Melbourne Dental School - Research Publications
Now showing items 1-12 of 293
A socio-ecological perspective on behavioural interventions to influence food choice in schools: alternative, complementary or synergistic?
(CAMBRIDGE UNIV PRESS, 2013-06-01)
OBJECTIVE: An increasing focus on legislation, policy and guidance on the nutritional content of school food has in part been in response to the limited impact of more behavioural or educational approaches. However, there is a risk that a sole focus on policy-level action may lead to neglect of the important contribution that more behavioural approaches can make as components of effective, coordinated, multilevel action to improve the dietary intake of schoolchildren. The current paper aims to highlight the potential importance of viewing alternative approaches as complementary or synergistic, rather than competing. DESIGN: The socio-ecological and RE-AIM frameworks are used to provide a theoretical rationale and demonstrate the importance of explicitly identifying the interdependence of policies, interventions and contextual structures and processes. School food case study evidence is used to exemplify how understanding and exploiting these interdependencies can maximise impact on dietary outcomes. SETTING: Case studies of trials in schools in the UK (South West England and Wales) and Australia (Victoria). SUBJECTS: Schoolchildren. RESULTS: The case studies provide examples to support the hypothesis that the reach, effectiveness, adoption, implementation and maintenance of school food policies and interventions can be maximised by understanding and exploiting the interdependence between levels in the socio-ecological framework. CONCLUSIONS: Rather than being seen as competing alternatives, diverse approaches to improving the diets of schoolchildren should be considered in terms of their potential to be complementary and synergistic, acting at multiple levels to improve acceptability, fidelity, effectiveness and sustainability.
An innovative prostheses design for rehabilitation of severely mutilated dentition: a case report
(KOREAN ACAD PROSTHODONTICS, 2011-01-01)
Partial edentulism has multiple implications in relation to function, esthetics and future rehabilitative treatment. This case report illustrates the management of a patient with extreme consequences of partial edentulism. The main clinical findings were unopposed remaining teeth, overeruption of the remaining teeth, loss of vertical dimension of occlusion, and significant disfigurement of the occlusal plane. Following the diagnostic procedure, a well-coordinated prosthodontic treatment involving liaison with other dental disciplines was indicated. The management involved an innovative combination of fixed and removable prostheses in conjunction with crown lengthening surgery and strategic implant placement. Series of provisional prostheses were applied to facilitate the transition to the final treatment.
Body mass index and dental caries in children and adolescents: a systematic review of literature published 2004 to 2011.
(Springer Science and Business Media LLC, 2012-11-21)
THE OBJECTIVE: The authors undertook an updated systematic review of the relationship between body mass index and dental caries in children and adolescents. METHOD: The authors searched Medline, ISI, Cochrane, Scopus, Global Health and CINAHL databases and conducted lateral searches from reference lists for papers published from 2004 to 2011, inclusive. All empirical papers that tested associations between body mass index and dental caries in child and adolescent populations (aged 0 to 18 years) were included. RESULTS: Dental caries is associated with both high and low body mass index. CONCLUSION: A non-linear association between body mass index and dental caries may account for inconsistent findings in previous research. We recommend future research investigate the nature of the association between body mass index and dental caries in samples that include a full range of body mass index scores, and explore how factors such as socioeconomic status mediate the association between body mass index and dental caries.
Dysmorphometrics: the modelling of morphological abnormalities
BACKGROUND: The study of typical morphological variations using quantitative, morphometric descriptors has always interested biologists in general. However, unusual examples of form, such as abnormalities are often encountered in biomedical sciences. Despite the long history of morphometrics, the means to identify and quantify such unusual form differences remains limited. METHODS: A theoretical concept, called dysmorphometrics, is introduced augmenting current geometric morphometrics with a focus on identifying and modelling form abnormalities. Dysmorphometrics applies the paradigm of detecting form differences as outliers compared to an appropriate norm. To achieve this, the likelihood formulation of landmark superimpositions is extended with outlier processes explicitly introducing a latent variable coding for abnormalities. A tractable solution to this augmented superimposition problem is obtained using Expectation-Maximization. The topography of detected abnormalities is encoded in a dysmorphogram. RESULTS: We demonstrate the use of dysmorphometrics to measure abrupt changes in time, asymmetry and discordancy in a set of human faces presenting with facial abnormalities. CONCLUSION: The results clearly illustrate the unique power to reveal unusual form differences given only normative data with clear applications in both biomedical practice & research.
