Melbourne Dental School - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 50
-
ItemNo Preview AvailableStreptococcus salivarius K12 inhibits Candida albicans aggregation, biofilm formation and dimorphism(TAYLOR & FRANCIS LTD, 2021-08-09)Candida albicans causes candidiasis, particularly in immunocompromised patients. Streptococcus salivarius K12 (K12) is a probiotic isolated from a healthy oral cavity. The study aimed to determine the effect of K12 on C. albicans aggregation, biofilm formation and dimorphism. C. albicans ATCC MYA-4901, acquired immunodeficiency syndrome (AIDS) isolate (ALC2), and oral cancer isolate (ALC3) and K12 were used in the study. All C. albicans strains and K12 were grown in yeast peptone dextrose agar and brain heart infusion agar, respectively, prior to aggregation, biofilm and dimorphism assays. Auto-aggregation of C. albicans MYA-4901 and ALC2 was categorised as high, while the co-aggregation of the strains was low in the presence of K12. C. albicans total cell count decreased significantly when co-cultured with K12 compared with monocultured C. albicans biofilm (p < 0.05). Inhibition of yeast-to-hyphae transition was also observed when co-cultured with K12. In conclusion, K12 inhibits C. albicans aggregation, biofilm formation and dimorphism.
-
ItemTaxonomy of Oral Bacteria(ELSEVIER ACADEMIC PRESS INC, 2018-01-01)The oral cavity is a collection of diverse microenvironments, each inhabited by a community of microorganisms, the majority of which are bacteria and their phages. Given the appropriate conditions, some of these bacteria can cause destruction of the teeth or their supporting hard and soft tissues. For over 300 years microbiologists have been characterising these microbial communities, in both oral health and disease. In this chapter, we take the reader on a journey through time as we discuss the various methods that have been utilised in the characterisation of the bacteria calling the oral cavity home, and how the use of these methods has informed our understanding of oral bacterial communities and the diversity of their members.
-
ItemThe prebiotic effect of CPP-ACP sugar-free chewing gum(ELSEVIER SCI LTD, 2019-12)OBJECTIVES: To determine if chewing gum containing casein phosphopeptide stabilised amorphous calcium phosphate (CPP-ACP) promoted an increase in the abundance of Streptococcus sanguinis and other species associated with dental health in supragingival plaque in a clinical study. MATERIALS AND METHODS: Nineteen participants were recruited for a three-leg cross-over, randomised, controlled clinical trial. Participants chewed a sugar-free gum with or without CPP-ACP six times daily for 20 min over two weeks. The study also involved no gum chewing (no gum) for the same two week period. Participants were randomly assigned to one of the test gums or no gum for each intervention period. Participants abstained from oral hygiene and had washout periods of two weeks between intervention periods. After each intervention period, supragingival plaque was collected and analysed for bacterial composition by sequencing the V4 variable region of the 16S rRNA gene. Data were analysed using a linear mixed model. RESULTS: The CPP-ACP gum intervention produced a significant (p < 0.01) increase in the proportions of S. sanguinis (112%), as well as the commensal species Rothia dentocariosa (127%), Corynebacterium durum (80%) and Streptococcus mitis (55%) when compared with the no gum intervention. All the species that were promoted by the CPP-ACP gum are known to possess one or both of the alkali-producing enzymes arginine deiminase and nitrate reductase. CONCLUSION: This clinical study demonstrated that chewing a sugar-free gum containing CPP-ACP promoted prebiosis by significantly increasing the proportion of S. sanguinis and other health-associated bacterial species in supragingival plaque. CLINICAL SIGNIFICANCE: Regular chewing of CPP-ACP sugar-free gum increases the proportions of health-associated commensal species in supragingival plaque to promote prebiosis and oral homeostasis.
-
ItemPolymicrobial interactions of Candida albicans and its role in oral carcinogenesis(WILEY, 2019-08)The oral microbiome is composed of microorganisms residing in the oral cavity, which are critical components of health and disease. Disruption of the oral microbiome has been proven to influence the course of oral diseases, especially among immunocompromised patients. Oral microbiome is comprised of inter-kingdom microorganisms, including yeasts such as Candida albicans, bacteria, archaea and viruses. These microorganisms can interact synergistically, mutualistically and antagonistically, wherein the sum of these interactions dictates the composition of the oral microbiome. For instance, polymicrobial interactions can improve the ability of C albicans to form biofilm, which subsequently increases the colonisation of oral mucosa by the yeast. Polymicrobial interactions of C albicans with other members of the oral microbiome have been reported to enhance the malignant phenotype of oral cancer cells, such as the attachment to extracellular matrix molecules (ECM) and epithelial-mesenchymal transition (EMT). Polymicrobial interactions may also exacerbate an inflammatory response in oral epithelial cells, which may play a role in carcinogenesis. This review focuses on the role of polymicrobial interactions between C albicans and other oral microorganisms, including its role in promoting oral carcinogenesis.
