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 Anodized Sample - 10V

Anodized Sample - 80V

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 Response to Modified Implants After Surgery

(Anodized 10V and 80V)

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.

Q&A