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Sökning: WFRF:(Wennerberg Ann 1955 ) > Göteborgs universitet > Tidskriftsartikel

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  • Reigstad, Ole, et al. (författare)
  • Different patterns of bone fixation with hydroxyapatite and resorbable CaP coatings in the rabbit tibia at 6, 12, and 52 weeks.
  • 2011
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - 1552-4981. ; 99:1, s. 14-20
  • Tidskriftsartikel (refereegranskat)abstract
    • Applying bioactive coatings on orthopedic implants can increase the fixation and long-term implant survival. In our study, we compared a resorbable electrochemically deposited calcium phosphate coating (Bonit®) to a thin (40 μm) plasma-sprayed hydroxyapatite (HA) coating, applied on grit-blasted screw-shaped Ti-6Al-4V implants in the cortical region of rabbit tibia, implanted for 6, 12, and 52 weeks. The removal torque results demonstrated stronger bone-to-implant fixation for the HA than Bonit-coated screws at 6 and 12 weeks. After 52 weeks, the fixation was in favor of the Bonit-coated screws, but the difference was statistically insignificant. Coat flaking and delamination of the HA with multinucleated giant cell activity and bone resorption observed histologically seemed to preclude any significant increase in fixation comparing the HA implants at 6 versus 12 weeks and 12 versus 52 weeks. The Bonit-coated implants exhibited increasing fixation from 6 to 12 weeks and from 12 to 52 weeks, and the coat was resorbed within 6 weeks, with minimal activity of multinucleated giant cells or bone resorption. A different fixation pattern was observed for the two coatings with a sharper but time limited increase in fixation for the HA-coated screws, and a slower but more steadily increasing fixation pattern for the Bonit-coated screws. The side effects were more serious for the HA coating and limiting the expected increase in fixation with time.
  • Reigstad, Ole, et al. (författare)
  • Improved bone ingrowth and fixation with a thin calcium phosphate coating intended for complete resorption
  • 2007
  • Ingår i: J Biomed Mater Res B Appl Biomater. ; 83:1, s. 9
  • Tidskriftsartikel (refereegranskat)abstract
    • Bonit(R) is claimed to be a resorbable electrochemically deposited calcium phosphate coating consisting mainly of brushite, which is a hydroxyapatite precursor. This study involved a comparison of Ti6Al4V screw-shaped implants with and without a 15 +/- 5 mum Bonit coating in rabbit tibia and femur, after 6 and 12 weeks of insertion. The biomechanical removal torque test showed significantly increased values for the coated implants after 12 weeks (p < 0.05) but not after 6 weeks of integration. Higher bone-implant contact was found for the coated implants in the tibia after 6 weeks and for both tibial and femoral screws after 12 weeks (p < 0.05). There was no difference in the inflammatory reaction around the implants, and possible grains of the coating could be detected after 6 weeks, but not after 12 weeks of follow-up. This unloaded short-term study has shown promising results for the easily applicable and resorbable coat (Bonit) compared to uncoated titanium-alloy implants. (c) 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007.
  • Sul, Young-Taeg, 1960-, et al. (författare)
  • Characteristics of the surface oxides on turned and electrochemically oxidized pure titanium implants up to dielectric breakdown: the oxide thickness, micropore configurations, surface roughness, crystal structure and chemical composition.
  • 2002
  • Ingår i: Biomaterials. - 0142-9612. ; 23:2, s. 491-501
  • Tidskriftsartikel (refereegranskat)abstract
    • Titanium implants have been used widely and successfully for various types of bone-anchored reconstructions. It is believed that properties of oxide films covering titanium implant surfaces are of crucial importance for a successful osseointegration, in particular at compromized bone sites. The aim of the present study is to investigate the surface properties of anodic oxides formed on commercially pure (c.p.) titanium screw implants as well as to study 'native' oxides on turned c.p. titanium implants. Anodic oxides were prepared by galvanostatic mode in CH3COOH up to the high forming voltage of dielectric breakdown and spark formation. The oxide thicknesses, measured with Auger electron spectroscopy (AES), were in the range of about 200-1000 nm. Barrier and porous structures dominated the surface morphology of the anodic film. Quantitative morphometric analyses of the micropore structures were performed using an image analysis system on scanning electron microscopy (SEM) negatives. The pore sizes were < or = 8 microm in diameter and had 1.27-2.1 microm2 opening area. The porosity was in the range of 12.7-24.4%. The surface roughness was in the range of 0.96-1.03 microm (Sa), measured with TopScan 3D. The crystal structures of the titanium oxide were amorphous, anatase, and a mixtures of anatase and rutile type, as analyzed with thin-film X-ray diffractometry (TF-XRD) and Raman spectroscopy. The chemical compositions consisted mainly of TiO2, characterized with X-ray photoelectron spectroscopy (XPS). The native (thermal) oxide on turned implants was 17.4 nm (+/- 6.2) thick and amorphous. Its chemical composition was TiO2. The surface roughness had an average height deviation of 0.83 microm (Sa). The present results are needed to elucidate the influence of the oxide properties on the biological reaction. The results of animal studies using the presently characterized surface oxides on titanium implants will be published separately.
