Use of XPS to investigate the mechanism
of uptake of fluoride ions by dental filing materials
Dr F Jones
The structure (Chemical/Physical) of a
tooth was described, using SEM images and XPS/SIMS data.
The surface has a interlocking scale like structure, which
contains inorganic and organic components. This structure
is destroyed by decay due to the absorption of bacteria
onto the surface of the tooth, which produce acids as a
bye product of their digestive process. Thankfully this
is in most cases a slow process, which can be retarded further
by the use of treatments such as fluorides. Obviously filing
materials must also be resistant to this type of attack
and as well as having good levels of adhesion to the tooth.
Some of the most advanced filing materials can also be used
to take-up excess fluoride and then release the material
when exposed to moisture, such that it can be transported
to other areas of the tooth and inhibit the corrosion process.
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Dr F Jones
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Using pseudo "tooth"/cement
surfaces, composed of glass, PAA and Fluoride, a series
of experiments were performed on the release of F-, following
exposure to moisture. The XPS measurements show that F,
which has been added to the bulk materials to levels of
up to 900ppm cannot be detected on fresh samples. When these
are exposed to water, the F- is released as CaF2 and adsorbed
onto the surface of the host material. Similar trends are
found from SIMS analysis of the surface. SIMS images using
the CaF+ ion show a relatively uniform distribution of the
CaF2 on the surface of the material.
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