Dental trauma in dogs and cats is a relatively frequent event. Falls from a height, fights with other animals, car accidents, and masticatory trauma are some of the most common causes. The type of injury is determined in particular by the energy and direction of the impact. Trauma often leads to dental fracture. However, teeth may also become displaced, especially if the bone is resilient.

Some of these injuries represent dental emergencies. In these cases, tooth survival depends upon the length of time between trauma and treatment.

Dento-Alveolar Trauma

Dento-alveolar injuries include, in increasing order of severity, concussion, subluxation, luxation and avulsion.

Concussion is a mild lesion characterized by focal periodontal hemorrhage and oedema. In humans, the tooth is normally sensitive to percussion, but in dogs and cats it may be difficult to diagnose. Treatment is normally not necessary, as periodontal and endodontic tissues are only mildly injured.

In subluxation injuries, laceration of some periodontal ligament fibers develops. The tooth normally shows slightly increased mobility, but it is not displaced. In dogs and cats it may still be difficult to diagnose, but fortunately treatment is normally not necessary.

Luxation is the partial displacement of a tooth from the alveolus. It may happen in apical (intrusion), coronal (extrusion) or lateral direction. Luxation is accompanied by alveolar bone fracture and laceration of a large percentage of the periodontal ligament fibers. Often, the periapical vessels are severely injured as well, and endodontic complications are common. The tooth may show increased (extrusion and lateral luxation) or decreased (intrusion) mobility.

Avulsed teeth are completely displaced from their alveolus. The periodontal ligament fibers are totally lacerated and the apical vessels severed.

Luxation and avulsion injuries represent dental emergencies. Manual replacement of the tooth in the socket should be performed within a very short period of time, ideally within 30–60 minutes from the time of injury. However, patients are rarely brought to the veterinarian so quickly. The length of time between the time of injury and replantation (avulsed teeth) or repositioning (luxated teeth) greatly influences the prognosis. In particular, prolonged drying of the dental root causes loss of vitality of the periodontal ligament and necrosis of the pulp. Before replantation, therefore, an avulsed tooth should be maintained in a moist environment, using a suitable storage medium (i.e., cold low-fat milk, or specialized commercially available solutions). To avoid complications, an antibiotic treatment should also be started immediately following injury.

A preoperative radiographic examination should be performed to evaluate the injured tooth and socket. To avoid any damage to the remaining periodontal fibers, aggressive curettage of alveolus and root surfaces should be avoided, and blood clots or debris should be simply removed with gentle irrigation with sterile saline or Ringer's solution and suction. The use of any other chemical solutions, such as chlorhexidine solution, should be avoided. The tooth should be held from the crown, and gently, manually replanted or repositioned.

After confirming radiographically the correct tooth position, lacerated soft tissues should be sutured and the injured tooth splinted to adjacent teeth, using an acid-etch resin splinting technique. After scaling and polishing the teeth to be included in the splint, the wire is properly positioned to reduce tooth dislocation. The teeth are acid-etched for 15 seconds, then the acid etch is washed out trying to avoid any contact with the soft tissues. Finally, composite material or an acrylic resin is applied to the teeth, completely covering the wire. The splint is smoothened and occlusion checked before recovery.

The splinting duration should be as short as possible, to reduce the risk of dentoalveolar ankylosis (normally, 7–10 days for avulsed teeth, and up to 4–6 weeks for luxated teeth with extensive bone fracture).

In the postoperative period, systemic antibiotics (to reduce the occurrence of inflammatory resorption and pulp infection) and analgesics should be prescribed. Biting should be minimized, chew toys withdrawn and a soft diet offered. Oral home care (i.e., tooth brushing and rinsing with chlorhexidine solution) should be recommended.

As luxation and avulsion injuries frequently result in pulp necrosis, in most instances injured teeth should be endodontically treated. Root canal treatment should be performed at least 10–14 days after repositioning or at the time of splint removal rather than at the time of trauma, to minimize the risk of further periodontal damage.

Potential long-term complications following displacement and treatment include inflammatory root resorption, replacement root resorption and ankylosis. Replanted and repositioned teeth should therefore be followed-up radiographically for a long period of time.

Complicated Fracture of Immature Teeth

Pulp health is very important for normal tooth development. Untreated tooth pulp exposure (usually caused by trauma) inevitably leads to pulp inflammation, infection and necrosis. Following pulp death, root development, apexogenesis (i.e., closure of the apex) and dentin deposition are hampered.

In mature (with a closed apex) teeth, the treatment of choice following pulp exposure is total pulpectomy and root canal therapy, which entails accessing, debriding, shaping, disinfecting, and obturating the root canal and restoring the access and/or fracture sites.

Treatment options for endodontically diseased immature teeth are very limited. If the apex is open, a standard root canal therapy cannot be performed as an apical fluid-tight seal is impossible to achieve with any obturating technique. A vital pulp therapy should be performed instead, which aims to maintaining the pulp tissue vital and functional. Necessarily, this type of procedure should be performed soon after trauma, as the longer the pulp is exposed, the higher the risk of pulp infection and death. Ideally, treatment should be implemented within 48 hours from pulp exposure, even though some degree of success has been shown for exposure of longer duration (up to three weeks).

Vital pulp therapy entails partial pulpectomy (removal of the inflamed and infected coronal pulp), direct pulp capping (placement of a dressing directly over the amputated pulp) and access or fracture site restoration (with bonded composite resins or different materials). It should be performed aseptically and under strict radiographic examination. The treatment should create a tight seal above the healthy pulp, and allow or even stimulate the formation of a compact layer of reparative dentin between the restoration and the remaining pulp tissue. The pulp capping material of choice is currently mineral trioxide aggregate (MTA).

Vital pulp therapy should be re-evaluated radiographically at 6 months, and ideally yearly thereafter. As late complications are possible, it may be wise to perform root canal therapy once apexogenesis has been achieved, even if radiographic signs of endodontic disease are not visible.

References

1.  Clarke DE. Vital pulp therapy for complicated crown fracture of permanent canine teeth in dogs: a three-year retrospective study. J Vet Dent. 2001;18(3):117–121.

2.  Gracis M. Management of periodontal trauma. In: Verstraete FJM, Lommer MJ, Bezuidenhout AJ, eds. Oral and Maxillofacial Surgery in Dogs and Cats. Edinburgh, NY: Saunders Elsevier; 2012:201–215.

3.  Niemiec BA. Assessment of vital pulp therapy for nine complicated crown fractures and fifty-four crown reductions in dogs and cats. J Vet Dent. 2001;18(3):122–125.