  • Sul, Young-Taeg, 1960-, et al. (författare)
  • Optimum surface properties of oxidized implants for reinforcement of osseointegration: surface chemistry, oxide thickness, porosity, roughness, and crystal structure
  • 2005
  • Ingår i: Int J Oral Maxillofac Implants. - 0882-2786. ; 20:3, s. 349-59
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: To investigate detailed surface characterization of oxidized implants in a newly invented electrolyte system and to determine optimal surface oxide properties to enhance the bone response in rabbits. MATERIALS AND METHODS: A total of 100 screw-type titanium implants were prepared and divided into 1 control group (machine-turned implants) and 4 test groups (magnesium ion-incorporated oxidized implants). Forty implants were used for surface analyses. A total of 60 implants, 12 implants from each group, were placed in the tibiae of 10 New Zealand white rabbits and measured with a removal torque test after a healing period of 6 weeks. RESULTS: For the test groups, the oxide thicknesses ranged from about 1,000 to 5,800 nm; for the control group, mean oxide thickness was about 17 nm. The surface morphology showed porous structures for test groups and nonporous barrier film for the control group. Pore diameter ranged from &lt; or = 0.5 microm to &lt; or = 3.0 microm. In regard to surface roughness, arithmetic average height deviation (Sa) values varied from 0.68 to 0.98 microm for test implants and 0.55 microm for control implants; developed surface ratio (Sdr) values ranged from 10.6% to 46% for the test groups and were about 10.6% for the control group. A mixture of anatase and rutile-type crystals were observed in the test groups; amorphous-type crystals were observed in the control group. After a healing period of 6 weeks, removal torque measurements in all 4 test groups demonstrated significantly greater implant integration as compared to machine-turned control implants (P &lt; or = .033). DISCUSSION: Determinant oxide properties of oxidized implants are discussed in association with bone responses. Of all surface properties, RTVs were linearly increased as relative atomic concentrations of magnesium ion increase. CONCLUSIONS: Surface properties of the oxidized implants in the present study, especially surface chemistry, influenced bone responses. The surface chemistry of the optimal oxidized implant should be composed of approximately 9% magnesium at relative atomic concentration in titanium oxide matrix and have an oxide thickness of approximately 1,000 to 5,000 nm, a porosity of about 24%, and a surface roughness of about 0.8 microm in Sa and 27% to 46% in Sdr; its oxide crystal structure should be a mixture of anatase- and rutile-phase crystals.
  • Sul, Young-Taeg, 1960-, et al. (författare)
  • Oxidized implants and their influence on the bone response.
  • 2001
  • Ingår i: Journal of Materials Science: Materials in Medicine. - 0957-4530. ; 12:10-12, s. 1025-31
  • Tidskriftsartikel (refereegranskat)abstract
    • Surface oxide properties are regarded to be of great importance in establishing successful osseointegration of titanium implants. Despite a large number of theoretical questions on the precise role of oxide properties of titanium implants, current knowledge obtained from in vivo studies is lacking. The present study is designed to address two aspects. The first is to verify whether oxide properties of titanium implants indeed influence the in vivo bone tissue responses. The second, is to investigate what oxide properties underline such bone tissue responses. For these purposes, screw-shaped/turned implants have been prepared by electrochemical oxidation methods, resulting in a wide range of oxide properties in terms of: (i) oxide thickness ranging from 200 to 1000 nm, (ii) the surface morphology of barrier and porous oxide film structures, (iii) micro pore configuration - pore sizes<8 microm by length, about 1.27 microm2 to 2.1 microm2 by area and porosity of about 12.7-24.4%, (iv) the crystal structures of amorphous, anatase and mixtures of anatase and rutile type, (v) the chemical compositions of TiO2 and finally, (vi) surface roughness of 0.96-1.03 microm (Sa). These implant oxide properties were divided into test implant samples of Group II, III, IV and V. Control samples (Group I) were turned commercially pure titanium implants. Quantitative bone tissue responses were evaluated biomechanically by resonance frequency analysis (RFA) and removal torque (RT) test. Quantitative histomorphometric analyses and qualitative enzyme histochemical detection of alkaline (ALP) and acidic phosphatase (ACP) activities were investigated on cut and ground sections after six weeks of implant insertion in rabbit tibia. In essence, from the biomechanical and quantitative histomorphometric measurements we concluded that oxide properties of titanium implants, i.e. the oxide thickness, the microporous structure, and the crystallinity significantly influence the bone tissue response. At this stage, however, it is not clear whether oxide properties influence the bone tissue response separately or synergistically. Copyright 2001 Kluwer Academic Publishers
  • Sul, Young-Taeg, 1960-, et al. (författare)
  • Resonance frequency and removal torque analysis of implants with turned and anodized surface oxides.
