The effects of fruit smoothies on enamel erosion

Objectives: This prospective, randomised in vitro study was to investigate the pH and titratable acidity of fruit smoothie drinks and to assess the effect of these drinks on enamel erosion. Method: Fifty enamel slabs were divided into five groups which were allocated to the sample solutions groups: Innocent® smoothie strawberries and bananas (SB), Innocent® smoothie mangoes and passion fruit (MP) and Diet Coke. Distilled deionised water (DD) was used as negative control and citric acid 0.3 % as positive control. All the slabs were subjected to a 21-day pH cycling regime involving 2 min of immersions, five times a day with appropriate remineralization periods in between. Measurement of surface loss was assessed using profilometry. Independent sample t tests were used to compare mean. Results: The titratable acidity for both test smoothies were 3.5-4 times more than that needed to neutralise Diet Coke and citric acid 0.3 %. The pH of SB, MP smoothie and Diet Coke was found to be 3.73, 3.59 and 2.95, respectively. MP smoothie caused the greatest amount of surface loss followed by Diet Coke. Both smoothies were found to cause significant surface loss. MP smoothie resulted in significantly higher surface loss compared with MB smoothie and citric acid 3 %. Conclusion: The smoothies tested were acidic and had high titratable acidity. They produced a significant erosion of enamel in vitro. The results of this study suggest that there should be increased awareness of the erosive effects of smoothies especially as their consumption seems to be on the increase

Investigating the biological properties of carbohydrate derived fulvic acid (CHD-FA) as a potential novel therapy for the management of oral biofilm infections.

Background: A number of oral diseases, including periodontitis, derive from microbial biofilms and are associated with increased antimicrobial resistance. Despite the widespread use of mouthwashes being used as adjunctive measures to control these biofilms, their prolonged use is not recommended due to various side effects. Therefore, alternative broad-spectrum antimicrobials that minimise these effects are highly sought after. Carbohydrate derived fulvic acid (CHD-FA) is an organic acid which has previously demonstrated to be microbiocidal against Candida albicans biofilms, therefore, the aims of this study were to evaluate the antibacterial activity of CHD-FA against orally derived biofilms and to investigate adjunctive biological effects.<p></p> Methods: Minimum inhibitory concentrations were evaluated for CHD-FA and chlorhexidine (CHX) against a range of oral bacteria using standardised microdilution testing for planktonic and sessile. Scanning electron microscopy was also employed to visualise changes in oral biofilms after antimicrobial treatment. Cytotoxicity of these compounds was assessed against oral epithelial cells, and the effect of CHD-FA on host inflammatory markers was assessed by measuring mRNA and protein expression.<p></p> Results: CHD-FA was highly active against all of the oral bacteria tested, including Porphyromonas gingivalis, with a sessile minimum inhibitory concentration of 0.5%. This concentration was shown to kill multi-species biofilms by approximately 90%, levels comparable to that of chlorhexidine (CHX). In a mammalian cell culture model, pretreatment of epithelial cells with buffered CHD-FA was shown to significantly down-regulate key inflammatory mediators, including interleukin-8 (IL-8), after stimulation with a multi-species biofilm.<p></p> Conclusions: Overall, CHD-FA was shown to possess broad-spectrum antibacterial activity, with a supplementary function of being able to down-regulate inflammation. These properties offer an attractive spectrum of function from a naturally derived compound, which could be used as an alternative topical treatment strategy for oral biofilm diseases. Further studies in vitro and in vivo are required to determine the precise mechanism by which CHD-FA modulates the host immune response.<p></p&gt

Differences between normal and demineralized dentine pretreated with silver fluoride and potassium iodide after an in vitro challenge by Streptococcus mutans

