Biomedical subjects
Publications and source records attributed to H Brömer.
In the field of bone surgery, bone cement has gained a considerable importance for the fixation of osteosynthesis material. This paper deals with the investigation of a new bone cement which is mixed with bioactive glass ceramic. In comparison to the conventional bone cement, all data pertaining to the material are improved, and histological examinations reveal an osseous connection to the superficially located glass ceramic particles.
In 38 rabbits defects of the bridge of the nose or the nasal septum were reconstructed by means of glass ceramic implants. Over a 15 months follow-up period no inflammatory reaction was observed. The mucoperichondrium remains unchanged over the implant and mucosa defects up to one square centimeter close over it. A bone lamina inserts between the mucoperichondrium and the implant surface near bone structures. New bone formations were found on glass ceramic implants that were placed into the subperichondral space of the rabbits' ears and on those implants that were covered by autologeous periost and situated in the thigh muscles of the animals.
Compound bone cement on a PMMA base with an additive of bioactive glass ceramic particles in different portions and different particle sizes are tested in animal experiments. The tissue reactions to extracorporal polymerized specimens and to in situ polymerized specimens are observed. The experiments with an implantation period up to six months demonstrate a tight bonding between the newly formed osseous tissue and the glass ceramic particles at the interface. The inflammatory reactions in the vicinity of the implant are small. It is the objective of the investigations to improve the adherance of the bone cement at the interface to achieve a more durable anchorage of bone cement in the tissue.
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Report of preparatory investigations about the usefulness of 'glass ceramics' in keratoplasty in a modification of Strampelli's method: Under the available implantation materials, glass ceramics seem to be the best as they join strongly to the bone and to interstitial tissues. As glass ceramics are suitable to keratoplasty, the necessity of loosing a tooth in osteo-odonto-keratoprosthesis after Strampelli can be avoided. Other advantages are standardization of the whole procedure, shortening of operation time and extension of indications for the operation. Based on our results, further investigations with longer implantation times, especially in eyes, are being performed at another place.
The bioactive glass ceramic Ceravital forms a physicochemical bonding with bone which is capable of withstanding stress caused by tension. This glass ceramic may already be put to clinical use as replacement for minor osseous parts. However, physical data are limited for maximum stress withstanding or gracile whole ceramic implants. In this study, metal cylinders from an alloy of CoCrMo are initially coated with a bio-compatible adhesive layer of enamel, approximately 0,2 to 0,3 mm thick. The adhesive strength of this kind of enamel amounts to about 120 to 140 kp/cm2. After the enamelling process, the glass ceramic is pressed into the enamel in granules at a particle size of 100 to 200 micrometer. As the first results show, this new process is suitable for the combination of metal implant stability and tissue compatibility of glass ceramic.
A high percentage of plastic keratoprosthesis is rejected again or intraocular infections occur because there is a cleft-like open junction between anterior chamber and lacrimal film. Only the ketratoprosthesis by Strampelli (1970) settles firmly in the cornea without the above risks, because the autogenous transplanted bone unites well with the grafted labial mucosa. 5 years of investigation have confirmed that glass ceramic Ceravital unites firmly with bones (Blencke et al. 1973, Strunz et al. 1977c, Bunte et al. 1977). For the osteo-keramo-keratoprosthesis Ceravital is used the same location as Dentin for the osteo-odonto-keratoprosthesis. The new surgical method has the advantage that 1. toothless patients can be operated, 2. the anterior chamber cannot flatten because the ceramic disk has the same shape as the corneal surface, and 3. broader optical cylinders can be used, by which a widening of the visual field is achieved.
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The use of alloplastic material in the reconstruction of the defective or atrophic mandible appears obvious as the difficulties and risks of bone or cartilage transplants are well known. It appears that all the materials used up to now were demarcated by the bone as foreign bodies so that one could only observe strong union without a connective tissue line of separation with glass ceramics. In experimental operations in the pig, box shaped osteotomies were cut into the lower jaw and glass ceramic bodies were fixed into the clefts. Clinical and histological examinations proved the bone acceptance. It appears that these bio-active glass ceramics are particularly suited as bone replacement.
After earlier experiments showed that bone became adherent to glass ceramic, the maximum mechanical stress on the bone-ceramic interface, as compared with polymethylmethacrylate (PMMA) and aluminium oxide ceramic, was investigated for shearing force and tension. Whereas the PMMA and aluminium oxide ceramic test objects which had been inclosed in the connective tissue were very easily pushed out without measurable pressure, the average fracture load for 15 smooth glass ceramic objects was 466 p/mm2 in the pushed out test and 167 p/mm2 in the tension test.
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This report describes the implantation of glass and glass-ceramics into soft tissues. These experiments revealed that our new glass and glass-ceramic materials are well compatible with soft tissues. The fibrous membrane surrounding such an implantat consists of normal dense collageneous connective tissue. The cells are fibroblasts and fibrocyt-like cells without any abnormal morphology. Macrophages could not be detected. However, the degree of implants solubility must be chosen with care, because high solubility of the implant increases the reaction of the surrounding soft tissues. The described materials are also compatible with osseous tissues. In our previous experiments we have already pointed out, that bonding developed between glass material and bone. Few weeks after implatation we have seen mature lamellar homegeneously mineralized bone opposed to the implant. There was no fibrous membrane between implant and bone. Longtime studies show that hitherto the described bonding exists about 2 years.
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