Nanopore Literature


Sul YT, Johansson CB, AlbrektssonT . Oxidized titanium screws coated with calcium ions and their performance in rabbit bone.
Int J Maxillofac Implants A 2002;17(5):625-634.

Abstract

PURPOSE:
The aim was to answer a fundamental question: Do the chemical properties of titanium implants influence osseointegration?

MATERIALS AND METHODS:
Screw-type implants produced of turned commercially pure (grade 1) titanium (controls) and electrochemically calcium-deposited titanium implants (Ca test implants) were placed in the tibiae and femora of a total of 10 mature New Zealand white rabbits. The macro arc oxidation method was applied for Ca implants. Surface oxides were characterized with different analytic techniques, including x-ray photoelectron spectroscopy, auger electron spectroscopy, scanning electron microscopy, thin-film x-ray diffractometry, and TopScan 3D. The bone response was evaluated by biomechanical tests, histology, and histomorphometry.

RESULTS:
After a follow-up period of 6 weeks, test Ca implants showed a significant increase in mean peak removal torque (P = .0001) and in the histomorphometric measurement of bone-to-metal contact around the implants (P = .028) in comparison to controls. In addition, more mature mineralized bone was observed adjacent to test Ca implants compared to controls, as evaluated on 10-microm undecalcified, toluidine blue-stained, cut, and ground sections.

DISCUSSION:
The potential role of surface Ca chemistry to a superior bone response is discussed with specific reference to interaction with Ca(+)-binding proteins and function as binding sites of calcium phosphate mineral.

CONCLUSION:
The present results suggest that the surface chemical composition of titanium implants is of great importance for the bone response. Ca ion-deposited titanium implants showed fast and strong osseointegration in the rabbit bone model.


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Sul YT, Johansson CB , Kang Y , Jeong D G, Albrektsson T . Bone reactions to oxidized titanium implants with electrochemical anion sulphuric acid and phosphoric acid incorporation.
Clin Implant Dent Relat Res.C 2002;4(2):78-87.

Abstract

BACKGROUND:
The importance of the surface properties of implants for a successful osseointegration has been emphasized. It is generally known that bone response to implant surfaces is considerably related to the various surface properties.

PURPOSE:
The purpose of this study was to investigate bone tissue reactions to multifactorial biocompatibility of the surface oxide of electrochemically oxidized titanium implants. The ultimate objective was to improve surface quality, resulting in enhancement of clinical outcomes of osseointegrated implants. Materials and

METHODS:
Three different surface types of commercially pure titanium (c.p. Ti) implants were prepared. Turned implants were used for controls and test implants were prepared by the micro arc oxidation (MAO) method, either in sulphuric acid (S implants) or in phosphoric acid (P implants). Implants were inserted in the femur and tibia of 10 mature New Zealand White rabbits. The bone response was evaluated by biomechanical tests, histology, and histomorphometry. The follow-up time was 6 weeks.

RESULTS:
The mean peak values of the removal torque showed significant differences between control and test S implants (p =.022) but showed no significant differences between control and test P implants (p =.195) or between test S and test P implants (p =.457). In addition, the histomorphometric comparisons of the bone-to-metal contact around entire implants demonstrated 186% increase in S implants (p =.028) and 232% increase in P implants (p =.028) compared with the paired control groups. Quantification of the bone area in the threads did not show any significant differences.

CONCLUSIONS:
The present results suggest that the primary mode of action in strong bone response to S implants is mechanical interlocking, and to P implants, it is biochemical interaction. It is possible that the phosphate groups in the titanium oxide of P implants provide potential chemical bonding sites for calcium ions and hydroxyapatite of the bone matrix during biologic mineralization. key words: bone responses, histomorphometry, oxidized implants, removal torque test, surface oxide properties


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Sul YT, Byon ES, Jeong Y . Biomechanical measurements of calcium-incorporated oxidized implants in rabbit bone: effect of calcium surface chemistry of a novel implant.
Clin Implant Dent Rel Res. 2004;6(2):101-110.

Abstract

BACKGROUND:
In oral implantology there has been a general trend away from machine-turned minimally rough and acid-etched and blasted implants toward intermediary roughened surfaces. Mechanical interlocking at micron resolution is claimed to be the dominant reason for the fixation of such implants in bone. However, clinical demands for stronger and faster bone bonding to the implant (eg, in immediately loaded and compromised bone cases) have motivated the development of novel surfaces capable of chemical bonding.

PURPOSE:
The purpose of the present study is to investigate bone tissue reactions to a newly developed calcium incorporated oxidized implant. The specific aim is to assess the effect of calcium surface chemistry on the bone response.

