Oral and Maxillofacial Surgery and Anesthesia
What this domain tests
Items test extraction and third molar assessment, spread of odontogenic infection, facial trauma classification, and the safe delivery of local anaesthesia and sedation with recognition of emergencies.
Surgery
- Third molar difficulty: Winter's classification (mesioangular, distoangular, horizontal, vertical) and Pell and Gregory for ramus relationship and depth. Deep impactions near the canal risk inferior alveolar and lingual nerve injury.
- Alveolar osteitis (dry socket) follows fibrinolysis of the clot; risk rises with smoking, oral contraceptives and traumatic extraction. Management is irrigation and a eugenol-based dressing, not antibiotics alone.
- Odontogenic infection spreads along fascial planes. Ludwig's angina is bilateral submandibular, sublingual and submental cellulitis with floor-of-mouth elevation, tongue displacement and airway compromise; treatment is airway protection, urgent surgical drainage and intravenous antibiotics.
- Trauma: mandibular angle is the commonest mandibular fracture; Le Fort I is low transverse, II pyramidal, III craniofacial dysjunction. Orbital blowout fractures may trap the inferior rectus, producing diplopia and the oculocardiac reflex.
Anaesthesia and sedation
- Preoperative airway assessment includes Mallampati class, mouth opening, thyromental distance and neck mobility; ASA class summarises systemic risk.
- Fasting: clear fluids 2 hours, light meal 6 hours before sedation.
- Inferior alveolar block landmarks: coronoid notch, pterygomandibular raphe, occlusal plane height; the Gow-Gates and Vazirani-Akinosi techniques are alternatives.
- Commonest emergency is vasovagal syncope: supine position, legs raised, oxygen, monitor. Anaphylaxis needs intramuscular adrenaline; angina needs rest, oxygen and glyceryl trinitrate; hypoglycaemia needs glucose.
Worked example
A patient with a lower molar infection has bilateral submandibular swelling, a raised floor of the mouth and difficulty swallowing. Reasoning: this is Ludwig's angina with impending airway obstruction. Do not attempt office drainage and discharge; arrange emergency admission, secure the airway if needed, take cultures, start broad-spectrum intravenous cover for aerobes and anaerobes, and drain all involved spaces, then remove the causative tooth.
Traps
Treating dry socket with antibiotics; ignoring trismus and dysphagia as danger signs; assuming a Le Fort I fracture is stable because the face looks intact; forgetting the oculocardiac reflex in orbital trauma.