Biomedical subjects

A K Lundgren

Publications and source records attributed to A K Lundgren.

8 recordsLinked to original sources

PubMed2000

Influence of decortication of the donor bone on guided bone augmentation. An experimental study in the rabbit skull bone.

The aim of the present study was to evaluate if early access to the endosteal bone compartment by removal of the outer cortical bone plate will enhance bone augmentation in a secluded space. Two titanium cylinders were placed on the skull of each of 8 rabbits. Each cylinder was placed into a circular slit, secured to the skull bone via two mini-screws and supplied with a titanium lid. On the test side, the outer plate of the cortical bone, demarcated by the slit, was removed. The subsequent bleeding resulted in blood fill of the cylinders to various degrees. On the control side, the corfical bone plate was left intact and no bleeding was observed at the time of the placement of the titanium lids. After 3 months, the animals were sacrificed to obtain histology and histomorphometry. No differences in the total amount of augmented bone tissue, in relation to the total experimental area (75.5% +/- 10.9% at the test sites and 71.2% +/- 13.5% at the control sites) or of the augmented mineralized bone tissue in relation to the total amount of augmented bone tissue, was revealed (17.8% +/- 3.0% and 16.0% +/- 4.9% respectively). There was no difference in the morphological appearance of the augmented bone between test and control sites and there were no obvious similarities in the appearance between the newly formed bone tissue and the donor bone. The augmented bone consisted of slender bone trabeculae, distributed in abundant marrow spaces. A conspicuous finding was that the bone trabeculae tended to climb along the inner walls of the titanium cylinder. It is concluded that decortication of the calvarial bone in the rabbit does not result in more bone formation beyond the skeletal envelope after a healing period of 3 months compared to no removal of the cortical bone plate inside a secluded experimental area.

Animals↗

PubMed1999

Influence of surface roughness of barrier walls on guided bone augmentation: experimental study in rabbits.

BACKGROUND: By using the guided tissue regeneration concept it is possible to augment bone, beyond the skeletal envelope, provided certain biologic, surgical, and barrier-related demands are met. Among barrier-related factors of importance are the surface properties. PURPOSE: The aim of this study was to evaluate whether different surface roughness of the barrier wall influences the amount and morphology of augmented bone in a secluded space, using a titanium cylinder as barrier device placed on the rabbit skull. MATERIALS AND METHODS: Cylinders of commercially pure titanium were fabricated by machining, using a turning tool. The inner cylinder wall was either left untreated or grit-blasted with titanium dioxide to increase surface roughness. The topographic profile of the inner surface of two cylinders (1 turned and 1 grit-blasted) was measured in vitro to achieve a numeric characterization of each type of surface topography. Two cylinders, one with grit-blasted and one with turned inner walls, were surgically placed and secured to the skull bone of each of eight rabbits. The plate of the cortical bone, facing the experimental area framed by the cylinder wall was removed, and care was taken to ensure total blood fill of the cylinders. After 3 months, the animals were sacrificed to obtain histology for histomorphometry. RESULTS: The relative volume of augmented tissue in the grit-blasted cylinders (77.9 +/- 10.5%) did not differ significantly from that in the turned cylinders (73.4 +/- 5.5%, p = .118), neither did the volume of mineralized bone (20.1 +/- 8.2% vs. 22.1 +/- 7.2%, p = .064). The trabecular density of the augmented bone was higher close to the walls of both the turned and the grit-blasted cylinders compared to the overall trabecular density within the cylinders, but no significant difference between the two groups. However, the area of mineralized bone in direct contact with the inner surface of the titanium cylinder was significantly larger in the grit-blasted (33.9 +/- 13.3%) compared to the turned cylinders (12.0 +/- 8.5%, p = .01). CONCLUSIONS: The use of titanium barriers with a grit-blasted inner surface compared to barriers with a turned surface resulted in the formation of similar amounts of bone beyond the skeletal envelope of the rabbit skull. However, a larger area of augmented mineralized bone was found in direct contact with the inner surface of the grit-blasted cylinders.

Animals↗

PubMed1998

Guided jaw-bone regeneration using an experimental rabbit model.

The aims of this study were to evaluate the space-maintaining capacity of two biocompatible barrier materials and to assess the effect of barrier occlusiveness on the amount of regenerated bone. Defects were prepared in the edentulous area on both sides of the maxillas in 22 rabbits. The rabbits were divided into three groups. Gore-Tex augmentation material (GTAM) (ePTFE)-barriers were placed to cover the experimental defects and compared with totally occlusive or perforated titanium foils and uncovered control defects respectively. After four weeks of healing, histological analyses and morphometrical measurements demonstrated that the amount of regenerated bone tissue was about the same underneath the collapsed GTAM-barriers as in the controls. The highest degree of regeneration was obtained in defects underneath the titanium foils, particularly if they were perforated, whether or not they were covered by GTAM-barriers. It was concluded that the space-maintaining properties of a barrier may be at least as important as barrier occlusiveness when regenerating bone defects.

Animals↗

PubMed1997

An experimental rabbit model for jaw-bone healing.