The document attached has been archived with permission from the Australian Dental Association (8 March 2008). An external link to the publisher’s copy is included.Background: The application of diamine silver fluoride (Ag(NH3)2F) and potassium iodide (KI) to demineralized dentine has been shown to inhibit the growth of Streptococcus mutans. The purpose of this study was to observe the differences between demineralized and non-demineralized dentine treated with AgF/KI. Methods: Thirty-five dentine discs were bonded to the bases of 5mL polycarbonate screw top vials which were filled with nutrient medium, sterilized and placed into the overflow from a continuous culture of S. mutans. Samples were divided as follows: 10 samples of demineralized dentine; 10 samples of demineralized dentine treated with AgF/KI; 5 samples of non-demineralized dentine; and 10 samples of non-demineralized dentine treated with AgF/KI. Following two weeks connected to the Chemostat, an electron probe microanalysis (EPMA) of percentage weights and penetration depths of calcium, phosphorous silver and fluoride was conducted. Bacterial growth was monitored by taking optical density readings of the growth medium in each vial and outer surfaces of the specimens were examined by scanning electron microscopy (SEM). Results: AgF/KI treatment of demineralized and non-demineralized dentine prevented biofilm formation and reduced further demineralization by S. mutans. AgF/KI treatment of demineralized dentine was more effective in reducing dentine breakdown and the growth of S. mutans. Significantly higher levels of silver and fluoride were deposited within demineralized dentine. Conclusions: A topical treatment with AgF/KI on dentine reduced in vitro caries development and inhibited surface biofilm formation. Reduction of in vitro caries development and viability of S. mutans was more pronounced on the dentine samples that had been demineralized prior to the application of AgF/KI.GM Knight, JM McIntyre, GG Craig, Mulyani, PS Zilm and NJ Gull

Remineralization of initial carious lesions in deciduous enamel after application of dentifrices of different fluoride concentrations

The aim of the present study was to evaluate the remineralization potential of five dentifrices with different fluoride concentrations. Initial caries lesions were created in 72 cylindrical enamel blocks from deciduous teeth. The specimens were randomly distributed among six experimental groups corresponding to six experimental periods. Each of the six volunteers carried two deciduous enamel specimens fixed in an intraoral appliance for a period of 4 weeks. They brushed their teeth and the enamel blocks at least two times a day with dentifrices containing 0 ppm (period 1), 250 ppm (period 2), and 500 ppm fluoride (period 3), respectively. A second group of volunteers (n = 6) used dentifrices with a fluoride content of 0 ppm (period 4), 1,000 ppm (period 5), or 1,500 ppm (period 6). At the end of the respective period, the mineral content was determined by transversal microradiography (TMR). The use of dentifrices containing 500 ppm fluoride (38% MR), 1,000 ppm fluoride (42% MR), and 1,500 ppm fluoride (42% MR) resulted in a statistically significant higher mineral recovery compared to the control group (0 ppm fluoride). Mineral recovery was similar after use of dentifrices containing 0 and 250 ppm fluoride (24%; 25%). It is concluded that it is possible to remineralize initial carious lesions in deciduous enamel in a similar way as it has been described for enamel of permanent teeth

Effect of pH of amine fluoride containing toothpastes on enamel remineralization in vitro

<p>Abstract</p> <p>Background</p> <p>One of the important factors of the demineralization and remineralization equilibrium of enamel is the pH of the surrounding solutions. Effort has been laid in the formulation of different fluoride compounds and the fluoride content in toothpastes but much less is known about the influence of the pH of the toothpastes on their effectiveness. It was therefore the aim of this study to investigate the influence of different pH levels on enamel remineralization in an in vitro experiment using polarization light microscopy and EDX quantitative element analysis.</p> <p>Methods</p> <p>A 5 × 5 mm window on the enamel surface of 40 caries free extracted human premolars was demineralized in a hydroxyethylcellulose solution at pH 4.8. The teeth were divided into 8 groups and the lower half of the window was covered with varnish serving as control. Each group was then immersed in toothpaste slurry containing amine fluoride (1400 ppm) at pH 4.1, 4.5, 5.1 and 6.9 or control toothpaste slurry without fluoride at pH 4.3, 4.7, 5.3 and 7.0. Serial sections were cut through the lesions and investigated with polarization light microscopy and quantitative EDX element analysis.</p> <p>Results</p> <p>The PLM results showed a decreased porous volume of the body of the lesion after incubation with fluoridated toothpaste at pH 4.53 and 5.16. No differences between the experimental window and the control window were found in the other groups. The quantitative element analysis showed no differences in the element content of any of the groups.</p> <p>Conclusion</p> <p>From the results it can be concluded that slightly acidified fluoridated dentifrices may have a certain positive effect on enamel remineralization.</p

Do red deer stags (Cervus elaphus) use roar fundamental frequency (F0) to assess rivals?

