Gender diversity of the oral health leadership in Australia.

BACKGROUND: Gender diversity in oral health leadership is important. Globally, this is dominated by men and does not equitably represent the increasing women in the workforce. METHODS: Publicly available and gathered data on leadership positions for Australian professional associations, accrediting body, specialist academies, training institutions and the public dental sector were analysed for gender (men and women) diversity. RESULTS: The gender diversity of the leadership varies across the oral health organizations and training institutions. Of the 383 identified leadership positions, 229 (60%) are held by men. Of the eight national dentist association presidents, six (75%) are men. Of the 65 leadership positions across 13 training institutions, 39 (59%) are held by men, and all schools training dentists are led by men. Men also dominate leadership roles in the specialist academies (62%), the research organizations (56%) and public dental sector (67%). Women do have the majority of senior leadership roles in the accrediting body (67%). CONCLUSION: Gender diversity of the oral health leadership shows some positive findings, but there is still an effort required to increase women leaders across many areas of this leadership. This should urgently be recognized as a problem, with the implementation of strategies to address this important issue. © 2023 Australian Dental Association.

Positive impacts of oral health services provision by a student-led primary care clinic to an Australian rural indigenous community.

BACKGROUND: This study aimed to determine whether oral health services provision by a dental student clinical outplacement embedded within a Community Controlled Health Service positively impacted a rural Indigenous community and to explore the nature of these benefits. METHODS: Aggregated and de-identified 2017, 2018 and 2019 student-led clinic services provision data were retrospectively analysed. The change in services mix over time was measured. Rural outplacement clinic operational costs to the university were estimated. Government-funded local public dental clinic waiting list and services provision data were used to identify any student clinic establishment effect. RESULTS: The student-led clinic services mix shifted over time from mainly acute care for toothache towards prevention of disease and tooth restoration, indicating an improvement in patient oral health and correspondingly reduced system costs. Imputed value of 2017-2019 student-led clinic services provision totalled almost AUD$1 million. Government public clinic waiting list times decreased after full establishment of the student-led clinic, indicating decreased pressure on the public system. CONCLUSION: The Community Controlled Health Service and university partnership improved community oral health care access, its timely delivery and simultaneously provided valuable human capital development from the student training experience. The student-led clinic's targeted Indigenous community showed oral health improvement over time. © 2023 Australian Dental Association.

Workforce Planning Models for Oral Health Care: A Scoping Review.

BACKGROUND: For health care services to address the health care needs of populations and respond to changes in needs over time, workforces must be planned. This requires quantitative models to estimate future workforce requirements that take account of population size, oral health needs, evidence-based approaches to addressing needs, and methods of service provision that maximize productivity. The aim of this scoping review was to assess whether and how these 4 elements contribute to existing models of oral health workforce planning. METHODS: A scoping review was conducted. MEDLINE, Embase, HMIC, and EconLit were searched, all via OVID. Additionally, gray literature databases were searched and key bodies and policy makers contacted. Workforce planning models were included if they projected workforce numbers and were specific to oral health. No limits were placed on country. A single reviewer completed initial screening of abstracts; 2 independent reviewers completed secondary screening and data extraction. A narrative synthesis was conducted. RESULTS: A total of 4,009 records were screened, resulting in 42 included articles detailing 47 models. The workforce planning models varied significantly in their use of data on oral health needs, evidence-based services, and provider productivity, with most models relying on observed levels of service utilization and demand. CONCLUSIONS: This review has identified quantitative workforce planning models that aim to estimate future workforce requirements. Approaches to planning the oral health workforce are not always based on deriving workforce requirements from population oral health needs. In many cases, requirements are not linked to population needs, while in models where needs are included, they are constrained by the existence and availability of the required data. It is critical that information systems be developed to effectively capture data necessary to plan future oral health care workforces in ways that relate directly to the needs of the populations being served. KNOWLEDGE TRANSFER STATEMENT: Policy makers can use the results of this study when making decisions about the planning of oral health care workforces and about the data to routinely collect within health services. Collection of suitable data will allow for the continual improvement of workforce planning, leading to a responsive health service and likely future cost savings.

A state-wide study of dental comorbidities in psychiatric disorders resulting in avoidable emergency department presentations.

