Converse Magnetoelectric Composite Resonator for Sensing Small Magnetic Fields.

Magnetoelectric (ME) thin film composites consisting of sputtered piezoelectric (PE) and magnetostrictive (MS) layers enable for measurements of magnetic fields passively, i.e. an AC magnetic field directly generates an ME voltage by mechanical coupling of the MS deformation to the PE phase. In order to achieve high field sensitivities a magnetic bias field is necessary to operate at the maximum piezomagnetic coefficient of the MS phase, harnessing mechanical resonances further enhances this direct ME effect size. Despite being able to detect very small AC field amplitudes, exploiting mechanical resonances directly, implies a limitation to available signal bandwidth along with the inherent inability to detect DC or very low frequency magnetic fields. The presented work demonstrates converse ME modulation of thin film Si cantilever composites of mesoscopic dimensions (25 mm × 2.45 mm × 0.35 mm), employing piezoelectric AlN and magnetostrictive FeCoSiB films of 2 µm thickness each. A high frequency mechanical resonance at about 515 kHz leads to strong induced voltages in a surrounding pickup coil with matched self-resonance, leading to field sensitivities up to 64 kV/T. A DC limit of detection of 210 pT/Hz1/2 as well as about 70 pT/Hz1/2 at 10 Hz, without the need for a magnetic bias field, pave the way towards biomagnetic applications.

Trial design for assessing analytical and clinical performance of high-sensitivity cardiac troponin I assays in the United States: The HIGH-US study.

BACKGROUND: High-sensitivity cardiac troponin I (hs-cTnI) assays have been developed that quantify lower cTnI concentrations with better precision versus earlier generation assays. hs-cTnI assays allow improved clinical utility for diagnosis and risk stratification in patients presenting to the emergency department with suspected acute myocardial infarction. We describe the High-Sensitivity Cardiac Troponin I Assays in the United States (HIGH-US) study design used to conduct studies for characterizing the analytical and clinical performance of hs-cTnI assays, as required by the US Food and Drug Administration for a 510(k) clearance application. This study was non-interventional and therefore it was not registered at clinicaltrials.gov. METHODS: We conducted analytic studies utilizing Clinical and Laboratory Standards Institute guidance that included limit of blank, limit of detection, limit of quantitation, linearity, within-run and between run imprecision and reproducibility as well as potential interferences and high dose hook effect. A sample set collected from healthy females and males was used to determine the overall and sex-specific cTnI 99th percentile upper reference limits (URL). The total coefficient of variation at the female 99th percentile URL and a universally available American Association for Clinical Chemistry sample set (AACC Universal Sample Bank) from healthy females and males was used to examine high-sensitivity (hs) performance of the cTnI assays. Clinical diagnosis of enrolled subjects was adjudicated by expert cardiologists and emergency medicine physicians. Assessment of temporal diagnostic accuracy including sensitivity, specificity, positive predictive value, and negative predictive value were determined at presentation and collection times thereafter. The prognostic performance at one-year after presentation to the emergency department was also performed. This design is appropriate to describe analytical characterization and clinical performance, and allows for acute myocardial infarction diagnosis and risk assessment.

Magnetisation switching of FePt nanoparticle recording medium by femtosecond laser pulses.

Manipulation of magnetisation with ultrashort laser pulses is promising for information storage device applications. The dynamics of the magnetisation response depends on the energy transfer from the photons to the spins during the initial laser excitation. A material of special interest for magnetic storage are FePt nanoparticles, for which switching of the magnetisation with optical angular momentum was demonstrated recently. The mechanism remained unclear. Here we investigate experimentally and theoretically the all-optical switching of FePt nanoparticles. We show that the magnetisation switching is a stochastic process. We develop a complete multiscale model which allows us to optimize the number of laser shots needed to switch the magnetisation of high anisotropy FePt nanoparticles in our experiments. We conclude that only angular momentum induced optically by the inverse Faraday effect will provide switching with one single femtosecond laser pulse.

Reduction in Clostridium difficile infection associated with the introduction of hydrogen peroxide vapour automated room disinfection.

The clinical impact of implementing hydrogen peroxide vapour (HPV) disinfection of rooms vacated by patients with Clostridium difficile infection (CDI) was evaluated. Breakpoint time series analysis indicated a significant reduction (P<0.001) in the CDI rate at the time when HPV disinfection was implemented, resulting in a reduction in the CDI rate from 1.0 to 0.4 cases per 1000 patient-days in the 24 months before HPV usage compared with the first 24 months of HPV usage. HPV should be considered to augment the terminal disinfection of rooms vacated by patients with CDI.

Complete dentures revisited.

UNLABELLED: The aim of the article is to assist practitioners in the diagnosis and management of complete denture problems by addressing the problems from a theoretical viewpoint and in a clinically diagnostic way. CLINICAL RELEVANCE: To assist practitioners and undergraduates to understand the clinical basis of complete denture prosthodontics.