MATERIALS AND METHODS:
Calcium (Ca) ion-incorporated implants were prepared by micro arc oxidation methods. Surface oxide properties were characterized by using various surface analytic techniques involving scanning electron microscopy, x-ray diffractometry, x-ray photoelectron spectroscopy, and optical interferometry. Twenty screw-shaped commercially pure (CP) titanium implants (10 turned implants [controls] and 10 Ca-incorporated implants [tests]) were inserted in the femoral condyles of 10 New Zealand White rabbits.

RESULTS:
After a healing period of 6 weeks, resonance frequency analyses and removal torque measurements of the Ca-incorporated oxidized implants demonstrated statistically significant improvements of implant integration with bone in comparison to machine-turned control implants (p = 0.013 and p = 0.005, respectively).

CONCLUSIONS:
The Ca-reinforced surface chemistry of the oxidized implants significantly improved bone responses in a rabbit model. The present study suggests that biochemical bonding at the bone-implant interface, in combination with mechanical interlocking, may play a dominant role in the fixation of Ca-incorporated oxidized implants in bone. The observed rapid and strong integration of test Ca implants may have clinical implications for immediate or early loading and improved performance in compromised bone.


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Suh JY, Jeung OC, Choi BJ, Park JW. Effects of a novel calcium titanate coating on the osseointegration of blasted endosseous implants in rabbit tibiae.
Clin Oral Implants Res.2007;( Epub)

Abstract

OBJECTIVE:
The purpose of this study was to investigate the effects of a nanostructured calcium coating on the surfaces of blasted Ti implants on peri-implant bone formation in the rabbit tibiae.

MATERIAL AND METHODS:
Threaded implants (3.75 mm in diameter, 6 mm in length) were roughened by hydroxyapatite (HA) blasting (control; blasted implants). The implants were then hydrothermally treated in a Ca-containing solution for 24 h to prepare Ca-incorporated Ti surfaces (experimental; blasted/Ca implants). Surface characterizations were performed by scanning electron microscopy and stylus profilometry before and after Ca coating. Forty-two implants (21 control and 21 experimental) were placed in the proximal tibiae of seven New Zealand White rabbits. Each rabbit received six implants. To evaluate the effects of the nanostructured Ca coating on the peri-implant bone-healing response, removal torque tests and histomorphometric analyses were performed 6 weeks after surgery.

RESULTS:
The Ca coating did not significantly change the surface properties produced by blasting at the micron level. Histologically, active bone apposition was observed in the blasted/Ca implants in the marrow space. Compared with the blasted implants, the blasted/Ca implants showed significantly increased bone-to-implant contact over the total implant length (P<0.01) and greater mean removal torque values (P<0.05).

DISCUSSION AND CONCLUSION:
The nanostructured, Ca-incorporated surface significantly enhanced the peri-implant bone-healing response of HA-blasted Ti implants. It may be concluded that the use of nanostructured, Ca-coated surfaces may have synergic effects in enhancing osseointegration of blasted Ti implants due to their micron-scaled surface properties and biologically active surface chemistry.


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Sul YT, Johansson C, Albrektsson T . Which surface properties enhance bone response to implants?
Comparison of oxidized magnesium, TiUnite and Osseotite Implant surfaces.
Int J Prosthodont B 2006;19(4):319-328.

Abstract

PURPOSE:
This study compared the speed and strength of osseointegration and osteoconductivity between an oxidized experimental magnesium (Mg) implant, an oxidized commercially available TiUnite implant, and a dual acid-etched surface Osseotite implant. The aim was to investigate which surface properties enhance bone response to implants, and thereby to test a biochemical bonding theory.

MATERIALS AND METHODS:
A total of 60 screw implants (20 of each design) were inserted through 1 cortex into the tibiae of 10 rabbits. Surface chemistry, oxide thickness, morphology, crystal structure, and surface roughness were evaluated. After healing times of 3 and 6 weeks, all bone implants were unscrewed with removal torque (RTQ) devices, and the bone specimens were subjected to histomorphometry.

RESULTS:
RTQ values for Mg, TiUnite, and Osseotite implants were 27.1, 21.3, and 15.4 Ncm, with new bone formation values of 29%, 18%, and 15%, respectively, at 3 weeks. At 6 weeks the RTQ values were 37.5, 36.4, and 21.5 Ncm, with new bone formation values of 39%, 31%, and 26%, respectively. Discussion: Mg implants demonstrated significantly greater RTQ values (P = .008 and P = .0001) and more new bone formation (P = .031 and P = .030) than Osseotite at 3 and 6 weeks, respectively. Mg implants also showed higher RTQ values at 3 weeks and new bone formation at 6 weeks than TiUnite, but neither were significant (P > .05). TiUnite showed significantly higher RTQ values than Osseotite at 6 weeks (P = .001), but was not significant at 3 weeks (P > .05). Osseointegration rate (deltaRTQ/deltaweeks) was significantly faster for Mg (P = .011) and TiUnite (P = .001) implants between 3 and 6 weeks of healing time, but was not significant for Osseotite.