  • 2002
  • Ingår i: Clin Oral Implants Res. - 0905-7161. ; 13:3, s. 252-9
  • Tidskriftsartikel (refereegranskat)abstract
    • The present experimental study was designed to address two issues. The first was to investigate whether oxide properties of titanium implants influenced bone tissue responses after an in vivo implantation time of six weeks. If such a result was found, the second aim was to investigate which oxide properties are involved in such bone tissue responses. Screw-shaped implants with a wide range of oxide properties were prepared by electrochemical oxidation methods, where the oxide thickness varied in the range of 200 nm to 1000 nm. The surface morphology was prepared in two substantially different ways, i.e. barrier and porous oxide film structures. The micropore structure revealed pore sizes of 8 microm in diameter, with a range in opening area from 1.27 microm 2 to 2.1 microm 2. Porosity ranged from 12.7% to 24.4%. The crystal structures of the titanium oxide were amorphous, anatase and a mixture of anatase and rutile type. The chemical compositions consisted mainly of TiO2. Surface roughness ranged from 0.96 microm to 1.03 microm (Sa). Each group of test samples showed its own, defined status with respect to these various parameters. The oxide properties of turned commercially pure titanium implants were used in the control group, which was characterized by an oxide thickness of 17.4 +/- 6.2 nm, amorphous type in crystallinity, TiO2 in chemical composition, and a surface roughness of 0.83 microm (Sa). Bone tissue responses were evaluated by resonance frequency measurements and removal torque tests that were undertaken six weeks after implant insertion in rabbit tibia. Implants that had an oxide thickness of approximately 600, 800 and 1000 nm demonstrated significantly stronger bone responses in the evaluation of removal torque values than did implants that had an oxide thickness of approximately 17 and 200 nm (P < 0.05). However, there were no difference between implants with oxide thicknesses of 17 and 200 nm (P = 0.99). It was concluded that oxide properties of titanium implants, which include oxide thickness, micropore configurations and crystal structures, greatly influence the bone tissue response in the evaluation of removal torque values. However, it is not fully understood whether these oxide properties influence the bone tissue response separately or synergistically.
  • Wennerberg, Ann, 1955-, et al. (författare)
  • Titanium release from implants prepared with different surface roughness
  • 2004
  • Ingår i: Clin Oral Implants Res. ; 15:5, s. 505
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: There may be a risk of greater ion release for surface-enlarged implants than conventionally turned components. The major aim of the present paper was to investigate whether a correlation exists between ion release and a surface roughness relevant for today's commercial implants. Other aims were to compare ion release after two insertion times and concentration in bone tissue as a function of distance from the implant surface. MATERIAL AND METHODS: Lactic acid aqueous solution (pH=2.3) and phosphate-buffered saline were used for the in vitro investigation. For the in vivo investigation, synchrotron radiation X-ray fluorescence (SRXRF) spectroscopy and secondary ion mass spectroscopy (SIMS) were performed 12 weeks and 1 year after implantation in rabbit tibiae. RESULTS: The average height deviation (S(a)) was 0.7, 1.27, 1.43 and 2.21 microm, respectively, for the four surfaces investigated. No difference in ion release was found in vitro. In vivo, SRXRF demonstrated slightly higher values for the roughest surface up to a distance of 400 microm from the implant surface; thereafter no difference was found. SIMS demonstrated no difference in ion release for the roughest and smoothest surfaces, but slightly more titanium in bone tissue after 1 year than after 12 weeks. Titanium rapidly decreased with distance from the implant surface. CONCLUSION: At a level relevant for commercial oral implants, no correlation was found between increasing roughness and ion release, neither in vitro nor in vivo.
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