Jukka Lausmaa

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Papers by Jukka Lausmaa

The effect of load on the bone around bone-anchored amputation prostheses

Journal of Orthopaedic Research, 2016

Osseointegrated transfemoral amputation prostheses have proven successful as an alternative metho... more Osseointegrated transfemoral amputation prostheses have proven successful as an alternative method to the conventional socket-type prostheses. The method improves prosthetic use and thus increases the demands imposed on the bone-implant system. The hypothesis of the present study was that the loads applied to the bone-anchored implant system of amputees would result in locations of high stress and strain transfer to the bone tissue and thus contribute to complications such as unfavourable bone remodelling and/or elevated inflammatory response and/or compromised sealing function at the tissue-abutment interface. In the study, site-specific loading measurements were made on amputees and used as input data in finite element analyses to predict the stress and strain distribution in the bone tissue. Furthermore, a tissue sample retrieved from a patient undergoing implant revision was characterised in order to evaluate the long-term tissue response around the abutment. Within the limit of the evaluated bone properties in the present experiments, it is concluded that the loads applied to the implant system may compromise the sealing function between the bone and the abutment, contributing to resorption of the bone in direct contact with the abutment at the most distal end. This was supported by observations in the retrieved clinical sample of bone resorption and the formation of a soft tissue lining along the abutment interface. This article is protected by copyright. All rights reserved.

Biomimetic ion substituted apatite coating on titanium implants: surface composition and morphology control

by Peter Sjövall and Jukka Lausmaa

Biomimetic ion substituted hydroxyapatite coatings on titanium for orthopedic implants

Ion Substituted Calcium Phosphate Coatings

Method for analyzing the spatial distribution of a chemical substance retained by a biological matter

by Peter Sjövall and Jukka Lausmaa

Co-mineralization of strontium substituted hydroxyapatite on polycrystalline rutile surface through a biomineralization process

Aspects of surface physics on titanium implants

Swedish Dental Journal Supplement, Feb 1, 1985

Biological properties of ion substituted apatite coatings

Implant, method for producing the implant, and use of the implant

Some Aspects on the Determination of Surface Chemical Composition and Wettability of Modified Wood

Surface coating for biomedical application

Layer arranged on implant for bone or tissue structure, such an implant, and a method for application of the layer

Glow discharge plasma treatment for surface cleaning and modification of metallic biomaterials

Journal of Biomedical Materials Research, Apr 1, 1997

Glow discharge plasma treatment is a frequently used method for cleaning, preparation, and modifi... more Glow discharge plasma treatment is a frequently used method for cleaning, preparation, and modification of biomaterial and implant surfaces. The merits of such treatments are, however, strongly dependent on the process parameters. In the present work the possibilities, limitations, and risks of plasma treatment for surface preparation of metallic materials are investigated experimentally using titanium as a model system, and also discussed in more general terms. Samples were treated by different low-pressure direct current plasmas and analyzed using Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), atomic force microscopy, scanning electron microscopy, and light microscopy. The plasma system is a home-built, ultra-high vacuum-compatible system that allows sample introduction via a load-lock, and precise control of pressure, gas composition and flow rate, etc. This system allows uniform treatment of cylindrical and screw-shaped samples. With appropriate plasma parameters, argon plasma remove all chemical traces from former treatments (adsorbed contaminants and other impurities, and native oxide layers), in effect producing cleaner and more well-controlled surfaces than with conventional preparation methods. Removal (sputtering) rates up to 30 nm/min are possible. However, when inappropriate plasma parameters are used, the result may be increased contamination and formation of unintentional or undesired surface layers (e.g., carbides and nitrides). Plasma-cleaned surfaces provide a clean and reproducible starting condition for further plasma treatments to form well-controlled surface layers. Oxidation in pure O2 (thermally or in oxygen plasmas) results in uniform and stoichiometric TiO2 surface oxide layers of reproducible composition and thicknesses in the range 0.5-150 nm, as revealed by AES and XPS analyses. Titanium nitride layers were prepared by using N2 plasmas. While mild plasma treatments leave the surface microstructure unaffected, heavy plasma treatment can give rise to dramatic morphologic changes. Comparison of these results with corresponding analyses of commercial implants and electropolished and/or anodically oxidized samples shows that the plasma treatment offers superior control of the surface status. However, it is also shown that improper control of the plasma process can produce unwanted and irreproducible results.