CONCLUSIONS:
The results indicate that surface chemistry facilitated more rapid and stronger osseointegration of the Mg implants despite their minimal roughness compared to the moderately roughened TiUnite. This suggests potential advantages of Mg implants for reducing high implant failure rates in the early postimplantation stage and in compromised bone, making it possible to shorten bone healing time from surgery to functional loading, and enhancing the possibility of immediate/early loading.


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Sul YT, Jeong Y, Johansson C, Albrektsson T. Oxidized bioactive implants are rapidly and strongly integrated into bone.
Clin oral Implants Res. A 2006:17(5):521-526.

Abstract

OBJECTIVES:
The study presented was designed to investigate the speed and the strength of osseointegration of oxidized implants at early healing times in comparison which machined, turned implants.

MATERIAL AND METHODS:
Screw-shaped titanium implants were prepared and divided into two groups: magnesium ion incorporated, oxidized implants (Mg implants, n=10) and machined, turned implants (controls, n=10). Mg implants were prepared using micro-arc oxidation methods. Surface oxide properties of implants such as surface chemistry, oxide thickness, morphology/pore characteristics, crystal structures and roughness were characterized with various surface analytic techniques. Implants were inserted into the tibiae of ten New Zealand white rabbits. After a follow-up period of 3 and 6 weeks, removal torque (RTQ), osseointegration speed (DeltaRTQ/Deltahealing time) and integration strength of implants were measured. Bonding failure analysis of the bone-to-implant interface was performed.

RESULTS:
The speed the and strength of osseointegration of Mg implants were significantly more rapid and stronger than for turned implants at follow-up periods of 3 and 6 weeks. Bonding failure for Mg implants dominantly occurred within the bone tissue, whereas bonding failure for turned implants mainly occurred at the interface between implant and bone.

CONCLUSIONS:
Oxidized, bioactive implants are rapidly and strongly integrated in bone. The present results indicate that the rapid and strong integration of oxidized, bioactive Mg implants to bone may encompass immediate/early loading of clinical implants.


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Sul YT, Johansson C, Byon E , Albrektsson T . The bone response of oxidized bioactive and non-bioactive titanium implants.
Biomaterials 2005;26(33):6720-6730

Abstract

A number of experimental and clinical data on so-called oxidized implants have reported promising outcomes. However, little is investigated on the role of the surface oxide properties and osseointegration mechanism of the oxidized implant. Sul [On the Bone Response to Oxidized Titanium Implants: The role of microporous structure and chemical composition of the surface oxide in enhanced osseointegration (thesis). Göteborg: Department of Biomaterials/Handicap Research, University of Göteborg, Sweden; 2002; Biomaterials 2003; 24: 3893-3907] recently proposed two action mechanisms of osseointegration of oxidized implants, i.e. mechanical interlocking through bone growth in pores/other surface irregularities (1) and biochemical bonding (2). The aim of the present study is two-fold: (i) investigating the role of the implant surface chemistry on bone responses; (ii) investigating the validity of the biochemical bonding theory of the oxidized, bioactive bone implants with specific implant surface chemistry. Two groups of oxidized implants were prepared using micro arc oxidation process and were then inserted in rabbit bone. One group consisted of magnesium ion incorporated implants (MgTiO implant), the other consisted of TiO2 stoichiometry implants (TiO implant). Surface oxide properties of the implants were characterized with various surface analytic techniques. After 6 weeks of follow up, the mean peak values of removal torque of Mg implants dominated significantly over TiO implants (p < or = 0.0001). Bonding failure generally occurred in the bone away from the bone to implant interface for the MgTiO implant and mainly occurred at the bone to implant interface for the TiO implant that consisted mainly of TiO2 chemistry and significantly rougher surface as compared to the MgTiO implant. Between bone and the Mg- incorporated implant surface, ionic movements and ion concentrations gradient were detected. The current in vivo experimental data may provide positive evidence for the surface chemistry-mediated biochemical bonding theory of oxidized bioactive implants. However, the present study does not rule out potential synergy effects of the oxide thickness, micro-porous structure, crystal structure and surface roughness on improvements of bone responses to oxidized bioactive implants.


