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Biomedical subjects

J P Duprez

Publications and source records attributed to J P Duprez.

At least 19 recordsLinked to original sources
PubMed1997

Comparative evaluation of polishing systems on the surface of three aesthetic materials.

This study compared the efficacy of three different polishing methods on a resin composite, a glass ionomer cement (GIC) and a compomer. Thirty samples of each material were prepared. Ten of them were randomly assigned to one of the three polishing methods. The surface roughness (Ra) of the samples were measured before and after the polishing procedure with a profilometer. There was no statistical difference between the composite and the compomer prior to polishing but statistical difference was found between the GIC and the two other materials. After polishing, the smoothest surfaces were obtained using Sof-Lex discs for the three materials, and the roughest surface, with tungsten carbide burs for the composite and the compomer, and with Enhance kit for the GIC. The composite gave the smoothest surface with the three methods.

Compomers↗
PubMed1994

Removal of calcified attached denticle with a pulsed dye laser. A case report.

This article presents the removal of an attached pulp denticle with the use of a pulsed dye laser. The quartz fiber was introduced in the root canal and placed in direct contact with the free border of the denticle. Thirty-two pulses were necessary to fragment the pulp stone. A scanning electron-microscopic study shows a sharp section at the base of the pulp stone.

Dental Pulp Calcification↗
PubMed1993

An in vitro study of two adhesive systems: third and fourth generations.

The aim of this in vitro study was to compare the adhesive properties of a manufacturer's third and fourth generation dentin adhesive. Vestibular sections of recently extracted third molars were embedded in chemical-cured acrylic resin and ground with 600-grit silicon carbide sandpaper. Fifteen samples were prepared with the adhesive products and the dentin surfaces were analysed by SEM. Twenty-four samples were divided into two groups and prepared with third and fourth generation systems, respectively. Composite filled tubes were then positioned on the prepared dentin surfaces and photopolymerized. The treated samples were kept in distilled water at 37 degrees C for 24 h. Four samples were used to analyze the resin-dentin surface. A tension test was performed on the remaining twenty samples at a crosshead speed of 0.5 mm/min. The results were analyzed using the Fisher and Student t-tests. The fractured surfaces were examined by SEM. The resistance to tensile forces of specimens prepared with the fourth generation system was significantly higher than that obtained after using the third generation system. Thus, as expected from the in vitro tests, the fourth generation system provided better adhesion to dentin than the third generation material.

Adhesiveness↗
PubMed1991

Crystal growth on enamel in relation to acid etching.

Crystal formation may occur during etching of enamel surfaces with phosphoric acid. In this in vitro study we observed, from a morphological standpoint, some crystals left after etching, on the surfaces, using the scanning electron microscope. More often, after water-spraying, a thin generalized precipitate remains on the surface. This precipitate may be harmful for the retention of composite resins. On few specimens we obtained needle-shaped or petal-like crystals. Crystal deposits were spread evenly, on the surface, or nucleated from different points. We tempted to identify these crystal formations by X-ray diffraction and microprobe analysis. Chemical identification seems very important because calcium phosphates solubility varies. Crystal dissolution in saliva can lead to marginal leakage and impairs the quality of esthetic restorations. On the contrary insoluble crystals may ensure microscopic retentions and crystal growth is now considered as an alternative for enamel pretreatment in bracket bonding. Crystal formation, in these first experiments, is too scarce to be used for crystal bonding. But it appears that two factors may enhance the crystal number: a preliminary topical application of fluoride and adsorption of an acidic protein, on the surface, before etching. However, further investigations are still necessary.

Acid Etching, Dental↗
PubMedDate not supplied

[Evaluation of an immediate cleaning and decontamination device].

A new technical approach for immediate cleansing and decontamination was studied. Control of cleansing was observed using macroscopic and microscopic (S.E.M.) examinations on different instruments currently used in dentistry. Antiseptic solution was tested regarding four bacterial strains representative of the normal oral flora. The synergistic action of the combined solution plus pressure was effective for removal of debris before they dry. Antiseptic solution was bacteriostatic and at concentration level recommended by the manufacturer, viable colonies were not detected.

Chlorhexidine↗
PubMedDate not supplied

[Enamel, composites and Coca-cola].

The purpose of the present investigation was to evaluate the action of coca-cola on two composite materials (Silux and Valux) and on enamel. Discoloration of the composites was estimated according to Smales Index and enamel surfaces were analyzed by SEM. No discoloration was observed on restorative resins but coca-cola produced an important demineralization of the enamel. This demineralization was similar to enamel acid etched with 50% phosphoric acid for 2 mn.

Beverages↗