Biomimetic coatings enhance tribocorrosion behavior and cell responses of commercially pure titanium surfaces

CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOBiofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were ( 1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation ( MAO) to improve the surface properties of biomedical implants, ( 2) to investigate the TiO2 layer stability under wear and corrosion, and ( 3) to evaluate human mesenchymal stem cells ( hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group ( p<0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops ( 0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops ( 0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces. (C) 2016 American Vacuum Society.Biofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were ( 1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation ( MAO) to improve the surface properties of biomedical implants, ( 2) to investigate the TiO2 layer stability under wear and corrosion, and ( 3) to evaluate human mesenchymal stem cells ( hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group ( p<0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops ( 0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops ( 0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces.113114CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO11838-13-22013/08451-1The authors would like to thank the University of Illinois at Chicago for providing the facilities to perform this study, Rush University Medical Center on behalf of R. Urban for the SEM facility, Denise Carleto Andia for providing the human bone marrow stromal cells for some cell experiments, Rafael Parra from Univ Estadual Paulista (Sorocaba, Brazil) for his contribution and support in the Plasma Technology Laboratory, the Coordination for the Improvement of Higher Level Personnel (CAPES) from Brazil for the doctoral fellowship of the first author (PDSE Proc. 11838-13-2), the State of Sao Paulo Research Foundation (FAPESP) for Grant No. 2013/08451-1, the National Science Foundation (NSF) for Grant No. 1067424, and finally financial support from NIH R03 AR064005

Gene Expression Dynamics During Bone Healing and Osseointegration

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141010/1/jper1007.pd

Gingival Fibroblasts as a Promising Source of Induced Pluripotent Stem Cells

Induced pluripotent stem (iPS) cells efficiently generated from accessible tissues have the potential for clinical applications. Oral gingiva, which is often resected during general dental treatments and treated as biomedical waste, is an easily obtainable tissue, and cells can be isolated from patients with minimal discomfort.We herein demonstrate iPS cell generation from adult wild-type mouse gingival fibroblasts (GFs) via introduction of four factors (Oct3/4, Sox2, Klf4 and c-Myc; GF-iPS-4F cells) or three factors (the same as GF-iPS-4F cells, but without the c-Myc oncogene; GF-iPS-3F cells) without drug selection. iPS cells were also generated from primary human gingival fibroblasts via four-factor transduction. These cells exhibited the morphology and growth properties of embryonic stem (ES) cells and expressed ES cell marker genes, with a decreased CpG methylation ratio in promoter regions of Nanog and Oct3/4. Additionally, teratoma formation assays showed ES cell-like derivation of cells and tissues representative of all three germ layers. In comparison to mouse GF-iPS-4F cells, GF-iPS-3F cells showed consistently more ES cell-like characteristics in terms of DNA methylation status and gene expression, although the reprogramming process was substantially delayed and the overall efficiency was also reduced. When transplanted into blastocysts, GF-iPS-3F cells gave rise to chimeras and contributed to the development of the germline. Notably, the four-factor reprogramming efficiency of mouse GFs was more than 7-fold higher than that of fibroblasts from tail-tips, possibly because of their high proliferative capacity.These results suggest that GFs from the easily obtainable gingival tissues can be readily reprogrammed into iPS cells, thus making them a promising cell source for investigating the basis of cellular reprogramming and pluripotency for future clinical applications. In addition, high-quality iPS cells were generated from mouse GFs without Myc transduction or a specific system for reprogrammed cell selection

Tribocorrosive behaviour of commonly used temporomandibular implants in a synovial fluid-like environment: Ti-6Al-4V and CoCrMo

