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  • 1
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This investigation was performed to assess the bone-to-implant surface contact at fixtures of titanium that either had a standard machine prepared or a TiO2-blasted surface. Five beagle dogs were used in the experiment. Extractions of the premolars were performed in the maxilla. After 4 months of healing, 5 standard machine-prepared fixtures and 5 prepared according to the TioBlast technique were inserted. Two months later another 5 “standard” and 5 TiO Blast-prepared implants were inserted. Four months after the first fixture installation, the animals were killed and ground sections prepared from each implant site. Of the 20 implants installed, 19 were successfully incorporated. The mean bone-to-implant surface for “standard” fixtures was about 40% both at the 2 and 4 months observation interval. The corresponding figures for the TiO Blast-prepared fixtures were similar during the first 2 months of observation, while subsequently the TioBlast-prepared fixture surface seemed to stimulate to a more close bone-to-implant contact (65%) than the “standard” one.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim: The aim of present study was to evaluate if an enamel matrix derivative (Emdogain®) may enhance bone formation and osseointegration of titanium implants, using a well-documented rabbit model.Material and methods: Thirty-six threaded commercially pure titanium (cp.ti.) implants were inserted in six New Zealand white rabbits. One implant was placed in each femur and two in each tibia. Prior to implant insertion approximately 0.5 mL of Emdogain (EMD) (test) or the vehicle gel (PGA: propylene glycol alginate) (control) was injected into the surgically prepared implant site. The follow-up time was 6 weeks. Biomechanical evaluations by resonance frequency analysis (RFA) and removal torque measurements (RTQ) were performed. Histomorphometrical quantifications were made on ground sections by measurements of the percentage of bone-to-metal contact, bone area inside the threads as well as outside the threads (mirror image). Bone lengths along the implant surface were also measured and used for shear strength calculations.Results: The results demonstrated no beneficial effects from the EMD treatment on bone formation around titanium implants in any of the tested parameters. Significant differences were demonstrated with removal torque test and shear force calculations for the control implants. No other parameter demonstrated a statistically significant difference.Conclusion: The results of the present study may indicate that EMD does not contribute to bone formation around titanium implants. This observation may indicate that the bone formation that occurs after EMD treatment in periodontal defects is the result of functional adaptation. However, further research is required to evaluate the effect of EMD treatment on bone formation.
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  • 3
    ISSN: 1420-9071
    Keywords: Key words. Development; differentiation; regeneration; neuron; glia.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The central nervous system is generated from neural stem cells during embryonic development. These cells are multipotent and generate neurons, astrocytes and oligodendrocytes. The last few years it has been found that there are populations of stem cells also in the adult mammalian brain and spinal cord. In this paper, we review the recent development in the field of embryonic and adult neural stem cells.
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  • 4
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Bone augmentation around implant fixtures using the technique of guided tissue regeneration has been described in a number of reports. The aim of this study was to evaluate bone fill around dehiscence defects at matched defects randomly allocated to test (expanded polytetrafluoroethylene; Gore-Tex) or control treatments within the same patient. Six edentulous subjects were treated with overdentures supported by 2 fixtures ad modum Brinemark. In addition, 2 experimental 7 mm fixtures with nearly identical dehiscence defects on the labial aspect were placed in the anterior part of the mandible. Baseline defect heights ranged from 2.5 to 4.0 mm with 2 to 4 threads exposed. The test fixture dehiscence was covered with a Gore-Tex membrane secured with a cover screw. The experimental fixtures were exposed after 5 months at stage 2 surgery and measurements and photographs repeated. The fixtures were then removed with a trephine and processed for histological evaluation. Regeneration of a hard tissue resembling bone was observed in 4 of 6 cases treated with Gore-Tex, amounting to between 95 and 100% elimination of the dehiscence and total coverage of the threads. However, in one of these cases, histological evaluation showed that it was soft tissue and not bone, and in a further case soft tissue regeneration was apparent both clinically and histologically. In another case there was no significant regeneration at either test or control defects. Although there was a trend for the Gore-Tex treated dehiscences to respond more favourably, the differences in clinical and histological measurements between test and control failed to reach statistical significance.
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  • 5
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Screw-shaped commercially pure (c.p.) niobium and c.p. titanium implants were inserted in rabbit bone. After a healing period of 3 months, a significantly higher removal torque was demonstrated to unscrew the niobium implants (average 32.9 Ncm) compared to the c.p. titanium implants (average 25.3 Ncm). In the histomorphometric part of the study, there were no significant differences in bone-to-metal contact between the 2 implant materials. An average of 41.1% bony contact was demonstrated for the niobium screws compared to an average of 37.2% for the c.p. titanium ones. Our removal torque findings could be related to the differences that we observed between the 2 implant surfaces as indicated by SEM. Since niobium implants showed a more irregular surface topography and niobium is a softer metal than c.p. titanium, this seems the most probable reason for the differences observed in removal torque between the 2 metals. Hypothetically, a more “positive biocom-patibility” of the c.p. niobium in comparison to the c.p. titanium remains as another possible reason for the observed differences. However, against such a difference in biocompatibility between c.p. niobium and c.p. titanium, there is the very similar amount of bony contact registered 1 in the histomorphometric analysis.
