Biomedical Engineering Reference
In-Depth Information
the material, but rather to the difficulty of treating and sealing a multi-channelled tooth. The
use of CA's as root canal sealers is indirectly supported in “Introduction to Dental
Materials” by van Noort (van Noort, 1994), where the following materials characteristics are
looked for; biocompatible, dimensionally stable, antibacterial and bioactive. The results in
this study can be interpreted as a success in meeting these materials requirements.
Already in the 1970s, Calcium aluminate (CA) was suggested as a biomaterial and tested
in
vivo
. Hentrich et al (Hentricht et al, 1994) compared CA with alumina and zirconia in an
evaluation of how the different ceramics influenced the rate of new bone formation in
femurs of rhesus monkeys. Hamner et al (Hamnar and Gruelich, 1972) presented a study in
which 22 CA roots were implanted into fresh natural tooth extraction sites in 10 baboons for
periods ranging from 2 weeks to 10 months. In both studies CA successfully met the criteria
for tissue adherence and host acceptance.
4.1.3 Dental filling materials
An important feature of the hydration mechanisms of the Ca-aluminate based materials is
the nanostructural integration with and the high shear strength developed towards dental
tissue. This makes both undercut (retention) technique and bonding techniques redundant.
The Ca-aluminate approach to dental filling technique is new. With this technique, the
chemical reactions cause integration when the bioceramic material is placed in the oral
cavity at body temperature and in a moist treatment field. Figure 11 shows a TEM
(transmission electron microscopy) illustration of the interface between the CA-based
material and dentine. This establishes a durable seal between bioceramic and tooth.
Whereas amalgam attaches to the tooth by mechanical retention and resin-based materials
attach by adhesion, using bonding agents, etchants, light-curing or other complementary
techniques, the CA-materials integrate with the tooth without any of these, delivering a
quicker, simpler and more robust solution.
Fig. 11. Nanostructural integration of CAPH-material with dentine (gray particles in the
biomaterial are glass particles)
The general aspects of Ca-aluminate based materials have been presented in two Ph D
Thesis-publications. Important aspects of Ca-aluminate materials as dental filling materials
are dealt with, such as dimensional stability, acid corrosion and wear resistance, and
biocompatibility and mechanical properties (Kraft 2002, Lööf et al 2003).
4.1.4 Coatings on dental implant and augmentation
For successful implantation of implants in bone tissue, early stabilisation is of great
importance (Ellingsen and Lyngstaadas, 2003). This includes both orthopaedic and dental