BACKGROUND: Attendances at emergency departments (EDs) for dental conditions are unnecessary and come at a significant cost to health services. METHODS: A population-based record-linkage analysis of a retrospective cohort over 2 years across state-based facilities in Queensland. This was to determine if people with mental illness were more likely than the general population to attend EDs for a range of non-traumatic or avoidable dental conditions. RESULTS: There were 1 381 428 individuals in the linked database, of whom 177 157 (13%) had a psychiatric history and 22 046 (1.5%) had one or more avoidable dental presentations. These were toothache (n = 9619), dental abscesses (n = 8449), caries (n = 1826), stomatitis (n = 1213) and gum disease (n = 939). After adjusting for confounders, psychiatric patients were significantly more likely to present with toothache, dental abscesses and caries but not stomatitis or gum disease. Depending on the dental outcome, other risk factors were male sex, lower income, rurality and Indigenous status. CONCLUSIONS: Given these findings, possible interventions should include an increased emphasis on assessing oral health in mental health or primary care, especially in non-metropolitan areas, as well as early dental referral. Service planning for this population should including easier navigation of dental services, availability outside normal office hours and free outreach dental clinics.

An exploratory study of perfectionism, professional factors and psychological well-being of dentistry academics.

BACKGROUND: Well-being might be lower among dentistry professionals than other health professionals, and differ by personal, professional and sociodemographic factors. Few studies have considered dentistry academics who have different work roles and functions than clinicians. This exploratory study focused on well-being among dentistry academics and aimed to explore associations with perfectionism, professional factors and sociodemographics. METHOD: An online survey was carried out with academic staff in Dentistry and Oral Health departments of nine Universities in Australia and New Zealand. Well-being was assessed using the 22-item Psychological General Well-Being Index, with a maximum score of 110 indicating good well-being. Perfectionism was assessed using the 8-item Short Almost Perfect Scale, with a maximum score of 56 and a higher score indicating perfectionism. Twenty items were used to assess professional and 7 items assessed sociodemographic factors. Associations were explored using correlation and multiple linear regression. RESULTS: There was no significant bivariate association between perfectionism and well-being. Multiple linear regression indicated a significant association between hours of undergraduate teaching and psychological well-being, after adjustment for age, gender, income and overall health. CONCLUSION: This exploratory study showed poor well-being among dentistry academics, particularly in those teaching undergraduate students for more than 6 h/week.

A Causative Approach to Demographic and Socioeconomic Factors Affecting Parental Ratings of Child Oral Health.

INTRODUCTION: Many studies have investigated associations between demographic, socioeconomic status (SES), behavioral, and clinical factors and parental ratings of child oral health. Caries experience, pain, missing teeth, malocclusions, and conditions and treatments likely to negatively affect the child or family in the future have been consistently associated with poorer parental ratings. In contrast, effect sizes for associations between demographic and SES indicators (race/ethnicity, country of birth, family structure, household income, employment status, and parental education levels) and parental ratings vary greatly. OBJECTIVES: The primary objectives of this study were to estimate effect sizes for associations between demographic and SES variables and parental ratings of child oral health and then to consider possible causal implications. METHODS: This article uses a nationally representative data set from 24,664 Australian children aged 5 to 14 y, regression analyses guided by a directed acyclic graph causal model, and sensitivity analyses to investigate effects of demographic and SES factors on parental ratings of oral health. RESULTS: One in 8 children had oral health rated as fair or poor by a parent. Indigenous children, older boys, young children with a migrant parent, children from single-parent families, low-income households and families where no parent worked full-time, and children whose parents had lower education levels were much more likely to receive a fair or poor parental oral health rating in crude and adjusted models. CONCLUSION: This cross-sectional study helps to clarify inconsistent findings from previous research and shows many demographic and SES variables to be strong determinants of parental ratings of child oral health, consistent with the effects of these variables on other health outcomes. Sensitivity analyses and consideration of the potential for chance and bias to have affected these findings suggest that many of these associations may be causal. KNOWLEDGE TRANSFER STATEMENT: Based on regression analyses driven by a directed acyclic graph causal model, this research shows a strong impact of demographic and socioeconomic determinants on parental ratings of child oral health, consistent with associations between these variables and other oral and general health outcomes. Many of these associations may be causal. We demonstrate the value of causal models and causal thinking when analyzing complex multilevel observational data.

Global, Regional, and National Levels and Trends in Burden of Oral Conditions from 1990 to 2017: A Systematic Analysis for the Global Burden of Disease 2017 Study.