A contemporary update on 'soft' linings.

UNLABELLED: This article presents a contemporary overview of soft or compliant denture lining materials. It does not focus on denture bases, which are intrinsically flexible, and suggests some clinical options which readers might wish to consider. CLINICAL RELEVANCE: The aim of this article is to update clinicians on the types of compliant linings currently available and to advise on how some might be used.

Designing cobalt chromium removable partial dentures for patients with shortened dental arches: a pilot survey.

The aim of this survey was to investigate the quality of prescription for the fabrication of cobalt chromium removable partial dentures (RPDs) that are used to extend the shortened dental arches (SDAs). A survey of four commercial dental laboratories located in northern England was conducted. The target of this survey was cobalt chromium RPDs that were requested to restore SDAs comprising the anterior teeth and 2-4 premolars. Dentists' prescriptions were scrutinised, and a special data collection form was completed accordingly. A total of 94 dentists' prescriptions and associated SDA casts were examined. Almost all the requested cobalt chromium RPDs were clasp-retained RPDs (97%). Scrutinising the 91 prescriptions for clasp-retained cobalt chromium RPDs showed that dentists' prescriptions did not have any instructions about the design of the partial denture in a considerable proportion of the cases (32%). Teeth to be clasped were identified clearly in 45% of the prescriptions. A majority of the dentists (64%) failed to provide any instructions about the design of the rests to be placed on the most posterior premolar abutment teeth. A considerable proportion of the dentists delegated the task of selecting the type of the major connector to the dental technician (41%). Only 21 (23%) of the examined casts had clearly defined rest seat preparation. The outcome of this pilot survey shows inadequate quality of prescription in designing RPDs for patients with SDAs. This finding has an ethical and clinical bearing and does not fit with current legal guidelines relevant to designing RPDs.

Risk management in clinical practice. Part 6a. Identifying and avoiding medico-legal risks in complete denture prosthetics.

The provision of complete dentures is often perceived as a clinical 'black art' as it relies on a blend of clinical skill, scientific evidence and no little artistic interpretation. Coupled to this is a heavy reliance on patient ability to control their dentures in a muscular environment while, hopefully, coping with the various oral functions in addition to appearance. This article deals with the potential problem areas in the provision of complete dentures, reinforcing the importance of practitioners obtaining appropriate informed consent and of maintaining clinical knowledge and skills.

An update on the replica denture technique.

UNLABELLED: This paper reviews the principles of the replica denture technique, including some of the techniques previously described. The failing of any previous technique to cater for specific support problems is brought to light and the remainder of the article is devoted to describing how the replica denture technique may be modified to treat patients more appropriately and, hopefully, result in better treatment outcomes. CLINICAL RELEVANCE: This article offers general dental practitioners a practical guide on how to adapt a useful denture replication technique to suit patients with denture-support problems.

Contemporary techniques for denture fabrication.

This article reviews the fabrication of complete dentures and presents findings of recent technological studies that have relevance to current complete denture practice. In addition, summaries of two recent randomized controlled studies demonstrate the need for more deliberate prescription of impression materials.

Altered free radical metabolism in acute mountain sickness: implications for dynamic cerebral autoregulation and blood-brain barrier function.

We tested the hypothesis that dynamic cerebral autoregulation (CA) and blood-brain barrier (BBB) function would be compromised in acute mountain sickness (AMS) subsequent to a hypoxia-mediated alteration in systemic free radical metabolism. Eighteen male lowlanders were examined in normoxia (21% O(2)) and following 6 h passive exposure to hypoxia (12% O(2)). Blood flow velocity in the middle cerebral artery (MCAv) and mean arterial blood pressure (MAP) were measured for determination of CA following calculation of transfer function analysis and rate of regulation (RoR). Nine subjects developed clinical AMS (AMS+) and were more hypoxaemic relative to subjects without AMS (AMS-). A more marked increase in the venous concentration of the ascorbate radical (A(*-)), lipid hydroperoxides (LOOH) and increased susceptibility of low-density lipoprotein (LDL) to oxidation was observed during hypoxia in AMS+ (P < 0.05 versus AMS-). Despite a general decline in total nitric oxide (NO) in hypoxia (P < 0.05 versus normoxia), the normoxic baseline plasma and red blood cell (RBC) NO metabolite pool was lower in AMS+ with normalization observed during hypoxia (P < 0.05 versus AMS-). CA was selectively impaired in AMS+ as indicated both by an increase in the low-frequency (0.07-0.20 Hz) transfer function gain and decrease in RoR (P < 0.05 versus AMS-). However, there was no evidence for cerebral hyper-perfusion, BBB disruption or neuronal-parenchymal damage as indicated by a lack of change in MCAv, S100beta and neuron-specific enolase. In conclusion, these findings suggest that AMS is associated with altered redox homeostasis and disordered CA independent of barrier disruption.

