DHA Oral & Maxillofacial Surgery exam questions

6 worked Oral & Maxillofacial Surgery practice questions

Original exam-style questions from the bank, spread across the blueprint domains. They are not real or recalled exam questions. Try each one, then open the answer for the rationale and reference. None of them appear in the free mock exam, so reading them will not spoil it.

1. Question 1 · Anaesthesia, Sedation and Medical Emergencies

   A healthy 70 kg adult is having multiple extractions. Using 2% lidocaine with 1:80,000 adrenaline in 2.2 mL cartridges and a maximum dose of 7 mg/kg, what is the maximum number of whole cartridges?

   1. A7 cartridges
   2. B15 cartridges
   3. C20 cartridges
   4. D11 cartridges
   Show answer and explanation

   Correct answer: D. 11 cartridges

   Each 2.2 mL cartridge of 2% lidocaine contains 44 mg. The maximum dose is 7 x 70 = 490 mg, and 490 / 44 is about 11.1, so 11 whole cartridges. In practice, the lowest effective dose should be used and lower limits apply to frail patients.

   Reference: Malamed, Handbook of Local Anesthesia, 7th ed.

2. Question 2 · Dentoalveolar Surgery

   Three days after extraction of a lower molar, a smoker returns with severe throbbing pain radiating to the ear. The socket is empty with exposed bone and a foul smell, and there is no fever or swelling. What is the most appropriate treatment?

   1. AOral antibiotics for 7 days
   2. BIrrigation and an obtundent socket dressing
   3. CIncision and drainage of the area
   4. DCurettage under general anaesthesia
   Show answer and explanation

   Correct answer: B. Irrigation and an obtundent socket dressing

   This is alveolar osteitis, in which the clot breaks down and bone is exposed. Treatment is local: gentle irrigation, a soothing antiseptic dressing and analgesia. Antibiotics are not routinely needed because it is not primarily an infection, and there is no collection to drain.

   Reference: Hupp, Ellis and Tucker, Contemporary Oral and Maxillofacial Surgery, 7th ed.

3. Question 3 · Dentoalveolar Surgery

   After surgical removal of a lower third molar with a distolingual approach, a patient reports numbness on the same side of the tongue. Which other symptom is she most likely to report?

   1. AAltered taste on the front of the tongue
   2. BNumbness of the lower lip and chin
   3. CWeakness of tongue protrusion
   4. DNumbness of the soft palate
   Show answer and explanation

   Correct answer: A. Altered taste on the front of the tongue

   The lingual nerve carries general sensation from the anterior two thirds of the tongue, and its chorda tympani fibres carry taste, so injury causes numbness and altered taste. Lip and chin numbness indicates inferior alveolar nerve injury. Tongue movement is supplied by the hypoglossal nerve.

   Reference: Hupp, Ellis and Tucker, Contemporary Oral and Maxillofacial Surgery, 7th ed.

4. Question 4 · Infections and Airway Emergencies

   Following a lower third molar infection, a patient develops severe trismus, pain on swallowing and medial bulging of the lateral pharyngeal wall pushing the tonsil across the midline. Which space is involved?

   1. ALateral pharyngeal space
   2. BSubmasseteric space
   3. CBuccal space
   4. DSublingual space
   Show answer and explanation

   Correct answer: A. Lateral pharyngeal space

   Infection of the lateral pharyngeal (parapharyngeal) space causes trismus from medial pterygoid irritation, dysphagia and medial displacement of the lateral pharyngeal wall. It can spread to the retropharyngeal space and mediastinum and needs CT, airway assessment and drainage. Submasseteric infection causes trismus without pharyngeal bulging.

   Reference: Hupp, Ellis and Tucker, Contemporary Oral and Maxillofacial Surgery, 7th ed.

5. Question 5 · Infections and Airway Emergencies

   A patient with an untreated infected upper canine develops periorbital oedema, proptosis, ophthalmoplegia and fever, and the other eye becomes involved next day. By which route did infection most likely reach the cavernous sinus?

   1. AInferior alveolar vein to the pterygoid plexus
   2. BLingual vein to the internal jugular vein
   3. CFacial vein through the angular and ophthalmic veins
   4. DPharyngeal plexus to the sigmoid sinus
   Show answer and explanation

   Correct answer: C. Facial vein through the angular and ophthalmic veins

   Infection from the upper anterior teeth can spread through the facial and angular veins into the ophthalmic veins and then the cavernous sinus, aided by the absence of effective valves. Spread through the pterygoid plexus is a route for posterior maxillary teeth. Bilateral eye signs reflect connection between the two sinuses.

   Reference: Hupp, Ellis and Tucker, Contemporary Oral and Maxillofacial Surgery, 7th ed.

6. Question 6 · Maxillofacial Trauma

   A simple undisplaced fracture of the mandibular angle is to be fixed with a single miniplate using Champy principles. Where should the plate be placed?

   1. AAlong the lower border on the outer cortex
   2. BAlong the external oblique ridge at the upper border
   3. CAcross the lingual cortex below the mylohyoid line
   4. DOn the inferior border with bicortical screws
   Show answer and explanation

   Correct answer: B. Along the external oblique ridge at the upper border

   Champy showed that tension forces act along the upper border of the mandible, so a single monocortical miniplate along the external oblique ridge neutralises tension at the angle. A plate on the lower border lies in the compression zone and does not resist the distracting forces. Bicortical screws at the lower border are used with larger reconstruction plates.

   Reference: Champy et al., Mandibular osteosynthesis by miniature screwed plates via a buccal approach, J Maxillofac Surg 1978