Clinical decision-making algorithm for the management of Oroantral fistula: A comprehensive guide

Abstract

Oroantral fistula (OAF) is a persistent pathological communication between the oral cavity and the maxillary sinus, often arising as a complication of dental extractions, trauma, or surgical procedures involving the maxilla. Despite various treatment options, a standardized, algorithmic approach remains lacking. To develop and present a comprehensive, evidence-based clinical decision-making algorithm for the diagnosis and management of OAF based on defect size, chronicity, sinus involvement, and infection status. A narrative review and synthesis of the literature were conducted, evaluating diagnostic modalities, microbiological profiles, and both conservative and surgical treatment options from 1990 to 2025. The resulting data informed the development of a stepwise flowchart that integrates clinical parameters and radiographic findings to guide practitioners in selecting the most appropriate therapeutic approach. The algorithm begins with an initial assessment including patient history, clinical and radiographic evaluation. Small asymptomatic OAFs (< 2 mm) are managed conservatively with hygiene protocols and nasal precautions. Infected small fistulas warrant antibiotics. Medium-sized OAFs (5–10 mm) in favorable locations are treated with local flaps, whereas large or unfavorably located fistulas (> 10 mm) require advanced surgical techniques such as buccal fat pad grafts, distant flaps, and regenerative materials like platelet-rich fibrin. Sinus health and chronicity are considered pivotal in determining treatment timing and method. This algorithm provides a structured, patient-centered framework for the management of OAF. By incorporating anatomical, pathological, and microbiological factors, it enhances clinical decision-making, improves treatment outcomes, and supports interdisciplinary coordination.

Introduction

The anatomical proximity between the maxillary posterior teeth and the maxillary sinus often results in an interrelationship between dental infections, surgical procedures, and sinus complications. Among the most significant clinical sequelae of this anatomical relationship is the formation of an oroantral communication (OAC), which, if left untreated or if it fails to close, may develop into a chronic oroantral fistula (OAF) (Bell et al. 2022).

An oroantral fistula is defined as an epithelialized, pathological communication between the oral cavity and the maxillary sinus. It is a persistent form of oroantral communication that fails to close within 48–72 h and becomes lined by epithelium (Verma and Verma 2022). The persistence of this fistulous tract leads to chronic maxillary sinusitis, recurrent infections, halitosis, and reduced quality of life due to discomfort, nasal regurgitation of fluids, and compromised oral function (Salgado-Peralvo et al. 2022).

While OACs are relatively common intraoperative or postoperative complications during dental extraction (particularly of the maxillary first and second molars), the transition from an acute communication to a chronic fistula depends on several factors size of the communication, infection, presence of sinus pathology, and host healing response (Salgado-Peralvo et al. 2022). Clinical management of oroantral fistula remains a significant challenge in oral and maxillofacial surgery due to the diversity in presentation, etiology, chronicity, and anatomical considerations.

OAFs most commonly arise as a complication of maxillary molar or premolar extractions, which account for approximately 48%–80% of all cases (Anish Poorna et al. 2022). The maxillary sinus floor is in close proximity or even in direct contact with the apices of these teeth, making surgical trauma or apical infections particularly risky. The other causes include removal of maxillary cysts or tumors, trauma involving the maxillofacial skeleton, implant placement, osteomyelitis, radiation therapy, pathological lesions such as odontogenic cysts and neoplasms, and iatrogenic injuries during endodontic or periodontal treatment (Visscher et al. 2010). Patients with systemic comorbidities such as diabetes, immunosuppression, or chronic rhinosinusitis are also at elevated risk for non-healing OACs and subsequent fistula formation.

Patients with OAF may present with complaints of fluid leakage from the mouth into the nose (especially during drinking), altered voice resonance, unilateral nasal discharge, recurrent maxillary sinusitis, halitosis, or even air reflux into the oral cavity during nose blowing. Examination may reveal an epithelialized tract, visible perforation, or evidence of purulence and sinusitis (Azzouzi et al. 2022). Radiological assessment, especially cone-beam computed tomography (CBCT), helps delineate the fistulous tract, assess maxillary sinus involvement, and plan surgical closure.

Small OACs (< 2 mm) may heal spontaneously via granulation and secondary intention (Bereczki-Temistocle et al. 2023). However, communications > 5 mm rarely close on their own, especially if there is concurrent sinus infection (Bhalla et al. 2021). Once communication becomes epithelialized, it ceases to heal and requires surgical intervention. The chronic inflammation leads to fibrosis, re-epithelialization, and the establishment of a persistent tract. The delay in diagnosis or inappropriate primary management increases the risk of chronic fistula formation. Early closure of OACs within 48–72 h of formation lead to superior outcomes, emphasizing the importance of early detection and appropriate intervention (Khandelwal and Hajira 2017).

