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Final year mds viva questions for oroantral communication

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Final-year MDS viva questions: Oroantral communication (OAC)

1. Define oroantral communication.

An oroantral communication (OAC) is an abnormal, non-epithelialized opening between the oral cavity and the maxillary sinus, most often following extraction of a maxillary posterior tooth.

2. Differentiate OAC from oroantral fistula (OAF).

  • OAC: Fresh communication, not lined by epithelium.
  • OAF: A persistent, epithelialized tract between the oral cavity and maxillary sinus, usually after failure of an OAC to heal.
An untreated OAC can become epithelialized and form an OAF, often with maxillary sinusitis. Recent clinical review

3. Which teeth are commonly associated with OAC?

Most commonly:
  1. Maxillary first molar
  2. Maxillary second molar
  3. Maxillary second premolar
  4. Maxillary third molar
Risk depends on root anatomy, sinus pneumatization, periodontal or periapical disease, and thickness of the sinus floor.

4. List the causes of OAC/OAF.

  • Extraction of maxillary premolars and molars, most common cause
  • Displacement of root, tooth, implant, or foreign body into the sinus
  • Tuberosity fracture
  • Periapical infection or cyst
  • Trauma
  • Maxillary pathology such as cysts or tumours
  • Implant surgery or sinus lift complications
  • Osteoradionecrosis
  • Failed flap closure or surgical dehiscence

5. What are the risk factors after extraction?

  • Close anatomical relation of roots to sinus
  • Large or divergent roots
  • Pneumatized maxillary sinus
  • Periapical infection
  • Periodontal bone loss
  • Previous surgery in the region
  • Injudicious use of elevators
  • Older age and reduced bone density

6. What are the clinical features?

  • Escape of air through extraction socket
  • Blood bubbling in the socket during expiration
  • Nasal regurgitation of fluids
  • Altered voice or nasal twang
  • Sensation of air passage between mouth and nose
  • Unilateral foul nasal discharge, facial pain, or heaviness if sinusitis develops
  • Halitosis or bad taste in chronic OAF

7. How do you diagnose OAC clinically?

  • History of difficult extraction or sudden loss of resistance
  • Direct visualization of the opening
  • Gentle observation for air bubbling
  • Gentle Valsalva maneuver, if needed, but do not force it
  • Probe only cautiously and only when indicated, as probing may enlarge the defect or displace material into the sinus
  • Assess for symptoms and signs of maxillary sinusitis

8. Which investigations are used?

  • Periapical radiograph
  • Maxillary occlusal radiograph
  • Orthopantomogram
  • Paranasal sinus radiograph, limited value
  • CBCT, preferred when defect size, sinus disease, root displacement, retained foreign body, or implant displacement must be assessed
  • CT of paranasal sinuses if extensive sinus disease is suspected

9. What are the complications of untreated OAC?

  • Acute or chronic odontogenic maxillary sinusitis
  • Epithelialization to form OAF
  • Food and fluid entry into sinus
  • Nasal regurgitation
  • Chronic purulent discharge and halitosis
  • Foreign body reaction
  • Failure of future implant rehabilitation
Published reviews report a high risk of sinusitis when a significant communication remains untreated. Review of surgical options

10. What is the significance of size of OAC?

A practical approach:
DefectUsual approach
<2 mmMay close spontaneously if sinus is healthy and a stable blood clot is maintained
2-5 mmAssess carefully. Suturing, collagen material, platelet-rich fibrin, or early local closure may be needed
>5 mmUsually needs surgical closure
Chronic or epithelialized defectSurgical excision of fistula tract and closure is required
Size alone should not dictate management. Sinus infection, chronicity, location, tissue quality, and planned implant rehabilitation also matter. Diagnostic and therapeutic review

11. When should an OAC be closed?

Ideally immediately or within 24-48 hours. Early closure lowers the chance of sinus contamination, sinusitis, and epithelialization into an OAF. Evidence on acute closure

12. What are the principles of management?

  1. Diagnose the communication early.
  2. Determine the size, duration, and presence of sinus infection.
  3. Prevent contamination of the maxillary sinus.
  4. Achieve tension-free, well-vascularized closure.
  5. Eliminate sinus infection before or together with definitive closure.
  6. Give sinus precautions and arrange follow-up.

13. How do you manage a small fresh OAC?

For a small fresh defect with no sinus infection:
  • Preserve the socket blood clot
  • Place a figure-of-eight suture
  • Consider collagen plug, gelatin sponge, PRF, or similar resorbable barrier
  • Give sinus precautions
  • Prescribe analgesia and medications as clinically indicated
  • Review within a few days

14. What sinus precautions do you advise?

Advise the patient for about 10-14 days:
  • Do not blow the nose
  • Sneeze with the mouth open
  • Avoid sucking through straws, smoking, forceful spitting, and vigorous rinsing
  • Avoid swimming, air travel, wind instruments, and pressure-changing activities
  • Take soft diet and maintain oral hygiene carefully
  • Return urgently for nasal discharge, fever, worsening facial pain, or persistent passage of fluid/air

15. What medical treatment may be given?

Depending on the clinical situation:
  • Analgesics
  • Nasal decongestant for a short period, if appropriate
  • Antibiotics when contamination, sinusitis, or surgery warrants them
  • Saline nasal irrigation may be advised in coordination with ENT for sinus disease
Medication is adjunctive. It does not substitute for closure of a significant defect.

16. What is the most commonly used flap?

The buccal advancement flap, also called the Rehrmann flap, is commonly used because it is simple, reliable, and well vascularized.

