bio-materials: paper review on bone response to titanium implants
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Michelle Calender
Ngozi Aberdeen
Jurinus Lesporis
Larsson et al.
International Journal of Biomaterials
1994
Background• Surface composition includes attributes
such as roughness and surface oxide
thickness.
• Titanium’s surface properties can be varied
systematically by electropolishing and
anodizing.
• Are implant-tissue interactions influenced
by implant surface composition?
Preparation Methods
Electropolishing
Polishing using
electrical current.
• Titanium oxides
dissolve
• methanol, butanol,
and perchloric acid
• 22.5 V
• -30 °C
Anodizing
Adding a layer of
surface oxide using
electrical current.
• Titanium oxides form
protective layer
• acetic acid
• 10 or 80 V
• Room temperature
Groups
Each rabbit received 4 threaded titanium
implants, two in each tibia:
1. Electropolishing
2. Electropolishing and 10 V anodizing
3. Electropolishing and 80 V anodizing
4. None
4 rabbits were examined after 7 weeks
6 rabbits, after 12 weeks
Analysis Method
Morphometry:
• Implants and surrounding tissue examined
under a microscope connected to a computer
• Measured surface oxide thickness and
smoothness
• Calculated contact between implant and
tissues
• Calculated percentage of different tissues
between threads
Modified Implant Surface Topography
Clinical
Control
• Rough surface, having grooves, pits and protrusions
• Deformations are plastically deformed
• Topographical features are less than 10µm in height
• Oxide layer 4nm
Modified Implant Surface Topography
Electropolished
• Smooth surface, having small pits
• Topographical features are less than 1µm in height
• Oxide layer 4-5nm
Modified Implant Surface Topography
Anodized 10V
• Smooth surface, having pits and porous regions
• Topographical features are approximately 10µm in height
• Oxide layer 21nm
Modified Implant Surface Topography
Anodized 80 V:
Smooth (left)
Rough (right)
• Heterogeneous surface, having grooves, pits and protrusions
• Topographical features are approximately10µm in height
• Oxide layer 180nm
Surface CharacteristicsPreparation Composition Oxide
Thickness
Surface Topography Substrate
Microstructure
Oxide Crystallinity
Clinical
Reference
TiO2 + 45-80%
C;
Traces of Ca, S,
Si, P, Cl, Na
4nm Rough, with grooves, pits
and protrusions, ≤10µm
R =29 ±4nm
Plastically deformed,
amorous metal surface
Non-crystalline oxide
Electropolished TiO2 + 55-90%
C;
Traces of Ca, S,
Si, P, Cl, Na
4-5nm Smooth, occasional pits,
≤1µm
R = 2.7 ± 0.9nm
Polycrystalline metal
surface
Non-crystalline oxide
Electropolished
and Anodized,
10V
TiO2 + 55-70%
C;
Traces of Ca, S,
Si, P, Cl, Na
21nm Smooth, with pits and
porous regions, ~10µm
R = 1.5 ± 1nm
Polycrystalline metal
surface
Non-crystalline oxide
Electropolished
and Anodized,
80V
TiO2 + 34-40%
C;
Traces of Ca, S,
Si, P, Cl, Na
180nm Heterogeneous, with
smooth or porous regions,
~10µm
R = 16 ± 2nm
Polycrystalline metal
surface
Crystalline oxide
(anatase)
Bone Response to Modified Implants After Surgery
(Clinical Control and Electropolished)
7 weeks 12 weeks
Bone Contact and Area in Threads
• Bone deposition occurred on the cut bone after modification by bone resorption, not directly on implant surface.
• Threads 1 and 2 in cortical portion of implant.
• Threads 3-5 in intramedullary portion of implant.
Bone Contact (7 weeks)
Bone Contact (12 weeks)
Bone Area (7 weeks)
Bone Area (12 weeks)
Bone Contact Results
The data suggests the 80V-anodized sample has the most bone contact and bone area within the threads.
Total Bone Contact Total Bone Area
Discussion: Findings
1. All had a high degree of bone contact, and there was no evidence of soft tissue encapsulation.
Why: for bone apposition the Oxide Layer surface chemical properties is a lot more important than its Thickness & Microstructure.
2. Electropolished implants had the lowest degree of bone contact and intra-thread bone amount.
Why: very smooth surface topography
Discussion: Findings (cntd.)
3. 80V Anodized Implant had faster bone formation
Why: I. Maybe Thicker oxide
II. Surface TopographyBut: Topographical features occurred on 1µm level and cells are only influenced by structures 10 times that.
Discussion: Limitations
• Longer implantation periods are especially
necessary for evaluating the clinical
implications of the results of this study.
• Oxide Microstructure was not looked at in
this study.
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