-
ItemFeasibility and development of a cariogenic diet scale for epidemiological research(WILEY, 2019-05)BACKGROUND: Diet cariogenicity plays a major role as both a protective and risk factor in the development of early childhood caries (ECC). AIM: Develop a scale measuring the cariogenicity of foods and beverages and employ it to describe the cariogenicity of young children's diets and predict dental caries outcomes. DESIGN: Scores of cariogenicity and consumption frequency were applied to food frequency questionnaire (FFQ) collected from an Australian children's cohort study with three time-points of data. One-way ANOVA, with post hoc Tukey test compared mean cariogenic scale measured at 18 months between the subsample of children with caries classification at age 5 years. RESULTS: At 6 months, children's mean cariogenic score was 10.05, increasing to 34.18 at 12 and 50.00 at 18 months. Mean cariogenic scale score at 18 months was significantly higher in children with advanced disease at 5 years (mean scale score: 59.0 ± 15.9) compared to those that were healthy (mean score 47.7 ± 17.5, P = 0.007) or had mild-moderate disease (mean score 48.2 ± 17.3, P = 0.008). CONCLUSIONS: The cariogenic diet scale provides a useful indication of the increasing cariogenicity of children's diets with age and highlights the incorporation of discretionary choice foods and beverages into the diets of young children much earlier than nutritionally recommended.
-
ItemIncorporation of the microencapsulated antimicrobial agent phytoncide into denture base resin(WILEY, 2018-09)BACKGROUND: This study aimed to fabricate a denture base resin (DBR) containing phytoncide microcapsules (PTMCs) and determine the mechanical properties of the resin and antifungal activity. METHODS: Fifty-four heat-cured rectangular DBR specimens (64 × 10 × 3.3 ± 0.2 mm) containing nine concentrations of PTMC between 0 and 5% (wt/wt) were fabricated and subjected to a three-point bending test. A phytoncide release bioassay was developed using DBR containing 0% and 2.5% PTMCs (wt/wt) in a 24 well-plate assay with incubation of Porphyromonas gingivalis at 37 °C for 74 h. The antifungal activity of PTMCs against Candida albicans, in a pH 5.5 acidic environment was determined in a plate assay. RESULTS: Flexural strength decreased with increasing PTMC concentration from 97.58 ± 4.79 MPa for the DBR alone to 53.66 ± 2.46 MPa for DBR containing 5.0% PTMC. No release of phytoncide from the PTMCs in the DBR was detected at pH 7.4. The PTMCs had a minimal inhibitory concentration of 2.6% (wt/vol) against C. albicans at pH 5.5. CONCLUSIONS: PTMCs can be added to DBR 2.5% (wt/wt) without adversely affecting flexural strength. PTMCs released the antimicrobial agent at pH 5.5 at concentrations sufficient to inhibit the growth of the C. albicans.
-
ItemOral Antibiotic for Empirical Management of Acute Dentoalveolar Infections-A Systematic Review(MDPI, 2021-03)Concerns regarding increasing antibiotic resistance raise the question of the most appropriate oral antibiotic for empirical therapy in dentistry. The aim of this systematic review was to investigate the antibiotic choices and regimens used to manage acute dentoalveolar infections and their clinical outcomes. A systematic review was undertaken across three databases. Two authors independently screened and quality-assessed the included studies and extracted the antibiotic regimens used and the clinical outcomes. Searches identified 2994 studies, and after screening and quality assessment, 8 studies were included. In addition to incision and drainage, the antibiotics used to manage dentoalveolar infections included amoxicillin, amoxicillin/clavulanic acid, cefalexin, clindamycin, erythromycin, metronidazole, moxifloxacin, ornidazole and phenoxymethylpenicillin. Regimens varied in dose, frequency and duration. The vast majority of regimens showed clinical success. One study showed that patients who did not receive any antibiotics had the same clinical outcomes as patients who received broad-spectrum antibiotics. The ideal choice, regimen and spectrum of empirical oral antibiotics as adjunctive management of acute dentoalveolar infections are unclear. Given that all regimens showed clinical success, broad-spectrum antibiotics as first-line empirical therapy are unnecessary. Narrow-spectrum agents appear to be as effective in an otherwise healthy individual. This review highlights the effectiveness of dental treatment to address the source of infection as being the primary factor in the successful management of dentoalveolar abscesses. Furthermore, the role of antibiotics is questioned in primary space odontogenic infections, if drainage can be established.
