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Greater osteoblast proliferation on anodized nanotubular titanium upon electrical stimulation.

Ercan B, Webster TJ - Int J Nanomedicine (2008)

Bottom Line: Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years.One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone.It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone.

View Article: PubMed Central - PubMed

Affiliation: Division of Engineering, Brown University, Providence, RI 02912, USA.

ABSTRACT
Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years. One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone. It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone. Additionally, electrical stimulation has been used in orthopedics to heal bone non-unions and fractures in anatomically difficult to operate sites (such as the spine). In this study, these two approaches were combined as the efficacy of electrical stimulation to promote osteoblast (bone forming cell) density on anodized titanium was investigated. To do this, osteoblast proliferation experiments lasting up to 5 days were conducted as cells were stimulated with constant bipolar pulses at a frequency of 20 Hz and a pulse duration of 0.4 ms each day for 1 hour. The stimulation voltages were 1 V, 5 V, 10 V, and 15 V. Results showed for the first time that under electrical stimulation, osteoblast proliferation on anodized titanium was enhanced at lower voltages compared to what was observed on conventional (nonanodized) titanium. In addition, compared to nonstimulated conventional titanium, osteoblast proliferation was enhanced 72% after 5 days of culture on anodized nanotubular titanium at 15 V of electrical stimulation. Thus, results of this study suggest that coupling the positive influences of electrical stimulation and nanotubular features on anodized titanium may improve osteoblast responses necessary for enhanced orthopedic implant efficacy.

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Osteoblast densities after 5 days on nonstimulated as well as 1 V, 5 V, 10 V, and 15 V stimulated conventional and anodized nanotubular titanium specimens.Notes: Values are mean ± SEM; n = 3, *p < 0.05 compared to Anod_Non; **p < 0.05 compared to Anod_1 V; ***p < 0.05 compared to Anod_5 V; +p < 0.05 compared to Conv_Non; ++p < 0.05 compared to Conv_10V.Abbreviations: Anod, anodized nanotubular titanium; Conv, conventional (nonanodized titanium); Non, nonelectrical stimulated.
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f6-ijn-3-477: Osteoblast densities after 5 days on nonstimulated as well as 1 V, 5 V, 10 V, and 15 V stimulated conventional and anodized nanotubular titanium specimens.Notes: Values are mean ± SEM; n = 3, *p < 0.05 compared to Anod_Non; **p < 0.05 compared to Anod_1 V; ***p < 0.05 compared to Anod_5 V; +p < 0.05 compared to Conv_Non; ++p < 0.05 compared to Conv_10V.Abbreviations: Anod, anodized nanotubular titanium; Conv, conventional (nonanodized titanium); Non, nonelectrical stimulated.

Mentions: However, in addition to confirming the results of other studies (Yao et al 2005), the present study also provided the first evidence that osteoblasts responded to lower amounts of electrical stimulation when cultured on anodized nano-tubular than unanodized titanium (Figure 4). Specifically, after 1 day of culture, statistically greater numbers of osteoblasts were counted on anodized nanotubular titanium electrically stimulated at 10 V compared to unstimulated anodized materials while the same event did not happen on unanodized titanium until 15 V. After 3 days of culture, statistically greater numbers of osteoblasts were counted on anodized nanotubular titanium stimulated at 10 V compared to 5 V; the same comparison was not statistically different until osteoblasts were stimulated at 15 V on conventional titanium (Figure 5). This same trend of less voltage increasing osteoblast densities on anodized nanotubular compared to unanodized titanium continued after 5 days of culture (Figure 6). Specifically, compared to unstimulated anodized materials, more osteoblasts were counted on anodized nano-tubular titanium stimulated at 10 V while the same levels of osteoblast numbers were not observed until 15 V was reached on conventional, nonanodized titanium after 5 days of culture. Moreover, of any of the substrates of interest to the present study, the largest numbers of osteoblasts were counted on anodized nanotubular titanium electrically stimulated at 15 V after 5 days of culture (Figure 6).