Treatment goals in managing OAF are twofold: eliminate pathological communication and restore functional sinus drainage and mucosal integrity. This necessitates a combined approach involving closure of the fistula and treatment of underlying sinus disease. Management options include conservative therapy (for recent, small, non-infected communications), surgical repair using local or regional flaps (buccal advancement flap, palatal flap, buccal fat pad flap), adjunctive endoscopic sinus surgery in cases of chronic sinusitis or large defects (Konate et al. 2021). Various flap techniques have been described over the years, each with advantages and limitations depending on the location, size of the defect, and patient-specific anatomical and pathological considerations (Konate et al. 2021). Moreover, emerging techniques such as autogenous bone grafts, platelet-rich fibrin (PRF), collagen membranes, and xenografts have been explored to improve healing and reduce recurrence rates.

Despite the plethora of surgical techniques available, clinicians often face challenges in selecting the most appropriate treatment modality. These challenges stem from lack of standardized treatment protocols, variability in defect size and chronicity, patient factors including sinus pathology, immune status, and smoking, surgeon’s experience and preference, and need for simultaneous management of sinusitis or prosthetic rehabilitation. This variability has led to a reliance on individual surgeon discretion rather than evidence-based guidelines, resulting in inconsistent outcomes. Moreover, there is a lack of algorithmic or protocol-based decision-making tools to guide clinicians through the diagnostic and therapeutic process.

Although many surgical techniques for OAF closure have been described, there is a paucity of literature that presents a comprehensive, evidence-based treatment algorithm that integrates clinical features, radiological findings, and patient-centered considerations. Furthermore, few studies offer comparative analysis of the long-term outcomes of different closure techniques stratified by patient and defect characteristics (Konate et al. 2021; Kwon et al. 2020; Melillo and Boschini 2021).

The need for an algorithmic approach is further emphasized by:

• Inconsistent terminology in describing OAFs vs OACs,

• Diverse treatment outcomes based on variable definitions of success,

• Lack of consensus on timing of closure and adjunctive sinus treatment.

The integration of emerging biomaterials and regenerative techniques into existing surgical protocols further necessitates updated, algorithm-based decision trees that can guide clinicians in resource-constrained or technologically diverse settings.

Rationale for algorithm development

In the face of these clinical complexities, a structured treatment algorithm offers the potential to:

• Streamline clinical decision-making,

• Promote early recognition of risk factors,

• Standardize the selection of treatment techniques based on evidence and anatomical parameters,

• Improve interprofessional coordination, particularly between dental surgeons and otolaryngologists,

• Reduce recurrence and complication rates,

• Optimize patient outcomes and quality of life.

Previous literature suggests success rates of over 90% for properly selected and executed surgical closures of OAFs (Kaba et al. 2023), but recurrence is seen where inappropriate techniques are used or underlying sinus pathology is not concurrently managed.

Algorithms are particularly useful in surgical decision-making when multiple treatment modalities exist. By incorporating parameters such as size and location of the fistula, chronicity, presence of infection or sinusitis, and patient comorbidities, a dynamic, tiered approach can be developed. Such an approach enhances patient-specific care while aligning with best-practice guidelines.

Objectives

The primary objective of this study is to design a comprehensive, evidence-based clinical algorithm for the management of oroantral fistula. The algorithm aims to:

• Classify OAFs based on etiology, size, chronicity, and associated sinus pathology.

• Integrate radiological and microbiological findings into the treatment decision pathway.

• Provide guidance on the timing and selection of appropriate closure techniques.

• Serve as a practical tool for general dental practitioners, oral surgeons, and ENT specialists in both primary and referral settings.

By developing a treatment algorithm, this study seeks to improve clinical outcomes, reduce complications, and contribute to the establishment of a standardized approach to a complex and often neglected clinical problem.

Classification and diagnosis of Oro-antral fistula

Table 1 demonstrates the classification of Oro-antral fistula according to its etiology, size, chronicity and associated pathologies.

Table 1.

