What are oronasal or oroantral fistulas?

What are oronasal or oroantral fistulas?

Photo 1: Notice the intact sutures (arrows) adjacent to an oronasal fistula as well as an oroantral fistula in the caudal premolar area.
The veterinary patient has a variety of health-care needs, and dental problems are common in both cats and dogs. Therefore, the annual physical exam should always include a complete oral examination. These routine evaluations along with a thorough history help veterinarians recognize potential problems. Oronasal and oroantral fistulas are communications between the oral cavity and the respiratory tract. The only difference is the location of these fistulas. The oronasal fistula is located more rostral (incisor, canine and premolar areas) compared to the oroantral fistulas which are situated in the caudal premolar and molar areas (Photo 1).

What is the cause of oronasal or oroantral fistulas?

Oronasal fistulas are more common than oroantral fistulas in my experience. These lesions often appear as complications associated with dental extractions. To avoid these complications, all extraction sites should be closed using a well-designed mucogingival flap. These flaps need to be designed with maximal blood supply, epithelium- free edges and of adequate size to cover the underlying defect. The flaps should be sutured in a tension-free manner and preferably overlying bone. I prefer 4-0 Monocryl suture; however many suitable suture materials are available.

Periodontal disease is also a very common cause for oronasal or oroantral fistulas. Dachshunds are frequently affected. In these cases, deep palatal pockets (vertical bone loss) are often probed adjacent to the palatal aspect of the upper canine teeth. To avoid the development of these lesions, early recognition and appropriate periodontal therapy is required.

Other causes for communications between the oral cavity and the respiratory tract include foreign-body penetration, bite wounds and neoplasia. Inherited or developmental clefts of the lip or palate are also well-recognized causes of these defects. Each case must be precisely diagnosed and treated appropriately.

History and clinical presentations

Photo 2: Draining track from the incisive area.
In some cases, patients with oronasal or oroantral fistulas will present with obvious holes that communicate with the respiratory track. Debris is usually evident within these lesions. These defects may be associated with a previous dental extraction. For some patients the fistulas appear as a draining track in the incisive area (Photo 2) and the communication with the respiratory tract is not evident during the initial visual examination.

Patients with these types of oronasal or oroantral fistulas may present for evaluation of sporadic or chronic sneezing. Unilateral or bilateral nasal discharge may also be characteristic. Alternately, patients with oronasal fistulas may present with no historical or clinical signs. A comprehensive oral health assessment and treatment must always include meticulous periodontal probing in the anesthetized patient. Dental radiographs frequently do not demonstrate these lesions. Dachshunds are the most common breed presented for oronasal fistula repair in my practice however; the problem has been identified in a variety of cat and dog breeds.

Diagnose first, and then treat optimally

Recognition of the cause of these lesions is fundamental to treatment planning and repair. A systematic approach to the oral examination helps to avoid missing lesions and helps with optimal treatment planning.

For patients with deep palatal pockets adjacent to the upper canine teeth, the determination of communication between the oral and respiratory track is essential. If vertical bone loss does not communicate with the oral cavity, dental extraction or periodontal therapy may be the optimal treatment.

If an oronasal or oroantral fistula is confirmed, any product placed within these defects will migrate into the respiratory tract and act as an irritant.. Therefore, therapies directed at periodontal rejuvenation (root planing followed with perioceutics such as Doxirobe gel) or guided tissue regeneration (root planing with placement of bulk matrix barriers such as Consil or grafting materials such as Osteoallograft Periomix) cannot be utilized.