Government and nongovernmental organizations need national and global estimates on the descriptive epidemiology of common oral conditions for policy planning and evaluation. The aim of this component of the Global Burden of Disease study was to produce estimates on prevalence, incidence, and years lived with disability for oral conditions from 1990 to 2017 by sex, age, and countries. In addition, this study reports the global socioeconomic pattern in burden of oral conditions by the standard World Bank classification of economies as well as the Global Burden of Disease Socio-demographic Index. The findings show that oral conditions remain a substantial population health challenge. Globally, there were 3.5 billion cases (95% uncertainty interval [95% UI], 3.2 to 3.7 billion) of oral conditions, of which 2.3 billion (95% UI, 2.1 to 2.5 billion) had untreated caries in permanent teeth, 796 million (95% UI, 671 to 930 million) had severe periodontitis, 532 million (95% UI, 443 to 622 million) had untreated caries in deciduous teeth, 267 million (95% UI, 235 to 300 million) had total tooth loss, and 139 million (95% UI, 133 to 146 million) had other oral conditions in 2017. Several patterns emerged when the World Bank's classification of economies and the Socio-demographic Index were used as indicators of economic development. In general, more economically developed countries have the lowest burden of untreated dental caries and severe periodontitis and the highest burden of total tooth loss. The findings offer an opportunity for policy makers to identify successful oral health strategies and strengthen them; introduce and monitor different approaches where oral diseases are increasing; plan integration of oral health in the agenda for prevention of noncommunicable diseases; and estimate the cost of providing universal coverage for dental care.

Community-level predictors of Australian children's dental caries and injury.

BACKGROUND: Social determinants of oral health are complex and have been described by conceptual frameworks. A widely embraced model of children's oral health was published by Fisher-Owens et al. (2007), identifying theoretical constructs influencing oral health. The current study aimed to investigate community-level constructs described in the conceptual model. METHODS: The Longitudinal Study of Australian Children is a cross-sequential dual cohort study, with a representative sample (n = 10090) of Australian children. Generalized estimating equations were applied to model seven waves of carer-reported oral health and community measures. RESULTS: In the final model, children living in Queensland had a 1.48 (CI 1.35-1.62) increased odds of dental caries over time. Children in low socio-economic status (SES) areas (OR 1.32 CI 1.20-1.44) had an increased odds of caries. The state of Queensland (OR 1.24 CI 1.05-1.46) and poor neighbourhood liveability (OR 1.17 CI 1.05-1.31) were predictors of dental injury. CONCLUSION: By modelling available community measures, this study found SES and rurality were predictors of caries over childhood. Our results highlight the difficulty of applying conceptual models to oral health. The use of qualitative studies and realist reviews should be considered to complement statistical models to provide contextualized insights into funding, policy and service delivery on children's oral health.

Salivary characteristics and dental caries experience in remote Indigenous children in Australia: a cross-sectional study.

BACKGROUND: While associations between salivary characteristics and dental caries have been well studied, we are not aware of this being assessed in a remote Indigenous child population, where lifestyles may be different from urban children. Our aim was to assess associations between caries experience and putative biomarkers in saliva, accounting for oral hygiene and dietary habits. METHODS: Children attending schools in an Indigenous community in remote north Queensland, Australia were invited to an oral examination by qualified and calibrated examiners. Salivary flow rate, pH, buffering capacity and loads of mutans streptococci (MS), lactobacilli (LB) and yeasts were determined. Also, data on tooth brushing frequency and soft drinks consumption were obtained via a questionnaire. Caries experience was recorded by the International Caries Detection and Assessment System (ICDAS-II), and quantified as decayed, missing and filled surfaces. Relationships between the salivary variables and the cumulative caries experience (dmfs+DMFS) in the deciduous and permanent dentitions were examined by multivariate analyses to control the effect of confounders. RESULTS: The mean cumulative decayed (DS + ds), missing (MS + ms) and filled (FS + fs) surfaces were 3.64 (SD: 4.97), 1.08 (4.38) and 0.79 (1.84) respectively. Higher salivary MS and LB counts, low tooth brushing frequency and daily soft drink consumption were significantly related to greater caries experience. Caries experience was about twice in those with ≥10^5 CFU/ml saliva counts of MS (mean = 6.33, SD: 8.40 vs 3.11, 5.77) and LB (7.03, 7.49 vs 4.41, 8.00). In the fully-adjusted multivariate model, caries experience in those with higher counts of MS and LB were 51 and 52% more than those with lower counts. CONCLUSIONS: As with studies in other populations, childhood salivary counts of MS and LB were significantly associated with greater caries experience in this remote Indigenous community. To address the serious burden of oral disease, we are researching ways to promote a healthy oral environment by encouraging good dietary habits, and emphasising the importance of daily tooth brushing with a fluoridated toothpaste. Our ongoing longitudinal studies will indicate the success of measures employed to reduce the counts of bacteria closely associated with cariogenesis and their impact on caries increment. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ( ANZCTR ), No: ACTRN12615000693527; date of registration: 3rd July 2015.

