Elimination of one or more of these
factors is required for the
prevention of dental caries. There is no single test that can take into
consideration all the above factors and accurately predict an indi-
vidual’s susceptibility to caries. The diet type and frequency of intake
is thought to play a significant role in the carious process.
Bacteria
in the dental plaque are capable of fermenting suitable carbohydrate
substrates to produce acid, causing the pH to fall within minutes,
resulting in demineralisation
of the tooth tissue
4
. The plaque remains
acidic for some time, taking 30–60 min to return to its normal pH in
the region of 7. These changes in pH can
be represented graphically
over a period of time following a glucose rinse, which is frequently
referred to as a Stephan curve (Fig. 1.9). The shaded area represents
the risk of carious attack to the tooth surface:
this area is larger in a
patient with extensive caries.
Caries diagnosis and assessment
As with all diagnostic tests, there is the potential for operator error,
therefore careful interpretation is required.
Visual examination
Visual inspection of the tooth is the first and most widely used
method; however it may be surprisingly inaccurate. The tooth must
Basic principles
15
Fig. 1.9
Stephan curve.
POOC01 02/18/2005 04:33PM Page 15
be clean, dry and well illuminated when carrying
out a visual examina-
tion. A blunt probe may be useful to clean debris off the tooth surface
or gently feel for cavities; however, a probe, blunt or otherwise, must
not be pushed against the tooth surface (especially into fissures) as
there is the risk of causing cavitation of
delicate early demineralised
lesions. The diagnosis of frank cavitation is relatively easy, but slight
discoloration, which is suggestive of caries, is much more difficult.
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