Twenty years ago, veterinarians dismissed root canal therapy as impractical and unnecessary in veterinary oral care. The old dental axiom "If it's broken, take it out" prevailed. Fortunately, all intradisciplines of modern veterinary dentistry have grown over the last two decades. Many veterinary dentists have continued their education with advanced training in endodontics and now offer excellent root canal treatment. The root canal is used to treat pathology of the tooth's endodontic system. Pulp dies from severe inflammation or disease and diseases of the pulp tissue can lead to sensitivity and pain that can be reversed with endodontic treatment. Since there is no subjective pain in animal patients, the veterinarians must use oral radiology to evaluate the endodontic system. The overt sign of advanced endodontic pathology is a radiolucent halo around the apex of the diseased tooth. Unfortunately, not all teeth that need endodontic treatment show advanced apical osteolysis (i.e. bone resorption around the apex of the tooth root). In acute apical periodontitis with acute apical inflammation, a painful condition occurs before alveolar bone is resorbed. In acute osteomyelitis secondary to an endodontic infection, bacteria can multiply in the marrow spaces of bone leading to bone necrosis with radiographic changes that are difficult to discern. Other patients radiographically present with only indistinct periodontal ligament structure, early apical resorption and indistinct periapical bone lysis. These cases are endodontic challenges and decisions on treatment are critical to the patient's well being. X-ray First Many patients present with a periapical radiolucency. If endodontic disease is left untreated, a granuloma with fistulation can occur (suppurative apical periodontitis). Never perform root canal therapy on a patient without a pre-X-ray, intra-operative X-ray, and follow up X-rays six to 12 months post-treatment. Many veterinarians are calling upon their human dentist friends to show them how to perform root canal therapy without a dental X-ray unit on site. This will only lead to complications. Human vs. Pet Dentistry The human dentist, unless well trained in veterinary dentistry, does not understand veterinary root canal morphology, pulp/root canal length, and/or common complications faced in veterinary endodontics as compared with human endodontics. It is true that there is a major overlap between human and veterinary endodontic treatment, but there is enough difference to warrant this caution if a human dentist is called upon to assist with root canal therapy. The Perfect Root Canal No human dentist and no veterinary endodontist has ever performed the perfect root canal. Veterinary and human endodontists realize that perfection is always sought but never completely reached because of the variation in canal size, shape and unexpected problems in treatment. The excellent root canal conclusion is not accomplished by reading an article on root canals or attending one laboratory session and then initiating patient care. Unexpected Problems Root canal therapy centers on the tooth being properly debrided, disinfected and obturated in three dimensions. The obturation and filling of the terminal apex with endodontic sealer and gutta-percha is not the end of the endodontic story. Radiographic follow-up is essential. Before obturation, the initiation of the treatment with complete canal preparation and debris removal cannot be underestimated. Most veterinary endodontists today use the crown-down approach to complete canal debridement. The coronal canal is instrumented first, starting with (larger and progressing to smaller files), the mid-canal second, and the apical third last. This technique keeps the canal pathway open and debris free. Files must be advanced slowly and gently. Only a few millimeters of canal should be debrided at one time to avoid stricture or file fracture. Many endodontists use rotary files. These are usually nickel-titanium and cut quickly and efficiently with excellent debris removal. If the clinician does not use a deliberate light touch, ledging or transporting of the canal can occur. Hand files may be used rather than rotary files. The same excellent results will occur. It takes longer, but safety is also increased during the period of endodontic treatment growth. It is better to face endodontic complications and challenge them than to rush into rotary instruments and face serious problems that you may not be able to reverse. --- Dr. DeForge is a fellow of the Academy of Veterinary Dentistry and adjunct instructor at Northwestern Connecticut Community College in oral radiology and periodontology. His website is www.vetdent.com.