It is well established that in humans, male voices are disproportionately lower pitched than female voices, and recent studies suggest that this dimorphism in fundamental frequency (F0) results from both intrasexual (male competition) and intersexual (female mate choice) selection for lower pitched voices in men. However, comparative investigations indicate that sexual dimorphism in F0 is not universal in terrestrial mammals. In the highly polygynous and sexually dimorphic Scottish red deer Cervus elaphus scoticus, more successful males give sexually-selected calls (roars) with higher minimum F0s, suggesting that high, rather than low F0s advertise quality in this subspecies. While playback experiments demonstrated that oestrous females prefer higher pitched roars, the potential role of roar F0 in male competition remains untested. Here we examined the response of rutting red deer stags to playbacks of re-synthesized male roars with different median F0s. Our results show that stags’ responses (latencies and durations of attention, vocal and approach responses) were not affected by the F0 of the roar. This suggests that intrasexual selection is unlikely to strongly influence the evolution of roar F0 in Scottish red deer stags, and illustrates how the F0 of terrestrial mammal vocal sexual signals may be subject to different selection pressures across species. Further investigations on species characterized by different F0 profiles are needed to provide a comparative background for evolutionary interpretations of sex differences in mammalian vocalizations

Screen or not to screen for peripheral arterial disease: Guidance from a decision model

__Abstract__ Background: Asymptomatic Peripheral Arterial Disease (PAD) is associated with greater risk of acute cardiovascular events. This study aims to determine the cost-effectiveness of one time only PAD screening using Ankle Brachial Index (ABI) test and subsequent anti platelet preventive treatment (low dose aspirin or clopidogrel) in individuals at high risk for acute cardiovascular events compared to no screening and no treatment using decision analytic modelling. Methods. A probabilistic Markov model was developed to evaluate the life time cost-effectiveness of the strategy of selective PAD screening and consequent preventive treatment compared to no screening and no preventive treatment. The analysis was conducted from the Dutch societal perspective and to address decision uncertainty, probabilistic sensitivity analysis was performed. Results were based on average values of 1000 Monte Carlo simulations and using discount rates of 1.5% and 4% for effects and costs respectively. One way sensitivity analyses were performed to identify the two most influential model parameters affecting model outputs. Then, a two way sensitivity analysis was conducted for combinations of values tested for these two most influential parameters. Results: For the PAD screening strategy, life years and quality adjusted life years gained were 21.79 and 15.66 respectively at a lifetime cost of 26,548 Euros. Compared to no screening and treatment (20.69 life years, 15.58 Quality Adjusted Life Ye

In vitro effect of fluoride oral hygiene tablets on artificial caries lesion formation and remineralization in human enamel

