What is the cause of severe unilateral headaches and significant sinus congestion and swelling on the same side as a recently extracted tooth, approximately 3-4 days post-extraction, in a patient with a history of tooth infection and recent dental extraction?

Acute Bacterial Sinusitis Secondary to Dental Infection

This patient most likely has acute bacterial sinusitis (maxillary) secondary to the infected tooth extraction, and requires immediate antibiotic therapy with amoxicillin-clavulanate given the dental source and recent procedural manipulation. 1, 2

Clinical Reasoning

The presentation is highly consistent with acute bacterial sinusitis originating from odontogenic infection:

• Dental extraction and periapical infections of maxillary molar teeth are a particularly important cause of maxillary sinusitis 1
• The timeline (3-4 days post-extraction) aligns with bacterial superinfection following the initial tooth infection 1, 2
• The unilateral nature of symptoms (headache, sinus congestion, facial swelling) on the same side as the extraction strongly suggests ipsilateral maxillary sinusitis 1
• Cardinal symptoms of acute bacterial sinusitis include facial pain/pressure (especially when unilateral and focused in the region of a particular sinus), nasal congestion, and postnasal drainage 1, 2

Critical Differential Considerations

While acute sinusitis is most likely, you must rule out life-threatening complications given the severity and dental source:

Intracranial Complications (Red Flags)

• Sinusitis can lead to intracranial suppurative complications including epidural or subdural empyema, brain abscess, or cavernous sinus thrombosis 1
• Severe unilateral headache with mental status changes, fever, or neurological signs requires immediate imaging 1
• If the patient has altered mental status, visual changes, proptosis, or severe systemic symptoms, obtain urgent CT or MRI with contrast to evaluate for venous sinus thrombosis or intracranial extension 1, 3

Oroantral Communication/Fistula

• Dental extraction can create direct communication between oral cavity and maxillary sinus 1
• This predisposes to ongoing bacterial contamination and chronic infection 1

Immediate Management Algorithm

1. Clinical Assessment

Evaluate for complications requiring urgent intervention:

• Mental status changes, visual disturbances, proptosis, or facial erythema/swelling suggest orbital or intracranial complications requiring immediate imaging 2
• Fever >103°F with severe symptoms warrants more aggressive evaluation 2
• If any red flags present, obtain CT scan with contrast or MRI/MRV before initiating treatment 1, 2

2. Antibiotic Selection

For odontogenic sinusitis, use amoxicillin-clavulanate rather than amoxicillin alone:

• Amoxicillin-clavulanate is preferred when there are risk factors for resistance or when anaerobic coverage is needed 2
• Dental infections involve oral anaerobes and polymicrobial flora that require beta-lactamase coverage 1
• Standard dosing: Amoxicillin-clavulanate 875mg/125mg twice daily or 500mg/125mg three times daily for 7-10 days 2
• If penicillin allergic: Levofloxacin 500mg daily or moxifloxacin 400mg daily 1

3. Symptomatic Management

• Intranasal saline irrigation and intranasal corticosteroids provide symptom relief 2
• Ibuprofen 400-800mg every 6-8 hours for pain and inflammation 4
• Decongestants may help but avoid prolonged use (>3 days for topical agents) 1

4. Follow-up and Monitoring

• If symptoms persist beyond 3 weeks despite pharmacologic therapy, surgical evaluation is warranted 1
• Re-evaluate in 48-72 hours to ensure clinical improvement 1, 2
• Persistent or worsening symptoms may indicate:
  • Antibiotic resistance requiring culture-directed therapy 1
  • Oroantral fistula requiring surgical closure 1
  • Graft infection if bone grafting was performed (unlikely in simple extraction) 1

Common Pitfalls to Avoid

Do not dismiss this as simple post-extraction pain or migraine:

• The dentist correctly recognized these symptoms should not be related to normal extraction healing 1
• "Sinus headaches" are often misdiagnosed as migraine or tension headache, but in this case with clear temporal relationship to infected tooth extraction and unilateral presentation, bacterial sinusitis is the primary concern 5, 6
• The extraction site being non-painful actually supports sinusitis rather than local wound infection 1

Do not use amoxicillin alone for odontogenic sinusitis:

• Dental sources require anaerobic coverage that amoxicillin alone does not provide 1, 2

Do not delay imaging if red flags are present:

• Severe unilateral headache in the setting of recent sinus infection can represent venous sinus thrombosis, which is a medical emergency 1, 3