Management of Oro-Antral Fistulas (OAF)

 

What is an OAF?

An oro‐antral fistula (OAF) or communication (OAC) is an unnatural opening between the oral cavity and maxillary sinus. When it fails to close spontaneously, it remains patent and is epithelialized to develop into an oro‐antral fistula. It is worth mentioning at this point that the term OAF is used when complete epithelialization had taken place. Various surgical and non-surgical techniques have been used for treating the condition. Surgical procedures include flaps, grafts, and other techniques like re-implantation of third molars. Non‐surgical techniques include allogenic materials and xenografts. 

                                 

Background

Oro‐antral communications (OAC) are pathological conditions characterized by the existence of an unnatural opening ('communication') between the oral cavity and maxillary sinus due to loss of soft and hard tissues that normally separate these compartments. The term 'oro‐antral communications' has been used synonymously with the terms 'oro‐antral perforation', 'antro‐oral communication', 'oro‐antral fistula', 'oro‐sinusal communication', and 'antro‐alveolar fistula'. Although the above‐mentioned terms are often used synonymously, there is a difference between an oro‐antral communication and an oro‐antral fistula: only when the communication becomes epithelialized and remains patent is it referred to as oro‐antral fistula (OAF). OAC is most commonly encountered during maxillary posterior teeth extraction due to the anatomical proximity between root apices and the maxillary antrum. Its frequency ranges between 0.31% and 4.7% following the extraction of upper teeth. It can also occur as a result of iatrogenic complications while performing dental procedures such as surgical removal of cysts. It can also be caused as a complication due to infection of the antral filling used to stabilize the zygomatic complex fracture. Various pathological lesions of the maxillary sinus like mucormycosis, periodontal infections, and trauma can also result in the formation of an OAC.

 

Signs and symptoms

 

 

Complications

Chronic communication between the oral cavity and maxillary sinus can act as a pathway for further bacterial and fungal penetration. Sinusitis has been reported to occur in 60% of cases on the fourth day after sinus exposure. Long‐standing OAF can cause a general systemic toxaemic condition leading to fever, malaise, morning anorexia, frontal and parietal headache, anosmia, and cacosmia.

 

Description of the intervention

Clinical decision‐making about how to treat an OAC/OAF depends on multiple factors that include the size of the communication, time of diagnosis, and presence of infection. Furthermore, the selection of treatment strategy is influenced by the amount and condition of tissue available for repair and the possible placement of dental implants in the future. Communications of 1 to 2 mm diameter heal spontaneously by the formation of a blood clot in the absence of any infection. Interventions for the closure of the OACs can be broadly categorized into surgical, non‐surgical, and pharmacological interventions.

Surgical interventions

Surgical interventions have been further divided into flaps, grafts, and other techniques:

  • Soft tissue flaps: some of the traditional methods include buccal advancement flaps, palatal rotational flaps, palatal transposition flaps, and tongue flaps. Other techniques include local flaps such as a combination of the buccal and palatal flap, pedicled buccal fat pad flap, Bichat's fat pad graft, and acellular dermal graft.
  • Grafts: autogenous grafts from the chin, retromolar area, zygoma, iliac crest, interseptal and inter‐radicular areas, plasma‐rich fibrin membrane, cryoplatelet gel, and septal cartilage have been advocated to close OAC. Xenografts (with flap closure) such as lyophilized porcine dermis, porcine collagen membrane, bovine bone and guided tissue regeneration (GTR) using bovine barrier membranes have also been used. Allogenous grafts such as lyophilized fibrin glue and GTR using allogenous barrier membranes have been reported for treating OAC.
  • Other techniques:re‐implantation of the third molar, gingival suturing, metal plates, foils, and polymethylmethacrylate plates by approximation of buccal and palatal flap, hydroxylapatite blocks and hemostatic gauze have been tried.

Non‐surgical interventions

  • Allogenous materials(without flap closure) such as fibrin glue, dura; synthetic bone graft materials such as polylactic acid/glycolic acid (PLGA)‐coated porous beta tri‐calcium phosphate, prolamine occlusion gel and absorbable polyglactin/polydioxanon implant are some of the non‐surgical interventions used to manage OAC.
  • Xenografts(without flap closure) such as porcine dermis and collagen.
  • Other methods: such as acrylic splints, laser light, root analogues, and N‐butyl cyanoacrylate gel have been tried. Biostimulation with laser light has also been used for closure of OAC.

Pharmacological interventions

Used as an adjuvant to surgical and non‐surgical interventions. The most commonly used drugs include antibiotics and nasal decongestants.

  • Antibiotics: a combination of antibiotics such as amoxicillin and clavulanate potassium 875 mg, clindamycin 300 mg 4 times daily, or moxifloxacin 400 mg) have been used in the treatment of OAC.
  • Nasal decongestants: can be used as adjuvants to the healing of OAC/OAFs if the patient has any sinus infection.

 

How the intervention might work

Surgical interventions

Surgical interventions are mostly based on mobilizing the tissue and advancing the resultant flap into the defect.

  • Soft tissue flaps: a small OAC can be closed immediately by suturing the gingiva, but when this does not provide adequate closure, a soft tissue flap is indicated. In the case of fully developed fistulae, the epithelium lining must be removed in order to facilitate healing. A buccal advancement flap can be used in small OACs when the alveolar ridge is very resorbed and the location of the fistula is more mesial. The palatal rotational flaps can be used in OAC larger than 1 cm in diameter. A modified palatal flap has been proposed that involves only the mucous membrane, leaving the submucosa and periosteum intact to reduce the complication (denudation of bone) of a palatal rotational flap.
  • Grafts: these are recommended for the closure of chronic OAF when soft tissue flap closure fails or when augmentation of the alveolar ridge in conjunction with closure is desired. The use of autogenous, allogenous, or xenografts helps to correct the residual bone defects during the closure of OACs. Foils and plates form a mechanical barrier encouraging the growth of healthy tissue for the closure of OAC. Plasma‐rich fibrin membrane is a natural fibrin‐based biomaterial which stimulates tissue regeneration and promotes cell migration in the site of interest.
  • Other techniques: cryoplatelet gel and GTR accelerate tissue healing and also promote bone reconstruction by the release of osteo‐inductive growth factors in cases of large OAC.

Non‐surgical interventions

Non‐surgical interventions promote closure of OAC without the need for a soft tissue flap. These interventions involve minimum tissue handling, hence reducing post‐surgical trauma during healing.

  • Allogenous materials: glues, adhesives and sealants have the structural ability to enhance the coagulation process and to create a mechanical barrier at the site of tissue breakdown that aids the closure of OAC. Synthetic absorbable implants are press-fitted directly into the defect to obtain the direct closure of the OAC.
  • Xenografts: prolamine occlusion gel is directly injected into the perforation, which hardens to form a barrier.
  • Other methods: acrylic splints act as mechanical barriers in people who are immunocompromised to facilitate the healing of OAC. Splints may also be appropriate in cases of large defects that do not respond to other treatment modalities.

Pharmacological interventions

  • Antibiotics:these are needed to control infections of the sinus thereby helping with better healing of the oro‐antral communication.
  • Nasal decongestants, sprays (steroidal and nonsteroidal), or a combination: should be used preoperatively to reduce the inflammation of the sinus mucosa thereby aiding a tension‐free closure of soft tissue flap over intact bone.

 

Postoperative care

Following all methods of OAC/OAF closure, the patients are instructed to avoid activities that could produce pressure changes between the nasal passages and oral cavity for at least 2 weeks due to the risk of disruption to the healing process. Nose blowing and sneezing with a closed mouth is prohibited and a soft diet is also often advocated during this period.