Practice Essay: Differences Between Caries- Infected and Caries- Affected Dentine
Intro
Caries is defined as a reversible (in its earliest stages) disease of the dental hard tissues brought
about by the metabolic action of cariogenic bacteria on fermentable carbohydrates in the oral cavity
leading to acid demineralisation and ultimately proteolytic destruction of the organic component of
the dental hard tissues.
Caries is one of the most common diseases in humans, and a great deal of a dental surgeon’s career
is devoted to its diagnosis, prevention and treatment. This essay will look at the histological and
clinical manifestations of dentine caries and its significance.
1 Caries- infected dentine
If caries is left long enough to penetrate enamel and reach the underlying dentine (mICDAS 2/3) and
is still left undisturbed the most superficial portions of dentine are liable to become caries- infected
dentine. This dentine is that which suffers the greatest degree of damage due to the carious process,
and its manifestations are shown below:
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Brown, ‘mushy’ appearance- due to the prolonged demineralistaion caused by the lactic acid
produced by the cariogenic bacteria, coupled to the degradation of the collagenous matrix
by the bacterial proteolytic enzymes and the host’s own matrix metalloproteinases, the
dentine is considered necrotic, has a very high bioload, and due to the loss of its tubular
structure, it is considered a very poor bonding substrate and must be removed prior to
restoration of the tooth.
Low compressive strength- the loss of the tubular structure found in sound dentine and even
caries- affected dentine means that in order for full function to be returned to the tooth,
and to prevent the tooth coming to greater harm under occlusal load, the infected dentine
must be removed.
2 Caries- infected dentine
This is the dentine found deep to the caries- infected dentine. Caries- affected dentine differs greatly
from caries- infected dentine not only histologically, but clinically, and can e discerned using tactile
and visual means.
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Time under attack- in contrast to the longer time for which caries- infected dentine has been
under carious attack, caries- affected dentine has been subjected to its effects for much less
time.
Degree of demineralistaion- although demineralised compared to sound dentine, cariesaffected dentine, unlike caries- infected dentine, has the capacity to remineralise under
suitable conditions.
Collagenous matrix- in CAD, there is much less evidence of the action of bacterial proteolytic
enzymes and host matrix metalloproteinases, meaning the collagen matrix is largely intact
and retains it tubular structure, making it suitable for bonding an adhesive restoration to.
Clinically
Caries- affected dentine is stained, but ‘scratchy’ when a probe is run over it, as well as being
hard and is suitable to be left in the tooth and covered with a suitable restoration/
Conclusion
The ability of the dentist to discern between the magnitude of damage done t the tooth and its
constituents by the carious process is the cornerstone of operative and restorative dentistry, and
a sound understanding of the histology of the carious process underpins the clinical findings and
how the dentist elects to manage the situation.