Classification of Oro-antral fistula

Classification Parameter	Category	Description/Example
Etiology	Dental Extraction	Most commonly maxillary molars and premolars
	Surgical Procedures	Cyst/tumor enucleation, sinus lift, implant placement
	Traumatic Injuries	Maxillofacial trauma leading to bone and mucosal perforation
	Pathological Lesions	Odontogenic cysts, malignancies, osteomyelitis
	Iatrogenic	Endodontic perforation, misplaced implants, failed sinus floor elevation
	Radiation or Bisphosphonate Therapy	Osteonecrosis causing fistula formation
	Congenital (Rare)	Clefts involving the alveolus and maxillary sinus
Size of Fistula	Small (< 2 mm)	May heal spontaneously if infection is absent
	Medium (2–5 mm)	May require surgical closure depending on infection and sinus involvement
	Large (> 5 mm)	Typically requires surgical intervention with flap or graft
Chronicity	Acute (< 1 week)	Recently formed, before epithelialization; higher chance of spontaneous closure
	Subacute (1–4 weeks)	Partially epithelialized; intermediate healing potential
	Chronic (> 4 weeks)	Fully epithelialized tract; unlikely to close without surgical intervention
Associated Sinus Pathology	Absent	Healthy sinus; better prognosis and simpler management
	Acute Maxillary Sinusitis	Purulent discharge, facial pain, nasal congestion; needs concurrent medical treatment
	Chronic Maxillary Sinusitis	Thickened mucosa, recurrent sinus infections; may require functional endoscopic sinus surgery (FESS)
	Sinus Mucosal Thickening (Radiographic)	Sign of subclinical or resolving sinus disease
	Mucocele, Fungal Infection, Polyps	Rare; may complicate surgical repair

Clinical diagnosis and interpretations

The clinical diagnosis of oroantral fistula (OAF) is primarily based on a detailed patient history, thorough clinical examination, and confirmation through specific diagnostic tests. Patients often present with characteristic symptoms such as fluid regurgitation from the mouth to the nose during drinking, nasal or sinus discharge, altered voice resonance, halitosis, and a history of recent maxillary tooth extraction, implant placement, or sinus surgery (Nizar and Nabil 2021). Clinical examination may reveal a visible or probe-patent opening in the alveolar ridge, with or without surrounding inflammation. Gentle probing of the suspected fistulous tract can indicate communication with the maxillary sinus. The Valsalva test, where the patient blows gently against closed nostrils, may demonstrate air escape through the fistula into the oral cavity, but it must be used cautiously to prevent enlarging the communication or forcing contaminants into the sinus (Shukla et al. 2021) (Fig. 1).

Fig. 1.

Clinical and Radiographical diagnosis of oroantral fistula (image created from Microsoft power point 2025) (Parvini et al. 2019)

Radiographical findings and interpretations

Oroantral fistula (OAF) is an abnormal communication between the oral cavity and the maxillary sinus, often resulting from dental extractions, trauma, or infections. Radiographic imaging plays a crucial role in the diagnosis, classification, and treatment planning of OAF (Fig. 1). The following outlines common radiological modalities used and their typical findings:

1. Periapical Radiograph

Findings:

• Discontinuity of the floor of the maxillary sinus.

• Periapical pathology of maxillary posterior teeth (apical radiolucency).

• May reveal proximity of the root apex to the sinus floor.

Interpretation:

• Limited field of view; useful for initial screening.

• Cannot confirm patency or size of fistula but may suggest risk factors or etiological clues.

• 2.Panoramic Radiograph (OPG)

Findings:

• Defect or discontinuity in the floor of the maxillary sinus.

• Evidence of retained root fragments or foreign bodies in the sinus.

• Clouding or opacification of the sinus indicating sinusitis.

Interpretation:

• Useful as a broad screening tool.

• Limited ability to delineate soft tissue involvement or measure exact size of the fistula.

• 3.Waters’ View (Occipitomental View)

Findings:

• Opacification or fluid levels in the maxillary sinus (sinusitis).

• Air-fluid levels indicating acute sinus infection.

• Disruption of continuity in the bony sinus wall.

Interpretation:

• Helps detect associated sinus pathology but less specific for small OAFs.

• Often used in emergency or resource-limited settings.

• 4.Cone-Beam Computed Tomography (CBCT)

Findings:

• Detailed visualization of the oroantral communication.

• Clear identification of the fistulous tract and its dimensions.

• Mucosal thickening, fluid accumulation, or sinus opacification.

• Associated dental pathology (periapical infection, root remnants).

Interpretation:

• Gold standard for diagnosis and treatment planning.

• Allows precise evaluation of bony anatomy, fistula size, and sinus health.

