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Biomedical subjects

R Geissler

Publications and source records attributed to R Geissler.

6 recordsLinked to original sources
PubMed1995

A light and scanning electron microscopic evaluation of electro-discharge-compacted porous titanium implants in rabbit tibia.

This study used light and scanning electron microscopic (SEM) histomorphometric methods to quantitate the rate of osseointegration of totally porous titanium alloy (Ti-6Al-4V) implants prepared by a novel fabrication technique--electrodischarge compaction (EDC). EDC was used to fuse 150-250-micrometer spherical titanium alloy beads into 4 X 6 mm cylindrical implants through application of a 300-microsecond pulse of high-voltage/high-current density. Two sterilized implants were surgically placed into each tibia of 20 New Zealand white rabbits and left in situ for periods corresponding to 2, 4, 8, 12, and 24 weeks. At each time point, 4 rabbits were humanely killed, and the implants with surrounding bone were removed, fixed, and sectioned for light and SEM studies. The degree of osseointegration was quantitated by means of a True Grid Digitizing Pad and Jandel Scan Version 3.9 software on an IBM PS/2 computer. The total pore area occupied by bone was divided by the total pore area available for bone ingrowth, and a Bone Ingrowth Factor (BIF) was calculated as a percent. The light microscopic results showed BIFs of 4% at week 2, 47% at week 4, 62% at week 8, 84% at week 12, and greater than 90% at week 24. The SEM results showed BIFs of 5% at week 2, 34% at week 4, 69% at week 8, 75% at week 12, and in excess of 90% at week 24. The results of this study show that EDC implants are biocompatible and support rapid osseointegration in the rabbit tibia and suggest that, after additional studies, they may be suitable for use as dental implants in humans.

Alloys↗
PubMed1994

An evaluation of electrodischarged prototype implants in rabbit tibia: a preliminary study.

This is the first in a series of biological investigations using a porous implant fabricated by a novel process known as electrodischarge compaction (EDC). This process uses Ti-6A1-4V powder and electrical energy to construct a beaded porous implant without any compromise in physical characteristics, often found with conventional sintering. The purpose of this study was to evaluate the bone response in rabbit tibia of a porous titanium prototype implant fabricated by this new technique. One hundred forty-four porous EDC-fabricated implants were placed into the tibia of 36 New Zealand rabbits. Animals were placed into one of six time periods (2, 4, 8, 12, 18, and 24 weeks). At the appropriate time period, animals were killed, and bone ingrowth was evaluated qualitatively by light and scanning electron microscopy. Bone/implant interface bond strength was also measured. Slight bone ingrowth was observed as early as the two-week time period and increased in depth at each time period for the duration of the study. Implant/bone bond strength was measurable at four weeks and continued until reaching a plateau at week 12. The results of this study suggest that this novel EDC implant may be suitable for continued development of an easily fabricated, cost-effective dental implant.

Aluminum↗
PubMed1990

Scanning electron microscopy of corneal incisions using steel, diamond, and sapphire blades.

In order to compare the wound morphology they produce, we used steel (Myocure), diamond (CILCO DK 121), and sapphire (Katena K2-6500) blades, to make parallel linear incisions, 500 microns deep, in 12 fresh enucleated porcine eyes. There was no discernible difference among the blades in terms of either the morphology of the collagen lamellae of the sides or the depth of the incisions produced. The major differences in the cuts produced were attributable primarily to the differences in the footplates.

Animals↗
PubMed1985

Supravalvular aortic stenosis. Clinical and pathologic observations in six patients.

Supravalvular aortic stenosis with a mean pressure gradient of 101 mm Hg was encountered in six patients aged 1 1/2 to 12 years. Three patients had Williams syndrome. In two other patients the stenosis was familial. The angiographic/anatomic subtype of deformity was hourglass in four patients, diffuse in one, and membranous in one. Four patients are alive following successful surgical repair; the other two died without surgery. Microscopically, disorganized medial elements with fibrotic intima sometimes containing lacunae were observed in five cases; the one other had valvelike tissue only. Ultrastructurally, thick irregular elastic fibers, abundant swirling collagen, hypertrophied smooth-muscle cells, and scant ground substance characterized the medial tissue defect. Although hemodynamics during intrauterine development may predispose to localization of the stenosis to the supra-aortic valvar region, the cause for the mural dysplasia remains uncertain.

Adult↗