ToF-SIMS analysis of oil-bearing fluid inclusions

by Peter Sjövall and Jukka Lausmaa

Long-term osseointegration of 3D printed CoCr constructs with an interconnected open-pore architecture prepared by electron beam melting

Acta biomaterialia, Jan 18, 2016

In orthopaedic surgery, cobalt chromium (CoCr) based alloys are used extensively for their high s... more In orthopaedic surgery, cobalt chromium (CoCr) based alloys are used extensively for their high strength and wear properties, but with concerns over stress shielding and bone resorption due to the high stiffness of CoCr. The structural stiffness, principally related to the bulk and the elastic modulus of the material, may be lowered by appropriate design modifications, to reduce the stiffness mismatch between metal/alloy implants and the adjacent bone. Here, 3D printed CoCr and Ti6Al4V implants of similar macro-geometry and interconnected open-pore architecture prepared by electron beam melting (EBM) were evaluated following 26 week in vivo implantation in adult sheep femora. Despite higher total bone-implant contact for Ti6Al4V (39 ± 4%) than CoCr (27 ± 4%), bone formation patterns were similar, e.g., densification around the implant, and gradual ingrowth into the porous network, with more bone in the outer half (periphery) than the inner half (centre). Raman spectroscopy revealed ...

Spectroscopic studies of surface chemical composition and wettability of modified wood

Http Dx Doi Org 10 1080 17480270903337659, Mar 1, 2009

Biomimetic hydroxyapatite growth on titanium oxide surfaces

Surface modification and analysis of Ti and Ti-6Al-4V implant materials

Micron and Microscopica Acta, 1990

Surface analysis of failed oral titanium implants

Journal of Biomedical Materials Research, 1999

The aim of the present study was to investigate the surface topography, composition, and oxide th... more The aim of the present study was to investigate the surface topography, composition, and oxide thickness of consecutively failed, oral Brånemark implants in order to determine possible causes for failure. The failure criterion was lack of osseointegration manifested as implant mobility. Ten implants were retrieved before loading (early failures) and 12 during a period of function up to 8 years (late failures). At retrieval, early losses did not display any clinical sign of infection. All late failures were radiographically characterized by peri-implant radiolucency and did not show infectious signs with one exception. No implant seemed to be lost due to peri-implantitis (plaque-induced progressive marginal bone loss). Twelve implants were analyzed by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and depth profiling using a blind protocol. Two pristine fixtures, which underwent the same preparation as the failed implants, were used as controls. In the SEM, control samples were essentially free from macroscopic contamination, whereas failed implants contained varying amounts of tissue residues. AES showed that all surfaces consisted of Ti oxide and varying amounts of additional elements, with C dominating in most cases. Nitrogen and sometimes Na, Ca, P, Cl, S, and Si were detected. The Si contamination was most likely due to ion leaching from the glass vials used for storage. Depth profiles showed a typical oxide thickness of 5-8 nm for all samples. In conclusion, no significant changes in the oxide layer composition or thickness as a result of implantation were observed. The results do not indicate any material-related cause for the failures of these implants. Possible reasons for these failures were impaired healing, asymptomatic infection, and overload.

The effect of heat- or ultra violet ozone-treatment of titanium on complement deposition from human blood plasma

Biomaterials, Apr 1, 2010

Titanium (Ti) is a well known metallic biomaterial extensively used in dental, orthopaedic-, and ... more Titanium (Ti) is a well known metallic biomaterial extensively used in dental, orthopaedic-, and occasionally also in blood contacting applications. It integrates well to bone and soft tissues, and is shown upon blood plasma contact to activate the intrinsic pathway of coagulation and bind complement factor 3b. The material properties depend largely on those of the nm-thick dense layer of TiO 2 that becomes rapidly formed upon contact with air and water. The spontaneously formed amorphous Ti-oxide has a pzcw5e6 and its water solubility is at the order of 1e2 micromolar. It is often subjected to chemical-and heat treatments in order to increase the anatase-and rutile crystallinity, to modify the surface topography and to decrease the water solubility. In this work, we prepared solegel derived titanium and smooth PVD titanium surfaces, and analysed their oxide and protein deposition properties in human blood plasma before and after annealing at 100e500 C or upon UVO-treatment for up to 96 hours. The blood plasma results show that complement deposition vanished irreversibly after heat treatment at 250e300 C for 30 minutes or after UVO exposure for 24 hours or longer. XPS and infrared spectroscopy indicated change of surface water/hydroxyl binding upon the heat-and UVO treatments, and increased Ti oxidation. XRD analysis confirmed an increased crystallinity and both control (untreated) and annealed smooth titanium displayed low XRD-signals indicating some nanocrystallinity, with predominantly anatase phase. The current results show that the behaviour of titanium dioxide in blood contact can be controlled through relatively simple means, such as mild heating and illumination in UV-light, which both likely irreversibly change the stoichiometry and structure of the outmost layers of titanium dioxide and its OH/H 2 O binding characteristics.

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