Michael A. Meenaghan

Degradative effects of conventional steam sterilization on biomaterial surfaces

Prior to implantation trials in animals, the effect of steam sterilization on the surface properties of metallic and coated biomaterials was studied. Pure germanium plates and cast surgical Vitallium discs and subperiosteal implants were treated to present three standard types of biomaterials surfaces prior to steam sterilization, ranging from scrupulously clean, high-energy metals to uniformly low-energy organic layers. Both before and after sterilization, the sample surfaces were characterized by a variety of nondestructive physiochemical techniques. The results indicate that steam sterilization is likely to compromise the properties of otherwise carefully prepared biomedical implants by depositing hydrophobic organic and hygroscopic salt contaminants over the implant surfaces.

An evaluation of early bone changes after the insertion of metal endosseous implants into the jaws of rhesus monkeys

Abstract Twenty metal endosseous implants were placed into the jaws of rhesus monkeys. Clinical, radiographic, and histologic analysis of specimens for periods of up to 3 months after placement showed that, generally, the implants were well tolerated by these primate tissues.

Evaluation of the crypt surface adjacent to metal endosseous implants: An electron microscopic study in clinically successful implants

Abstract The tissue lining the implant crypt surface in the upper and lower jaws of rhesus monkeys was examined by means of electron microscopic techniques. No epithelium or periodontal-like membrane was observed adjacent to the body of the blade but rather a highly vascular connective tissue with osteogenic potentialities. In general, no form of soft-tissue attachment to the titanium blade existed. This tissue has an outer dense cellular layer of fibroblast-like cells or mesenchymal cells, a middle layer of highly vascular osteogenic connective tissue which resembles an embryonic fibrous tissue with preosteoblasts, and a layer of osteoblasts next to osteoid matrix and bone.

The crypt surface of blade-vent implants in clinical failure: An electron microscopic study

Abstract An electron microscopic investigation was undertaken in an attempt to ascertain the nature of the blade-vent implant crypt wall in clinical failures. All observations were made on tissues removed from the crypt surface of endosseous metal implants placed in the jaws of both human subjects and rhesus monkeys. From the information currently available and the results obtained in this investigation, two conclusions appear to emerge with some degree of clarity. First, animal experimentation has demonstrated a highly vascular osteogenic connective tissue lining the implant crypt in clinically successful cases. Second, electron microscopic analysis of tissue obtained from both man and monkey and from all levels of the implant crypt surface of clinically failing blades revealed: (1) delayed osteogenesis, (2) epithelial cell migration along the entire crypt surface, (3) persistent inflammation, and (4) a thick subepithelial connective-tissue component composed of collagen fibers and inflammatory cells.

The failing blade-vent implant

Abstract The histopathologic events that follow the placement of metal endosseous blade implants are discussed. Cases were selected from groups of animals in which implants remained in place for 6 months to 2 years. In most cases, clinical symptoms correlated directly with microscopic findings. It is concluded that mobile dental implants of this type should be removed.

Physiochemical Properties of Stabilized Umbilical Vein

From the State University of New York at Buffalo, and the Calspan Corporation, Buffalo, New York. The glutaraldehyde-stabilized human umbilical cord vein has come to a successful stage of routine use for peripheral vascular reconstruction only after passing through the developmental stages of all major new biomedical products: enthusiasm, disenchantment, search for product flaws and their elimination, and, finally, careful documentation of all those procurement and processing steps necessary to satisfy the most stringent regulatory agencies. We are rewarded, now, by having achieved at least 4 years of excellent patency in human subjects with functional grafts in the most difficult peripheral locations. Their stabilized veins have been changed only moderately by lipid uptake and by fixation to the surrounding muscles and other tissues. And the thromboresistant surface properties of the luminal wall, upon which their original processing was premised have been maintained. I, 2

Immunohistochemical study of carbonic anhydrase in mixed tumours from major salivary glands and skin

Immunohistochemical distribution of carbonic anhydrase isoenzyme I and II was studied in mixed tumours of major salivary glands and skin. The normal salivary glands displayed strong carbonic anhydrase activity in both ductal epithelium and serous acinar cells and the serous demilune cells in the submandibular glands, including the eccrine ducts. Pleomorphic adenoma salivary gland origin exhibited positive staining in the innerlayer of epithelial cells of tubular, duct-like and glandular structures. No enzymatic staining was noted in the outer layer of tumour cells in these structures. Spindle tumour cells or the fibroblast-like cells with long cytoplasmic processes identified in the adjacent hyalin and myxomatous stroma were rarely positive, while chondroidal and osteo-chondroidal cells were highly reactive. Mixed tumours of eccrine gland origin showed the most reactive staining cells scattered throughout neoplastic epithelium in all tissues examined. Immunohistochemical stainability was usually higher for carbonic anhydrase II than I for both normal and tumour tissues. The biological roles of the distribution profiles of carbonic anhydrase are discussed.

Immunohistochemical localization of carbonic anhydrase in submandibular salivary glands of mice and hamsters treated with phenylephrine, testosterone or duct-ligation

Using the peroxidase antiperoxidase (PAP) technique, the submandibular glands (SMG) from normal mice showed positive carbonic anhydrase (CA) staining in both striated duct (SD) and granular convoluted tubule (GCT) cells, which varied from moderate to strong. In normal hamsters, the GCT showed strong focal staining. Phenylephrine in mice and hamsters resulted in a decrease in CA in GCT cells; staining was much reduced in the GCT segments of the mouse. One hour after a phenylephrine injection into testosterone-treated mice, there was no change in the staining intensity of GCT cells but an increase in cell size. Only a slight decrease in immunostaining occurred in mouse and hamster SD cells. CA staining in duct-ligated glands of mice decreased within 3 days but regenerated duct-like structures at later stages showed moderate staining.

Histological evaluation of pore size and shape in silicone implants in rhesus monkeys.

: Silastic has been used with varying success as an implant material. When Silastic implants fail, migration and infection are generally involved. Perforation of the implant has been suggested as a means of minimizing implant migration. In this study, 30 implants were studied in Rhesus monkeys. The implants varied in external geometric form and in perforation size. Results indicated that fibrous encapsulation of the implant occurred within two weeks. The tissue readily invaded the perforations regardless of pore size. The configuration of connective tissue was unaffected by external geometry. Perforated implants were less mobile than non-perforated implants, and implants with perforations of 3 mm or more contained dense fibrous connective tissue supported by an underlying vascular mesenchymal tissue not seen in implants with smaller pores. As a result of this study, we recommend that perforations be used in Silastic implants and that these perforations be at least 3 mm in diameter.

Seromucous cystadenoma of the oral cavity

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