Parenting practices and children's dental caries experience: A structural equation modelling approach.

AIM: To evaluate the direct and mediated associations between parenting practices and dental caries experience in Indian school children. METHODS: The target population consisted of school children and their parents (N=1539) of Medak district in the state of Telangana, India. Parents completed a questionnaire that consisted of questions related to socioeconomic status (SES), family structure, the number of children, their own oral hygiene behaviour and parenting practices. Parenting practices were assessed using a translated version of the short form of Parent-Child Relationship Questionnaire (PCRQ) which was found to have two factors, power assertion (ie over control and coercion) and positive parenting (warmth and positive parent-child interaction). Children completed a questionnaire on tooth brushing frequency, dental visiting and sugar consumption practices to evaluate their oral hygiene behaviour, and underwent a clinical examination for dental caries by a single examiner. Path analysis was used to explore the influence of parent-child relationship, SES and other family-level variables on dental caries experience of children. RESULTS: Parents' oral hygiene behaviour was positively (ß=0.18, P=0.009), and power assertion negatively (ß=-0.06, P=0.041) associated with children's oral hygiene behaviours. Families reporting higher SES had children with less dental caries experience (ß=-0.10, P=0.028) and better oral hygiene behaviour (ß=0.13, P=0.009). Power assertion parenting had an indirect association with dental caries experience (ß=0.003, P=0.038). CONCLUSIONS: Children had higher dental caries experience when they lived in families with lower SES and used more power assertion parenting practices.

The role of parental rearing practices and family demographics on oral health-related quality of life in children.

OBJECTIVES: To evaluate the direct and indirect (via oral health-related behaviour) effects of parental rearing practices on children's Oral Health-Related Quality of Life (OHRQoL) within a family-focused, comprehensive predictive model. METHODS: Participants were 11- to 14-year-old children and their parents living in Telangana State, India (N = 1130). Children were clinically assessed for dental caries, gingivitis, oral hygiene status, fluorosis, and malocclusion, and completed a self-administered questionnaire on oral health-related behaviour and OHRQoL. Parents answered questions related to their socioeconomic status (SES), family circumstances, parent's perceptions of child's OHRQoL, and child rearing practices. Structural equation modelling was used to evaluate the pathways through which parenting practices were associated with children's OHRQoL. RESULTS: Parents with higher positive (ß = -0.106) and lower power assertion rearing practices (ß = 0.103) had children with better OHRQoL. Parental rearing practices did not have any effect on children's oral hygiene behaviour. Children who had malocclusion (ß = 0.076) and fluorosis (ß = 0.38) had lower OHRQoL. Family SES had a significant effect on children's oral hygiene behaviour and oral hygiene status with children of higher SES demonstrating better oral hygiene behaviour and status. Children living in single-parent families reported poorer oral hygiene behaviour (ß = -0.048) than those living in other types of families. CONCLUSIONS: Parental rearing practices had direct effects on OHRQoL. However, the hypothesised indirect effects of these practices on OHRQoL via poor oral health behaviour were not supported.

Antibiotic prescription patterns of South African general medical practitioners for treatment of acute bronchitis.

