Papers by Author: Th. Gerber

Abstract: Various bone graft substitutes were used in clinical practise in the treatment of bone defects after trauma or osteoporosis. Many synthetic biomaterials were developed in recent years primarily based on hydroxyapatite (HA). NanoBone^® is a nanocrystalline hydroxyapatite (HA) embedded in a porous matrix of silica (SiO₂). The ratio of HA:SiO₂ varied between 76:24 (wt%; NanoBone^®) and 61:39 (wt%; Nanobone^® S). The two bone substitutes NB and NB S and a natural bovine bone substitute Bio-Oss^® (BO) were evaluated by means of implantation in the tibia of the rat. The aim of this study was to analyze the remodelling process and to measure new bone formation and degradation after implantation of these biomaterials. A tibia defect model was used for all investigations with testing periods of 12, 21 and 84 days. (n=5 for each time point). The results showed, that all bone grafts were well accepted by the host tissue without inflammatory reactions. In comparison to the biomaterial BO, NanoBone^® and NanoBone^® S were quickly degraded, whereas autologous proteins were incorporated into nanopores. New bone formation was statistically higher in NanoBone^® S compared to Bio-Oss^® in defect area after 84 days implantation. The presence of osteoclasts in tissue sections were demonstrated by TRAP- and ED1-immunohistology.

Abstract: In clinical practice arises an increasing need for bone substitute materials. The main inorganic part of bone is the hydroxyapatite (HA). A new hydroxyapatite formula was created by a sol-gel-process at low temperature level [4]. The aim of this investigation was to test the biodegradation and the induction of bone formation by this new material and to compare these versus conventional fabricated HA and ß-TCP. 30 one-year-old Goettingen minipigs were divided into five groups. Critical size defect (>5 m3) in the mandible was treated differently in all 5 groups:-group I- filling with pure HA, which was fabricated by sol-gel-technique, group II- control, only gelatinous material was given, group III- conventional ß-TCP [Cerasorb®], in group IV- conventional HA [Endobone®] and in group V [Targobone®], a non denatureted bovine collagen matrix was used. Macroscopical and microscopical investigations of the former defects were made eight months postoperatively. The bone formation was superior in the sol-gel-HA-group (group I) in comparison with the control groups (group II) and the conventional fabricated ceramics groups (III and IV). In the sol-gel-HA group, the biodegradation of this new biomaterial was considered to very good with a resorption rate of more than 98%; eight months postoperatively. In this group complete bone formation was seen in former defects. In the control group, only an incomplete bone formation with 48.4% of the defect area was noted. This difference was significant (p<0,001). A less bone formation was also observed in group III and IV with 57.6% and 56.9%. The bovine non-denaturated collagen matrix (group V) leads to only 20% of new formed bone. The new calcium phosphate formula made by a sol-gel method seems to be superior and suitable for filling bone defects.