Biomedical Engineering Reference
In-Depth Information
Currently, titanium and its alloys are used for dentistry devices
such as implants, crowns, bridges, overdentures, and dental implant
prosthesis components (screw and abutment). There are currently
four cp Ti grades and one titanium alloy specially made for dental
implant applications. These metals are speciied according to ASTM
as grades 1 to 5. Grades 1 to 4 are unalloyed while grade 5, with
6% aluminum and 4% vanadium, is the strongest. However, for
permanent implant applications, the Ti-6Al-4V alloy has a possible
toxic effect resulting from the released vanadium and aluminum
[4, 5]. For this reason, vanadium- and aluminum-free alloys have
been introduced for implant applications. These new alloys include
Ti-6Al-7Nb (ASTM F1295), Ti-13Nb-13Zr (ASTM F1713), and
Ti-12Mo-6Zr (ASTM F1813) [11].
13.2
Dental Implants with Nanosurface
Nanoscale modiication can alter the chemistry and/or topography
of the implant surface [36]. There are many different methods
to impart nanoscale features to the implant surface (Table 13.3).
Several of these methods have already been used to modify implants
available commercially. Such changes alter the implant surface
interaction with ions, biomolecules, and cells. These interactions
can favorably inluence molecular and cellular activities and alter
the process of osseointegration.
Till now, a few nanoscale surface topography modiications have
been used to enhance bone responses at clinical dental implants.
For example, the Osseo-Speed surface (Astra Tech AB, Molndal,
Sweden) possesses nanostructured features created by TiO
2
blasting followed by a proprietary hydroluoric acid treatment [1, 7,
13]. Greater osteoblastic gene expression (Runx2, Osterix, Alkaline
Ph-osphatase, and Bone Sialoprotein) was measured in cells adherent
to the nanoscale HF-treated surface compared to the micron-scale
surface [23]. This nanotopography is associated with the
elevated levels of gene expression that indicate rapid osteoblastic
differentiation. Other studies have demonstrated an increased bone
formation, torque removal value [12]. In the rabbit tibia model of
osseointegration, histomorphometric evaluations demonstrated
higher bone-to-implant contact for the nanoscale OsseoSpeed im-
plants compared to the micron-scale TiOblast™ implants (Astra
Tech AB, Mölndal, Sweden) at 1 month (35 ± 14% vs 26 ± 8%) and
3 months (39 ± 11% vs 31 ± 6%) after placement [43].