• 5.Conventional CT scan (Axial and Coronal Sections)

Findings:

• Air or contrast passage between oral cavity and sinus.

• Sinus wall defects and mucosal thickening.

• Multiplanar views allow identification of inflammation, foreign bodies, or polyps.

Interpretation:

• More comprehensive soft tissue evaluation than CBCT.

• Preferred in chronic or complicated cases with suspected sinus disease.

Radiological imaging is essential in identifying the presence, extent, and complications of oroantral fistula. CBCT is the preferred modality due to its high spatial resolution and ability to delineate both hard tissue defects and sinus involvement. Integration of radiographic findings with clinical examination ensures accurate diagnosis and effective treatment planning.

Microbiological findings and interpretations

The pathological communication of maxillary sinus and oral cavity facilitates the translocation of oral microorganisms into the maxillary sinus, often resulting in acute or chronic sinusitis. The microbiological profile of OAF is typically polymicrobial, involving both aerobic and anaerobic organisms. Aerobic bacteria commonly isolated include Streptococcus species, particularly members of the viridans group such as Streptococcus mitis, S. anginosus, and S. pneumoniae, which are part of the normal oral flora. Staphylococcus aureus is also frequently reported, especially in cases associated with nosocomial infections or postoperative complications (Parvini et al. 2019). Pseudomonas aeruginosa may be encountered in chronic or refractory infections, particularly in immunocompromised individuals or in those with a history of prior antibiotic therapy.

Anaerobic bacteria, such as Fusobacterium spp., Prevotella spp., Porphyromonas spp., and Peptostreptococcus spp., are commonly detected in chronic OAF cases and reflect the anaerobic component of the oral microbiota. The presence of these organisms is of particular concern due to their ability to form biofilms and contribute to chronic inflammation and treatment resistance (Kovach et al. 2021). In some instances, especially in patients with prolonged fistula duration, poor oral hygiene, or immunocompromise, fungal organisms such as Candida albicans or Aspergillus fumigatus may also be isolated, complicating the clinical picture and requiring antifungal therapy Table 2.

Table 2.

Radiographic signs suggestive of OAF

Radiographic Feature	Interpretation
Bony defect in the floor of the sinus	Indicates communication between oral cavity and sinus
Sinus opacification	Suggests sinusitis, often secondary to chronic OAF
Air-fluid level in sinus	Indicates active infection or inflammation
Root tip/root fragment in sinus	Foreign body reaction, possible cause of persistent fistula
Mucosal thickening of sinus lining	Chronic sinus irritation or inflammation
Loss of lamina dura or periapical radiolucency	Indicates periapical pathology contributing to OAF

The diagnostic approach to microbiological evaluation includes culture of nasal or antral swabs, direct sampling of exudate from the fistula, and, where indicated, endoscopic-guided sinus aspiration. Conventional culture methods remain the mainstay, but molecular diagnostic tools such as polymerase chain reaction (PCR) and 16S rRNA gene sequencing have improved the detection of fastidious and non-cultivable organisms, particularly in the context of biofilm-associated infections (Kovach et al. 2021) (Table 3). Identification of the specific microbial flora is essential for guiding appropriate antimicrobial therapy.

Table 3.

Different microbial tests and interpretation done for diagnosis of oroantral fistula

Diagnostic Test	Microorganisms Detected	Technique/Medium	Interpretation
Aerobic Culture	Streptococcus spp., Staphylococcus aureus, Pseudomonas aeruginosa	Blood agar, MacConkey agar	Indicates presence of oral flora or hospital-acquired organisms; useful in acute infections
Anaerobic Culture	Fusobacterium spp., Prevotella spp., Peptostreptococcus spp., Porphyromonas spp.	Anaerobic culture media (e.g. CDC anaerobic blood agar)	Confirms chronic or polymicrobial infection from oral origin; typically seen in longstanding fistulas
Fungal Culture	Candida albicans, Aspergillus spp.	Sabouraud dextrose agar	Seen in immunocompromised or chronic OAF cases, requires antifungal therapy
Gram Stain	Mixed gram-positive and gram-negative organisms	Direct smear from exudate or sinus aspirate	Rapid identification of bacterial morphology; guides initial therapy
Ziehl–Neelsen Stain	Mycobacterium tuberculosis (rare)	Acid-fast stain	Considered in chronic, non-healing OAF with systemic symptoms
Polymerase Chain Reaction (PCR)	Difficult-to-culture bacteria; anaerobes; resistance genes	DNA amplification of microbial targets	Highly sensitive and specific; identifies pathogens missed by culture
16S rRNA Gene Sequencing	Broad range of bacterial species, including uncultivable ones	Molecular sequencing	Provides detailed microbiome profiling; useful in biofilm-associated infections
Biofilm Detection (e.g., CLSM or SEM)	Mixed microbial communities	Confocal laser scanning microscopy (CLSM) or Scanning electron microscopy (SEM)	Indicates presence of organized biofilms; explains antibiotic resistance and recurrence

