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Biomedical subjects

R Bedini

Publications and source records attributed to R Bedini.

At least 19 recordsLinked to original sources
PubMed2006

Cyclic fatigue resistance and three-dimensional analysis of instruments from two nickel-titanium rotary systems.

AIM: To determine how instrument design affects the fatigue life of two nickel-titanium (Ni-Ti) rotary systems (Mtwo and ProTaper) under cyclic fatigue stress in simulated root canals. METHODOLOGY: Cyclic fatigue testing of instruments was performed in stainless steel artificial canals with radii of curvature of 2 or 5 mm and an angle of curvature of 60 degrees . A total of 260 instruments were rotated until fracture occurred and the number of cycles to failure were recorded. The morphology of Ni-Ti rotary instruments was investigated by measuring the volume of millimetre slices of each instrument size starting from the tip to the shank by means of microCT analysis. The fracture surface of three representative samples of each size was analysed by scanning electron microscopy (SEM). Data were analysed by one-way anova, Holm t-test, paired t-test and linear regression; the significance was determined at the 95% confidence level. RESULTS: Cycles to failure significantly decreased as the instrument volume increased for both the radii of curvature tested (P < 0.01). The radius of curvature had a statistically significant influence on the fatigue life of the instruments (P < 0.05). Larger instruments underwent fracture in less time under cyclic stress than smaller ones. SEM evaluation showed typical features of fracture through fatigue failure. CONCLUSIONS: The metal volume in the point of maximum stress during a cyclic fatigue test could affect the fatigue life of Ni-Ti rotary instruments. The larger the metal volume, the lower the fatigue resistance.

Analysis of Variance↗
PubMed2006

Quality assessment and cataloguing of telemedicine applications.

We created a Web catalogue of approved telemedicine systems that authoritative Italian research bodies had made available for more general use. The evaluation process was divided into two stages: (1) classification of the telemedicine systems and rough preliminary evaluation; (2) assessment of the telemedicine products and services. The scoring method was applied to four well-known telemedicine systems that had been tested in health-care settings: an echocardiology teleconsulting and analysis system; a ward nursing management system; a virtual cooperative system for the management of oncology patients and a telepathology system based on remotely controlled microscopy. After technical revision during the standardization/qualification process, the applications were transferred successfully to eight new health-care facilities. The methodology achieved the main goal of providing effective tools, such as a set of quality control procedures for telemedicine and telehealth projects and a Web catalogue of telemedicine applications with a standardized level of quality, available to all interested parties.

Cataloging↗
PubMed2000

Evaluation of guided bone regeneration in rabbit femur using collagen membranes.

The aim of the study was to evaluate the mechanical performance and the structure of neoformed bone around hydroxyapatite-coated titanium fixtures according to guided bone regeneration techniques. Ten hydroxyapatite-coated titanium fixtures were inserted in the femurs of five rabbits, in which a cortical defect was created and after the insertion of the fixture, covered with a resorbable membrane obtained from bovine Achilles tendon collagen Type I (A implant). In the same femur, a second fixture was inserted in similar cavities without application of the membrane (B implant). After 60 days, the animals were sacrificed, and block sections of the femoral bone containing the implants were embedded in polymethylmetacrylate and subjected to tensile shear-stress at break testing. After the detachment of the implants from the bone, their surfaces were examined with a scanning electron microscope. Tensile shear-stress values for A and B implant specimens were comparable to some extent, but the former had a lower performance. In this regard, scanning electron microscope observations showed that the neoformed cortical bone present cervically around implant A was much thicker than around implant B.

Absorbable Implants↗
PubMed1994

A PC-based generator of surface ECG potentials for computer electrocardiograph testing.

The system is composed of an electronic circuit, connected to a PC, whose outputs, starting from ECGs digitally collected by commercial interpretative electrocardiographs, simulate virtual patients' limb and chest electrode potentials. Appropriate software manages the D/A conversion and lines up the original short-term signal in a ring buffer to generate continuous ECG traces. The device also permits the addition of artifacts and/or baseline wanders/shifts on each lead separately. The system has been accurately tested and statistical indexes have been computed to quantify the reproduction accuracy analyzing, in the generated signal, both the errors induced on the fiducial point measurements and the capability to retain the diagnostic significance. The device integrated with an annotated ECG data base constitutes a reliable and powerful system to be used in the quality assurance testing of computer electrocardiographs.