<p>Abstract</p> <p>Background</p> <p>Aim of this <it>in-vitro</it>-study was to assess the remineralization potential of a tooth cleaning tablet with different fluoride content.</p> <p>Methods</p> <p>Twenty three caries free impacted third molars were examined, enamel surfaces were wax coated leaving two 3 × 4 mm windows for exposure to demineralization/remineralization cycles. The teeth were randomly assigned to 4 groups of 5 control and 6 experimental teeth. Demineralization by standardised HEC-gel, pH 4.7 at 37°C for 72 h, was alternated by rinsing in remineralization solution, pH 7.0 at 37°C for 72 h, total challenge time 432 h. The negative control group N was treated during remineralization cycles with saline; positive control group P was treated with remineralization solution; experimental group D1 was exposed to remineralization solution containing Denttabs^®-tablets with 1450 ppm F; experimental group D2 was exposed to remineralization solution and Denttabs^®-tablets with 4350 ppm F. Each tooth was cut into serial sections and analyzed by polarized light microscopy for assessment of the different zones of white-spot lesions in 3 representative sections. Statistical analysis was based on the <it>Mann-Whitney</it>-Test.</p> <p>Results</p> <p>Both control groups N(-) and P(+) exhibited characteristic white-spot lesions. The remineralization and the demineralization inhibition of the lesions increased considerably from N<P < D1<D2. Denttabs^®-2 administration showed partial/total remineralization including lamination and/or disappearance of the body of the lesion. The different results of all 4 groups were statistically highly significant (p < 0.01) with both tests.</p> <p>Conclusion</p> <p>Based on these results the novel Denttabs^®formulation represents a highly effective oral hygiene product and the remineralization is correlated to the fluoride content.</p

Identifying educator behaviours for high quality verbal feedback in health professions education: literature review and expert refinement

Background Health professions education is characterised by work-based learning and relies on effective verbal feedback. However the literature reports problems in feedback practice, including lack of both learner engagement and explicit strategies for improving performance. It is not clear what constitutes high quality, learner-centred feedback or how educators can promote it. We hoped to enhance feedback in clinical practice by distinguishing the elements of an educator’s role in feedback considered to influence learner outcomes, then develop descriptions of observable educator behaviours that exemplify them. Methods An extensive literature review was conducted to identify i) information substantiating specific components of an educator’s role in feedback asserted to have an important influence on learner outcomes and ii) verbal feedback instruments in health professions education, that may describe important educator activities in effective feedback. This information was used to construct a list of elements thought to be important in effective feedback. Based on these elements, descriptions of observable educator behaviours that represent effective feedback were developed and refined during three rounds of a Delphi process and a face-to-face meeting with experts across the health professions and education. Results The review identified more than 170 relevant articles (involving health professions, education, psychology and business literature) and ten verbal feedback instruments in health professions education (plus modified versions). Eighteen distinct elements of an educator’s role in effective feedback were delineated. Twenty five descriptions of educator behaviours that align with the elements were ratified by the expert panel. Conclusions This research clarifies the distinct elements of an educator’s role in feedback considered to enhance learner outcomes. The corresponding set of observable educator behaviours aim to describe how an educator could engage, motivate and enable a learner to improve. This creates the foundation for developing a method to systematically evaluate the impact of verbal feedback on learner performance

The do's, don't and don't knows of supporting transition to more independent practice

Introduction: Transitions are traditionally viewed as challenging for clinicians. Throughout medical career pathways, clinicians need to successfully navigate successive transitions as they become progressively more independent practitioners. In these guidelines, we aim to synthesize the evidence from the literature to provide guidance for supporting clinicians in their development of independence, and highlight areas for further research. Methods: Drawing upon D3 method guidance, four key themes universal to medical career transitions and progressive independence were identified by all authors through discussion and consensus from our own experience and expertise: workplace learning, independence and responsibility, mentoring and coaching, and patient perspectives. A scoping review of the literature was conducted using Medline database searches in addition to the authors’ personal archives and reference snowballing searches. Results: 387 articles were identified and screened. 210 were excluded as not relevant to medical transitions (50 at title screen; 160 at abstract screen). 177 full-text articles were assessed for eligibility; a further 107 were rejected (97 did not include career transitions in their study design; 10 were review articles; the primary references of these were screened for inclusion). 70 articles were included of which 60 provided extractable data for the final qualitative synthesis. Across the four key themes, seven do’s, two don’ts and seven don’t knows were identified, and the strength of evidence was graded for each of these recommendations. Conclusion: The two strongest messages arising from current literature are first, transitions should not be viewed as one moment in time: career trajectories are a continuum with valuable opportunities for personal and professional development throughout. Second, learning needs to be embedded in practice and learners provided with authentic and meaningful learning opportunities. In this paper, we propose evidence-based guidelines aimed at facilitating such transitions through the fostering of progressive independence