Oro-antral fistula occurs after a tooth extraction when an opening is created between the sinus and mouth. The teeth or tooth's proximity to the floor of the sinus is either close or actually beyond the floor (extending into the sinus), so when the tooth or teeth are extracted, the result is a hole. The treatment depends on the size and location of the fistula as well as the health of the patient.
In rare cases, when the size of the perforation is small and sinusitis does not occur, the possibility exists that the hole will heal and close on its own. However, in most cases, the hole is large enough that treatment must be implemented. A non-surgical course of treatment exists, but its success rate is limited. If the patient wears a palatinal plate to prevent airflow between the mouth and sinus, rinses with physiological solution, rinses with antibiotic solvent and administers topical antibiotic, spontaneous closure may occur once the inflamed sinus is cured. However, the longer the duration of the fistula's existence the less likely closure will occur.
Spontaneous closure will not happen in most cases and it is important that the hole closes. Otherwise, there will be flow of microflora from the mouth into the sinus, causing inflammation and other negative side effects such as discharge, liquid ingested entering the sinuses, and infection. The health of the patient is compromised the longer the hole is open. The typical treatment utilises an non-evasive minor surgical technique taking tissue from the vestibulum to make a vestibular flap to the close the hole. The success rate of the technique is high and the patient recovery is usually quick. In previous times, radical surgery that required the removal of the mucous membrane was considered but now is avoided. The only instance in which this was a course of action was if the sinus fills with a hyperplastic mucuous membrane. Hyperplasia is the abnormal collection of cell and in this context, the mucuous membrane increases and thickens creating irritation, discomfort, and a loss of function. This is generally a result of unsuccessful attempts to close the oro-antral fistula or a persistent fistula.