Electrocardiography↗
PubMed1994

Mechanical performance of dental amalgam--composite interfaces.

Composite veneering of amalgam is the most aesthetical solution to extensive direct tooth restoration and is applied with success in specific clinical situations. An in-vitro technique has been used to evaluate the mechanical performance of one amalgam bonded to four different composites. The amalgam-composite interfaces were subjected to tensile stress and shear stress at break tests, using dumb-bell and sandwich specimens in a PC-controlled electronic dynamometer equipped with innovative grips. Mean values were higher for tensile stress than for shear stress. Further studies and clinical experimentation will be necessary to explore the question of long-term reliability.

Acrylic Resins↗
PubMed1993

VAD Biomer blood sacs: mechanical tests and ultrastructural observations.

Ventricular Assist Devices (VADs) are a support to the heart function and are used as bridge to transplantation for a brief period in patients awaiting a donor heart. They consist of two sacs with two artificial valves that allow blood flow, the whole connected to a specific electronic equipment. This study examines the performance of a segmented-polyurethane elastomer, namely Biomer, that has been extensively used to manufacture pneumatically actuated VAD blood sacs. Specimens obtained from three VAD blood sacs explanted from three human patients and specimens from one unimplanted blood sac were investigated for mechanical performance of the material and for the changes it undergoes as a result of mechanical stress and interaction with the surrounding biological environment. The application of tensile strength at break yielded no relevant differences between unimplanted and explanted specimens. Biomer exhibited a high elongation at break for both groups, with somewhat lower values for explanted specimens. SEM observations carried out on the inner surface--in contact with blood--of unstressed explanted specimens showed no thrombotic deposits, calcifications, microbial contamination or structural changes. The complementary broken surfaces of stressed specimens showed a distinctive fracture pattern.

Biocompatible Materials↗
PubMed1992

'Ciliated' tumour cells in ascitic fluid from two cases of cystadenocarcinoma of the ovary.

We report two cases of primary carcinoma of the ovary in which 'ciliated' adenocarcinoma cells were found in the ascitic fluid. Transmission electron microscopy revealed that these were not true cilia but rather a prolific growth of abnormal microvilli. The cytological findings were compared with the histological appearances of the primary tumour. No ciliated cells were seen in the primary tumour, suggesting that the formation of the microvilli represented an independent proliferation of the cells in the fluid. Special staining reactions for mucin, alkaline phosphatase and epithelial membrane antigen were identical in the primary tumour and the cells in the ascitic fluid.

Adult↗
PubMed1991

Evaluation of an experimental periodontal ligament for dental implants.

To improve the devices used in dental implantology, a new experimental supporting element has been developed. The device, made of titanium, poly(methylmethacrylate) and Dacron tissue, has been tested for the osteointegrability of its outer Dacron coat by implants in mandibular bone of rabbits. The Dacron filamentous tissue became incorporated by the bone at 3 month post-implantation. This might provide a reliable mechanical anchorage of the device and a barrier against epithelial proliferation and microbial contamination. Preliminary results relating to in vitro evaluation of the poly(methyl methacrylate)-Dacron fixation strength predict favourable mechanical behaviour at this interface and in the complete implanted device.

Animals↗
PubMed1988

Pacemaker registration electronic-card. A proposal for a computerised system of storing of the pacemaker registration card.

This paper describes an example of a computerised system dedicated to store an Emergency Health Card into a compact and portable memory support such as the CMOS RAM CARD. Details are given from the system used and of the program developed for this task. In particular, patient, pacemaker and lead data are stored by the prototype system. The acquisition layout is similar to that of the European pacemaker registration card but some other sections are added. The possibilities of an introduction of a card system like this on E.E.C. countries is discussed.

Computer Systems↗
PubMed1976

Methods for the study of regional myocardial perfusion in patients with atherosclerotic coronary artery disease: findings at rest after nitroglycerin and during angina pectoris.

In patients with ischemic heart disease the evaluation of regional myocardial perfusion by 133Xenon intracoronary injection using a gamma camera computer system allows the detection of regional alterations of myocardial perfusion. While at rest a minority of the patients studied shows large alterations, during pacing induced angina a severe reduction of regional myocardial perfusion can be evidenced both in initial distribution scintigrams, when the injection is performed during angina, and on the washout curves when angina is induced immediately after the injection, during the course of the washout.

Angina Pectoris↗