Oroantral Communication and Oroantral Fistula

An oroantral communication (opening) is an abnormal pathological channel connecting the oral cavity with the maxillary sinus (antrum of Highmore). If this communication is not eliminated and persists for a prolonged period (more than 2–3 weeks), its walls become epithelialized, and it transforms into an oroantral fistula — a stable tract that does not heal spontaneously.

Thus, the communication represents the acute stage of the process, while the fistula is its chronic, final form. This channel disrupts the natural barrier function, allowing oral microflora to infect the sinus and leading to chronic odontogenic maxillary sinusitis.

Aetiology and Pathophysiology

Perforation of the floor of the maxillary sinus during dental procedures is the most common cause. This is due to the anatomical proximity of the roots of the maxillary posterior teeth to the sinus.

Common causes include:

• Tooth extraction: Responsible for more than 80 % of cases. Perforation most often occurs during extraction of the upper molars and premolars (teeth 4, 5, 6, 7).
• Dental surgeries: Complications during implant placement, sinus lifting, or removal of maxillary cysts or tumors.
• Trauma: Fractures of the maxilla or zygomatic bone.
• Infections: Destruction of the bony partition as a result of chronic periodontitis, osteomyelitis, or tumor breakdown.

A fistula tends to form through epithelial migration from the oral cavity along the walls of the wound canal toward the sinus. Complete epithelialization of the tract prevents spontaneous healing and maintains chronic inflammation within the sinus.

Clinical significance

Clinical manifestations depend on the size and duration of the defect. Diagnosis is based on patient complaints and clinical tests.

Characteristic features:

• Passage of fluids: Entry of liquid food from the oral cavity into the nose during eating or drinking.
• Passage of air: Free movement of air between the mouth and nose.
• Voice changes: Development of a nasal tone in speech (rhinolalia).
• Symptoms of sinusitis: Unilateral nasal obstruction, purulent discharge from the corresponding nostril, pain, and a feeling of heaviness in the buccal region.

The key diagnostic test is the Valsalva maneuver: the patient is asked to pinch the nose and exhale gently through it. If air bubbles or a hissing sound in the socket of the extracted tooth are noted, the communication is confirmed. To assess the condition of the sinus and bone tissue, radiography or cone-beam computed tomography (CBCT) is used. The only option is surgery aimed at plastic closure of the defect.

Differential Diagnosis

Acute oroantral communication must be differentiated from post-extraction alveolitis (“dry socket”), which also causes pain but lacks the characteristic signs of air and fluid passage. In cases of chronic fistula with symptoms of sinusitis, it is important to exclude other causes of unilateral sinusitis, such as a foreign body in the sinus (e.g., filling material), fungal infection, or neoplasm. In such cases, CBCT findings are decisive.