A novel transposon construct expressing PhoA with potential for studying protein expression and translocation in Mycoplasma gallisepticum
BACKGROUND: Mycoplasma gallisepticum is a major poultry pathogen and causes severe economic loss to the poultry industry. In mycoplasmas lipoproteins are abundant on the membrane surface and play a critical role in interactions with the host, but tools for exploring their molecular biology are limited. RESULTS: In this study we examined whether the alkaline phosphatase gene (phoA ) from Escherichia coli could be used as a reporter in mycoplasmas. The promoter region from the gene for elongation factor Tu (ltuf) and the signal and acylation sequences from the vlhA 1.1 gene, both from Mycoplasma gallisepticum , together with the coding region of phoA , were assembled in the transposon-containing plasmid pISM2062.2 (pTAP) to enable expression of alkaline phosphatase (AP) as a recombinant lipoprotein. The transposon was used to transform M. gallisepticum strain S6. As a control, a plasmid containing a similar construct, but lacking the signal and acylation sequences, was also produced (pTP) and also introduced into M. gallisepticum . Using a colorimetric substrate for detection of alkaline phosphatase activity, it was possible to detect transformed M. gallisepticum . The level of transcription of phoA in organisms transformed with pTP was lower than in those transformed with pTAP, and alkaline phosphatase was not detected by immunoblotting or enzymatic assays in pTP transformants, eventhough alkaline phosphatase expression could be readily detected by both assays in pTAP transformants. Alkaline phosphatase was shown to be located in the hydrophobic fraction of transformed mycoplasmas following Triton X-114 partitioning and in the membrane fraction after differential fractionation. Trypsin proteolysis confirmed its surface exposure. The inclusion of the VlhA lipoprotein signal sequence in pTAP enabled translocation of PhoA and acylation of the amino terminal cysteine moiety, as confirmed by the effect of treatment with globomycin and radiolabelling studies with [14C]palmitate. PhoA could be identified by mass-spectrometry after separation by two-dimensional electrophoresis. CONCLUSION: This is the first study to express PhoA as a lipoprotein in mycoplasmas. The pTAP plasmid will facilitate investigations of lipoproteins and protein translocation across the cell membrane in mycoplasmas, and the ease of detection of these transformants makes this vector system suitable for the simultaneous screening and detection of cloned genes expressed as membrane proteins in mycoplasmas.
Oral Human Papillomavirus in Men Having Sex with Men: Risk-Factors and Sampling
(PUBLIC LIBRARY SCIENCE, 2012-11-16)
BACKGROUND: Human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma is becoming more common. We examined prevalence and risk factors for oral HPV among men who have sex with men (MSM) and compared sampling and transport methods. METHODS: In 2010, 500 MSM (249 HIV-positive) attending Melbourne Sexual Health Centre answered a questionnaire, swabbed their mouth and throat and collected a gargled oral rinse sample. Half the oral rinse was transported absorbed in a tampon (to enable postage). HPV was detected by polymerase chain reaction, and genotyped by Roche Linear Array®. Men with HPV 16 or 18 were retested after six months. RESULTS: Any HPV genotype was detected in 19% (95% confidence intervals (CI) 15-25%) of HIV-infected men and 7% (95% CI 4-11%) of HIV-negative men (p<0.001), and HPV 16 was detected in 4.4% (95% CI 2-8%) of HIV-infected men and 0.8% (0.1-2.8%) of HIV-negative men. Oral HPV was associated with: current smoking (adjusted odds ratio (aOR) 2.2 (95%CI: 1.2-3.9)), time since tooth-brushing (aOR per hour 0.87, 95%CI: 0.8-0.96) and number of lifetime tongue-kissing partners aOR 3.2 95%CI: (1.2-8.4) for 26-100 partners and 4.9 95%CI: (1.9-12.5) for>100 partners. Lifetime oral-penile sex partner numbers were significantly associated in a separate model: aOR 2.8(1.2-6.3) for 26-100 partners and 3.2(1.4-7.2) for>100 partners. HPV 16 and 18 persisted in 10 of 12 men after a median six months. Sensitivities of sampling methods compared to all methods combined were: oral rinse 97%, tampon-absorbed oral rinse 69%, swab 32%. CONCLUSIONS: Oral HPV was associated with HIV infection, smoking, recent tooth-brushing, and more lifetime tongue-kissing and oral sex partners. The liquid oral rinse sample was more sensitive than a tampon-absorbed oral rinse or a self-collected swab.
