Avsändare: Institutionen för kliniska vetenskaper Sahlgrenska akademin, Göteborgs universitet 

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Disputationer vid institutionen för kliniska vetenskaper, avdelningen för biomaterial- vetenskap


Disputation - Furqan Ali Shah

(This dissertation will be held in English)

“Osteocytes as indicators of bone quality - multiscale structure-composition characterisation of the bone-implant interface

Tid: fredag 22 september, 2017

kl. 13.00 - ca 15.30

Länk direkt till avhandlingen

En kort sammanfattning av vad Furquan Ali Shahs forskning handlar om finns längst ner i detta mail

 

Lokal: Hörsal Arvid Carlsson, Academicum, Medicinaregatan 3, Göteborgs universitet

Opponent: Professor Serena M. Best Department of Materials Science and Metallurgy, University of Cambridge, UK
Betygsnämnd: Ingemar Abrahamsson, Tomas Albrektsson och Regine Willumeit

Huvudhandledare: Anders Palmquist
Bihandledare: Peter Thomsen och Aleksandar Matic


Osteocytes as indicators of bone quality- multiscale structure-composition characterisation of the bone-implant interface

The research and dissertation in brief
Furqan Ali Shah dissertation concerns bone healing around metal implants (e.g., titanium and cobalt chromium) for dental and orthopaedic applications, and understanding osseointegration in terms of bone quality, with a focus on the role of osteocytes. In his work, he has studied commercially pure titanium (cp-Ti) implants with site-specific surface modification using a high-energy Nd:YAG laser, as well as 3D printed, macro-porous implants of titanium alloy (Ti6Al4V) and cobalt chromium alloy (CoCr) manufactured using electron beam melting (EBM).

What clinical benefit or patient benefit will the result have

Osseointegration is generally studied in terms of the amount of bone formed around implants.

- It is possible that certain implant materials support the formation of large amounts of structurally inadequate or mechanically incompetent bone. Moreover, metal implants (due to their high stiffness) endure most of the functional/physiological loads while the peri-implant bone experiences stress-shielding due to lack of mechanical stimulation. In normal bone, lack of mechanical stimulation leads to decrease in the numbers of osteocytes. Osteocytes are aligned along the lamellar direction, and also exhibit a directional relationship with collagen fibres and bone apatite. Therefore, osteocytes can be used as structural markers for bone healing around currently available materials and novel implant materials, or 3D printed metals/alloys with macro-porous geometries, says Furqan Ali Shah

Figure: Laser-ablation of titanium results in the formation of globular features due to resolidifiation of metal with a highly ordered titanium dioxide on the surface. The image shows osteocytes in bone communicating with an osseointegrated implant surface via the lacuno- canalicular network. The structures have been revealed by sequential exposure of a resin embedded, explanted bone-implant specimen to mild acid and alkali solutions. Scanning electron microscopy (×10,000).

Any surprising or important discoveries?
– A surprising discovery was the identification of highly crystalline, 80 nm to 3 µm wide, magnesium whitlockite particles within post-apoptotic osteocyte lacunae. This is a calcium phosphate phase having a structure similar to β-tricalcium phosphate (β-TCP) which does not commonly exist in bone. Magnesium whitlockite formation requires lower pH conditions than apatite, and therefore points towards an altered biochemical environment within apoptotic osteocytes.

Another surprising finding was the direct attachment of osteocytes (in explanted bone-implant specimens) to not only titanium but also cobalt chromium alloy.


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