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Sul YT, Johansson CB , Jeong Y , Wennerber A, Albrektsson T.
Resonance frequency and removal torque analysis of implants with turned and anodized surface oxides.
Clin Oral ImplantsRes. B . 2002;13(3):252-259.

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.


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Fröjd V, Franke-StenpoV, Meirelles L, Wennerberg A . Increased bone contact to a calciumincorporated oxidized commercially pure titanium implant: an in-vivo study in rabbits, Int J Oral
Maxillofac Surg (2008) doi:10.1016/j.ijom.2008.01.020).

Abstract

The aim of this study was to evaluate the bone response to an oxidized titanium implant (Ox) and a calcium-incorporated oxidized titanium implant (Ca). A blasted titanium implant (Bl) was used as control. The implants were topographically characterized using an optical interferometer and placed: one in each distal femoral metaphysis and two in each proximal tibial metaphysis in rabbits. The rabbits were killed 12 weeks after implant insertion, and the implants and their surrounding tissues were removed en bloc for histomorphometrical evaluations. Topographical evaluation revealed three different surfaces: average height deviation (S(a), microm) values for Ca:Ox:Bl implants were 0.3:0.6:0.9, developed surface area ratios (%) 17:44:31, number of summits per microm(2) 208:136:118, and core fluid retention index values 1.33:1.33:1.38. The mean percentages of bone contact to the implants placed in the tibia (Ca:Ox:Bl) were 47:30:34 and to the implants placed in the femur (Ca:Ox) 32:20. The mean percentages of surrounding bone area for the implants placed in the tibia were 40:47:37 and for the implants placed in the femur 43:46. A significant increase in bone contact was found for smooth (S(a) <0.5 microm) but more densely peaked calcium-incorporated oxidized implants when compared to slightly rougher (S(a)=0.5-1.0 microm) oxidized or blasted implants.


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Sul YT. The significance of the surface properties of oxidized titanium to the bone response: special emphasis on the potential biochemical bonding of oxidized titanium implants.
Biomaterials 2 03;24:389-33 907.

Abstract

The aim of the present study is to investigate bone tissue reactions to various surface oxide properties, in particular to different surface oxide chemistry of oxidized titanium implants (grade 1). One control and three test screw-shaped implant groups were prepared. Controls were turned implants. Test implants, i.e. S implants, P implants and Ca implants were by the micro-arc oxidation (MAO) method. The surface characterizations were performed with X-ray photoelectron spectroscopy, Auger electron spectroscopy, scanning electron microscopy, X-ray diffractometry and TopScan 3D. Eighty implants were inserted in the femora and tibiae of ten mature New Zealand white rabbits for 6 weeks. The removal torque values (RTQ) showed significant differences between S implants and controls (p=0.022), Ca implants and controls (p=0.0001), Ca implants and P implants (p=0.005) but did not show significant differences between the others (p>0.05). In addition, the bone to metal contact (BMC) around the entire implants demonstrated 186% increase in S implants, 232% increase in P implants and 272% increase in Ca implants when compared to the paired control groups. Based on the comparative analysis of the surface characteristics resulting different bone responses between all groups, it was concluded that surface chemistry and topography separately or together play important roles in the bone response to the oxidized implants.


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Arvidsson A , Franke-stenport V, Andersson M, Kjellin P, Sul YT, Wennerberg A . Formation of calcium phosphates on titanium implants with different surface preparations. An in-vitro study. Accepted for publication.

Abstract

The aim of the present study was to compare the nucleating and growing behaviour on four types of bioactive surfaces by using the simulated body fluid (SBF) model. Titanium discs were blasted and then prepared by alkali and heat treatment, anodic oxidation, fluoridation, or hydroxyapatite coating. The discs were immersed in SBF for 1, 2, 4 and 6 weeks. Calcium phosphates were found on all specimens, as analysed with scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). After 1 and 2 weeks of SBF immersion more titanium was accessible with SEM/EDX on the blasted surfaces than the four bioactive surface types, indicating a difference in coverage by calcium phosphates. The Ca/P mean ratio of the surfaces was approximately 1.5 after 1 week, in contrast to the fluoridated specimens which displayed a Ca/P mean ratio of approximately 2. Powder X-ray diffraction (P-XRD) analyses showed the presence of hydroxyapatite on all types of surfaces after 4 and 6 weeks of immersion. The samples immersed for 6 weeks showed a higher degree of crystallinity than the samples immersed for 4 weeks. In conclusion, differences appeared at the early SBF immersion times of 1 and 2 weeks between controls and bioactive surface types, as well as between different bioactive surface types.


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