The effect of calcium hydroxide on the antibiotic component of Odontopaste (R) and Ledermix (R) paste
AIM: To investigate the chemical interaction of calcium hydroxide with the antibiotics demeclocycline calcium in Ledermix Paste and clindamycin hydrochloride in Odontopaste. METHODOLOGY: Validated methods were developed to analyse the interaction of calcium hydroxide in two forms, Pulpdent and calcium hydroxide powder, with the two antibiotics. High-performance liquid chromatography (HPLC) was used to analyse the mixed samples of the pastes and calcium hydroxide. The concentration of demeclocycline calcium over 0-, 1-, 18-, 24-, 72-h and 7-day time-points was determined. The concentration of clindamycin hydrochloride over 1-, 6-, 24-, 72-h and 7-day time-points was determined. All tests with HPLC involved testing of the standard in duplicate alongside the samples. Linearity, precision and specificity of the testing procedures and apparatus were validated. Descriptive statistics are provided. RESULTS: The antibiotics in both Odontopaste and Ledermix Paste were affected by the addition of calcium hydroxide. When mixed with calcium hydroxide powder, Odontopaste had a 2% loss of clindamycin hydrochloride over 7 days, but when mixed with Pulpdent, there was a 36% loss over 7 days. Ledermix Paste showed an 80% loss of demeclocycline calcium over 7 days when mixed with calcium hydroxide powder and a 19% loss when mixed with Pulpdent over the 7-day period. CONCLUSION: The addition of calcium hydroxide to Odontopaste or Ledermix Paste results in reductions of the respective antibiotic over a 7-day time period.
Hypoxia Enhances the Proliferative Response of Macrophages to CSF-1 and Their Pro-Survival Response to TNF
(PUBLIC LIBRARY SCIENCE, 2012-09-19)
In chronic inflammatory lesions there are increased numbers of macrophages with a possible contribution of enhanced survival/proliferation due, for example, to cytokine action; such lesions are often hypoxic. Prior studies have found that culture in low oxygen can promote monocyte/macrophage survival. We show here, using pharmacologic inhibitors, that the hypoxia-induced pro-survival response of macrophages exhibits a dependence on PI3-kinase and mTOR activities but surprisingly is suppressed by Akt and p38 MAPK activities. It was also found that in hypoxia at CSF-1 concentrations, which under normoxic conditions are suboptimal for macrophage proliferation, macrophages can proliferate more strongly with no evidence for alteration in CSF-1 receptor degradation kinetics. TNF promoted macrophage survival in normoxic conditions with an additive effect in hypoxia. The enhanced hypoxia-dependent survival and/or proliferation of macrophages in the presence of CSF-1 or TNF may contribute to their elevated numbers at a site of chronic inflammation.
Consumption patterns of sweet drinks in a population of Australian children and adolescents (2003-2008)
(BIOMED CENTRAL LTD, 2012-09-12)
BACKGROUND: Intake of sweet drinks has previously been associated with the development of overweight and obesity among children and adolescents. The present study aimed to assess the consumption pattern of sweet drinks in a population of children and adolescents in Victoria, Australia. METHODS: Data on 1,604 children and adolescents (4-18 years) from the comparison groups of two quasi-experimental intervention studies from Victoria, Australia were analysed. Sweet drink consumption (soft drink and fruit juice/cordial) was assessed as one day's intake and typical intake over the last week or month at two time points between 2003 and 2008 (mean time between measurement: 2.2 years). RESULTS: Assessed using dietary recalls, more than 70% of the children and adolescents consumed sweet drinks, with no difference between age groups (p = 0.28). The median intake among consumers was 500 ml and almost a third consumed more than 750 ml per day. More children and adolescents consumed fruit juice/cordial (69%) than soft drink (33%) (p < 0.0001) and in larger volumes (median intake fruit juice/cordial: 500 ml and soft drink: 375 ml). Secular changes in sweet drink consumption were observed with a lower proportion of children and adolescents consuming sweet drinks at time 2 compared to time 1 (significant for age group 8 to <10 years, p = 0.001). CONCLUSION: The proportion of Australian children and adolescents from the state of Victoria consuming sweet drinks has been stable or decreasing, although a high proportion of this sample consumed sweet drinks, especially fruit juice/cordial at both time points.
