Biomedical subjects

M P Dariel

Publications and source records attributed to M P Dariel.

4 recordsLinked to original sources

PubMed2001

[Value of total thyroidectomy in amiodarone-induced hyperthyroidism].

The potential severity of amiodarone-induced hyperthyroidism, particularly in severe cardiopathy cases, necessitates a regular clinic and biologic thyroid control. The break in amiodarone and a medical treatment (synthetic antithyroid drugs, steroids, perchlorate of potassium) can be ineffective. The authors report the case of a patient with an right ventricle arythmogenic dysplasia, without thyroid history, who came back 3 years after the introducing of amiodarone with major hyperthyroidism. After failure of medical treatment, a total thyroidectomy permitted to quickly stop hyperthyroidism and to early reintroduce amiodarone. Surgery seems to be the radical treatment when hyperthyroidism doesn't respond to the medical treatment and when the cardiopathy requires amiodarone.

Adult↗

PubMed1996

Direct metallic amalgam alternative: a research update.

Discussions between two group leaders at the National Institute of Standards and Technology (NIST) led to the suggestion that a mercury-free, silver-based material could be used for dental direct-filling applications. This concept brought about a new approach that, nonetheless, is still based on powder technology such as amalgams. The resulting material also retains the tin and silver components of conventional amalgams. The condensation of a loose powder mixture into a cohesive solid relies, however, on cold-welding across atomically clean silver-silver interfaces after a mild acid treatment of the surfaces. The National Institute of Dental Research (NIDR) and American Dental Association Health Foundation (ADAHF) became involved in the research in 1992, and ADAHF scientists continue to collaborate with NIST metallurgists and electrochemists toward the further development of this promising new technology.

Dental Amalgam↗

PubMed1995

A new technology for direct restorative alloys.

OBJECTIVES: The purpose of this study was to develop a new technology for preparing mercury-free metallic dental restorative materials. METHODS: The novel approach relies on the cold welding of surface treated silver particles. At ambient temperature, intermetallic compound formation takes place spontaneously at the silver-tin interface. The ability of a loose powder to consolidate at ambient temperature under moderate pressure and within a short time duration was investigated for various mixtures of elemental silver, tin, and pre-alloyed silver-coated powders. Surface treatment aimed at removing silver surface oxide layers is done with a dilute acid. The compressive and the transverse rupture strengths of several of the consolidated powder mixtures were determined. RESULTS: Cold-welding of surface-treated powder particles takes place across the silver-silver interface and is promoted by exposure to a mild acid. Powder mixtures containing approximately 50% silver powder, 40% silver-coated silver-tin intermetallic compound particles, and a small silver-tin fraction deposited from an aqueous solution display very good condensability, depending on the amount of silver-silver interface area available. The attained rupture strength values (200 Mpa) were higher than those of amalgams; the compressive strengths (120 MPa) and hardness values (100 KHN), however, were lower than those found for amalgams. SIGNIFICANCE: Mercury-free silver-tin powder mixtures can be processed for use as metallic composite dental restorative materials.

Analysis of Variance↗

PubMedDate not supplied

Surface treatment of mercury-free alloys.

Finishing and polishing methods were examined for two metallic direct restorative materials being proposed as possible alternatives to amalgam, namely a gallium alloy and a consolidated silver alloy. The polished surfaces were compared to a conventional spherical amalgam (Tytin). After initial surface treatment with a 12-fluted tungsten carbide bur in a high-speed dental hand-piece, three polishing methods were evaluated: slow-speed polishing burs, rubber polishing points, and polishing disks (Sof-Lex). Each of these methods was followed by an additional surface treatment in which a pumice-flour/water slurry was applied with a rotary brush and a final surface treatment with a zinc-oxide/ethanol slurry that was applied with rotary rubber cups. The surface roughness was evaluated by profilometric measurements and light microscopy. The results showed that the smoothest surfaces for all metals were achieved with rotary finishing and polishing disks. Using the rubber points resulted in surfaces that were statistically similar to the disk-polished surfaces on all three materials. The polished surface of gallium alloy was consistently slightly rougher than that of amalgam. The consolidated silver also presented a consistently rougher surface than did amalgam, although these differences were not statistically significant. The additional polishing with pumice and zinc oxide improved the luster, but did not significantly improve the measured surface smoothness in any of the restorative materials studied.

Dental Alloys↗