Greater osteoblast proliferation on anodized nanotubular titanium upon electrical stimulation.

Ercan B, Webster TJ - Int J Nanomedicine (2008)

Osteoblast densities after 5 days on nonstimulated as well as 1 V, 5 V, 10 V, and 15 V stimulated conventional and anodized nanotubular titanium specimens.Notes: Values are mean ± SEM; n = 3, *p < 0.05 compared to Anod_Non; **p < 0.05 compared to Anod_1 V; ***p < 0.05 compared to Anod_5 V; +p < 0.05 compared to Conv_Non; ++p < 0.05 compared to Conv_10V.Abbreviations: Anod, anodized nanotubular titanium; Conv, conventional (nonanodized titanium); Non, nonelectrical stimulated.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2636582&req=5

f6-ijn-3-477: Osteoblast densities after 5 days on nonstimulated as well as 1 V, 5 V, 10 V, and 15 V stimulated conventional and anodized nanotubular titanium specimens.Notes: Values are mean ± SEM; n = 3, *p < 0.05 compared to Anod_Non; **p < 0.05 compared to Anod_1 V; ***p < 0.05 compared to Anod_5 V; +p < 0.05 compared to Conv_Non; ++p < 0.05 compared to Conv_10V.Abbreviations: Anod, anodized nanotubular titanium; Conv, conventional (nonanodized titanium); Non, nonelectrical stimulated.
Mentions: However, in addition to confirming the results of other studies (Yao et al 2005), the present study also provided the first evidence that osteoblasts responded to lower amounts of electrical stimulation when cultured on anodized nano-tubular than unanodized titanium (Figure 4). Specifically, after 1 day of culture, statistically greater numbers of osteoblasts were counted on anodized nanotubular titanium electrically stimulated at 10 V compared to unstimulated anodized materials while the same event did not happen on unanodized titanium until 15 V. After 3 days of culture, statistically greater numbers of osteoblasts were counted on anodized nanotubular titanium stimulated at 10 V compared to 5 V; the same comparison was not statistically different until osteoblasts were stimulated at 15 V on conventional titanium (Figure 5). This same trend of less voltage increasing osteoblast densities on anodized nanotubular compared to unanodized titanium continued after 5 days of culture (Figure 6). Specifically, compared to unstimulated anodized materials, more osteoblasts were counted on anodized nano-tubular titanium stimulated at 10 V while the same levels of osteoblast numbers were not observed until 15 V was reached on conventional, nonanodized titanium after 5 days of culture. Moreover, of any of the substrates of interest to the present study, the largest numbers of osteoblasts were counted on anodized nanotubular titanium electrically stimulated at 15 V after 5 days of culture (Figure 6).

Bottom Line: Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years.One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone.It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone.

View Article: PubMed Central - PubMed

Affiliation: Division of Engineering, Brown University, Providence, RI 02912, USA.

ABSTRACT
Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10-15 years. One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone. It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone. Additionally, electrical stimulation has been used in orthopedics to heal bone non-unions and fractures in anatomically difficult to operate sites (such as the spine). In this study, these two approaches were combined as the efficacy of electrical stimulation to promote osteoblast (bone forming cell) density on anodized titanium was investigated. To do this, osteoblast proliferation experiments lasting up to 5 days were conducted as cells were stimulated with constant bipolar pulses at a frequency of 20 Hz and a pulse duration of 0.4 ms each day for 1 hour. The stimulation voltages were 1 V, 5 V, 10 V, and 15 V. Results showed for the first time that under electrical stimulation, osteoblast proliferation on anodized titanium was enhanced at lower voltages compared to what was observed on conventional (nonanodized) titanium. In addition, compared to nonstimulated conventional titanium, osteoblast proliferation was enhanced 72% after 5 days of culture on anodized nanotubular titanium at 15 V of electrical stimulation. Thus, results of this study suggest that coupling the positive influences of electrical stimulation and nanotubular features on anodized titanium may improve osteoblast responses necessary for enhanced orthopedic implant efficacy.

Show MeSH
Related in: MedlinePlus