The temporomandibular joint implant metal alloys, Ti6Al4V and CoCrMo, (n = 3/group) were tested under free-potential and potentiostatic conditions using a custom-made tribocorrosion apparatus. Sliding duration (1800 cycles), frequency (1.0 Hz) and load (16 N) mimicked the daily mastication process. Synovial-like fluid (bovine calf serum, pH = 7.6 at 37 °C) was used to simulate the in vivo environment. Changes in friction coefficient were monitored throughout the sliding process. Changes in surface topography, total weight loss and roughness values were calculated using scanning electron microscopy and white-light interferometry. Finally, statistical analyses were performed using paired t-tests to determine significance between regions within each metal type and also independent sample t-tests to determine statistical significance between metal alloy types. Ti6Al4V demonstrated a greater decrease of potential than CoCrMo, a higher weight loss from wear (Kw = 257.8 versus 2.62 μg; p \u3c 0.0001), a higher weight loss from corrosion (Kc = 17.44 versus 0.14 μg; p \u3c 0.0001) and a higher weight loss from the combined effects of wear and corrosion (Kwc = 275.28 versus 2.76 μg; p \u3c 0.0001). White-light interferometry measurements demonstrated a greater difference in surface roughness inside the wear region in Ti6Al4V than CoCrMo after the sliding (Ra = 323.80 versus 70.74 nm; p \u3c 0.0001). In conclusion, CoCrMo alloy shows superior anti-corrosive and biomechanical properties. © 2013 IOP Publishing Ltd

Effects Of Dextrose And Lipopolysaccharide On The Corrosion Behavior Of A Ti-6al-4v Alloy With A Smooth Surface Or Treated With Double-acid-etching

Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (α = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the I pass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (p&lt;0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the I corr (corrosion current density) and Ipass (p&lt;0.05). The acid-treated groups showed a significant increase in Cdl values and reduced Rp values (p&lt;0.05, t-test). According to the topography, there was an increase in surface roughness (R2 = 0.726, p&lt;0.0001 for the smooth surface; R2 = 0.405, p = 0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p&lt;0.05) and that of the treated Ti-6Al-4V alloy increased (p&lt;0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no dose-response corrosion behavior could be observed. 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Influence Of Corrosion On Lipopolysaccharide Affinity For Two Different Titanium Materials

