Transosseous Suture Fixation of an Inverted Palatal Mucoperiosteal Flap to Residual Buccal Alveolar Bone for Oronasal Fistula Repair in a Dog

Advanced periodontal disease can compromise the recipient tissues available for flap fixation during oronasal fistula repair. This report describes double-layer repair of an acquired periodontal oronasal fistula in an eight-year-old castrated male Beagle. Radiographs and computed tomography (CT) identified regional bone loss and residual alveolar bone adjacent to the defect. Following extraction of the left maxillary canine and second premolar and debridement of the fistula margins, an inverted hard palatal mucoperiosteal flap was anchored to residual buccal alveolar bone through four transosseous bone holes created with an 18-gauge needle. Transosseous suture fixation used 4-0 polydioxanone simple interrupted sutures. A buccal mucosal advancement flap covered the inverted flap and palatal donor site; no interpositional graft was used. Healing without clinically evident dehiscence was documented on postoperative day 18, and nasal discharge had resolved by day 45. At 555 days, visual oral examination revealed an intact repair, with concordant CT findings obtained for an unrelated otologic indication. This case illustrates the use of residual buccal alveolar bone for palatal flap attachment when periodontal tissue loss limits gingival recipient margins, with maintained closure documented at late clinical and imaging reassessment.