Biomedical Engineering Reference
In-Depth Information
Despite the specific points concerning clinical evaluation of implants, it is important
to highlight the need for double-blind studies and for registration of trials in order to
mitigate against publication bias, to prevent study duplication, and to evidence gaps in
the knowledge base favoring international collaboration. To date, there are only three pub-
lished randomized controlled double-blinded studies of implant surface treatments. Given
that endosseous implants have been in clinical practice for several decades, it is surpris-
ing that effectiveness studies in the general practice setting have not been reported. The
vast majority of clinical studies are based on outcomes from specialists and medical and
university centers.
Implant Retrieval Analysis
The retrieval of previously functional implants is one of the valuable tools for character-
izing short- and long-term host-implant interactions as well potential failure mechanisms
(Lemons, 2004).
The relative value of implant retrieval analysis is directly related to the amount of infor-
mation available from patient, clinician, implant therapy modality, and implant system
(i.e., lot number). Nonetheless, a lack of knowledge of any of these variables does not limit
specific information that can be acquired from retrieved specimens even though limita-
tion of critical information could ultimately lead to erroneous conclusions. For instance,
if data concerning the patient medical history and functional habits are not available, it is
difficult to relate specific failure mechanisms obtained from retrieval analysis to associ-
ated risk factors.
SurfaceTreatmentstoModifyImplantTopography
A considerable number of in vitro studies using cell culture has documented that rough
surfaces promote greater cell adhesion, proliferation, and differentiation compared with
smooth or machined surfaces (Boyan et al., 1998; Brunette, 1988; Cooper et al., 1999;
deOliviera and Nanci, 2004; Masaki et al., 2005; Makihira et al., 2007; Ricci et al., 2000).
In
vivo studies have demonstrated higher bone-implant contact and greater bone volume
around the implant with rough surfaces compared to those with smooth or machined sur-
faces (Buser et al., 1999, 2001; Butz et al., 2006; Frenkel et al., 2002; Klokkevold et al., 1997;
Suzuki et al., 1997; Yamamuro et al., 1991).
Commercial and experimental methods to produce surfaces of different implant sur-
face topographies or roughness or modifying the homogeneity or thickness of the TiO
2
layer have included: (1) grit blasting with abrasives (e.g., alumina, silica, Ti oxide, calcium
phosphate); (2) treatment with an acid or combination of acids (e.g., HCl, H
2
SO
4
, HF,
HCl/H
2
SO
4
), with an alkali (NaOH)] or with H
2
O
2
; (3) anodization; (4) laser-texturing;
(5) deposition of metal powder or beads (cpTi, Ti alloy or Co-Cr-Mo alloy) or metallic
oxide (TiO
2
) coatings by plasma spraying, or arc-oxidation; (6) high temperature fusion
(e.g., TiO
2
powder with Ti alloy); or (7) combinations of different methods, such as grit-
blasting and acid treatment, alkali treatment and heating (Beatty, 1999; Citeau et al.,
2004; Coelho and Lemons, 2009; Coelho et al., 2009; Guo et al., 2007; Ishikawa et al.,
1997; Lakstein et al., 2009; LeGeros et al., 1996; LeGeros and LeGeros, 2006; Nishiguchi
et al., 2001; Ong and Lucas, 1994; Park et al., 2005, 2008; Ricci et al., 2000; Rohanizadeh