Statement of problem Titanium is subject to corrosion in the oral cavity, which could contribute to periimplantitis. However, the effect of corrosion on the lipopolysaccharide affinity for titanium remains unknown. Purpose This study evaluated the role of corrosion (in artificial saliva at pHs 3, 6.5, and 9) on the lipopolysaccharide (LPS) affinity for commercially pure titanium (cp-Ti) and Ti-6Al-4V alloy. Material and methods Seventy-two titanium disks were anodically polarized in a controlled environment (n=9). Control specimens were not corroded. Deionized water with different concentrations of LPS (1.5, 15, and 150 μg/mL) were used to treat the disks for 24 hours to investigate LPS adherence (n=3). Then specimens were immersed in LPS-free water to evaluate LPS elution at 24, 48, and 72 hours. Data were analyzed by the 2-way, 3-way, and 3-way repeated measures ANOVA, t tests, and the Tukey honestly significant difference (HSD) tests (α=.05). Results A greater corrosion rate of cp-Ti and Ti-6Al-4V alloy and a higher LPS adherence to titanium surfaces (P<.05) were noted at acidic pH. The LPS affinity was higher for the Ti-6Al-4V alloy than for cp-Ti (P<.05). More LPS was eluted from titanium surfaces after a 24-hour interval. Conclusion Lipopolysaccharide affinity for cp-Ti and Ti-6Al-4V alloy is influenced by the corrosion process.1106462470Nakagawa, M., Matsuya, S., Udoh, K., Effects of fluoride and dissolved oxygen concentrations on the corrosion behavior of pure titanium and titanium alloys (2002) Dent Mater J, 21, pp. 83-92Gil, F.J., Canedo, R., Padros, A., Baneres, M.V., Arano, J.M., Fretting corrosion behaviour of ball-and-socket joint on dental implants with different prosthodontic alloys (2003) Biomed Mater Eng, 13, pp. 27-34Nakagawa, M., Matsuya, S., Shiraishi, T., Ohta, M., Effect of fluoride concentration and pH on corrosion behavior of titanium for dental use (1999) J Dent Res, 78, pp. 1568-1572Nikolopoulou, F., Saliva and dental implants (2006) Implant Dent, 15, pp. 372-376Vieira, A.C., Ribeiro, A.R., Rocha, L.A., Celis, J.P., Influence of pH and corrosion inhibitors on the tribocorrosion of titanium in artificial saliva (2006) Wear, 261, pp. 994-1001Azzi, M., Szpunar, J.A., Tribo-electrochemical technique for studying tribocorrosion behavior of biomaterials (2007) Biomol Eng, 24, pp. 443-446De Assis, S.L., Wolynec, S., Costa, I., Corrosion characterization of titanium alloys by electrochemical techniques (2006) Electrochim Acta, 51, pp. 1815-1819Mabilleau, G., Bourdon, S., Joly-Guillou, M.L., Filmon, R., Basle, M.F., Chappard, D., Influence of fluoride, hydrogen peroxide and lactic acid on the corrosion resistance of commercially pure titanium (2006) Acta Biomater, 2, pp. 121-129Souza, M.E., Lima, L., Lima, C.R., Zavaglia, C.A., Freire, C.M., Effects of pH on the electrochemical behaviour of titanium alloys for implant applications (2009) J Mater Sci Mater Med, 20, pp. 549-552Huang, H.H., Effect of fluoride and albumin concentration on the corrosion behavior of Ti-6Al-4V alloy (2003) Biomaterials, 24, pp. 275-282Correa, C.B., Pires, J.R., Fernandes-Filho, R.B., Sartori, R., Vaz, L.G., Fatigue and fluoride corrosion on Streptococcus mutans adherence to titanium-based implant/component surfaces (2009) J Prosthodont, 18, pp. 382-387Joska, L., Fojt, J., Corrosion behaviour of titanium after short-term exposure to an acidic environment containing fluoride ions (2010) J Mater Sci Mater Med, 21, pp. 481-488Quirynen, M., De Soete, M., Van Steenberghe, D., Infectious risks for oral implants: A review of the literature (2002) Clin Oral Implants Res, 13, pp. 1-19Morgan, T.D., Wilson, M., The effects of surface roughness and type of denture acrylic on biofilm formation by Streptococcus oralis in a constant depth film fermentor (2001) J Appl Microbiol, 91, pp. 47-53Bollen, C.M., Papaioanno, W., Van Eldere, J., Schepers, E., Quirynen, M., Van Steenberghe, D., The influence of abutment surface roughness on plaque accumulation and peri-implant mucositis (1996) Clin Oral Implants Res, 7, pp. 201-211Quirynen, M., Bollen, C.M., Willems, G., Van Steenberghe, D., Comparison of surface characteristics of six commercially pure titanium abutments (1994) Int J Oral Maxillofac Implants, 9, pp. 71-76Simon, B.I., Goldman, H.M., Ruben, M.P., Baker, E., The role of endotoxin in periodontal disease. I. A reproducible, quantitative method for determining the amount of endotoxin in human gingival exudate (1969) J Periodontol, 40, pp. 695-701Wilson, M., Biological activities of lipopolysaccharides from oral bacteria and their relevance to the pathogenesis of chronic periodontitis (1995) Sci Prog, 78 (PART 1), pp. 19-34Quirynen, M., Vogels, R., Peeters, W., Van Steenberghe, D., Naert, I., Haffajee, A., Dynamics of initial subgingival colonization of 'pristine' peri-implant pockets (2006) Clin Oral Implants Res, 17, pp. 25-37Giannelli, M., Bani, D., Tani, A., Pini, A., Margheri, M., Zecchi-Orlandini, S., In vitro evaluation of the effects of low-intensity Nd:YAG laser irradiation on the inflammatory reaction elicited by bacterial lipopolysaccharide adherent to titanium dental implants (2009) J Periodontol, 80, pp. 977-984Nelson, S.K., Knoernschild, K.L., Robinson, F.G., Schuster, G.S., Lipopolysaccharide affinity for titanium implant biomaterials (1997) J Prosthet Dent, 77, pp. 76-82Knoernschild, K.L., Tompkins, G.R., Schuster, G.S., Lefebvre, C.A., Russell, C.M., Effect of treatment concentration on lipopolysaccharide affinity for two alloys (1997) Dent Mater, 13, pp. 111-117Knoernschild, K.L., Bacon, W.L., Fischman, G.S., Campbell, S.D., Effect of pH on endotoxin affinity for metal-ceramic alloys (2001) J Prosthet Dent, 86, pp. 644-649Knoernschild, K.L., Lefebvre, C.A., Schuster, G.S., Payant, L.M., Gagnon, F.M., Endotoxin adherence to and elution from two casting alloys (1994) Int J Prosthodont, 7, pp. 22-29Knoernschild, K.L., Tompkins, G.R., Lefebvre, C.A., Schuster, G.S., Porphyromonas gingivalis lipopolysaccharide affinity for two casting alloys (1995) J Prosthet Dent, 74, pp. 33-38Gagnon, F., Knoernschild, K.L., Payant, L., Tompkins, G.R., Litaker, M.S., Schuster, G.S., Endotoxin affinity for provisional restorative resins (1994) J Prosthodont, 3, pp. 228-236Knoernschild, K.L., Tompkins, G.R., Lefebvre, C.A., Griffiths, L.L., Schuster, G.S., Effect of pH on Porphyromonas gingivalis endotoxin affinity for resins (1996) Int J Prosthodont, 9, pp. 239-247Robinson, F.G., Knoernschild, K.L., Sterrett, J.D., Tompkins, G.R., Porphyromonas gingivalis endotoxin affinity for dental ceramics (1996) J Prosthet Dent, 75, pp. 217-227Barao, V.A., Mathew, M.T., Assuncao, W.G., Yuan, J.C., Wimmer, M.A., Sukotjo, C., The role of lipopolysaccharide on the electrochemical behavior of titanium (2011) J Dent Res, 90, pp. 613-618Mathew, M.T., Barao, V.A., Yuan, J.C., Assuncao, W.G., Sukotjo, C., Wimmer, M.A., What is the role of lipopolysaccharide on the tribocorrosive behavior of titanium? 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Corrosion Kinetics And Topography Analysis Of Ti-6al-4v Alloy Subjected To Different Mouthwash Solutions