Different management according to the published literature

Management discussed in studies published from 1990–2000

A review of literature spanning a decade reveals evolving approaches and significant advancements in the diagnosis and management of oroantral communications (OACs) and fistulas (OAFs) (El-Hakim and El-Fakharany 1999). The buccal fat pad (BFP) technique emerged as a reliable and simple option for closing OACs, especially in cases with compromised buccal or Palatal mucoperiosteum. The exposed fat tissue typically epithelializes within 2–4 weeks with minimal complications or sulcus depth loss. However, BFP should be reserved for selected cases and not replace the conventional buccal sliding flap, which remains suitable for small to moderate defects (El-Hakim and El-Fakharany 1999). The use of guided tissue regeneration (GTR) using gelatin membranes and bone grafts has also been explored, promoting selective cellular healing and bone regeneration at the site of communication. Clinical findings indicate that OACs larger than 2 mm, or even smaller ones in patients with chronic sinusitis, warrant surgical intervention to prevent progression to chronic fistula. Most OACs were linked to extractions of maxillary first and second molars, with the palatal root often implicated, particularly in older patients (Allais et al. 2008).

Various surgical techniques have been advocated depending on the size and site of the defect. For lateral and mid-alveolar defects (5–10 mm), buccal sliding and palatal rotation flaps are preferred, while anterior tongue flaps and temporalis flaps are indicated for larger or posterior defects (Zide and Karas 1992). Conservative methods, including laser bio stimulation therapy, have shown promise in promoting closure of small oroantral defects, avoiding surgery and reducing the need for antibiotics due to the antimicrobial effect of laser beams. In implant-related procedures, proper patient selection and preoperative evaluation are crucial, as sinus augmentation may lead to complications such as OAC/OAF (El-Hakim and El-Fakharany 1999). Finally, the literature advises against unnecessary sinus drainage, suggesting that proper intraoperative irrigation and postoperative antibiotic coverage are sufficient for favorable outcomes (El-Hakim and El-Fakharany 1999). Collectively, the findings support a tailored approach to OAC/OAF closure, with considerations for defect size, sinus health, anatomical site, and patient-specific factors.

Management discussed in studies published from 2000–2010

Between 2000 and 2010, various surgical and conservative techniques were evaluated and refined for the closure of oroantral communications (OACs) and oroantral fistulas (OAFs), with emphasis on case-specific anatomical and pathological considerations. Closure techniques ranged from traditional buccal and palatal flaps to more novel methods involving bone grafts, biomaterials, and even tooth transplantation. Buccal flaps, while simple and widely used, were found to have limitations in large or recurrent fistulas due to poor vascularity and potential sulcus depth reduction, complicating prosthodontic rehabilitation (Er et al. 2013; Kale et al. 2010). Palatal flaps offered superior perfusion and were preferred for larger or recurrent defects, though they required longer healing times and were associated with postoperative discomfort (Er et al. 2013; Kale et al. 2010).

Alternative techniques included the use of the pedicled buccal fat pad (BFP), which demonstrated reliable healing within 2–3 weeks and served as a viable option for larger defects (Loean and Coates 2003; Nezafati et al. 2012). Modified palatal connective tissue flaps and guided tissue regeneration (GTR) using Bio-Gide and Bio-Oss offered effective closure with potential for simultaneous implant placement (Visscher et al. 2010; Sandhya et al. 2013). Tooth auto transplantation was explored as a minimally invasive option for closing OACs, with long-term follow-ups showing functional and esthetic success in selected patients (Visscher et al. 2011).

Bone grafting strategies, such as monocortical chin grafts and zygomatic process grafts, were used to address chronic or large OAFs, often fixed with miniplates or screws, yielding stable closures and implant-friendly outcomes (Allais et al. 2008; Batra et al. 2010). The use of a serratus anterior free flap proved beneficial in obliterating recurrent OAFs in patients with extensive facial trauma or multiple prior surgeries (Loean and Coates 2003). In conservative approaches, biodegradable polyurethane foams demonstrated feasibility in animal models, hinting at future nonsurgical protocols (Kale et al. 2010). The incidence of OACs following upper third molar extractions remained low (5.1%), though it increased with deeper impactions and complex surgical techniques (Loean and Coates 2003). Overall, treatment success depended on factors such as sinus health, size and chronicity of the defect, presence of infection or epithelialization, and the patient's anatomical and systemic status.