The purpose of this investigation was to study the structural and topographical bone anatomy of the right and left edentulous areas between the incisors and molars in the rabbit maxilla with regard to the symmetry of the bone, and to assess the degree of spontaneous healing of surgical defects. Anatomical and radiographic examinations together with analysis of serial histological ground sections in ten rabbits disclosed no statistically significant differences between the two sides regarding the different bone-tissue structures, i.e. they exhibit a sufficient degree of symmetry to serve as a useful bilateral test-control model. Surgical defects were made on one side of the jaw (test side) in a group of eight rabbits. This resulted in an average loss of 17% of the total bone volume after a healing period of four weeks as compared to the untreated control side. It was concluded that surgically-created defects do not show completely spontaneous healing. From a histological section of the test side, it was possible to redraw the original bone contour by interpolation between unaffected areas of bone, coronal and apical to the defect. This means that the test side of this model can also serve as its own control with regard to the amount of regenerated tissue, given that there is unaffected bone, coronal and apical to the defect.

Animals↗

PubMed1997

Bone augmentation at titanium implants using autologous bone grafts and a bioresorbable barrier. An experimental study in the rabbit tibia.

The aim of the present investigation was to compare the effect of using autologous bone particles covered with a bioresorbable matrix barrier with the use of bone particles alone on bone augmentation at titanium implants installed in the rabbit tibia. Two Brånemark System implants, one in each tibia, were inserted in each of 9 rabbits in such a way that 5 threads were not covered with bone. Autologous bone particles were harvested from the skull and placed over the exposed implant surfaces on each tibia. The bone graft on one tibia was covered with a Guidor Matrix Barrier, while the bone graft on the other tibia served as a control. After a healing period of 12 weeks, the animals were sacrificed and specimens taken for histomorphometrical analyses. The analyses showed that a significantly larger volume of augmented bone tissue had formed at the test sites. There were, however, no differences in the amount of mineralized bone. In fact, the difference in tissue volume was due to an increased amount of bone marrow at the test sites. The degree of mineralized bone to implant contact as well as the degree of mineralized bone within the threads at the test implants were similar to that at the controls. In conclusion, it was found that the coverage of particulate autologous bone grafts with a bioresorbable barrier resulted in a larger volume of augmented bone than the use of bone grafts not covered with a barrier.

Animals↗

PubMed1997

Augmentation of skull bone using a bioresorbable barrier supported by autologous bone grafts. An intra-individual study in the rabbit.

The aim of this experimental investigation was to compare the effect of using autologous particulate bone grafts with and without a bioresorbable barrier covering for augmentation of the rabbit skull bone. For this purpose, bilateral, circular, 8 mm wide and 1 mm deep skull bone defects were prepared and overfilled with particulate bone grafts. The grafts placed in the test sites were covered with a bioresorbable barrier (Guidor Matrix Barrier). The grafts placed in the control sites were covered only by the repositioned, cutaneous flap. 12 weeks later, the animals were sacrificed, the experimental sites were defleshed and the height and volume of the augmented bone in the test and control sites were measured clinically. Histologically, morphometrical measurements of the bone tissue were performed in decalcified vertical cross-sections of the experimental sites. Statistically significant differences were found in favour of the coverage of the bone graft particles with the barrier, both with respect to the height and the volume of the augmented bone.

Animals↗

PubMed1995

The effect of mechanical intervention on jaw bone density.

The aim of this investigation was to test the hypothesis that jaw bone, subjected to mechanical intervention, will heal with increased density compared with conditions before the traumatic insult. The natural edentulous area between the incisor and the first molar on both sides of the maxillary jaw of 8 adult New Zealand white rabbits constituted the experimental model. On the test side, holes were drilled through the cortical plate and into the cancellous bone. No drilling was performed on the contralateral control side. One transversal ground section from each specimen, taken in the centre of and representing both the test and control site, was prepared to ensure that the same sagittal level of the jaw was represented. Morphometric measurements were performed and comprised assessments of the total cross-sectional area of 1) the edentulous part of the jaw, 2) the cortical bone plates and 3) the bone trabeculae and marrow spaces of the cancellous bone. The mechanical intervention resulted in a substantial alteration of the bone tissue morphology, the most conspicuous change being a markedly increased number of bone trabeculae per cancellous bone unit. Thus, the area occupied by bone trabeculae was about twice as large in the test sites compared with the control sites (+103%), whereas the area occupied by bone marrow cavities and cortical bone was significantly smaller. The clinical implications of the findings for potential treatment of fragile bone tissues and bone sites intended for implant insertion are discussed.

Alveolar Process↗

PubMed1995

Augmentation of intramembraneous bone beyond the skeletal envelope using an occlusive titanium barrier. An experimental study in the rabbit.

The aim of this investigation was to evaluate whether augmentation of intramembraneous bone beyond the skeletal envelope can be predictably achieved by placing a completely occlusive barrier on the skull bone of rabbits, hereby creating a secluded space with bone tissue being the only adjoining tissue. The experiment was carried out in 3 New Zealand white rabbits. In each animal, a midline incision was made down to the bone surface of the skull and a skin-periosteal flap was raised to expose the skull bone on both sides of the midline. Two prefabricated titanium domes with an inner diameter of 4.5 mm and an inner height of 3.0 mm were installed on each side. The domes were supplied with a horizontal, peripheral flange and a vertical edge, fitting tightly into a circular slit, prepared by a trephine into the skull bone. This arrangement ensured a stable anchorage of the dome and a reliable peripheral sealing of the space. The skin-periosteal flaps were relocated to cover the domes and sutured. After a healing period of 3 months, the animals were killed and the experimental areas excised and prepared for histological transversal ground sections with each dome in situ. The results demonstrated complete bone fill of all domes, with no signs of ingrowth of other types of tissues, indicating that the use of a barrier with total occlusiveness, sufficient stiffness and stability and reliable peripheral sealing will result in predictable bone augmentation of spaces also beyond the skeletal envelope.

Animals↗