17. Describe the Rehrmann buccal advancement flap.

  • Raise a broad-based trapezoidal mucoperiosteal flap from the buccal aspect.
  • Make two vertical releasing incisions.
  • Periosteally score the flap base to gain mobility.
  • Advance the flap over the defect without tension.
  • Suture it to palatal mucosa with interrupted sutures.
Advantages
  • Easy and dependable
  • Good blood supply
  • Suitable for many small to moderate posterior defects
Disadvantages
  • Reduces buccal vestibular depth
  • May complicate future denture construction
  • Less ideal where preservation of vestibular depth is important

18. Describe the palatal rotational flap.

A full-thickness palatal mucoperiosteal flap is raised based on the greater palatine neurovascular bundle, rotated laterally, and sutured over the defect.
Advantages
  • Thick, keratinized, well-vascularized tissue
  • Maintains buccal sulcus depth
  • Useful in premolar region and for recurrent defects
Disadvantages
  • Donor-site pain and raw palatal wound
  • Limited mobility
  • Risk to greater palatine vessels if poorly designed

19. What is the role of the buccal fat pad (BFP)?

The pedicled buccal fat pad is highly useful for larger posterior defects, recurrent OAF, and defects with poor local tissue.
Advantages
  • Excellent vascularity
  • Easy access in posterior maxilla
  • Can cover relatively large defects
  • Epithelializes in approximately 3-4 weeks
Limitations
  • Best for posterior defects
  • Excess traction may compromise vascularity
  • Not ideal for very anterior defects

20. What are double-layer closure techniques?

Two tissue layers are used for a more secure seal, such as:
  • Buccal fat pad + buccal advancement flap
  • Collagen membrane + buccal flap
  • Bone graft or PRF + mucoperiosteal flap
They are particularly useful for large, recurrent, or implant-related defects.

21. What is the role of PRF?

Platelet-rich fibrin may be used as an adjunct or, in selected small defects, as a biological barrier to support clot stability and soft-tissue healing. Evidence is promising but techniques and outcome measures are variable. A 2024 systematic review assessed blood-derived platelet-rich preparations for OAC/OAF closure (PMID 39519060).

22. How do you manage chronic OAF?

  • Assess with CBCT or CT where indicated.
  • Treat associated sinusitis first or coordinate treatment with ENT.
  • Excise the epithelialized fistulous tract.
  • Freshen the margins.
  • Close using a well-vascularized flap, often buccal advancement flap, palatal flap, buccal fat pad, or double-layer technique.
  • Remove any retained root, foreign body, diseased tooth, implant, or pathologic tissue.
  • Consider endoscopic sinus surgery if sinus drainage is impaired or disease persists.

23. What if there is maxillary sinusitis?

Do not perform simple closure without addressing significant sinus infection. Management may involve:
  • Elimination of dental source
  • Antibiotics and nasal measures where appropriate
  • ENT evaluation
  • Endoscopic sinus surgery, especially for persistent odontogenic sinusitis, blocked ostium, retained foreign body, or extensive sinus disease
  • Simultaneous or staged intraoral closure depending on disease severity and local protocol

24. How will you manage a root displaced into the maxillary sinus?

  • Do not blindly chase the root through the socket.
  • Obtain CBCT or CT localization.
  • Avoid repeated instrumentation that may displace it further.
  • Refer or plan retrieval by an appropriate approach, commonly transnasal endoscopic removal or selected intraoral approaches.
  • Manage the OAC and any sinusitis concurrently.

25. What are causes of failure after surgical closure?

  • Unrecognized sinusitis
  • Inadequate removal of epithelialized tract
  • Tension on flap
  • Inadequate flap vascularity
  • Inadequate flap size
  • Persistent foreign body or diseased tooth
  • Poor postoperative compliance with sinus precautions
  • Smoking
  • Diabetes or immunosuppression
  • Radiation-associated tissue damage

26. Which flap would you choose in common situations?

Clinical situationCommon preferred option
Small, fresh OACClot preservation, figure-of-eight suture, collagen/PRF as indicated
Moderate posterior OACBuccal advancement flap
Large posterior OAFBuccal fat pad, often with double-layer closure
Need to preserve vestibular depthPalatal rotational flap
Recurrent defect or poor local tissueBuccal fat pad with second-layer flap, or graft-based reconstruction
Active chronic sinusitisTreat sinus disease with ENT involvement, then or alongside closure

27. What is the viva answer for “Why should you not ask the patient to forcefully blow the nose?”

Forceful nose blowing raises intranasal and intrasinus pressure, which can enlarge the communication, dislodge the blood clot or flap, and force contaminated sinus contents into the oral cavity.

28. What is the key difference between closure of a fresh OAC and chronic OAF?

A fresh OAC may close with conservative measures or immediate closure if small and the sinus is healthy. A chronic OAF has an epithelialized tract, so the tract must be excised and the defect closed with healthy, tension-free vascularized tissue after controlling sinus disease.

29. One-minute viva summary

“Oroantral communication is an abnormal opening between the mouth and maxillary sinus, commonly following extraction of maxillary molars. A fresh non-epithelialized communication is termed OAC, while a persistent epithelialized tract is OAF. Diagnosis is clinical, supported by CBCT when the defect or sinus status is uncertain. Small fresh defects may heal with clot stabilization and sinus precautions, but larger, persistent, or infected defects require early surgical closure. Common techniques include buccal advancement flap, palatal rotational flap, and pedicled buccal fat pad. Treatment must be tension-free and associated sinusitis must be eliminated or controlled, often with ENT collaboration.”
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