BACKGROUND: Antibiotic resistance is a significant public health problem. Prudent use of antibiotics is crucial in reducing this resistance. Acute bronchitis is a common reason for consultations with general medical practitioners, and antibiotics are often prescribed even though guidelines recommend not prescribing them for uncomplicated acute bronchitis. OBJECTIVE: To analyse the antibiotic prescription patterns of South African (SA) general medical practitioners in the treatment of acute bronchitis. METHODS: The 2013 claims for members of 11 health insurance schemes were analysed to assess antibiotic prescription patterns for patients diagnosed with acute bronchitis. The patterns were assessed by type of bronchitis, chronic health status of the patients, sex and age group. The types of antibiotic prescribed were also analysed. RESULTS: Of 166 821 events analysed, an antibiotic was prescribed in more than half (52.9%). There were significant differences by type of bronchitis and chronic health status. Patients with viral bronchitis were more likely to be prescribed an antibiotic than those with bacterial bronchitis (odds ratio (OR) 1.17, 95% confidence interval (CI) 1.08 - 1.26). Patients with a chronic illness were less likely to be prescribed an antibiotic than those without (OR 0.58, 95% CI 0.57 - 0.60). More than 70% of the antibiotics prescribed were cephalosporins, penicillins and other beta-lactams. CONCLUSIONS: Prescription rates of antibiotics for acute bronchitis by SA general medical practitioners are high. There is an urgent need to follow the guidelines for antibiotic use for acute bronchitis to reduce the likelihood of increasing resistance to available antibiotics.

Endodontic treatment-related antibiotic prescribing patterns of South African oral health professionals.

AIM: To assess the antibiotic prescribing patterns of South African dentists for patients undergoing endodontic treatment. METHODOLOGY: This study used data from 2013 health insurance claims submitted by South African oral health professionals to determine the antibiotic prescribing patterns related to endodontic treatment. A logistic regression model was used to test the fully adjusted statistical significance of the association between the exploratory variables (gender, age group, event type, abscess treatment, chronic health) and the dependent variable (antibiotic prescription). Odds ratios with 95% confidence intervals (CI) are reported, and a 95% CI excluding 1 was considered statistically significant. RESULTS: Almost 10% of endodontic treatments were prescribed an antibiotic. There were no significant differences in prescribing patterns by gender, age and chronic health status. Prescriptions were more common at the preparatory stage (9.4%) of root canal treatment compared to the therapy (4.7%) and canal filling (2%) stages. Patients who received apical surgery (OR = 2.28; 95% CI 1.38-3.76) and treatment of an abscess (OR = 2.57; 95% 1.82-3.63) had a significantly increased odds of being prescribed an antibiotic. Almost three-quarters of prescriptions were for narrow spectrum antibiotics. CONCLUSION: The frequency of antibiotic prescribing by South African dental practitioners for patients undergoing endodontic treatment is relatively low and predominantly involved narrow spectrum antibiotics. It, however, remains important that antibiotics are only prescribed when clinically essential, such as when there are obvious systemic effects. These include fever above 37 degrees, malaise, lymphadenopathy, trismus, increase swelling, cellulitis, osteomyelitis and persistent infection. The wider dissemination and adherence to clear evidence-based prescribing guidelines for antibiotics in this clinical area are important.

Does fluoride in the water close the dental caries gap between Indigenous and non-Indigenous children?

BACKGROUND: Indigenous children experience significantly more dental caries than non-Indigenous children. This study assessed if access to fluoride in the water closed the gap in dental caries between Indigenous and non-Indigenous children. METHODS: Data from four states and two territories were sourced from the Child Dental Health Survey (CDHS) conducted in 2010. The outcomes were dental caries in the deciduous and permanent dentitions, and the explanatory variables were Indigenous status and access to fluoridated water (≥0.5 mg/L) prior to 2008. RESULTS: Dental caries prevalence and severity for Indigenous and non-Indigenous children, in both dentitions, was lower in fluoridated areas compared to non-fluoridated areas. Among non-Indigenous children, there was a 50.9% difference in mean dmft scores in fluoridated (1.70) compared to non-fluoridated (2.86) areas. The difference between Indigenous children in fluoridated (3.29) compared to non-fluoridated (4.16) areas was 23.4%. Among non-Indigenous children there was a 79.7% difference in the mean DMFT scores in fluoridated (0.68) compared to non-fluoridated (1.58) areas. The difference between Indigenous children in fluoridated (1.59) and non-fluoridated (2.23) areas was 33.5%. CONCLUSIONS: Water fluoridation is effective in reducing dental caries, but does not appear to close the gap between non-Indigenous children and Indigenous children.

Effectiveness of water fluoridation in caries reduction in a remote Indigenous community in Far North Queensland.