Vertical marginal and internal adaptation of all-ceramic copings made by CAD/CAM technology.

Vertical marginal and internal adaptation scores of all-ceramic copings made by Computer aided manufacturing/ computer aided design (CAD/CAM) were investigated. Scores were compared between Procera all-ceram copings, Cerec-in-lab copings and IPS Empress 2 copings. A stereomicroscope was used (at x45) to measure vertical marginal scores and also used to measure internal adaptation after dies were sectioned. Procera copings showed better vertical marginal adaptations on dies and master preparation and internal adaptation on dies than both IPS Empress 2 and Cerec- in-lab copings. All copings appeared to produce vertical marginal and internal adaptation scores well within the maximum clinically acceptable gaps.

Colonization and deterioration of soft denture lining materials in vivo.

Colonization of denture lining materials by microorganisms including Candida albicans can result in deterioration of the material, as observed by a previous in vitro study by the authors. The current in vivo study monitored the microbial colonisation and penetration of five types of denture liners and their topography over six months. There was no significant difference in the microbial colonisation on the denture liners and no penetration observed, indicating a slower rate of deterioration of materials in vivo. However the surface roughness of all materials increased during use, which might alter susceptibility to subsequent microbial colonisation.

RCT comparing posterior occlusal forms for complete dentures.

Complete dentures can be produced with different types of occlusal forms. There is some evidence to suggest that it may be advantageous to provide complete dentures with cusped posterior teeth. The aim of this research was to compare the levels of subject satisfaction with 3 types of posterior occlusal forms for complete dentures, in a randomized cross-over trial design. Forty-five participants were randomly assigned 3 sets of complete dentures with different posterior occlusal forms (zero-degree, anatomic, and lingualized occlusions). Subjective data were collected according to visual analogue scales after 8 weeks of denture-wearing. Statistical analysis consisted of repeated-measures analysis of variance, followed by paired t tests. Lingualized and anatomic occlusal forms were perceived to be significantly superior in terms of chewing ability, when compared with zero-degree posterior occlusal surfaces.

A randomized clinical trial comparing anatomic, lingualized, and zero-degree posterior occlusal forms for complete dentures.

STATEMENT OF PROBLEM: There is a lack of evidence to recommend a particular type of posterior occlusal form for conventional complete dentures. PURPOSE: The purpose of this study was to compare subject satisfaction with 3 types of posterior occlusal forms for complete dentures in a randomized cross-over controlled trial. MATERIAL AND METHODS: For each participant (n=45), 3 sets of complete dentures were fabricated, each of which had a different posterior occlusal form (0-degree, anatomic, and lingualized). Each set was worn for 8 weeks in a randomized order. Subjective data were collected using the Oral Health Impact Profile 20-EDENT (OHIP-EDENT). The Wilcoxon statistical test was used to compare differences between the groups (alpha=.05). RESULTS: Lingualized posterior occlusal forms were perceived to be significantly superior in terms of painful aching in the mouth (P=.01), sore spots (P<.001), eating ability (P=.02), and meal interruptions (P=.008), compared with 0-degree posterior occlusal forms. Subjects with anatomic posterior occlusal forms had significantly fewer problems eating (P=.05) compared with 0-degree posterior occlusal forms. There was no significant difference found between the lingualized and anatomic posterior occlusal forms. CONCLUSIONS: Participants provided with complete dentures having lingualized or anatomic posterior occlusal forms exhibited significantly higher levels of self-perceived satisfaction compared to those with 0-degree posterior occlusal forms.

The shortened dental arch--an assessment of patients' dental health state utility values.

OBJECTIVES: The aim of this study was to determine how patients value the potential outcomes from different treatments for the shortened dental arch (SDA). METHODS: 110 partially dentate patients were interviewed and presented with illustrative models as well as a description of the process and likely outcome of six possible treatments for the shortened dental arch. The patients were asked to indicate on a standardised visual analogue scale how they would value the health of their mouth if they had received each of the treatments described. RESULTS: With a utility value of 0.0 representing the worst possible health state for a mouth and 1.0 representing the best, the mean utility value for 'no treatment' for a SDA was 0.28 (sd=0.29). For a cobalt-chromium based removable partial denture, an acrylic-resin based removable partial denture, implant treatment, a resin-bonded cantilevered bridge and a conventional cantilevered fixed bridge the utility values were 0.42 (sd=0.3), 0.49 (sd=0.31), 0.53 (sd=0.35), 0.63 (sd=0.26) and 0.64 (sd=0.28) respectively. CONCLUSIONS: The treatment outcome from a cantilevered bridge attracted the highest mean utility value. Participants did not value implant treatment as highly as fixed bridgework, but they did rate the utility of implants more highly than the utility value of removable dentures. However, the patients placed a very low value on the outcome from 'no' treatment. Thus, the appropriateness of the shortened dental arch as an oral health goal can be questioned.

