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Aim: Periodontitis is a site-specific, chronic disease treated by non-surgical debridement of subgingival plaque. We aimed to determine the microbiome of sites that did not respond to this treatment (NR) compared with paired good responding (GR) sites before and after treatment. Materials and Methods: In a longitudinal cohort study, clinical parameters of disease and biological samples were taken prior to and 3 months after treatment. Twelve NR sites from six participants were paired with GR sites within the same participant. Subgingival plaque samples were subjected to bacterial community analysis using 16S rRNA gene sequencing. Results: There were no significant differences in clinical parameters and microbial communities at baseline between GR and NR sites. Bacterial communities in deep pockets were dominated by a small number of species, notably Porphyromonas gingivalis and Treponema denticola. In NR sites three months after treatment there was no significant change in bacterial composition whilst there was a collapse in the abundance of pathobionts in GR sites. Conclusion: NR sites were not identifiable prior to treatment by clinical or microbiological parameters. Treatment failed to disrupt pathogenic bacterial community in NR sites. Targeted suppression of particular species should be considered to initiate community collapse and aid disease resolution. [ABSTRACT FROM AUTHOR]

The proper selection of electrical contact materials is one of the critical steps in designing a metal contact microelectromechanical system (MEMS) switch. Ideally, the contact should have both very low contact resistance and high wear resistance. Unfortunately this combination cannot be easily achieved with the contact materials currently used in macroswitches because the available contact force in microswitches is generally insufficient (less than 1 mN) to break through nonconductive surface layers. As a step in the materials selection process, three noble metals, platinum (Pt), rhodium (Rh), ruthenium (Ru), and their alloys with gold (Au) were deposited as thin films on silicon (Si) substrates. The contact resistances of these materials and their evolution with cycling were measured using a specially developed scanning probe microscope test station. These results were then compared to measurements of material hardness and resistivity. The initial contact resistances of the noble metals alloyed with Au are roughly proportional to their resistivities. Measurements of contact resistance during cycling of different metal films were made under a contact force of 200–250 μN in a room air environment. It was found that the contact resistance increases with cycling for alloy films with a low concentration of gold due to the buildup of contamination on the contact. However, for alloy films with a high gold content, the contact resistance increase due to contamination is insignificant up to 108 cycles. These observations suggest that Rh, Ru, and Pt and their gold alloys of low gold content are prone to contamination failure as contact materials in MEMS switches. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the effect of treatment with the saliva biomimetic, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and SnF2 /NaF compared with SnF2 /NaF alone on coronal surface caries progression in head-and-neck cancer patients undergoing radiotherapy.Methods: Twenty-four participants were randomized into two groups. Both groups used 0.4% SnF2 gel and a 0.32% NaF toothpaste; the test group also applied a crème containing 10% CPP-ACP three times daily while the control group used an identical crème without CPP-ACP (placebo). Resting saliva flow rate and saliva fluoride concentrations were determined. Caries status was assessed using ICDASII at baseline and 12-weeks postradiotherapy. Data were statistically analysed using a linear mixed effects model.Results: Both groups showed significantly reduced resting saliva flow rate (P < 0.001) postradiotherapy. There were no significant differences in flow rates and fluoride concentration between groups. The CPP-ACP group exhibited a significant (P < 0.05) 51% reduction in coronal surface caries progression compared with the placebo group.Conclusion: Resting salivary flow rate was significantly reduced in head-and-neck cancer patients following radiotherapy and use of CPP-ACP with SnF2 /NaF significantly lowered caries progression compared with SnF2 /NaF alone. [ABSTRACT FROM AUTHOR]

Dry frictional sliding of two elastic bodies, one of which has a periodic wavy surface, is considered. Such a model represents the frictional sliding of two nominally flat surfaces of which has periodically spaced asperities. The dependence of the true contact area on loading is analyzed by using the plane strain theory of elasticity. Fourier series and integral transform techniques are applied to reduce the problem to an integral equation which is solved using a series of Jacobi polynomials. For steady-state dynamic frictional sliding with given values of the friction coefficient, materials constants, and sliding velocity, the dependence of the contact zone length on the remotely applied tractions is determined. The results indicate a decrease of the minimum applied traction required to close the gap between the bodies, with an increase of the friction coefficient and/or the sliding velocity. A resonance exists as the sliding velocity approaches the Rayleigh wave speed of the flat body. [S0742-4787(00)01403-X]

Background Carbohydrate is accepted as the principal nutrient affecting blood glucose in diabetes; however, current guidelines are unable to specify the optimal quantity of carbohydrate for glycaemic control. No studies exist that describe current practice amongst healthcare professionals giving carbohydrate advice in type 2 diabetes. The present study aims to improve understanding of the degree of variation in the current practice of UK registered dietitians ( RDs) by describing how RDs advise patients. Methods UK RDs were contacted through national networks and asked to complete an online survey, which was analysed using stata, version 12 (StataCorp, College Station, TX, USA). Three consultations between dietitians and patients with type 2 diabetes were observed, followed by semi-structured interviews with the dietitians. Results In total, 320 complete survey responses were received. Dietitians' advice varied according to expertise, training and confidence, and the complexity of the patient's blood glucose treatment. Some 48% ( n = 154) of respondents advised patients to restrict carbohydrate intake either occasionally or frequently, with 35.6% ( n = 114) considering 30-39% of total energy from carbohydrate to be a realistic expectation. The overall theme from the interviews was 'Conflicting Priorities', with three sub-themes: (i) how treatment decisions are made; (ii) the difference between empowerment and advice; and (iii) contradictory advice. A disparity existed between what was observed and interview data on how dietitians rationalise the type of carbohydrate advice provided. Conclusions Dietitians' advice varies for a number of reasons. Consensus exists in some areas (e.g. carbohydrate awareness advice); however, clear definitions of such terms are lacking. Clarification of interventions may improve the consistency of approach and improve patient outcomes. [ABSTRACT FROM AUTHOR]