Oro-nasal/Oro-antral Fistulae & Palatal Defects
Oro-nasal and oro-antral fistulae are a relatively common complication following extraction of maxillary canine or carnassial teeth when a flap or open extraction fails to heal properly. Some breeds are more susceptible than others with the Dachshund more heavily represented than any other breed. Other common causes are injuries to the mouth for chewing live electric cables, foreign body injuries (often sticks or bone splinters) and gunshot wounds.
Sometimes a fistula already exists before removal of a maxillary canine. Probing depths of more than 4mm on the palatal aspect is an early warning. If a communication exists between oral and nasal cavity, careful closure of a wide based flap with minimal tension and apposition of freshly debrided edges will help.
Fistulae may take around six weeks post-extraction to manifest fully themselves because tissues contract as they heal. The fistula may cause functional problems if large enough to allow food and fluids to migrate into the nasal cavity when inhaling. This results in a chronic rhinitis which the owners find distressing. Dogs sneeze continuously in such cases.
Functional fistulae can be closed by a number of techniques involving single or double advancement or rotational flaps. Double flaps provide greater support and stability than advancement flaps and have greater success rates in our experience. Often the best flap is the first flap as subsequent procedures are disadvantaged by the lack of bone support and previously scarred tissues.
Palatal defects have several techniques described. Techniques such as split palatal U-flaps and other island flaps have the advantage of carrying a blood supply with the flap. The likelihood of dehiscence is much reduced.
Surgical extraction of difficult teeth are a common reason for referral. Lower canine teeth and lower molar 1’s are the most difficult teeth to remove without collateral damage with the upper canine the third most common. If in doubt, do not start an extraction you may not be able to complete without a high speed air drill and a selection of good luxators.