Papers by Keyword: Histomorphometry

Abstract: NanoBone^® Block is the alternative to autogenous bone blocks and offers doctors a rapid, simple operating procedure in combination with a low risk of complications. Aim of this work was to develop a bone grafting block with elastic properties for dental and orthopedic surgery which is ready to use. An easy handling has to be connected with quick regeneration. Therefore, NB granules have been combined with an elastic hydrogel carrier based on Polyvinylpyrrolidone (PVP) and silica sol. Mechanical properties were optimized for an enhanced handling by cross linking and simultaneous sterilization of the PVP with gamma radiation. Cross linked PVP has the capability of swelling in water without being solved. To approve biocompatibility of adjusted material an in vivo study was analyzed using a standardized bone defect model in rat tibiae. Defect was filled with elastic bone grafting material. After 21 and 63 days rats were sacrificed and tibias analyzed. Histomorphological analysis showed an increased bone formation but even a decelerated resorption of elastic biomaterial. Quantitative compositional analysis showed a decrease in silicon content of granules as a process of matrix change.

Abstract: The aim of this study was to evaluate the osteoconductive properties of synthetic porous hydroxyapatite prepared by low-temperature microwave processing OssaBase^® HA (SPHA) in comparison with biological apatite, non-sintered deproteinized bovine bone Bio-Oss^® (DBB). The materials were implanted into the bone sockets of the tibia of Beagle dogs for 3 and 6 months. The bone response to granules of the materials of similar sizes was compared. Histological analysis of the specimens with histomorphometry was performed at different times after in vivo implantation. Based on the histological analysis, the level of bone formation in the spaces between the implanted granules and through the interconnected pores of both implanted materials within a cortical region was significantly higher (bone area ingrowth 72–85%) than within a cancellous bone site (bone area ingrowth 16–28%) at three and six months after implantation. According to our study, the bioactive and osteoconductive properties (bone implant contact and bone area ingrown) of the synthetic porous hydroxyapatite are very high and comparable with the biological apatite, non-sintered deproteinized bovine bone. The favourable influence of the high specific surface area and carbonate content of the synthetic, porous hydroxyapatite on bone formation was confirmed.

Abstract: The comparative investigation of a highly nanoporous bone grafting material (NanoBone S, NBS) and a sintered hydroxyapatite ceramic (Cerabone, CB) aimed to show the influence of the structure of the material on osteoinductivity.NBS consists of synthetic nanocrystalline hydroxyapatite embedded in a porous silica gel matrix. Its specific surface amounts 206 m²/g in contrast to CB with a specific surface of 0.4 m²/g.The biomaterials were implanted in the neck region of 18 sheep and left there for the periods of 6, 12 and 26 weeks. In each case granulate was implanted superficially into the trapezius muscle and into the subcutaneous adipose tissue respectively. The samples were analysed by micro-CT, histochemistry, immunohistochemistry and histomorphometry. In the case of NBS ossicles had developed. An intensive remodelling process was verifiable. The bone formation in CB was marginal.As a basic phenomenon in NBS, the substitution of the original SiO₂ gel matrix by organic molecules forming an organic matrix around the embedded hydroxyapatite seams to be the key event causing these results.

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: Many attempts had been made to improve the durability of artificial joint replacement and other orthopaedic implants by approaching the mechanical properties of bone and artificial material. The most joint prostheses used today are manufactured of metal alloys based on cobalt, chromium or titanium. The mechanical stiffness of these materials is much higher than that of natural bone resulting in adverse effects such as local overloading on one hand or stress shielding phenomena with the lack of adequate mechanical load on the other. Both mechanisms contribute to earl loosening and failure of implants. Polymer materials may deliver mechanical properties very similar to bone and their mechanical behaviour may be modified in a wide range during the process of manufacturing. First attempts to lower the stiffness of the implant material and to gain the stiffness range of natural bone were made in the seventies by R. Matthys with his concept of “isoelastic hip prosthesis”. In this prosthesis the femoral stem was manufactured of polyacetal, a thermoplastic polymer with very good biocompatibility and elastic properties which are much nearer to bone than common metal alloys. While the prosthesis showed good results during the mechanical testing the clinical use in vivo became a disaster. Shortly after implantation polyacetal was degraded in the body and broke down under the immense loading of the human hip joint. Later attempts to use polymer materials alone for load bearing implants also failed in clinical practice over a long time because the mechanical interlocking between bone and implant was not sufficient for the biological demand. To make the outstanding properties of polymer materials useable for load bearing implants they are backed with metal alloys (as polyethylene for hip joint cups) until the presence. Only recent developments of polymer science succeeded in the use of polymers for loaded implants. One of the most interesting materials seems to be the polyetheretherketone (PEEK) which is successfully used for spinal fusion cages [2] and computerdesigned individual implants for defect reconstruction in the skull [4] meanwhile. A pre-clinical study of a new anatomically shaped flexible acetabular cup reported satisfactory results recently [3].

