Dental Caries

Typical Signalment

• Dental caries can occur in any breed or size of dog.
• Greater risk of the condition with salivary gland dysfunction or dehydration as well as with diets high in fermentable carbohyrates or simple sugars.

Description

Dental caries is a plaque-induced demineralization of the teeth caused by the action of cariogenic bacteria on fermentable carbohydrates. The acid which is produced demineralizes the enamel and dentine. Bacteria is then able to invade the dentine and dentainal tubules, undermining the enamel and eventually causing the collapse of the enamel and cavitation of the tooth. The occlusal surfaces of the molar teeth are partiularly prone to caries.

Dental caries is a multi-factorial disease which requires all four of the following:

1. Susceptible tooth surfaces
2. A fermentable carbohydrate source
3. Cariogenic bacteria (ie. Streptococci and Lactobacillus)
4. Time

The occurance of dental caries is low in dogs when compared with humans. Several reasons for this have been proposed:

• Few cariogenic bacteria in the normal oral flora
• High salivary pH, acting to neutralize acid produced by the bacteria
• Canine tooth surfaces are not prone to food impaction
• Diets are normally low in fermentable carbohydrates
• Lower frequency of food intake compared with humans

Diagnosis

Clinical Signs

• dysphagia
• reluctance to eat
• tooth pain and thermal sensitivity
• excessive salivation
• pain on mastication
• lethargy
• weight loss

Dental Examination

Examination of the tooth surface may reveal a 'white spot' (early lesions) or a brown/grey discolouration (advanced lesions) of the tooth surface. Severe lesions may present with a cavitation of the tooth surface. A sharp dental probe can be gently used to identify defects in the tooth surface. The probe will stick when removed from a carious lesion due to the softened dentine.

Diagnostic Imaging

Radiographs of the tooth may show a radiolucency within the tooth or below the occlusal surface. The extent of lesions may be underestimated as a 40% loss of mineral content is required before a radiolucency is seen on a radiograph. In addition this means that advanced lesions are also more difficult to interpret.

Treatment

Factors that have contributed to the formation of the caries should be assessed and addressed:

• Diet (reduce amount of fermentable carbohydrate)
• Salivary gland (investigate the possibility of salivary gland dysfunction)
• Anatomical structure of the tooth (Deep pits and fissures on the tooth surface)

Non-cavitated white spot lesions may remineralise and require conservative treatment:

• Dietary advice
• Home dental care focusing on plaque control
• Regular check-ups and assessments

Cavitated lesions may require restorative treatment:

• Removal of diseased enamel and dentine and the placement restorative material such as composite resin or glass ionomer.
• Extraction may be required if there is extensive loss of the tooth structure.

References

• Tutt, C., Deeprose, J. and Crossley, D. (2007) BSAVA Manual of Canine and Feline Dentistry (3rd Edition) BSAVA

From Pathology

• Only really seen in primates, but may be seen in horse caused by bacterial decalcification of enamel.
• Acid producing organisms enter dentine and underun enamel.
• Infection may spread to pulp cavity.

Stages of tooth infection (Courtesy of Alun Williams (RVC))