Biomedical subjects

Jean-Marc Meyer

Publications and source records attributed to Jean-Marc Meyer.

4 recordsLinked to original sources

PubMed2007

Cementable implant crowns composed of cast superstructure frameworks luted to electroformed primary copings: an in vitro retention study.

OBJECTIVE: The aim of this in vitro study was to investigate, on ITI solid abutments, the retention values of single crowns fabricated using an alternative prosthetic solution: secondary cast superstructure luted to an electroformed primary coping. MATERIALS AND METHODS: Fifty standard 4.1 mm ITI implants and 5.5 mm high ITI machined abutments were assembled and mounted in acrylic resin. Implant/abutment assemblies were randomly divided into two groups. In the test group, primary galvanic caps were directly fabricated on implant abutments (A.G.C. Micro machine), and a secondary cast noble alloy superstructure was luted on each primary galvanic cap with a resin cement (Nimetic Cem). In the control group, prefabricated burn-out caps were used for casting the metal frameworks. Test and control crowns were cemented using a resin cement (Panavia 21). After storage at 37 degrees for 24 h, the specimens were subjected to a pull-out test using an Instron universal testing machine. The load required to dislodge each sample and the respective mode of failure were recorded. Means and standard deviations of loads at failure were analyzed using ANOVA. Statistical significance was set at P< or =0.05. RESULTS: The retention values (+/-SD) of loads at failure were 67.26 (+/-16.61) for the test group and 44.03 (+/-9.45) for the control group. In the test group no separation occurred between the electroformed (galvanic) primary cap and the secondary superstructure. CONCLUSIONS: The results showed that this prosthetic solution is superior on retentive performance than the conventional cast framework. An added clinical advantage of this novel method is its potential to provide a totally passive fit. Further in vitro and in vivo studies involving multiple-unit restorations are needed in order to more generally validate this prosthetic concept.

Cementation↗

PubMed2005

Ultrasound of the ankle: anatomy of the tendons, bursae, and ligaments.

Ankle tendon and ligament disorders are commonly encountered in everyday orthopedic practice. Whereas tendons can be affected by traumatic, degenerative, and inflammatory conditions, ligaments are mostly involved by tears. Ultrasonography (US) has been accepted worldwide as an efficient, ready, dynamic, and noninvasive tool in assessing ankle tendons and ligaments. The recent technological advances in software and hardware of US equipment have improved the possibilities of US in ankle assessment, and modern equipment allows an accurate depiction of ankle structures. As with all imaging modalities, knowledge of the scanning technique and knowledge of normal US anatomy are prerequisites for a successful examination. In this article we briefly review the normal anatomy of ankle tendons and main ligaments relevant to the US examination. Then we present the routine US technique of examination for the anterior, posterolateral, posteromedial, and posterior region followed by a description of the normal US appearance of tendons, bursae, and ligaments.

Achilles Tendon↗

PubMed2003

[Characterization of three light sources. Study of their efficiency].

Light-emitting sources are currently used to activate the setting reaction of restorative composite resins. It is well known that the polymerization extent of the resins will highly influence their clinical behavior. The monomer-polymer transformation will mostly depend on the chemical nature of the photo-initiators used and on the luminous energy given by the curing device. The aims of this study were to characterize three light curing devices and to compare their efficiency to polymerize a composite resin (SureFil). For that purpose, the emission spectra and the irradiance of a plasma arc (Flipo), a QTH visible light (Elipar Trilight), and a LEDs curing device (Elipar Freelight) were measured. Then, the depth of cure and the Vickers hardness of composite samples were evaluated, for each curing device, as a function of the exposure time. The emission spectra obtained showed the irradiance of the visible light emitted as a function of the wavelength, which was different for each light-curing device. The maximum cured depth (approximately 4 mm) give only a qualitative indication of the extent of the polymerization, as the hardness of the composite samples diminished as a function of the depth. Moreover, it strongly depended on the exposure time. Hence, to obtain a hardness of approximately 100 HV 0.5 at 2 mm depth, the illumination time must be at least of 3 s with the plasma arc Flipo, 10 s with the LEDs Elipar Freelight and 20 s with the QTH Elipar Trilight. In order to efficiently polymerize a composite resin, the emission spectra of the luminous source shall correspond with the absorption spectra of the photo-initiators. The present study showed that the LEDs Elipar Freelight is the most efficient curing device when the camphorquinone is used, as 92% of the emitted energy will be absorbed by the initiator. However, the power of this source is relatively low, hence higher exposure time shall be used.

Composite Resins↗

PubMed2002

Bonding to dentin achieved by general practitioners.

The objectives of this study were (1) to investigate the effect of operator variability on the shear bond strength of adhesives to dentin and (2) to determine the effectiveness of education on bonding performance for different types of adhesives. Thirty general practitioners were recruited for a CE course by a regional mailing. They used bovine dentin as a substrate for bonding the adhesive system they routinely used in practice and two other materials (no previous experience). Each adhesive OptiBond FL, ScotchBond Multipurpose Plus, ScotchBond 1 and Clearfil SE was applied according to manufacturer's instructions and immediately tested using a shear bond strength test. Shear bond strengths between adhesives and dentin were compared before and after a 90 min lecture on bonding principles and materials. For dentists with and without previous experience with a material, there were no statistically significant differences seen before and after the lecture (paired t-tests, p < or = 0.05). However, in every case, the bond strengths after the lecture were higher than those before (range of improvement from 15 to 150%). For dentists with routine experience with a particular material, all materials were statistically equivalent after the lecture, although the OptiBond FL was the highest. For dentists who had no previous experience with a material, the ScotchBond 1 had lower bond strengths than the other materials after the lecture. There was a large range in the ability of dentists to manipulate adhesive systems correctly. However, if a dentist has sufficient experience and receives sufficient education, any of these materials can give reasonable results.

Analysis of Variance↗