Abstract: The aim of this paper was to evaluate the usefulness of coupling digital image analysis with immunohistochemistry and histomorphometry data to the study of tissue response to hydroxyapatite in a model of critical size bone defect in calvaria of rats. A transosseous defect measuring 8 mm in diameter was performed with a surgical trephine in the parietal bone of 40 rats and divided into two experimental groups according to the treatment: group I (blood clot, control), group II (HA) and killed 1, 3, 6 and 9 months after implantation (n=5/group/period). The skullcaps with overlaying skin were collected and processed for paraffin embedding. The specimens were cut in the laterolateral direction into 5-µm thick semi-serial sections and stained with hematoxylin-eosin for identification and counting of polymorphonuclears cells, mastocytes, and multinucleated giant cells, MNG, or immunolabeled with anti- lysozyme, -factor VIII and –PCNA. Digital images were obtained and analyzed with the ImagePro-Plus® software for cell couting (polymorphonuclears cells, mastocytes, macrophages and MNG) and microvessel density. Image segmentation of anti-PCNA immunostaining was used for cell proliferation analysis. The digital images obtained allowed clear identification of cells of interest by through morphological aspects or immunostaining. Data recording and analysis was facilitated by the use of specific software for image processing and graphical and statistical analysis. It can be concluded that the techniques applied were usefull to identify and count cells, structures and process of interest making easier the effectiveness of hydroxyapatite in the critical size defect in rat calvaria model.

Abstract: Biomaterials for treatment of bone defects have been studied for a long time. Alloplastic materials, mainly hydroxyapatite (HA), are under intense investigation due to its biocompatibility and osteoconductive properties. The HA can be modified by the incorporation of bivalent cations as Zn2+ known as a positive effectors for bone repair. The purpose of this study was to evaluate comparatively the effectiveness of 5% zinc-containing hydroxyapatite (ZnHA) in the treatment of critical size defect (CSD) in rat’s calvaria. CSD (8mm diameter) created in the skull of forty-five Wistar rats were filled with autogenous bone, HA and ZnHA. Skulls harvested after 30, 90 and 180 days were submitted to histological processing for paraffin embedding. Sections of 5 µm-thick stained with hematoxylin and eosin (HE) allowed histomorphometric analysis. The area of neoformed bone increased (p<0.001) from 30 to 180 days irrespective to treatment groups. ZnHA and the control group showed a large at 180 days but no significant difference compared to HA. Therefore, we concluded that both biomaterials are biocompatibles and osteoconductors, promoting new bone formation and apposition of bone on the surface throughout the periods and the addition of zinc improved the osteogenesis.

Abstract: In order to develop bone substitute with osteogenic properties, a novel strategy of grafting cyclo-DfKRG peptides to enhance cells adhesion and osteointegration of hydroxyapatite (HA) implants was developed. Objectives of the study were (1) to evaluate the osteogenic properties of HA implants grafted with RGD peptides and (2) to compare histomorphometry and micro-computed tomography ((CT) with bone quantification. Pure HA grafted or not with cyclo- DfKRG peptides and autologous stromal cells was implanted in femoral condyle on 2 groups (2 and 4 weeks) of 6 New Zealand rabbits. Measurements concerning bone reconstruction and material structure were obtained with a (CT and the results were compared to those obtained after histomorphometry. Finally, it appears that grafting cyclo-DfKRG on HA implants enhances nonsignificantly the rate of bone formation, and a high correlation of the results was found comparing histomorphometry and (CT analysis.

Abstract: To analyze the importance of bone quality, we studied 21 primary compressive trabecular system by micro-computed tomography(micro-CT), finite element analysis and destructive mechanical test. Significant correlations were found between histomorphometry and biomechanical parameters. The results indicate that the bone quality of primary compressive trabecular system is determined more by its combined micro-structural parameters (histomorphometry) and biomechanical parameters than histomorphometry only. Assessment of trabecular bone by finite element analysis may become important not only for assessment of bone quality but also for prediction of bone fracture risk of bone degeneration.

Abstract: Zirconia was introduced into the dentistry as a metal-replacement material because of its outstanding mechanical properties like high flexural strength and fracture toughness. The purpose of this study was to evaluate bone response and examine the surface characteristics of zirconiabased implant. Screw shaped c.p. titanium implants(group 1), HA-based composite implants(group 2), HA/FA coated ZrO2 implants(group 3) and FA coated ZrO2 implants(group 4) were installed in rabbit tibias. After 4 and 12 weeks of healing period, the histomorphometric analysis was performed with an Olympus BX microscope connected to a computer. The percentage of bone-to-implant contact in the 3 best consecutive threads and the percentage of bone inside the same threads were calculated. the present study demonstrated the excellent bone response of ZrO2-based implants fabricated by various methods to combine the advantages of ZrO2, HA, and FA.