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.

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.

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.

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.

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.

Free radicals and inflammation: protection of synovial fluid by superoxide dismutase.

Enzymatically genierated superoxide radical. by reactitng with hydrogen peroxide to prduce the hydroxyl radical, depolymerized puirified hyaluronic acid and bovine synovial flulid. Since phagocytizing polymorphonuclear leukocytes produce superoxide radicals, this reac-tion is sutggested and shown to be quantitatively feasible as the ini vivo mechanism of synovial fluid degradation in anl inflamed joint. Superoxide dismutase, and catalase protect synaovial fluid against such degradation in vitro.

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.

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.

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.

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.

Free radicals and inflammation. Protection of phagocytosine leukocytes by superoxide dismutase.

Isolated human polymorphonuclear leukocytes engaged in phagocytosis liberate superoxide radical and hydrogen peroxide into the surrounding medium. These two chemical species react to produce the hydroxyl radical, which attacks the leukocyte and leads to premature death of the cell. The hydroxyl radical may be scavenged by mannitol, or its formation can be prevented by the addition of superoxide dismutase or catalase to the medium, thereby eliminating the premature death of the cells. This phenomenon may partially explain the observed anti-inflammatory activity of superoxide dismutase.

Superoxide dismutases in polymorphonuclear leukocytes.

Isolated human polymorphonuclear leukocytes were found to contain two distinct superoxide dismutases, electrophoretically identical to the superoxide dismutases found in other human tissues. One is inhibited by cyanide and is located in the cytosol. The other is not inhibited by cyanide and is mitochondrial. These findings disagree with reports by other laboratories, which did not find the cyanide-sensitive cytoplasmic enzyme. The superoxide dismutase-containing preparation of leukocytes released large amounts of superoxide into the medium when the cells were phagocytizing, suggesting that, if the cell population is homogeneous, superoxide production probably takes place on the outer surface of the cell membrane, in addition to inside the phagocytic vacuole.

Mitochondrial respiration scavenges extramitochondrial superoxide anion via a nonenzymatic mechanism.

We determined that mitochondrial respiration reduced cytosolic oxidant stress in vivo and scavenged extramitochondrial superoxide anion (O2-.) in vitro. First, Saccharomyces cerevisiae deficient in both the cytosolic antioxidant cupro-zinc superoxide dismutase (Cu,Zn-SOD) and electron transport (Rho0 state) grew poorly (P < 0.05) in 21% O2 compared with parent yeast and yeast deficient only in electron transport or Cu,Zn-SOD, whereas anaerobic growth was the same (P > 0.05) in all yeast. Second, isolated yeast and mammalian mitochondria scavenged extramitochondrial O2-. generated by xanthine/xanthine oxidase. Yeast mitochondria scavenged 42% more (P < 0.05) extramitochondrial O2-. during pyruvate/malate-induced respiration than in the resting state. Addition of either antimycin (respiratory chain inhibitor) or FCCP (respiratory chain uncoupler) prevented increased O2-. scavenging. Mitochondria isolated from yeast deficient in the mitochondrial manganous superoxide dismutase (Mn-SOD) increased (P < 0.05) O2-. scavenging 56% during respiration. This apparent SOD activity, expressed in units of SOD activity per milligram of mitochondrial protein, was the same (9 +/- 0.6 vs. 10 +/- 1.0; P = 0.43) as the O2-. scavenging of mitochondria with Mn-SOD, suggesting that respiration-dependent mitochondrial O2-. scavenging was nonenzymatic. Finally, isolated rat liver and lung mitochondria also increased (P < 0.05) O2-. scavenging during respiration. We speculate that respiring mitochondria, via the protonmotive pump, present a polarized, proton-rich surface that enhances nonenzymatic dismutation of extramitochondrial O2-. and that this is a previously unrecognized function of mitochondrial respiration with potential physiological ramifications.

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.

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.

Calmodulin-dependent stimulation of the NADPH oxidase of human neutrophils.

The NADPH oxidase of human neutrophils is highly sensitive to calcium concentration and is inhibited in intact cells and cell-free preparations by various phenothiazine drugs. Addition of calmodulin to preparations of NADPH oxidase stimulates enzymatic rates from 1.4-2.5-fold. Addition of calmodulin and calcium, but not calcium alone, to NADPH oxidase preparations which have been inactivated by EDTA results in the restoration of activity. No activation is observed when membrane preparations containing latent NADPH oxidase are exposed to calcium and calmodulin. These studies suggest a role for calmodulin in the control of NADPH oxidase but that calmodulin alone is not sufficient for activation.

Ninety-minute exclusion of acute myocardial infarction by use of quantitative point-of-care testing of myoglobin and troponin I.

BACKGROUND: Diagnostic strategies with ECG and serum cardiac markers have been used to rule out acute myocardial infarction in 6 to 12 hours. The present study evaluated whether a multimarker strategy that used point-of-care measurement of myoglobin, creatine kinase (CK)-MB, and troponin I could exclude acute myocardial infarction in