Management discussed in studies published from 2010–2025

OAF management discussed in the studies published from 2010 to 2025 were almost similar to the managements discussed earlier. A systematic review by Oliva et al. (2024) evaluated the efficacy of various surgical techniques for treating oroantral communications (OACs) and fistulas (OAFs), focusing on closure success rates, recurrence risks, and patient morbidity (Oliva et al. 2024). The analysis included nine studies published from 2010 to 2024, predominantly randomized controlled trials, comparing treatments such as buccal advancement flaps, buccal fat pad (BFP) flaps, palatal rotational flaps, and platelet-rich fibrin (PRF). The results demonstrated that the buccal fat pad flap was statistically superior to both buccal advancement and palatal rotational flaps, with a lower risk of recurrence and higher success rates (Oliva et al. 2024). BFP's rich vascularization promotes rapid epithelialization, making it effective for medium to large defects, though complications like restricted mouth opening were noted. The buccal advancement flap, while widely used, often resulted in vestibular depth loss, and the palatal flap, though reliable, caused postoperative pain due to exposed bone. PRF demonstrated potential benefits for small OACs, including minimal morbidity and preservation of mucogingival architecture; however, current evidence is restricted to a single study (Craig et al. 2020). The review emphasized that defect size, location, and surgeon expertise should guide treatment selection, with BFP emerging as the preferred option for optimal outcomes (Kaba et al. 2023).

Algorithms based on size, duration and sinus involvement

This flowchart presents a clinical decision-making algorithm for the management of oroantral fistula (OAF), beginning with a thorough initial assessment. The assessment includes recording the patient's history onset, duration, and previous treatment and performing a clinical examination to evaluate the size of the OAF, the condition of adjacent teeth, and any signs of secondary infection. Radiographic imaging, such as panoramic radiographs, cone beam computed tomography (CBCT), or conventional CT scans, is recommended to determine the exact size and extent of the OAF.

If the OAF is less than 2 mm and asymptomatic, conservative management is advised. This includes educating the patient to avoid smoking and nose blowing, using nasal decongestants, maintaining good oral hygiene (chlorhexidine mouthwash), and close monitoring. If the OAC (oroantral communication) resolves during follow-up, the patient is considered healed.

In cases where the OAF is less than 2 mm but with infection, medical management is warranted. This involves prescribing antibiotics such as amoxicillin or clindamycin, along with drainage if an abscess is present. If infection subsides but the fistula does not resolve, the pathway progresses to surgical management based on size and location.

For OAFs larger than 5 mm but less than or equal to 10 mm in a favorable location, surgical closure using a local flap is recommended. Options include buccal or Palatal flaps. If the OAF is greater than 10 mm in an unfavorable location, more complex surgical interventions are needed. These may involve advanced techniques such as combining local and distant flaps, using a buccal fat pad graft, or applying biomaterials like platelet-rich fibrin or guided tissue regeneration (GTR).

After any surgical intervention, healing should be monitored closely, and any complications assessed. If the OAC eventually resolves, the patient is considered healed. This algorithm ensures a structured, evidence-based approach to managing OAF, tailored to the fistula's size, infection status, and anatomical considerations Fig. 2.

Fig. 2.

Algorithm based on size and chronicity of OAF (image created on Microsoft power point version 2505)

Discussion

Clinical decisions regarding the management of OAF should be based on parameters such as defect size, chronicity, sinus involvement, tissue availability, and the presence of infection. Recent literature supports a tiered approach that guides the use of conservative, flap-based, regenerative, or combined techniques. This discussion integrates findings from the literature to justify a structured clinical decision-making algorithm.

Clinical considerations in treatment planning

A fundamental principle in the treatment of OAFs is the complete resolution of sinus pathology before surgical closure. Persistent OAFs, especially those present for more than three weeks, often become epithelialized and fail to heal spontaneously, necessitating surgical intervention and debridement of the fistulous tract, diseased bone, and sinus mucosa (Khandelwal and Hajira 2017; Konate et al. 2021). Flap-based techniques remain the cornerstone of surgical closure, but newer biologic and regenerative methods are enhancing outcomes.

