Biomedical Engineering Reference
In-Depth Information
The standard for cellular biocompatibility in
in vitro
testing has been stated in the
International Organization for Standardization (ISO) standards documents. The standard
allows for the contact testing of solid dental materials for cytotoxicity with cell lines. Due to
several disadvantages of direct contact testing, indirect testing methods have been
developed and compared to the direct testing assays (Tang et al 2002). Introduction of a
standard cell culture device, i.e. cell culture insert or transwell, provided an opportunity for
such cytotoxicity screening of dental materials with indirect contact between material
specimens and cell culture monolayer. It is believed that such a testing system more closely
mimics the
in vivo
exposure pattern by providing the test of the material in both its solid and
dissolved phases at the same time. It has been shown that this testing system has produced
the most stable results as compared to other testing systems, such as direct contact test. In a
complementary cytotoxicity test using the pulp derived cell response, the experimental CA-
material showed no sign of toxicity (Schmalz 2002).
Harmonized standard ISO 10993:2003
Further cytotoxicity and other biocompatibility aspects are summarised according to the
outline in the harmonized standard ISO 10993:2003. An experimental orthopaedic Ca-
aluminate-based material was the test material. This material is judged as mildly cytotoxic
during the initial curing, and as non-cytotoxic as cured material. See Table below.
Type of test Method Cytotoxicity (scale 0-4 or 100-0%
During curing, undiluted ISO 10993-5, § 8.2 2 (mild)
During curing, diluted ISO 10993-5, § 8.2 0-1 (none-slight)
During curing XTT-test 60 % (slight)
During curing, diluted XTT-test > 70 % (none)
Cured, undiluted ISO 10993-5, § 8.2 0 (none)
Cured, diluted
diluted XTT-test > 70% (none)
Table 8. Cytotoxicity testing of an orthopaedic Ca-aluminate based material
A sensitization test (ISO 10993-10), Guinea Pig Maximization Test was performed with the
orthopaedic Ca-aluminate material during curing. No sensitizing potential was obtained.
Additional irritation and delayed hypersensitivity testing according to ISO 10993-10:2002
was conducted with both polar and non-polar extract from cured material, and the results
showed no discrepancies after intracutaneous injections in the rabbit compared to the blank
injections. The acute systemic toxicity study according to ISO 10993-11 was performed with
both polar and non-polar extracts from cured Ca-aluminate material (Xeraspine), and the
results showed no signs of acute systemic toxicity. Sub-acute, sub-chronic and/or chronic
toxicity studies according to ISO 10993-11 were not conducted explicitly, since data from the
two implantation studies in rabbit (see below) were judged to support that no long term
toxicity is expressed. From the implantation studies histopathological organ and tissue data
is available, and no adverse effects were reported.
Additionally, in an
in vivo
genotoxicity assay, the mice micronucleus test of bone marrow
was used. The extract (The experimental Ca-aluminate material during curing and cured
material) was administered intraperitoneally twice. The results showed no clastogenic effect.
Three
in vivo
implantation studies based on ISO 10993-6 have been performed. Two studies
in rabbit (femur) and one in sheep (vertebrae).
In vivo
implantation studies are judged as the
most relevant studies for documentation of safety of a product. In the rabbit implantation
