Biomedical subjects
Publications and source records attributed to A Pizzoferrato.
This study presents a histologic evaluation of the healing process of dental extraction sites in dogs with and without the use of collagen sponge as an extraction site dressing. The healing process was evaluated at 3 days, 1 week, and 6 months after tooth extraction and appears comparable in both collagen-filled and nonfilled extraction sites.
Discontinuity defects were created in the mandibles of dogs and then reconstructed immediately with fresh autogenic cancellous bone grafts and Dacron-urethane prostheses. The grafts were irradiated to a total dose of 5000 rads after waiting intervals of between 3 and 12 weeks. Nonirradiated grafts served as controls. The grafts were evaluated clinically, radiographically, and histologically. There was complete incorporation of all grafts, regardless of the interval between surgery and radiotherapy. There were no soft-tissue complications. The controls were distinguishable from the irradiated grafts only by the presence of hematopoietic bone marrow. Fibrofatty marrow was observed in the irradiated grafts. Theoretical support for this technique is found in the biology of cancellous bone grafting and the pathology of radiation injury. In view of the difficulties associated with mandibular bone grafting in preoperatively irradiated patients, a new method of reconstructing selected cancer patients who require both mandibular resection and radiotherapy is suggested.
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Different factors involved in nosocomial infection and high risk hospital departments are examined. Methods of surveillance of infection in patients, in staff, and monitoring of environment and equipment are settled. The results obtained in environment monitoring and in some kinds of surgical operation are reported. A policy of epidemiological surveillance is proposed.
Surgical resection and replacement of a segment of the cervical trachea was performed in 8 mongrel dogs. The replacement was with a porous prosthesis made of Dacron cloth mesh stiffened with a heat-curing polyetherurethane. Ten tracheal rings were resected in each animal to create a complete circumferential defect of the trachea measuring 7 or 8 cm in length depending on the size of the dog. Animals were sacrificed periodically from 3 to 27 months post-reconstruction. The luminal surfaces of the reconstructed tracheae showed respiratory epithelium.
The main aspects of biocompatibility are discussed first then the methodology used and the results obtained. The cells used included epithelial cells, lymphocytes, fibroblasts, and macrophages. The most commonly used methods were morphological observation, radioactive tracer uptake, and chemotactic migration analysis. It is concluded that cell cultures are a reliable and sensitive method for initial screening in testing the biocompatibility of the materials used in the construction of prosthetic implants.
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Mandibular lengthening in mongrel dogs was evaluated in four animals. Extraoral approaches were used for mandibular exposure. Step osteotomies were performed on the buccal aspect and oblique osteotomies were performed on the lingual aspect of the mandible. The anterior fragment of the mandible was advanced 10 mm. A Dacron-urethane mesh tray, in the form of the mandible, was placed across the defect as a container of bone graft material and to help stabilize the segments. The bone graft material was harvested by aspirating the bone particles formed when the osteotomy cuts were made, thus creating a bone slurry which was placed within the implant. The results suggest that the use of the implant tray in conjunction with the bony slurry provided an appropriate physiologic setting for rapid new bone formation, restoring continuity to the defect.
The results of this preliminary evaluation of a tooth implant model combining a stylized tooth root design and a thin, highly biocompatible microporous carbon coating, although tentative, add support to the feasibility of developing a statisfactory system for the immediate replacement of selected teeth in healthy bone.
The causes of tissue reaction surrounding heterogeneous materials are: cell-mediated hypersensitivity due to an implant material; infection; post-surgery hematoma, following lysis of red cells and deposition of hemosiderin; "True" implant reaction, i.e., tissue modifications produced by wear particles of components of the prosthetic devices used. The stages of inflammation due to wear particles are: phagocytosis of particles by newly formed fibrous capsule cells; lymphatic drainage of particles through the newly formed joint capsule; granulation tissue reaction in the internal surface of the joint capsule which stores non-removed particles from inadequate drainage; necrosis of granulation tissue in contacting the artificial joint surface; formation of free masses of necrotic tissue in the joint cavity; formation of new granulation tissue due to these necrotic masses and by wear particles liberated from them (the beginning of a vicious cycle); insufficient storage by granulation tissue; formation of "auxiliary" granulation tissue in the fibrous layer of the bone-cement interfaces and in the R.E.S. of the bone-marrow; bone resorption and its replacement by granulation tissue; loosening of the prosthesis.
32 carbon coated tooth replicas were implanted in the jaws of 8 mongrel dogs for periods ranging from 3 months to 2 years. Fourteen of 16 molor implants and 10 of 16 premolar implants had 0.5 min. of mobility or less. Histology of specimens from 4 dogs sacrificed at 3 months showed new bone directly in contact with the implant surface.
The purpose of this study was to evaluate a porous Dacron - urethane mesh tracheal prosthesis in large dogs with surgically created discontinuous defects of the cervical trachea. Some protheses were carbon coated in an attempt to improve biocompatibility. Histology was performed on 2 dogs. The mucosa regenerated entirely covering the prosthesis. Respiratory epithelium was formed over a large central portion of the tracheas.
Laboratory tests carried out by means of body environment simulators have proved to be very important for the evaluation of endoprostheses potentially useful for implantation. The present paper examines the problems connected with the design of such a simulator. The results obtained with an initial, very primitive simulator concerning the outlines of the phenomena of wear, corrosion, and friction and some wear properties of commercially available hip endoprostheses are presented. From these results, the motivation that led to the design of a more advanced simulator is presented. This latter simulator is also described.
Ceramic pelletes (in Al2O3 92% and in calcium aluminate) implanted into the muscles of rabbits for varying periods of time, and samples of similar material, not implanted but mixed with organic substances, have been analyzed by means of thermal differential analysis (TDA). Which hydrated calcium aluminates are formed from implants after contract with the tissue fluid, has been established. It has also been ascertained that the ceramic implants absorb organic substances from the tissue fluid, which, from a first evaluation, seem to be composed of simple molecules. The results of this initial inquiry have provided positive indications of the utility of TDA to assist in elucidating the phenomena that occur between implant and tissue.
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