BACKGROUND: Children in remote Indigenous communities in Australia have levels of dental caries much greater than the national average. One such, the Northern Peninsula Area of Far North Queensland (NPA), had an oral health survey conducted in 2004, shortly before the introduction of fluoridated, reticular water. Children were again surveyed in 2012, following five years exposure. METHODS: An oral examination was conducted on all consenting children enrolled in schools across the community, using WHO Basic Oral Health Survey methodology. RESULTS: Few teeth had restorations in both surveys. Age-weighted overall caries prevalence and severity declined from 2005 to 2012 by 37.3%. The effect was most marked in younger children, dmft decreasing by approximately 50% for ages 4-9 years; at age 6, mean decayed score decreased from 5.20 to 3.43. DMFT levels also decreased by almost half in 6-9 year olds. However, significant unmet treatment needs exist at all ages. CONCLUSIONS: There has been considerable improvement in child dental health in the NPA over the past 6-7 years. In light of continued poor diet and oral hygiene, water fluoridation is the most likely explanation. The cost-effectiveness for this small community remains an issue which, in the current climate of political antagonism to water fluoridation in many quarters, requires continued study.

Trends and ethnic disparities in oral and oro-pharyngeal cancers in South Africa, 1992-2001.

OBJECTIVE: To describe trends in the epidemiology of oral and of oro-pharyngeal (OAP) cancers in South Africa for the atest period available. METHODS: Data were obtained from the South African pathology-based National Cancer Registry. All new cases of OAP cancers diagnosed and confirmed histologically from 1992 to 2001 are included for the ICD-10 sites C00 to C14, excluding those involving the major salivary glands (C07-C08) and the nasopharynx (C11). OAP cancer incidence is reported by demographics (gender, age, race/ethnicity) and the anatomical sites involved. The analysis on anatomical sites was restricted to squamous cell carcinomas. RESULTS: Overall, males had a much higher OAP cancer incidence rate (world age-Standardised incidence rate [ASIR] = 7.01/100 000 per year) than females (ASIR = 1.99). However, among Asian/Indian South Africans, OAP cancer incidence was higher among females (ASIR = 4.60) than among males (ASIR = 3.80). OAP cancer, excluding those involving the lip, was highest among Coloureds (ASIR = 5.72) and lowest among Blacks (ASIR = 3.16). OAP cancer incidence was stable overall, but incidence rates increased significantly among Coloured South Africans over the period under review (p < 0.05). Cancer specifically involving the oro-pharyngeal was most common among Coloureds and showed an increasing trend during the period under review. CONCLUSIONS: Variations in the incidence of OAP cancers by gender, race/ethnicity and anatomic site indicate a need for culturally-targeted reductions in major risk factors, including promoting tobacco cessation and prevention of risky alcohol use. The implications of the role of the human papillomavirus (HPV) in the prevention of squamous cell carcinomas involving the oro-pharyngeal in South Africa require further investigation.

Enamel demineralization and bracket bond strength when etching with acid and /or Er:YAG laser.

BACKGROUND: Enamel etching for brackets is usually done with phosphoric acid. Er:YAG lasers have been recently used for this purpose with conflicting results. The effects of lasers on tooth demineralization and the effects of different combinations of laser treatments and bonding agents were evaluated in this study. METHODS: The enamel contents of fluorine, calcium oxide and phosphorus pentoxide (P(2) O(5)) were analysed using acid etching, laser treatment or both. The tensile bond strength of metallic and ceramic brackets using Transbond XT and Fuji Ortho LC were also tested, using acid etching, laser treatment or a combination of both. RESULTS: All treatments reduced the contents of fluorine, P(2)O(5) and calcium oxide, and acid reduced P(2) O(5) levels more than laser. The bond strength with laser was weaker than with acid, and stronger when combining both. When using laser, the best adhesive was the Fuji Ortho LC. The combination of laser and acid produced the best results when using Transbond XT. CONCLUSIONS: The demineralization promoted by laser was lower than the one produced with acid. Laser treatment produced lower tensile stress strength than acid, but still enough to produce clinically efficient retention. The combination of laser and acid produced the best retention results.

Effects of fluoridated milk on artificial enamel carious lesions: a pH cycling study.