Patient-specific factors significantly influence treatment outcomes. Smoking impairs mucosal healing due to vasoconstriction and reduced oxygenation, often leading to flap dehiscence or delayed epithelialization. Systemic conditions such as diabetes mellitus or immunosuppression reduce the host's healing capacity and increase infection risk. Furthermore, patients who have undergone head and neck radiotherapy exhibit compromised bone vascularity, increasing the risk of osteonecrosis and flap failure. Such individuals may require hyperbaric oxygen therapy preoperatively and alternative reconstructive strategies such as distant pedicled flaps or free tissue transfer. Tailoring treatment based on systemic health status is essential for achieving durable closure.

Defect size and chronicity

The size of the oroantral defect is a primary determinant of the treatment modality. Communications less than 2 mm may heal spontaneously, particularly in the absence of sinus infection. However, defects larger than 3 mm, or any OAF associated with sinus disease, typically require surgical intervention (Kwon et al. 2020; Kovach et al. 2021; Mainassara Chekaraou et al. 2021). Chronic OAFs are less likely to respond to simple closure due to tract epithelialization and must be excised before flap reconstruction (Nizar and Nabil 2021; Mustakim et al. 2023; Obermeyer et al. 2022). In these cases, combined approaches often yield superior outcomes.

Flap-based techniques: Foundational strategies

The anatomical location of the defect plays a critical role in flap selection. Lateral alveolar defects, commonly located in the posterior region, often have adequate buccal tissue but limited Palatal mobility. These are typically closed using buccal advancement or buccal fat pad flaps. The buccal advancement flap remains one of the oldest and most widely employed techniques. It is particularly suitable for small to moderate defects in the anterior maxilla, with reported success rates exceeding 90% (Seigneur et al. 2023). However, drawbacks include loss of vestibular depth, which may hinder prosthodontic rehabilitation (Verma and Verma 2022). In contrast, mid-alveolar or anterior defects may benefit from palatal rotational flaps due to their superior vascular supply and tissue bulk (Singh et al. 2023). The palatal flap’s arc of rotation and robust blood supply from the greater palatine artery make it especially useful for defects in the premolar region. The choice of flap must account for both the position and extent of the bone defect to ensure optimal tension-free closure and long-term success.

The palatal flap, which derives its vascular supply from the greater palatine artery, offers thicker tissue and better vascularity, preserving vestibular depth. However, patients often experience significant donor site morbidity, pain, and delayed epithelialization (Azzouzi et al. 2022; Burić et al. 2012).

The buccal fat pad (BFP) flap has gained popularity due to its rich vascularity, ease of harvest, and versatility in closing posterior and large OAFs. It has shown near-perfect success rates in long-term studies and is especially useful in layered reconstructions or after failed primary closures (Bell et al. 2022; Batra et al. 2010; Ben-Dor et al. 2021).

Double- and triple-layered closure techniques

Multi-layered closures combine the mechanical stability of flaps with the biological advantages of autologous materials. For example, a double-layered approach using a Palatal flap with sinus membrane suturing yielded 100% closure in 12 chronic cases (Bereczki-Temistocle et al. 2022). Similarly, triple-layered techniques involving buccal advancement flap, BFP, and platelet-rich fibrin (PRF) have been shown to reduce healing time, enhance tissue integration, and prevent recurrence (Blal et al. 2020).

Regenerative and biomaterial-assisted techniques

Bone healing serves as a critical marker for the successful resolution of oroantral fistulas. Evidence suggests that radiographic evidence of bone fill at the site of the defect is a reliable indicator of long-term success, especially in cases where future implant placement is anticipated. Cone-beam CT can be used postoperatively to monitor trabecular continuity and mucosal integration. According to Parvini et al. (2019), bone regeneration using autologous grafts or PRF enhances both mucosal and osseous healing, significantly reducing recurrence rates (Parvini et al. 2019). The re-establishment of bony architecture is essential not only for structural stability but also for stabilizing sinus separation and preventing microbial ingress. The incorporation of PRF has revolutionized the management of both acute and chronic OAFs. As a scaffold rich in platelets and growth factors, PRF enhances healing, reduces pain and inflammation, and promotes rapid epithelialization. Several studies have documented successful closure of acute OAFs > 3 mm using PRF alone, with complete mucosal coverage within three weeks (Nizar and Nabil 2021; Obermeyer et al. 2022; Pal et al. 2022). When combined with collagen membranes, PRF facilitates layered closure in chronic defects with promising results (Mustakim et al. 2023).

