Dental caries, or bacterial infections of the teeth, are common in humans, uncommon in dogs, and essentially nonexistent in cats.
Human saliva is more acidic, and the teeth contain many pits and fissures. In addition, the human diet is rich in highly refined carbohydrates. The saliva of dogs and cats is more alkaline, the teeth contain fewer pits and fissures, and their diet is less rich in carbohydrates. Cariogenic bacteria are less common in dogs and cats compared to humans.
Initial caries cause acidic demineralization of the enamel by bacteria that ferment sugar, thus releasing acids onto the tooth surface.
In dogs, caries usually occur on the occlusal surfaces of molar teeth. Caries have the appearance of a brown to black cavitated lesion with a soft surface into which a sharp explorer tip can penetrate the diseased dentin and “stick.” The surface has been described as having a leathery or tacky surface when a periodontal probe explorer is used.
Treatment of the carious lesion involves removal of the diseased hard tissue using a dental bur until healthy dentin is reached. A restoration is then placed to protect the exposed dentin that remains and to re-create a normally contoured tooth surface. A radiograph should be taken to determine whether the infection has spread to the pulp, causing endodontic disease, in which case the tooth requires root canal therapy or extraction.
Dogs with dental caries are predisposed to additional lesions.
Topical treatment with a stannous fluoride product every 2 weeks may help prevent future caries in these patients. Only small amounts of fluoride should be placed on the occlusal surfaces of affected or predisposed teeth; it can cause gastritis, and it can be nephrotoxic if appreciable amounts are ingested.