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Biomedical subjects

J J Pireaux

Publications and source records attributed to J J Pireaux.

7 recordsLinked to original sources
PubMed1998

Analysis of titanium dental implants after failure of osseointegration: combined histological, electron microscopy, and X-ray photoelectron spectroscopy approach.

A multitechnique approach has been used to characterize the surface of nonosseointegrated titanium implants and the surrounding biological tissues. Five pure titanium dental implants were used as reference, and 25 removed implants were studied. Surface and in-depth chemical compositions of the implants (from a total of 16 patients) were investigated by X-ray photoelectron spectroscopy (XPS). Histological slides of the surrounding tissues were examined by light microscopy, XPS, and electron microprobe analysis. None of the failed implants presented the regular surface composition and depth profile of the TiO2 overlayer; foreign elements (Ca, Na, P, Si, Cl, Zn, Pb, and Al) were observed on some implants. Fibrosis, lymphocytic and plasmocytic infiltrates, and granulomatous lesions were detected in the surrounding tissues. XPS and electron microprobe analysis indicated the presence of Zn, Fe, Sn, and Ti in the tissues. As a possible scenario for implant failure, we propose and discuss a oxidoreduction mechanism, leading to a partial dissolution or the complete dissociation of the protective titanium dioxide overlayer and to ion diffusion through the surrounding tissues.

Connective Tissue↗
PubMed1998

An XPS and SEM evaluation of six chemical and physical techniques for cleaning of contaminated titanium implants.

The purpose of the present study was to analyse clinically failed and retrieved implants prior to and after cleaning by means of scanning electron microscopy (SEM) and X-ray induced photoelectron spectroscopy (XPS) as compared to unused controls. Six different chemical and physical techniques for cleaning of contaminated titanium implants were evaluated: 1) rinsing in absolute ethanol for 10 min, 2) cleaning in ultrasonic baths containing trichloroethylene (TRI) and absolute ethanol, 10 min in each solution, 3) abrasive cleaning for 30 s, 4) cleaning in supersaturated citric acid for 30 s, 5) cleaning with continuous CO2-laser in dry conditions at 5 W for 10 s, 6) cleaning with continuous CO2-laser in wet conditions (saline) at 5 W for 10 s. SEM of failed implants showed the presence of contaminants of varying sizes and XPS showed almost no titanium but high carbon signals. XPS of unused titanium implants showed lower levels of titanium as previously reported, probably due to contamination of carbon which increased with time in room air. Cleaning of used implants in citric acid followed by rinsing with deionized water for 5 min followed by cleaning in ultrasonic baths with TRI and absolute ethanol gave the best results with regard to macroscopical appearance and surface composition. However, as compared to the unused implants the results from an element composition point of view were still unsatisfactory. It is concluded that further development and testing of techniques for cleaning of organically contaminated titanium is needed.

Air Abrasion, Dental↗
PubMed1996

Amination of polystyrene microwells: application to the covalent grafting of DNA probes for hybridization assays.

Amine functionalization of polystyrene microwells for covalent binding of DNA is described. Polystyrene support was first carboxylated by permanganate oxidation in diluted sulfuric acid. These functions were activated with water-soluble carbodiimide and grafted with N-methyl-1,3-propane diamine to introduce a free secondary amino group on the support. The samples were characterized by X-ray photoelectron spectroscopy and radiochemical assay. The conditions for covalent linkage of secondary amine on polystyrene microwells were optimized. Functionalized supports were used for covalent binding of a DNA capture probe for the detection of human cytomegalovirus in a sandwich hybridization assay. Sensitivity of the assay compared very well with a commercially available surface, Covalink-NH, microwell plate obtained by electromagnetic irradiation.

Amines↗
PubMed1992

Surface study of biomaterials by electron induced vibrational spectroscopy.

Besides the identification of elements and chemical groups on a material surface, the determination of its structure, or of the relative orientation of different chemical groups, is probably of utmost importance for biomaterials and their modified surfaces. 'Electron induced vibrational spectroscopy' is a new technique, as far as applications to biomaterials are concerned, and is capable of recording well-resolved vibrational bands from the extreme surface. Basics and the potentials of the technique are presented here for nonspecialists, with illustrations from model polymers, Langmuir-Blodgett films, carbon materials, and ceramics.

Biocompatible Materials↗
PubMed1991

Surface studies on titanium IMZ implants.

The aim of this study was to investigate the surface feature of the IMZ implant. Eight non-implanted new samples and four implanted samples removed one year after insertion were prepared. The 8 non-implanted samples were divided into two groups. The first group was sterilized and the second group was manipulated by bare hands. The implanted samples underwent a careful procedure to recover the metal surface. Then, both the non-implanted new samples and implanted samples were subjected to X-ray electron spectroscopy (XPS) and Rutherford back-scattering spectroscopy (KBS) analyses. Subsequently, all the samples were subjected to scanning electron microscopic (SEM) examination, and surface roughness and profilometric measurements. The SEM photomicrograph showed a rough surface composed of fused granular metal separated by gaps. Sometimes the presence of isolated well-shaped granules of 0.8-1.8 microns in diameter was observed. This structure was related to the manufacturing process of the IMZ implant. The implanted surfaces showed no intergranular gaps and appeared less rough (average roughness: Ra = 1.91 +/- 0.1 microns) compared with the new non-implanted surfaces (Ra = 4.93 +/- 0.3). XPS analysis at a maximum resolution depth of 1.5 nm revealed TiO2, C, O compounds on sterilized non-implanted surfaces. The hand-handled non-implanted surfaces on the contrary did not show TiO2 due to contamination. The elements Ca, C, O and N were found on the one-year implanted IMZ surfaces; TiO2, however, was absent. RBS analysis at a maximum resolution depth of 1000 nm, indicated a decrease of the total thickness of TiO2 after one year of IMZ implantation. The TiO2 thickness was 0.5-0.7 microns for the non-implanted new IMZ surfaces and 0.03-0.2 microns for implanted IMZ surfaces.

Adult↗
PubMed1989

Brushite in the pulp of primary molars.

This study was undertaken to investigate the mineral phase of spherulitic calcifications discovered in the pulpous mesenchyme of human primary molars by microradiography. Analytical scanning electron microscopy and x-ray diffraction disclosed that well-crystallized brushite is the major compound of the spherulites. The mechanism leading to the crystallization of brushite is far from well understood. Histologically, on decalcified sections, inflammatory cells and capillaries can be seen trapped in the spherulites. In the light of these findings, it could be suggested that metabolic conditions may promote the crystallization of brushite in the pulp of primary molars.

Adolescent↗