 removable PMMA dentures were screened for fluorescent plaque deposits under QLF conditions. Plaque samples taken were suspended in reduced transport fluid and frozen at -20 ºC. Total genomic DNA was extracted from the plaque samples and from pure cultures of Porphyromonas gingivalis, Prevotella intermedia, P. melaninogenica, Fusobacterium nucleatum, Actinomyces naeslundii, A. viscosus, A. israelii, Streptococcus sanguis, S. oralis, S. salivarius and Peptostreptococcus micros. Extracted DNA from denture plaque samples and pure cultures was amplified by PCR using universal primers for the 16S rRNA gene. DNA fragments were separated by DGGE to produce bacterial community profiles ‘fingerprints'. Banding pattern profiles were analysed for band composition and number, representing species present and species diversity within each plaque sample. Partial funding from Reckitt Benckiser. Results: Differences were seen in DGGE community profiles from red and green fluorescing sites. This indicated the presence of different bacterial species between sites. No single band was present in all samples, indicating no single species was present in all samples. Species diversity was much lower than expected and was not related to the fluorescence of the plaque samples. Red fluorescing microorganisms are not always cultured from red fluorescing sites, thus the microorganisms responsible for fluorescence in vivo may be dependent on the presence of other species which may be viable but non-cultivable. Conclusion: This study showed differences in the bacterial populations present in red and green fluorescent plaque on dentures, supporting results obtained from culture studies, where some obligate anaerobic species were associated with red fluorescence