Biomedical Engineering Reference
In-Depth Information
hydrofluoric and nitric acids. We use nitric acid addition to well known H
SO
4
/HF
electrolyte composition for electropolishing titanium as a precaution from possibility of
hydrogen adsorption during electropolishing. This method was successfully applied by
Higuchi & Sato, (2003). Decreased hydrogen concentration in the stainless steel samples
after MEP in comparison with EP, and MP ones, was recently reported by Hryniewicz et al.,
(2011).
The bath was unstirred during the process carried out with absence of externally applied
magnetic field. During magnetoelectropolishing the stirring was self imposed by Lorentz
Force as a result of interaction of electric and magnetic fields. For comparison, also Ti
samples after mechanical polishing using an abrasive paper of the grit size up to 1000 were
used.
4. Towards improving the titanium biomaterials
Much attention has been concentrated on improving the properties of titanium biomaterial
(Schenk, 2001; Rokicki, 1992; Gopal et al., 2003; Simka et al., 2011; Rokicki, 1990; Hryniewicz
et al., 2009; (2) Hryniewicz et al., 2009; Schultz & Watkins, 1998; Virtanen et al., 2008; Buly et
al., 1994; La Budde et al., 1994; Burstein et al., 2005; Virtanen & Curty, 2004; Burstein &
Souto, 1995; Mickay & Mitton, 1995; Khan et al., 1999; Hanawa et al., 1998; Budzynski et al.,
2006; Hayes et al., 2010). Osseointegration of a metallic implant into bone or adaptation in
soft tissue involves many complex physiological reactions related both to the material itself
and to the living host. It was thus realized that during implantation a hydrated oxide layer
grows on titanium, suggested to be due to the metabolic activity at the site of implantation
(Virtanen et al., 2008). A prerequisite for clinical success of orthopaedic and dental implants
is a strong and long-lasting connection between the implant and bone. Surface roughness
has been suggested as one important factor for establishing clinically reliable bone
attachments (Buly et al., 1994; La Budde et al., 1994; Burstein et al., 2005; Virtanen & Curty,
2004; Burstein & Souto, 1995). Implant-related factors, mechanical loading, surgical
technique, implant site and patient variables influence bonding between implants and bone
(Buly et al., 1994). Several authors suggest methods to modify the surface structure of
titanium implants, which all may lead to altered chemical and mechanical properties of the
metal surface (La Budde et al., 1994; Mickay & Mitton, 1995). Textured implant surfaces can
be produced by several methods, all of which provide different characteristics of the
biomaterial surface. It is not clear what influence these characteristics have on the bone
response after implantation, or to what extent the response depends on geometry and
degree of the surface roughness (Khan et al., 1999). Results from in vitro studies suggest a
positive correlation between surface roughness and cellular attachment and osteoblast-like
cell activity (Duisabeau et al., 2004).
5. Comparison of surface roughness
Definitions of roughness parameters are given in accordance to Polish Standard: PN-EN ISO
4287 (1999),
R
- parameter calculated from the roughness profile
Ra
- is the arithmetic mean of the sum of roughness profile values