OBJECTIVE: To investigate the relationship between concentration of fluoride in milk and its re-mineralizing efficacy, and to test whether increasing the volume of fluoridated milk has any effect on its re-mineralizing efficacy. METHODS: Third molars were painted leaving a 1 mm window on the buccal and/or lingual surfaces. Artificial carious lesions were induced using a de-mineralizing solution. The teeth were then sectioned longitudinally. Specimens were randomly assigned to 15 groups according to different concentrations and volume; i.e., 2.5 ppm, 5 ppm, 7.5 ppm, 10 ppm, 15 ppm, 20 ppm, and 250 ppm of fluoride with 25 ml/section and 50 ml/section. De-ionized water and plain milk were used as controls. Sections were subjected to pH cycling for 20 days. Polarized light microscopy and micro-radiography were utilized to record the lesion characteristics before and after pH cycling. RESULTS: Mean lesion depths decreased significantly in all the fluoride groups, and increased significantly in the control groups. There were no differences in percentage of lesion depth decrease when the volume was doubled for the same fluoride concentration. There were also no statistically significant differences between percentages of decrease in lesion depth when the concentration of fluoride in milk was increased. CONCLUSION: Fluoridated milk demonstrated a remineralization efficacy on early enamel carious lesions. A 2.5 ppm fluoride milk concentration provided similar remineralization potential to that of higher fluoride concentration in milk.

Derivation and validation of a risk-factor model for detection of oral potentially malignant disorders in populations with high prevalence.

BACKGROUND: Oral and pharyngeal cancers constitute the sixth most common type of cancer globally, with high morbidity and mortality. In many countries, most cases of oral cancer arise from long-standing, pre-existing lesions, yet advanced malignancies prevail. A new approach to early detection is needed. We aimed to validate a model for screening so that only high-risk individuals receive the clinical examination. METHODS: A community-based case-control study (n=1029) in rural Sri Lanka assessed risk factors and markers for oral potentially malignant disorders (OPMD) by administering a questionnaire followed by an oral examination. We then developed a model based on age, socioeconomic status and habits of betel-quid chewing, alcohol drinking and tobacco smoking, with weightings based on odds ratios from the multiple logistic regression. A total, single score was calculated per individual. Standard receiver-operator characteristic curves were plotted for the total score and presence of OPMD. The model was validated on a new sample of 410 subjects in a different community. RESULTS: A score of 12.0 produced optimal sensitivity (95.5%), specificity (75.9%), false-positive rate (24.0%), false-negative rate (4.5%), positive predictive value (35.9%) and negative predictive value (99.2%). CONCLUSION: This model is suitable for detection of OPMD and oral cancer in high-risk communities, for example, in Asia, the Pacific and the global diaspora therefrom. A combined risk-factor score of 12.0 was optimal for participation in oral cancer/OPMD screening in Sri Lanka. The model, or local adaptations, should have wide applicability.

Competitive exclusion as a mode of action of a novel Bacillus cereus aquaculture biological agent.

AIMS: To determine the contribution of potential modes of action of a Bacillus cereus aquaculture biological control agent in inhibition of the fish pathogen, Aeromonas hydrophila. METHODS AND RESULTS: When B. cereus was tested in plate well inhibition studies, no production of antimicrobial compounds was detected. Bacillus cereus had a high growth rate (0.96 h(-1)), whereas Aer. hydrophila concentration decreased by c. 70% in co-culture experiments. In nutrient limitation studies, B. cereus had a significantly higher growth rate when cultured under glucose (P < 0.05) and iron (P < 0.01) limitation in comparison with Aer. hydrophila. Bacillus cereus glucose (0.30 g l(-1) h(-1)) and iron (0.60 mg l(-1) h(-1)) uptake rates were also significantly higher (P < 0.01) than the Aer. hydrophila glucose (0.14 g l(-1) h(-1)) and iron (0.43 mg l(-1) h(-1)) uptake rates. Iron uptake was facilitated by siderophore production shown in time profile studies where relative siderophore production was c. 60% through the late exponential and sporulation phases. CONCLUSIONS: Competitive exclusion by higher growth rate, competition for organic carbon and iron, facilitated by siderophore production, could be identified as mechanisms of pathogen growth inhibition by B. cereus. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first elucidation of the mechanism of action of our novel B. cereus biological agent in growth attenuation of pathogenic Aer. hydrophila. This study enhances the application knowledge and attractiveness for adoption of B. cereus NRRL 100132 for exploitation in aquaculture.