Odontogenic Infections
This domain tests recognition of severity, anatomic spread, source control and antimicrobial stewardship.
Core rules
- Most odontogenic infections start from pulp necrosis or periodontal infection and have mixed aerobic-anaerobic flora.
- Severity signs: dysphagia, dyspnea, trismus, elevation of the floor of the mouth, drooling, voice change, systemic toxicity and rapidly spreading cellulitis.
- Spaces include buccal, submandibular, sublingual, submental, pterygomandibular, masseteric, temporal, lateral pharyngeal, retropharyngeal and mediastinal.
- Ludwig angina is bilateral submandibular, sublingual and submental cellulitis with airway risk. Treat urgently with airway assessment, IV antibiotics and surgical drainage.
- Antibiotics are adjuncts to drainage and source removal. Amoxicillin or amoxicillin-clavulanate is common; penicillin allergy may require clindamycin or metronidazole with appropriate cover. Consider local resistance patterns.
- Imaging with OPG, CBCT or CT defines spread; ultrasound can identify an abscess.
Worked example
A patient has lower molar pain, submandibular swelling, trismus and dysphagia. Do not wait for fluctuance. Secure the airway, obtain IV access, start antibiotics, order CT and perform extraoral incision and drainage; remove the offending tooth when safe.
Traps
Relying on antibiotics alone; missing retropharyngeal spread; prescribing without drainage; underestimating pediatric airway risk; failing to remove the odontogenic source.