A 10 month-old beagle was referred to Animal Dental Specialists by the dog's regular veterinarian after the owner noticed a broken tooth that presumably occurred when the beagle was playing with other dogs at a "doggie day-care" facility.  The crown of the right upper canine tooth has been fractured and the pulp tissue is exposed (arrow).  This is a painful injury, however most dogs do not cry or whimper.  Unfortunately, dogs do not have an effective way to let their humans know they broke a tooth.  The majority of dogs continue to wag their tail, they seem happy to go for a walk, and in general, they try to act normally.  "Normal" behavior does not mean the injury is not painful! Occasionally, owners may report that they noticed their dog drooling more than usual, and rarely, owners may observe their dog pawing at the mouth on the affected side.  Counter to what most people think, the majority of dogs with broken teeth will continue to eat.  Most dogs (and cats) swallow their dry pet food whole, without chewing every piece-that is, they gulp their food. Thus, the outward signs of a dental fracture are subtle, unless the lips are lifted and the oral cavity is examined.

Like human teeth, the teeth of all mammals are hollow and contain pulp tissue which consists of lots of sensory nerve endings that conduct pain impulses to the patient's brain, as well as a vast array of blood vessels, and lymphatic tissue. Blood vessels, nerves and lymphatic tissue enter and exit the tooth at the tip of the root, which is referred to as the root apex.  Studies have shown that the numbers and types of sensory nerves are the same in human teeth as in dog teeth! Ordinarily, the sensitive pulp tissue is completely surrounded by dental hard tissue which effectively protects the pulp from injury and prevents bacteria in the oral cavity from infecting the tissue.  In the case of this beagle patient, the crown of the tooth became fractured, allowing the pulp tissue to be exposed to the contaminated oral environment. The hollow pulp cavity can be seen on the radiograph as a darker grey space in the center of the tooth which is otherwise densely white.  In addition, the arrow is pointing to a dark area at the apex of the root where infection has oozed out of the channels that permitted blood vessels, nerve and lymphatic tissue to enter and exit the pulp cavity. Since the infection causes bone destruction, the area at the tip of the arrow is darker than the surrounding bone.  This is referred to apical periodontitis.

There are three options for treating this patient's broken tooth.  First, the tooth can be extracted.  Extraction will result in a large hole where the tooth used to be, and necessitates the tissues to be sutured together without tension to prevent food and debris from getting trapped in the wound.  Humans would gargle with warm salt water to help keep the wound clean, but most dogs do knot know how to gargle! Therefore, it is best to close an extraction site with absorbable stitches.  A second option is to remove a portion of pulp tissue then cover over the remaining pulp with medications that will serve to insulate and protect the pulp so that the tooth can continue to strengthen and mature.  However, the procedure referred to as vital pulp therapy should only be done in young animals (less than 18 months of age) and in those teeth with pulp exposure of less than 72 hours duration.  In the case of this beagle, the fracture occurred at least eleven days prior to presentation, therfore vital pulp therapy was not recommended.  Finally, instead of removing the entire tooth, only the contaminated pulp tissue can be removed.  The resulting hollow pulp cavity can then be sanitized and shaped, and a biologically inert filling can be placed into the tooth, effectively preventing any further bacterial contamination of the surrounding bone.  Any infection that may have already occurred will be rapidly cleared by the patient's immune system once the steady flood of bacterial contamination is stopped.  This procedure is called conventional endodontic therapy, sometimes referred to colloquially as "root canal" therapy.