Presentation of floating mass transducer and Vibroplasty Couplers on CT and Cone Beam CT

Various titanium coupling elements, Vibroplasty Couplers, maintaining the attachment of the Floating Mass Transducer (FMT) of the active middle ear implant Vibrant Soundbridge (VSB) to the round window, the stapes suprastructure or the stapes footplate are in use to optimally transfer energy from the FMT to the inner ear fluids. In certain cases it is of interest to radiologically verify the correct position of the FMT coupler assembly. The imaging appearance of FMT connected to these couplers, however, is not well known. The aim of this study was to present the radiological appearance of correctly positioned Vibroplasty Couplers together with the FMT using two different imaging techniques. Vibroplasty Couplers were attached to the FMT of a Vibrant Soundbridge and implanted in formalin fixed human temporal bones. Five FMT coupler assemblies were implanted in different positions: conventionally to the incus, a Bell-Coupler, a CliP-Coupler, a Round Window-Coupler and an Oval Window-Coupler. High spatial resolution imaging with Multi-Detector CT (MDCT) and Cone Beam CT (CBCT) was performed in each specimen. Images were blind evaluated by two radiologists on a visual basis. Middle ear details, identification of FMT and coupler, position of FMT coupler assembly and artefacts were assessed. CBCT showed a better spatial resolution and a higher visual image quality than MDCT, but there was no significant advantage over MDCT in delineating the structures or the temporal bone of the FMT Coupler assemblies. The FMT with its coupler element could be clearly identified in the two imaging techniques. The correct positioning of the FMT and all types of couplers could be demonstrated. Both methods, MDCT and CBCT, are appropriate methods for postoperative localization of FMT in combination with Vibroplasty Couplers and for verifying their correct position. If CBCT is available, this method is recommended due to the better spatial resolution and less metal artifacts.     

Can electrical stimulation be used to establish a physiologic occlusal position?

An electromyographic study was undertaken to discover the mechanism by which the Myo-monitor instrument causes muscle contraction. Our data, which strongly suggest that the distal axons of the motoneurons are directly stimulated, lend support to previous studies showing that the stimulus does not cause reflex activation of the jaw closing muscles. Inasmuch as the stimulus acts only in the periphery without the participation of the central nervous system, the ability of the instrument to produce a reflexly controlled occlusal position is highly questionable. Furthermore, we believe that there is no evidence that reflex jaw closure could ever be used to establish a physiologic occlusal position.     

Tissue oxygen tension and blood-flow changes in rat incisor pulp with graded systemic hyperoxia

The role of oxygen in the regulation of the pulpal microcirculation is unknown. This investigation is aimed to measure tissue oxygen tension and blood-flow changes in the pulp of rat lower incisors during graded systemic hyperoxia, and to determine the response of the pulpal vasculature to various oxygen tensions. Twenty-four Sprague-Dawley rats were anaesthetized and artificially ventilated with the appropriate gas mixture. Recessed oxygen-sensitive microelectrodes were used to measure pulpal tissue oxygen tension via a small access cavity filled with saline on the labial surface of the incisor. A laser Doppler flowmeter was used to record pulpal blood-flow. Inspired oxygen was increased stepwise from 20 to 100% in 20% steps. Systemic blood-gas concentrations were measured at each step. Systemic arterial oxygen tension at 100% oxygen ventilation reached 481.2 +/- 30.7% of the baseline at 20% oxygen breathing (n=21). Pulpal tissue oxygen tension did not change significantly whereas pulpal blood-flow fell dose-dependently to 74.6 +/- 5.0% at 100% oxygen ventilation (n=21). Systemic hyperoxia, therefore, induces a significant reduction in pulpal blood-flow whereas pulpal tissue oxygen tension remains relatively stable, indicating an oxygen-dependent local regulatory mechanism.     

Identification of a novel loss-of-function mutation of the <Emphasis Type="Italic">GLA</Emphasis> gene in a Chinese Han family with Fabry disease

Background

Fabry disease is an X-linked recessive lysosomal disorder caused by deficient enzymatic activity of α-galactosidase A (α-Gal A). The insufficient enzymatic activity leads to excessive accumulation of glycosphingolipids, the substrates of the enzyme, in lysosomes in organs and tissues. Mutations in the α-Gal A gene (GLA, Xq22) have been proven to be responsible for Fabry disease.

Methods

In this study, we report a four-generation pedigree with left ventricular hypertrophy and chronic renal failure that was diagnosed by sequencing the GLA gene. An over expression system was constructed to evaluate the function of the detected mutation.

Results

We identified a novel mutation in exon 6 of the GLA gene, p.Asn278Lys, which completely co-segregated with the disease phenotype. The protein level of α-Gal A was significantly lower in the variant group than in the wild-type group; additionally, the pharmacological chaperone 1-deoxy-galactonojirimycin (DGJ) effectively normalized the enzyme activity of α-Gal A and its decline at the protein level.

Conclusions

This study is the first to report a novel loss-of-function mutation, p.Asn278Lys, in exon 6 of the GLA gene as a genetic aetiology for Fabry disease. In addition, we analysed the feasibility of DGJ as a therapeutic approach for this particular GLA mutation.

     

Clinical Decision Making for a Tooth with Apical Periodontitis: The Patients' Preferred Level of Participation

Introduction

To effectively engage patients in clinical decisions regarding the management of teeth with apical periodontitis (AP), there is a need to explore patients' perspectives on the decision-making process. This study surveyed patients for their preferred level of participation in making treatment decisions for a tooth with AP.

Methods

Data were collected through a mail-out survey of 800 University of Toronto Faculty of Dentistry patients, complemented by a convenience sample of 200 patients from 10 community practices. The Control Preferences Scale was used to evaluate the patients' preferences for active, collaborative, or passive participation in treatment decisions for a tooth with AP. Using bivariate and logistic regression analyses, the Gelberg-Andersen Behavioral Model for Vulnerable Populations was applied to the Control Preferences Scale questions to understand the influential factors (P ≤ .05).

Results

Among 434 of 1,000 respondents, 44%, 40%, and 16% preferred an active, collaborative, and passive participation, respectively. Logistic regression showed a significant association (P ≤ .025) between participants' higher education and preference for active participation compared with a collaborative role. Also, immigrant status was significantly associated with preference for passive participation (P = .025).

Conclusions

The majority of patients valued an active or collaborative participation in deciding treatment for a tooth with AP. This pattern implied a preference for a patient-centered practice mode that emphasizes patient autonomy in decision making.     

Discordance Between Patient and Surgeon Satisfaction After Total Joint Arthroplasty

We surveyed 331 patients undergoing total hip or knee arthroplasty pre-operatively, and patients and surgeons were both surveyed 6 and 12 months post-operatively. We identified variables (demographic factors, operative factors and patient expectations) as possible predictors for discordance in patient–surgeon satisfaction. At 12 months, 94.5% of surgeons and 90.3% of patients recorded satisfaction with the outcome. The discordance between patient and surgeon satisfaction was mainly due to patient dissatisfaction–surgeon satisfaction. In an adjusted analysis, the strongest predictors of discordance in patient–surgeon satisfaction were unmet patient expectations and the presence of complications. Advice to potential joint arthroplasty candidates regarding the decision to proceed with surgery should be informed by patient reported outcomes, rather than the surgeon's opinion of the likelihood of success.