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  • 6
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Both tibial marrow cavities of 12 rabbits were evacuated and filled with curing bone cement. In one of the tibias conventional curing bone cement (Simplex P®) was injected, while the other tibia of the same animal was filled with a low temperature curing bone cement (Boneloc®). Three titanium implants were inserted along the proximal metaphysis of each tibia. Eight weeks after insertion the most distal implant in each tibia was removed while recording the removal torque. The implant was then once again screwed home into its bone bed. The animals were sacrificed 16 weeks after implant insertion. The previously removed implant and another implant in each tibia were then both removed while recording the removal torque. The third implant in each tibia was cut out en bloc with surrounding tissue and processed for ground section. We found no statistical differences in the mechanical or the histomorphometric evaluation of implant integration between the two cements, indicating that the low temperature curing bone cement does not result in a significantly different bone response from that of a conventional acrylic cement. ©©1999©Kluwer Academic Publishers
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  • 7
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Commercially pure (c.p.) titanium and Ti-6Al-4V implants were inserted in the abdominal wall of rats. The surrounding fluid space, inflammatory cells and fibrous capsule were evaluated after 1, 6 and 12 weeks. Light-microscopic morphometry demonstrated a fluid space around both implant materials which gradually decreased with time. Macrophages were preferentially distributed close to the implant surface in the innermost zone (0–25 µm from the surface). In contrast, fibroblasts and endothelial cells were located mainly in the outer three zones (25–100 µm from the surface). At all time periods studied and around both materials, lymphocytes were detected throughout the surrounding tissue. The outer border of the fibrous capsule, which consisted of macrophages, fibroblasts, endothelial cells and collagen, was difficult to define, in particular during the early phase of healing. At later time stages, 6 and 12 weeks, no difference in width (60–90 µm) was observed between the two materials. No major quantitative differences with respect to the number of different cells, fluid space width and fibrous capsule thickness were noted between the two materials studied. The observed mild inflammatory reaction and the absence of statistically significant differences between c.p. titanium and Ti-6Al-4V in soft tissue indicate that both materials could be suitable for use in soft tissues. In the context of previous comparative studies it may be concluded that the animal species as well as the different implantation locals play an important role in the determination of biocompatibility.
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  • 8
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Screw-shaped implants with an outer diameter of 3.7 mm and a total length of 8 mm were made from rods of commercially pure titanium (c.p. Ti) and commercially pure zirconium (c.p. Zr). Prior to insertion in rabbit tibia for 12 weeks, the surface roughness of two randomly chosen c.p. Ti and two c.p. Zr machined implants of the batch were numerically and visually described with a TopScan 3-D system. Irrespective of implant material, they demonstrated rather similar surface roughnesses, for example, the R a and R q values (that describe the average deviation from the mean line) were 0.79 and 1.18 for c.p. Ti versus 0.56 and 0.86 for c.p. Zr. Each rabbit had four implants inserted; two made of c.p. Ti in one leg and two made of c.p. Zr in the other. The bone tissue reactions to the materials were qualitatively and quantitatively examined. Removal torque tests were performed on the distal implants and histomorphometrical evaluations of the proximal ones. No qualitative or quantitative bone differences were observed. Removal torque measurements demonstrated a mean of 26.2 N cm±9.6 for c.p. Ti versus a mean of 25.9 N cm±7.1 for the c.p.Zr implants. Histomorphometrical comparisons of the bone-to-metal contact revealed a mean of 29 ±10.2% for c.p. Ti and a mean of 19±5.5% for the c.p. Zr samples. The mean bone area in the threads around the c.p. Ti samples was 49±16.6% compared to 43±7.9% for the c.p. Zr group. Commercially pure titanium and zirconium implants seemed to be well accepted by the bone bed after 12 weeks of insertion in rabbit bone.
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  • 9
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Nitrogen-ion implantation is a surface modification of interest for biomedical materials. In this study screw-shaped commercially pure titanium and Ti6AI4V alloy implants were nitrogen-ion implanted and analysed by scanning electron microscopy (SEM) and scanning Auger electron spectroscopy (AES). The surface topography was essentially similar for treated and non-treated samples. AES survey spectra showed an incorporation of nitrogen into the surface of the nitrogen-ion treated commercially pure titanium and Ti6AI4V implants, as judged by the ratio between the intensities of the peaks at 390 and 420 eV. AES depth profiles revealed a similar oxide thickness (7.5 nm) for the nitrogen-ion implanted and the non-treated samples. In nitrogen-ion implanted screws nitrogen was detected up to depths of about 150 nm below the surface, with a maximum nitrogen concentration at about 50 nm. Light microscopic examination of the 10 μm-thick ground sections 3 months after the insertion of nitrogen-ion implanted and non-treated commercially pure titanium and Ti6AI4V screws in the proximal tibial methaphysis of rabbits showed that bone filled a large portion of the area within the threads. A fibrous capsule was not observed. Light microscopic morphometry did not reveal any statistically significant differences in bone-metal contact or bone area within the threads of nitrogen-ion treated and non-treated implants. The “mirror-image” analysis showed that for all implants examined significantly more bone was present immediately outside than inside the threads. The results from this study indicate that nitrogen-ion implanted, screw-shaped, commercially pure titanium and Ti6AI4V implants heal as well in cortical bone as non-treated samples.
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  • 10
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Titanium implants were inserted in transgenic mice overexpressing bovine growth hormone. Four weeks after insertion the implants were cut out en bloc with the surrounding bone. The undecalcified specimens were cut and ground to a thickness of approximately 10 μm. Histomorphometry demonstrated significantly more direct bone to metal contact for the transgenic mice than for the non-transgenic littermates. The results indicate that endogenous high levels of bovine growth hormone result in improved early bone-implant integration. This study indicate that it may be possible to systemically administrate growth hormone in man, in the early healing in phase, to improve implant integration.
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