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  • 1
    Electronic Resource
    Electronic Resource
    Biocompatibility of solid poly (ortho ester) (1997)
    Springer
    Journal of materials science 8 (1997), S. 265-269 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In previous studies poly (ortho ester) (POE) has shown promise as a resorbable device, a hemostatic sealant and as a carrier for drugs in bone surgery. The aim of this study was to evaluate the tissue reactions of solid poly (ortho ester) implanted into both tibiae of 17 rabbits. One half of the rods were sterilized by gamma radiation and the other half by ethylene oxide. The follow-up times were from 1 week to 21 weeks, after which the animals were killed and the bony specimens examined histologically. The connective tissue samples were examined immunohistochemically in order to study the occurrences of two extracellular matrix glycoproteins, tenascin and fibronectin. The results showed that solid poly (ortho ester)s induce a moderate inflammatory reaction for 9 weeks. Tenascin and fibronectin were present in samples from 1 week up to 4 weeks. It was also found that gamma sterilized POE was resorbed at week 7 and ethylene oxide sterilized POE at week 13.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018552010027
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  • 2
    Electronic Resource
    Electronic Resource
    Mixture of ε-caprolactone-lactide copolymer and tricalcium phosphate: a histological and immunohistochemical study of tissue reactions (1999)
    Springer
    Journal of materials science 10 (1999), S. 69-74 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In cranio-maxillofacial surgery, bone transplantation is needed for treatment of bony defects. An autograft, allograft or biomaterial can be used. Autogenous bone grafts are considered to be the best materials available, but there are some disadvantages in their use including donorsite morbidity, need for a second operative site and limited graft supply. A search for new bone-graft materials therefore remains necessary. We prepared a mixture of tricalcium phosphate (TCP), which is a resorbable, non-toxic, osteoconductive ceramic material and ε-caprolactone-lactide copolymer P(ε-CL/DL-LA), a resorbable polymer, and placed it in the dermis and in mandibular bone defects in 13 rabbits. Follow-up times were two, three, seven, eight, 12, 15 and 18 weeks, tissue reactions were assessed, histologically and immunohistochemically. Times of resorption of the material from tissues were reported. We found that the mixture caused a mild inflammatory reaction when placed in bone and severe inflammation when placed in dermis. No highly fluorescent layer of tenascin or fibronectin was found surrounding the implant area. The mixture was excellent to handle and very easy to place into bone defects. The results are promising and have led us to continue development of the mixture. © 1999 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008912802263
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of shear strength of osteotomies fixed with absorbable self-reinforced poly-L-lactide and metallic screws (1992)
    Springer
    Journal of materials science 3 (1992), S. 288-292 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Nine experimental osteotomies on the neck of a sheep's left mandibular condyle were fixed with self-reinforced poly-L-lactide (SR-PLLA) screws. Metallic screws were used in a group of nine sheep for the same fixation of the osteotomy. The right condyle of each sheep acted as a control. Radiographic analysis was carried out at 3 weeks and at sacrifice (6, 12 or 24 weeks) when the shear force needed to break the osteotomy site was measured. No significant differences were detected at 3, 6 or 24 weeks, but at 12 weeks the SR-PLLA-fixed condyles seemed to tolerate shear force somewhat better. The results are very promising and have led us to continue with development of smaller screws and a self-reinforced poly-L-lactide plate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705295
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  • 4
    Electronic Resource
    Electronic Resource
    Strength retention of self-reinforced poly-L-lactide screws and plates: anin vivo andin vitro study (1992)
    Springer
    Journal of materials science 3 (1992), S. 426-431 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Self-reinforced poly-L-lactide (SR-PLLA) screws and multilayer plates were studied for their initial mechanical shear and/or tensile strength and strength retentionin vivo andin vitro up to 48 weeks. The plates were studiedin vitro up to 68 weeks. The loss of strength was fasterin vivo thanin vitro. The screws retained more than half of their initial shear strength up to 12 weeksin vivo and over 24 weeksin vitro. By 48 weeks they had lost nearly all of their mechanical strength in both groups. The plates retained over 54% of their initial tensile and 71% of shear strength up to 24 weeksin vivo. The shear strength did not particularly diminish up to 52 weeks of follow-upin vitro whereas the tensile strength was slightly decreased after 36 weeks. After this follow-up time the loss of strength was more rapid and by 68 weeks the shear strength had decreased to 17% and the tensile strength to 0%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00701239
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of polyglycolic acid membrane on bone regeneration around titanium implants inserted in bone sockets (1994)
    Springer
    Journal of materials science 5 (1994), S. 40-42 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: An experimental animal model was used to evaluate the value of resorbable, non-permeable polyglycolic acid (PGA) membranes in relation to fixtures implanted into simulated extraction sockets. Brånemark fixtures (length 7.0 mm, diameter 3.75 mm) were implanted into edentulous areas of maxillary bone in six sheep. Five fixtures were covered with 0.15-mm-thick PGA membrane (Biofix®) held in place with a cover screw (PGA group) and five were implanted without membrane (control group). The animals were killed after 4 months and undecalcified mesiodistal sections were prepared from resected jaw specimens. Histomorphometry was used to measure the distance from the shoulder of the fixture to the level of intimate bone contact (SB distance). SB distance was found to be greater in the PGA than in the control group in relation both to the mesial (1.44 ± 0.88 mm versus 0.96 ± 0.47 mm) and distal (1.13 ± 0.80 mm versus 0.77 ± 0.63 mm) aspects of implants. This statistically not significant difference in bone regeneration between the two groups is related to the physical properties of the PGA membrane used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121152
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  • 6
    Electronic Resource
    Electronic Resource
    Fibrous wound repair associated with biodegradable poly-L/D-lactide copolymer implants: study of the expression of tenascin and cellular fibronectin (1998)
    Springer
    Journal of materials science 9 (1998), S. 603-609 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Extracellular matrix (ECM) proteins are known to play a role in inflammatory and hyperplastic processes. Our aim in the present study was to study the distribution of tenascin (Tn), cellular fibronectins (cFn) and myofibroblasts around biodegradable poly-L/D-lactide (PLA) implants with monoclonal antibodies (MAb). Ethylene-oxide and gamma-irradiation sterilized PLA plate-type implants were inserted into the dorsal subcutaneous tissue of ten adult rabbits. Follow-up times were 4, 12, 16, 36 and 48 wk. Only some inflammatory cells were observed. In electron microscopy, a close coherence between the implant and the stromal tissue was seen. Immunoreactivity for Tn, cFn and α-actin was detected as a distinct layer bordering the implant, regardless of the sterilization method for the first 36 wk. From week 36 onwards, Tn immunoreactivity was downregulated while cFn immunoreactivity still persisted. A moderate upregulation for myofibroblasts was seen on the week 48 specimens, when hydrolysation of PLA implant had started. The persistent content of myofibroblasts, Tn and cFn suggests a prolonged wound healing produced by PLA implants. The absence of Tn at the week 48 specimens suggests that cFn, rather than Tn may be needed for α-actin-mediated contraction by myofibroblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008921811674
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