Bone grafts, whether autogenous (chin or zygoma) or alloplastic (titanium mesh), are useful in reconstructing osseous defects associated with OAF. The chin graft, when combined with BFP and a buccal flap, has been shown to restore bony continuity and prepare the site for implant rehabilitation (Melillo and Boschini 2021; Mainassara Chekaraou et al. 2021). Titanium mesh, used as a scaffold beneath palatal flaps, resists resorption and supports soft tissue healing in complex or recurrent OAFs (Kwon et al. 2020).

Special and alternative techniques

In challenging cases, alternative techniques provide valuable adjuncts. Autotransplantation of third molars into the defect has shown favorable outcomes, offering both closure and immediate replacement of the lost tooth (Parvini et al. 2019). Though technically demanding, it avoids the need for prosthetic or implant restoration.

Auricular cartilage grafts are biocompatible, infection-resistant, and easily harvested, making them effective in reconstructing large or recurrent OAFs when local flaps are inadequate (Verma and Verma 2022; Singh et al. 2023). Additionally, nasoseptal flaps, tongue flaps, and pedicled flaps harvested from distant sites have been described for complex or irradiated cases (Chinnaiah et al. 2023).

For defects smaller than 5 mm or in acute settings, non-surgical methods using PRF or polyurethane foam have demonstrated effectiveness in small case series, avoiding the morbidity of flap harvest (Salgado-Peralvo et al. 2022; Sabatino et al. 2023).

Sinus disease and the role of endoscopic surgery

Successful OAF closure is contingent upon a healthy maxillary sinus. In cases of chronic sinusitis or mucosal disease, functional endoscopic sinus surgery (FESS) or Caldwell-Luc approach may be performed preoperatively or concurrently to clear the sinus, restore ostial patency, and improve the success rate of OAF repair (Shukla et al. 2021; Seigneur et al. 2023). One-stage combined procedures using endoscopic antrostomy and BFP have reported nearly 98% closure rates (Sabatino et al. 2023).

Preventive strategy

Careful surgical planning during maxillary molar extraction, use of preoperative CBCT to assess sinus proximity, and gentle elevation of roots can reduce iatrogenic perforations. When sinus exposure is suspected intraoperatively, immediate closure using collagen membranes or primary mucosal flaps can prevent chronic fistula formation. Additionally, smoking cessation, management of underlying sinus pathology, and maintaining strict oral hygiene pre- and post-surgery are critical preventive strategies. Surgeons should also avoid sinus lifts in infected sinuses and be cautious with implant placements close to the sinus floor.

Future research should focus on prospective multicenter studies comparing flap techniques stratified by defect location, patient comorbidities, and adjunctive biomaterial use. Additionally, development of AI-guided decision support tools and long-term data on bone healing outcomes should be prioritized to refine existing algorithms.

Limitations

There are few limitations to the current algorithm. First, this algorithm is planned to guide clinicians in planning the treatment of OAF hence, microbiological aspect has not been studied. Second, this algorithm has evaluated studies published in English. Finally, the algorithm evaluated studies from 1990, hence, if there were some different clinical measures taken before 1990 were not evaluated.

Conclusion

The management of oroantral fistulas continues to evolve with innovations in biomaterials, surgical technique, and interdisciplinary collaboration. While flap-based closures remain foundational, the incorporation of biologics such as PRF, structural supports like titanium mesh, and regenerative techniques including autogenous bone grafting enhances the predictability and functionality of treatment. A standardized treatment planning algorithm, rooted in patient-specific and defect-related criteria, is essential to optimize outcomes and guide clinicians in selecting the most appropriate intervention. Future studies should aim to validate such algorithms in multicentric prospective trials.

Author contributions

Conceptualization, F.A., A.G.K, and S.S.A.; methodology, M.Z.K. and S.A.A.; software, F.A. and A.M.A.; validation, N.A.A. and S.H.A.; formal analysis, M.Z.K. and F.A.; investigation, A.G.K.; resources, F.A. and A.M.A.; data curation, L.Y.A. and S.H.A; writing—original draft preparation, F.A.; writing—review and editing, M.Z.K. and A.G.K. All authors have read and agreed to the published version of the manuscript.

Data Availability

On request from the corresponding author.

Declarations

Ethics statement

Ethical approval was not required as secondary data were utilized for data synthesis of the review.

Consent for publication

All the authors have read and confirmed the publication of the manuscript.