Constitutive and Inflammatory Immunopeptidome of Pancreatic beta-Cells
(AMER DIABETES ASSOC, 2012-11-01)
Type 1 diabetes is characterized by the autoimmune destruction of pancreatic β-cells. Recognition of major histocompatibility complex (MHC)-bound peptides is critical for both the initiation and progression of disease. In this study, MHC peptide complexes were purified from NIT-1 β-cells, interferon-γ (IFN-γ)-treated NIT-1 cells, splenic and thymic tissue of 12-week-old NOD mice, and peptides identified by mass spectrometry. In addition to global liquid chromatography-tandem mass spectrometry analysis, the targeted approach of multiple-reaction monitoring was used to quantitate the immunodominant K(d)-restricted T-cell epitope islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)₂₀₆₋₂₁₄. We identified >2,000 MHC-bound peptides; 1,100 of these presented by β-cells grown under normal conditions or after exposure to IFN-γ. These include sequences from a number of known autoantigens. Quantitation of IGRP₂₀₆₋₂₁₄ revealed low-level presentation by K(d) (~25 complexes/cell) on NIT-1 cells after IFN-γ treatment compared with the simultaneous presentation of the endogenously processed K(d)-restricted peptide Janus kinase-1₃₅₅₋₃₆₃ (~15,000 copies/cell). We have successfully sequenced peptides from NIT-1 β-cells under basal and inflammatory conditions. We have shown the feasibility of quantitating disease-associated peptides and provide the first direct demonstration of the disparity between presentation of a known autoantigenic epitope and a common endogenously presented peptide.
Splash!: a prospective birth cohort study of the impact of environmental, social and family-level influences on child oral health and obesity related risk factors and outcomes
(BIOMED CENTRAL LTD, 2011-06-27)
BACKGROUND: Dental caries (decay) is the most prevalent disease of childhood. It is often left untreated and can impact negatively on general health, and physical, developmental, social and learning outcomes. Similar to other health issues, the greatest burden of dental caries is seen in those of low socio-economic position. In addition, a number of diet-related risk factors for dental caries are shared risk factors for the development of childhood obesity. These include high and frequent consumption of refined carbohydrates (predominately sugars), and soft drinks and other sweetened beverages, and low intake of (fluoridated) water. The prevalence of childhood obesity is also at a concerning level in most countries and there is an opportunity to determine interventions for addressing both of these largely preventable conditions through sustainable and equitable solutions. This study aims to prospectively examine the impact of drink choices on child obesity risk and oral health status. METHODS/DESIGN: This is a two-stage study using a mixed methods research approach. The first stage involves qualitative interviews of a sub-sample of recruited parents to develop an understanding of the processes involved in drink choice, and inform the development of the Discrete Choice Experiment analysis and the measurement instruments to be used in the second stage. The second stage involves the establishment of a prospective birth cohort of 500 children from disadvantaged communities in rural and regional Victoria, Australia (with and without water fluoridation). This longitudinal design allows measurement of changes in the child's diet over time, exposure to fluoride sources including water, dental caries progression, and the risk of childhood obesity. DISCUSSION: This research will provide a unique contribution to integrated health, education and social policy and program directions, by providing clearer policy relevant evidence on strategies to counter social and environmental factors which predispose infants and children to poor health, wellbeing and social outcomes; and evidence-based strategies to promote health and prevent disease through the adoption of healthier lifestyles and diet. Further, given the absence of evidence on the processes and effectiveness of contemporary policy implementation, such as community water fluoridation in rural and regional communities it's approach and findings will be extremely informative.
Is bisphosphonate therapy for benign bone disease associated with impaired dental healing? A case-controlled study
BACKGROUND: Bisphosphonates are common first line medications used for the management of benign bone disease. One of the most devastating complications associated with bisphosphonate use is osteonecrosis of the jaws which may be related to duration of exposure and hence cumulative dose, dental interventions, medical co-morbidities or in some circumstances with no identifiable aggravating factor. While jaw osteonecrosis is a devastating outcome which is currently difficult to manage, various forms of delayed dental healing may be a less dramatic and, therefore, poorly-recognised complications of bisphosphonate use for the treatment of osteoporosis. It is hypothesised that long-term (more than 1 year's duration) bisphosphonate use for the treatment of post-menopausal osteoporosis or other benign bone disease is associated with impaired dental healing. METHODS/DESIGN: A case-control study has been chosen to test the hypothesis as the outcome event rate is likely to be very low. A total of 54 cases will be recruited into the study following review of all dental files from oral and maxillofacial surgeons and special needs dentists in Victoria where potential cases of delayed dental healing will be identified. Potential cases will be presented to an independent case adjudication panel to determine if they are definitive delayed dental healing cases. Two hundred and fifteen controls (1:4 cases:controls), matched for age and visit window period, will be selected from those who have attended local community based referring dental practices. The primary outcome will be the incidence of delayed dental healing that occurs either spontaneously or following dental treatment such as extractions, implant placement, or denture use. DISCUSSION: This study is the largest case-controlled study assessing the link between bisphosphonate use and delayed dental healing in Australia. It will provide invaluable data on the potential link between bisphosphonate use and osteonecrosis of the jaws.