What is an Oroantral Fistula? Why Does It Occur and How Is It Treated?

Prof. Dr. Gediz Murat Serin – Ear, Nose and Throat Specialist

What is an Oroantral Fistula (Oral–Sinus Opening)?

An oroantral fistula is the formation of an unwanted opening (passage) between the maxillary sinus located inside the upper jaw (maxilla) bone and the oral cavity.
In other words, an abnormal connection develops between the mouth and the sinus. In this case, food and water from the mouth can pass into the sinus and recurrent sinus infections occur.

Most Common Causes

This opening usually occurs due to:

• Difficult extraction of upper molar or premolar teeth,
• Sinus damage occurring during implant or sinus lift (bone elevation) surgery,
• Previously performed cyst or tumor operations,
• Trauma or bone weakening after radiotherapy.

In other words, it is most often noticed after a procedure performed in the dental area.

What Are the Symptoms?

Patients generally present with the following complaints:

• Fluid leakage from nose to mouth or mouth to nose,
• Air coming into the mouth when blowing the nose,
• Bad taste,
• Unilateral nasal congestion or discharge,
• A non-healing space or feeling of a hole after tooth extraction,
• Fullness and pain in the sinus area.

In some patients, this condition manifests as recurrent sinusitis.

How is the Diagnosis Made?

The diagnosis is usually made by examination and endoscopic examination.

• It is noticed by air passage from inside the mouth. What the patient drinks may come out from the nose.
• The inside of the sinus is evaluated with nasal endoscopy.
• In necessary cases, the location and size of the defect and the condition inside the sinus are clarified by taking dental and sinus tomography (CBCT).

At this stage, both the opening (fistula) and sinusitis if present are evaluated together.

How Is Treatment Performed?

The aim in oroantral fistula treatment is to clean the sinus from infection and close the opening between the mouth and the sinus.

Treatment consists of two stages:

1. Clearing the Infection

• If there is sinus inflammation, the sinus is first drained with medication or by endoscopic sinus surgery (FESS) method.
• The intraoral area is cleaned with antiseptic solutions and protected from pressure and trauma.

2. Closing the Opening

The closure method varies according to the size and location of the opening:

• Small openings (smaller than 5 mm) can sometimes be closed with stitches only.
• For larger openings, flaps (covers) taken from intraoral tissues are used.
  • Buccal flap: Closure is made by sliding tissue from inside the cheek.
  • Palatal flap: The opening is covered with healthy tissue taken from the palate.
  • Buccal fat pad (BFP): Closure can be made by sliding the natural fat tissue inside the cheek.
• In some special cases, a more solid repair is made using cartilage (from the ear or septum) or bone graft.

OAF Developing After Implant and Sinus Lift

Oroantral fistula can sometimes also occur due to the implant contacting the sinus or after sinus lift surgery.
In this case, the sinus and opening are first repaired, and then 4–6 months later when the bone tissue has healed, the implant is planned again.

Post-Surgery Precautions

• Nose blowing, vigorous coughing or sneezing should be avoided in the first weeks.
• Smoking should not be done.
• Activities such as air travel or diving that will cause pressure increase are not recommended.
• Soft foods are preferred in the first days.
• Antibiotics and painkillers recommended by the doctor should be taken regularly.
• Follow-up appointments should not be missed.

What Happens If Not Treated?

Untreated OAF can lead to chronic sinusitis, thickening and inflammation accumulation in the sinus mucosa, and sometimes bad breath and bone infection.
Therefore, early diagnosis and appropriate surgical repair are very important.

Conclusion

Oroantral fistula is often a simple but not-to-be-neglected condition.
If diagnosed early, the closure procedure is short and the success rate is high.
When delayed, sinusitis develops and more complex surgeries may be required.
For successful treatment, both closure of the opening and cleaning of the sinus should be planned together.