6.3 CARIES DETECTION AND DIAGNOSIS
The presentation of caries has been described as resembling an iceberg with the
clinically visual stages commencing with the white-spot lesion being above the
waterline. Below the waterline lie the lesions which need the use of some form of
additional aid to be identified. This can range from radiographs in the clinical
situation to histopathology in the in vitro setting.
Caries diagnosis is difficult, it is a multi-stage process. Unfortunately, current training
of undergraduate dental students and remuneration systems lead dentists frequently
just to think of the diagnostic process as a treatment, that is, a dentinal carious lesion
on the distal surface of a premolar being recorded as a DO amalgam.
The identification of caries depends on a systematic examination of clean dry teeth.
The basic equipment consists of adequate lighting, compressed air for drying, dental
mirror, and blunt or ball ended probe. The emphasis is on a visual examination, rather
than a visual-tactile examination. Sharp probes which were traditionally used to aid
diagnoses are contra-indicated for a number of reasons:
- The probe does not improve diagnosis⎯all a 'sticky' fissure means is that the probe
fits the fissure. - Probing a demineralized lesion will break the enamel matrix making
remineralization impossible, thus creating an iatrogenic cavity. - The probe may transfer cariogenic bacteria from one site to another, in effect
inoculate caries free sites with cariogenic bacteria.
A ball-ended or blunt probe may be used gently to confirm the presence of cavitation,
sealants, and restorations.
The first visible sign of caries is the white spot lesion, at first this can only be seen
when the surface is dried (234HFig. 6.9). This is because when demineralized enamel
becomes porous, these pores contain water, if dried, the water in the pores is replaced
with air and the lesion becomes more obvious. As the caries progresses the lesion will
become obvious even when wet.
Unfortunately active carious lesions are not the only causes of white areas on teeth;
hypoplasia, fluorosis, and arrested hypermineralized carious lesions to name but a few
can all mimic a white spot carious lesion. The decision as to the aetiology depends on
factors such as site and surface characteristics. Caries tends to occur at predilection
sites, therefore a white area at the gingival margin is much more likely to be caries
than one of similar appearance at the incisal edge. Active carious lesions are matt
white, while arrested lesions are glossy. A similar process is conducted for brown spot
lesions.
Although large cavities are relatively easily identified dentine caries presents its own
problems. On occlusal surfaces there may be no visible break in the surface, the
evidence of caries being shadowing under the enamel. A similar picture is seen for
approximal lesions.
Therefore as even the most thorough visual clinical examination will detect only some