Does the nature of the definitive impression material influence the outcome of (mandibular) complete dentures?

The effects of impression materials on the outcome of complete dentures are poorly understood. This double-blind cross-over randomized controlled trial investigated eleven adult edentulous patients. Each received a maxillary denture and three mandibular dentures (which differed only in the three materials used to record the definitive impressions). The three mandibular dentures were given in a random order. Patients' opinions of each denture were recorded using a Linear Analogue Scale. There was a statistically-significant difference between the outcome of the dentures constructed when zinc-oxide eugenol was used, this material being least favoured (p < 0.001). It would therefore appear that care should be exercised when selecting impression materials when constructing mandibular complete dentures.

Interventions for replacing missing teeth: denture chewing surface designs in edentulous people.

BACKGROUND: When constructing complete dentures for edentulous patients, ultimately patient satisfaction is key. Complete dentures can be produced with different types of occlusal schemes (chewing surfaces) and it is widely accepted that the occlusal scheme for complete dentures has a direct influence upon their success. OBJECTIVES: To assess the relative effectiveness of differing occlusal schemes for complete dentures with regard to patient satisfaction. The null hypothesis is that there is no difference in terms of patient satisfaction between different designs of chewing surfaces for complete dentures. SEARCH STRATEGY: Several electronic databases were searched in order to identify relevant trials: Cochrane Oral Health Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2004), MEDLINE (1966 to week 2 April 2004), OLDMEDLINE (1953 to 1965), EMBASE (1980 to week 16 2004),Zetoc (1993 to December 2003), SIGLE (1980 to December 2003), SCI (Science Citation Index) (1945 to 04 April 2004 ). Reference lists of identified, relevant trials and review articles were scanned. Unpublished data were sought through personal contact with experts in the field. There was no language restriction. SELECTION CRITERIA: Randomised or quasi-randomised controlled clinical trials (RCTs), recruiting edentulous adults, and comparing complete dentures produced with different occlusal schemes with regard to patient satisfaction and masticatory function. DATA COLLECTION AND ANALYSIS: The quality assessment of the included trials was undertaken independently and in duplicate by two reviewers based initially on what was written in the articles. Data were extracted by two reviewers independently. Disagreements were discussed and a third reviewer consulted as necessary. Authors were contacted for clarification or missing information. Data were excluded until further clarification if agreement could not be reached. MAIN RESULTS: 1076 titles and abstracts were identified through the electronic searches. Thirteen trials were thought to be potentially relevant. Ten of these studies were subsequently excluded following further analysis. Two trials require further information from the author before being considered eligible for inclusion. Only one cross-over trial (n = 30), comparing lingualised teeth and zero-degree teeth, fully met the review's inclusion criteria. Twenty patients preferred the lingualised denture, five the zero-degree denture and five patients had no preference. There was a statistically significant difference in favour of the lingualised denture with an odds ratio of 10 (95% confidence interval 2.04 to 48.96). AUTHORS' CONCLUSIONS: There is weak evidence that it may be advantageous, for dentists providing a complete denture service, to prescribe prosthetic posterior teeth with cusps to improve patient satisfaction compared to providing cuspless teeth. However, this conclusion may only be made tentatively until further well conducted trials comparing different occlusal schemes for complete dentures are undertaken.

A clinical investigation of the morphological changes in the posterior mandible when implant-retained overdentures are used.

OBJECTIVES: The widespread use and broad acceptance of osseointegrated dental implants as a means of retaining and supporting mandibular overdentures provide potentially stable three-dimensional reference structures, which have been used to examine the morphological changes of the surface contours of the mandibular ridges distal to implants. Unlike traditional methods that tended to measure changes in ridge morphology and quantity radiographically, this prospective study investigated the changes in the sagittal surface contours of the posterior residual ridges over a 1-year period by an alternative, non-radiographic method using serial casts of residual ridges of a group of patients. MATERIAL AND METHODS: The residual ridges of the serial casts produced were examined using a profiling apparatus and computer software programs that allowed the orientation, digitised recording and measurement of the sagittal surface contours of the posterior residual ridges of mandibular casts in terms of area (cm(2)). RESULTS: Statistical analysis revealed that the detected reductive changes in the surface contour of the posterior residual ridges following the wearing of an implant-retained mandibular overdenture over a 1-year period were highly significant (P<0.001). CONCLUSION: It is concluded that the methodology presented in this study can be used reliably as an alternative to radiographical examination for detecting changes that occur in the distal residual alveolar ridges of the implant containing edentulous mandible when implant-retained overdentures are used. Thus, the method presented may be used to contribute to a reduced exposure to ionising radiation for patients wearing implant-retained overdentures.