[Effect of fibrin on osseointegration of bioactive glass-ceramic materials--experimental study]

The aim of the experimental study is to find out how fibrin influences the speed of osteiontegration of bioactive glass-ceramic materials BAS-O, BAS-HA, BAS-R (LASAK Prague, Czech Republic) and how it influences the response of live tissue at the implant-bone interface in the interval of 1-8 weeks.

Dense materials BAS-0 (glass-ceramics), BAS-HA (hydroxyapatite) and BAS-R (beta tricalcium phosphate) in the form of 0.6-1 mm granules were implanted in artificially created defects in tibia of an experimental animal with the addition of 0.1 ml of fibrin adhesive system Beriplast. Control implantation was performed with the addition of physiological solution. Materials BAS-HA and BAS-R were implanted in the same way in the ratio of 7:3, 8:2 and 9:1. Duration of exposure was 1-8 weeks. Radiographs of samples were taken by Mammograph and decalcified sections were coloured by toluidine blue and examined at 60 times and 120 times magnification.

Surgical wounds were healed per primam. Radiographs of materials with the fibrin system showed clearly after one week defects and implants, after the third week part of the materials penetrated above the bone surface, after the fourth week there were evident signs of bone tissue formation between particles of BAS-HA, BAS-R and their mixtures. The most marked bone formation took place in the seventh and eighth weeks. With the use of glass-ceramics without fibrin the particles were after three weeks less clear, after the fourth week BAS-HA and BAS-R penetrated above the surface. A significant bone formation was obvious after the sixth and seventh weeks. There were no signs of resorption or fibrous encapsulating. Microscopic examination proved enveloping of particles of BAS-0 by fibrous tissue which was evident partially also after the eight week. With the use of fibrin the situation was analogical. In BAS-HA and BAS-R the finding in the first week was similar. With fibrin, there was after the third week a mature lamellar bone in the vicinity of granules and the fibrous interlayer disappeared. Neither positive nor negative impact of fibrin on the process of healing was found. With the application of BAS-R and fibrin system the bone tissue was after the third week more significant and trabeculae more bulky. The final result after eight weeks was the same: Ingrowth of the mixtures of the given materials proceeded in the same way.

The applied glass-ceramic materials are used in the clinical practice. The speed of osteointegration depends on the quality of the bone bed, and on the tolerance of these materials by live tissue. Osteintegration can be accelerated by the use of growth factors or stem cells cultivated in the tissue culture. Fibrin which creates a network along which osteoblasts can migrate should have a similar quality. It seems that of decisive importance is the thickness of the fibrin layer around the implants. If this layer is thick glass-ceramics is enveloped more probably to fibrous tissue. In a thin layer the process is accelerated within the first three weeks. After a longer exposure the differences are not evident. Samples of BAS-HA and BAS-R, both applied separately and in a mixture, showed a marked bioactivity in the experiment. During eight weeks no signs were found of resorption which is typical of tricalcium phosphate in a longer time interval.

In the experiment on an animal the fibrin adhesive system accelerated osteointegration of bioactive materials BAS-HA, BAS-R and their mixtures until the third week after the implantation. Small differences with the use of fibrin were adjusted within six weeks. Materials BAS-HA, BAS-R and their mixtures were completely osteointegrated. Glass-ceramics BAS-0 was partially enveloped by fibrous tissue, even with the use of fibrin adhesive system. During eight weeks no resorption of materials was found. The process of ingrowth can be seen on radiographs. X-ray picture of bone formation in BAS-HA, BAS-R correlates with the histological finding. The fibrin adhesive system facilitates manipulation with fine granules.