This study evaluated the corrosion kinetics and surface topography of Ti-6Al-4V alloy exposed to mouthwash solutions (0.12% chlorhexidine digluconate, 0.053% cetylpyridinium chloride and 3% hydrogen peroxide) compared to artificial saliva (pH 6.5) (control). Twenty Ti-6Al-4V alloy disks were used and divided into 4 groups (n = 5). For the electrochemical assay, standard tests as open circuit potential and electrochemical impedance spectroscopy (EIS) were applied at baseline, 7 and 14 days after immersion in the solutions. Scanning electron microscopy, atomic force microscopy and profilometry (average roughness - Ra) were used for surface characterization. Total weight loss of disks was calculated. Data were analyzed by ANOVA and Bonferroni's test (α = 0.05). Hydrogen peroxide generated the lowest polarization resistance (R p) values for all periods (P &lt; 0.05). For the capacitance (C dl), similar results were observed among groups at baseline (P = 0.098). For the 7 and 14-day periods, hydrogen peroxide promoted the highest Cdl values (P &lt; 0.0001). Hydrogen peroxide promoted expressive superficial changes and greater Ra values than the others (P &lt; 0.0001). It could be concluded that solutions containing cetylpyridinium chloride and chlorhexidine digluconate might be the mouthwashes of choice during the post-operatory period of dental implants. However, hydrogen peroxide is counter-indicated in these situations. Further studies evaluating the dynamics of these solutions (tribocorrosion) and immersing the disks in daily cycles (two or three times a day) to mimic a clinical situation closest to the application of mouthwashes in the oral cavity are warranted to prove our results. © 2014 Elsevier B.V.43110Ivanoff, C.J., Hallgren, C., Widmark, G., Sennerby, L., Wennerberg, A., (2001) Clin. Oral Implants Res., 12, pp. 128-134Barao, V.A., Mathew, M.T., Assuncao, W.G., Yuan, J.C., Wimmer, M.A., Sukotjo, C., (2012) Clin. 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La mondialisation au Sud : espaces et populations

Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (alpha = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the I-pass (passivation current density), C-dl (double-layer capacitance), and R-p (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the I-corr (corrosion current density) and I-pass (p<0.05). The acid-treated groups showed a significant increase in C-dl values and reduced R-p values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R-2 = 0.726, p<0.0001 for the smooth surface; R-2 = 0.405, p = 0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no dose-response corrosion behavior could be observed. These results suggest a greater susceptibility to corrosion of titanium implants in diabetic patients with associated infections