-
ItemBugs and Brains, the Gut and Mental Health Study: a mixed-methods study investigating microbiota composition and function in anxiety, depression and irritable bowel syndrome(BMJ PUBLISHING GROUP, 2021)INTRODUCTION: Research has highlighted relationships between the micro-organisms that inhabit our gastrointestinal tract (oral and gut microbiota) with host mood and gastrointestinal functioning. Mental health disorders and functional gastrointestinal disorders co-occur at high rates, although the mechanisms underlying these associations remain unclear. The Bugs and Brains Study aims to investigate complex relationships between anxiety/depression and irritable bowel syndrome (IBS) in two ways. First, its primary component will compare the gut and oral microbiota in females with anxiety/depression and/or IBS relative to controls, and investigate underlying physiological, endocrine and immune factors, as well as associations with diet and psychosocial factors. In an ancillary component, the study will also investigate gastrointestinal and mental health symptoms in a larger sample, and explore relationships with diet, exercise, oral health, substance use, medical history, early life adversity and psychosocial factors. METHODS AND ANALYSIS: The Bugs and Brains Study aims to recruit 160 females to the primary component: (1) 40 controls; (2) 40 participants with a depressive/anxiety disorder, but no IBS; (3) 40 participants with IBS, but no depressive/anxiety disorder and (4) 40 participants with both depressive/anxiety disorder and IBS. Participation is completed within 1 month, and involves comprehensive questionnaires, anthropometrics, a diagnostic clinical interview, collection of two saliva samples, and stool, urine and hair samples. This study aims to use a systems biology approach to characterise oral and gut microbial composition and function using 16S rRNA gene sequencing and nuclear MR spectroscopy. As part of the ancillary component, it will collect questionnaire data from 1000 participants aged 18-40 years, capturing mental health, gastrointestinal health, oral health, diet and psychosocial factors. ETHICS AND DISSEMINATION: Approval was granted by the University of Melbourne Human Research Ethics Committee (#1749221). All participants voluntarily provided informed consent. Results will be published in peer-reviewed journals and presented at scientific conferences.
-
ItemNo Preview AvailableNutrition and oral health in early childhood: associations with formal and informal childcare(CAMBRIDGE UNIV PRESS, 2021-04)OBJECTIVE: To examine associations between childcare type and nutrition and oral health indicators. DESIGN: Cross-sectional data extracted from a longitudinal birth cohort. Parent-completed FFQ and questions regarding oral health and childcare use. The associations between childcare type, classified into four groups: parent care only (PCO), formal childcare only (FCO), informal childcare only (ICO) or combination of care (F&I), and nutrition and oral health indicators were examined. SETTING: Home and childcare. PARTICIPANTS: Families with children aged 3 years (n 273) and 4 years (n 249) in Victoria, Australia. RESULTS: No associations were observed between childcare type and core food/beverage consumption or oral health indicators. For discretionary beverages, compared with children receiving PCO at age 3 years, children in FCO or F&I were less likely to frequently consume fruit juice/drinks (FCO: adjusted OR (AOR) 0·41, 95 % CI 0·17, 0·96, P = 0·04; F&I: AOR 0·32, 95 % CI 0·14, 0·74, P = 0·008). At age 4 years, children receiving FCO or ICO were less likely to consume sweet beverages frequently compared with children receiving PCO: fruit juice/drink (ICO: AOR 0·42, 95 % CI 0·19, 0·94, P = 0·03; FCO: AOR 0·35, 95 % CI 0·14, 0·88, P = 0·03) and soft drink (ICO: AOR 0·23, 95 % CI 0·07, 0·74, P = 0·01; FCO: AOR 0·14, 95 % CI 0·03, 0·76, P = 0·02). CONCLUSIONS: Associations between childcare type and discretionary beverage intake were observed. Investigation into knowledge, attitudes and activities in formal and informal childcare settings is required to explore different health promotion practices that may influence nutrition and oral health.
-
ItemThe VicGeneration study - a birth cohort to examine the environmental, behavioural and biological predictors of early childhood caries: background, aims and methods(BMC, 2010-02-25)BACKGROUND: Dental caries (decay) during childhood is largely preventable however it remains a significant and costly public health concern, identified as the most prevalent chronic disease of childhood. Caries in children aged less than five years (early childhood caries) is a rapid and progressive disease that can be painful and debilitating, and significantly increases the likelihood of poor child growth, development and social outcomes. Early childhood caries may also result in a substantial social burden on families and significant costs to the public health system. A disproportionate burden of disease is also experienced by disadvantaged populations. METHODS/DESIGN: This study involves the establishment of a birth cohort in disadvantaged communities in Victoria, Australia. Children will be followed for at least 18 months and the data gathered will explore longitudinal relationships and generate new evidence on the natural history of early childhood caries, the prevalence of the disease and relative contributions of risk and protective biological, environmental and behavioural factors. Specifically, the study aims to:1. Describe the natural history of early childhood caries (at ages 1, 6, 12 and 18 months), tracking pathways from early bacterial colonisation, through non-cavitated enamel white spot lesions to cavitated lesions extending into dentine.2. Enumerate oral bacterial species in the saliva of infants and their primary care giver.3. Identify the strength of concurrent associations between early childhood caries and putative risk and protective factors, including biological (eg microbiota, saliva), environmental (fluoride exposure) and socio-behavioural factors (proximal factors such as: feeding practices and oral hygiene; and distal factors such as parental health behaviours, physical health, coping and broader socio-economic conditions).4. Quantify the longitudinal relationships between these factors and the development and progression of early childhood caries from age 1-18 months. DISCUSSION: There is currently a lack of research describing the natural history of early childhood caries in very young children, or exploring the interactions between risk and protective factors that extend to include contemporary measures of socio-behavioural factors. This study will generate knowledge about pathways, prevalence and preventive opportunities for early childhood caries, the most prevalent child health inequality.
- 1 (current)
- 2
- 3
- 4
- 5