Nepal Medical Council - Specialist registration exam Practice Questions - MDS Oral and Maxillofacial Surgery Part 2

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Nepal Medical Council - Specialist registration exam Practice Questions - MDS Oral and Maxillofacial Surgery Part 1

Section 1: Maxillofacial Trauma

1. Which of the following is the most common site of mandibular fractures?

A) Symphysis

B) Angle

C) Condyle

D) Body

Answer: C. Explanation: Epidemiological studies consistently show the condylar region is the most frequently fractured site of the mandible (accounting for 25-35% of cases), often acting as a protective mechanism to prevent transmission of forces to the middle cranial fossa.

2. A "teardrop" sign on a Waters view radiograph is highly indicative of:

A) Zygomatic arch fracture

B) Le Fort II fracture

C) Orbital floor blowout fracture

D) Nasoethmoidal orbital (NOE) fracture

Answer: C. Explanation: The teardrop sign represents herniated orbital fat and/or the inferior rectus muscle protruding through a fractured orbital floor into the maxillary sinus.

3. Which of the following paths of fracture is classical for a Le Fort I osteotomy/fracture?

A) Through the nasofrontal suture and orbital floors

B) Through the piriform aperture, anterior and lateral maxillary walls, and pterygoid plates

C) Through the zygomaticofrontal sutures and zygomatic arches

D) Through the infraorbital rim and nasal bridge

Answer: B. Explanation: A Le Fort I (Guérin) fracture separates the palate from the maxilla, running horizontally above the apices of the maxillary teeth, through the piriform aperture, maxillary sinuses, and inferior pterygoid plates.

4. Battle's sign (ecchymosis over the mastoid process) is typically associated with a fracture of the:

A) Anterior cranial fossa

B) Middle cranial fossa

C) Posterior cranial fossa

D) Zygomaticomaxillary complex

Answer: B. Explanation: Battle's sign indicates a basilar skull fracture, specifically involving the middle cranial fossa (often the petrous temporal bone).

5. During a submandibular (Risdon) approach to the mandible, which nerve is at the highest risk of iatrogenic injury?

A) Lingual nerve

B) Hypoglossal nerve

C) Marginal mandibular branch of the facial nerve

D) Great auricular nerve

Answer: C. Explanation: The marginal mandibular nerve loops below the inferior border of the mandible (in about 20% of cases) and lies deep to the platysma, making it highly vulnerable during submandibular incisions.

6. The most appropriate initial radiographic imaging for evaluating a suspected zygomaticomaxillary complex (ZMC) fracture is:

A) Orthopantomogram (OPG)

B) Submentovertex (SMV) view

C) Cone Beam Computed Tomography (CBCT) or Medical CT of the facial bones

D) Posterior-anterior (PA) mandible

Answer: C. Explanation: A non-contrast CT scan of the facial bones (axial and coronal views) is the gold standard for accurately assessing midface and ZMC fractures, including orbital volume and displacement.

7. In the management of a pan-facial trauma, the classic standard sequence of reduction and fixation begins with:

A) Mandibular reconstruction (establishing the lower jaw framework)

B) Frontal sinus and orbital roof (top-down)

C) Zygomatic arches (outside-in)

D) Maxillary alveolus

Answer: A. Explanation: The classic approach is "bottom-up and inside-out." Re-establishing the mandibular framework and restoring occlusion provides a stable base upon which the midface can be reconstructed.

8. Cerebrospinal fluid (CSF) rhinorrhea is most commonly associated with fractures involving the:

A) Cribriform plate of the ethmoid bone

B) Pterygomaxillary fissure

C) Greater wing of the sphenoid

D) Frontal process of the maxilla

Answer: A. Explanation: Fractures of the naso-orbito-ethmoid (NOE) complex or anterior cranial fossa often involve the cribriform plate, tearing the dura and leading to CSF leakage.

9. Telecanthus following facial trauma is a cardinal sign of which fracture?

A) Le Fort III

B) ZMC fracture

C) Naso-orbito-ethmoid (NOE) fracture

D) Mandibular symphysis fracture

Answer: C. Explanation: Traumatic telecanthus (increased distance between the medial canthi) occurs due to lateral displacement of the medial canthal-bearing bone fragment in NOE fractures.

10. What is the standard duration of maxillo-mandibular fixation (MMF) for a closed reduction of a condylar fracture in an adult?

A) 1-2 weeks

B) 4-6 weeks

C) 8-10 weeks

D) No MMF is ever indicated

Answer: A. Explanation: For closed management of condylar fractures, a short period of MMF (7-14 days) is used to control pain and establish occlusion, followed by aggressive physiotherapy to prevent ankylosis.

Section 2: Oral Pathology & Oncology

11. The most common malignant tumor of the salivary glands is:

A) Adenoid cystic carcinoma

B) Polymorphous low-grade adenocarcinoma

C) Mucoepidermoid carcinoma

D) Acinic cell carcinoma

Answer: C. Explanation: Mucoepidermoid carcinoma is the most common malignant salivary gland neoplasm in both adults and children, most frequently occurring in the parotid gland.

12. A 45-year-old patient presents with a multilocular radiolucency in the posterior mandible. Histopathology shows islands of epithelial cells with reverse nuclear polarity and subnuclear vacuolization. The diagnosis is:

A) Odontogenic keratocyst (OKC)

B) Ameloblastoma

C) Central giant cell granuloma

D) Myxoma

Answer: B. Explanation: The classic histological features of ameloblastoma include peripheral palisading of columnar cells with reverse polarity (nuclei moving away from the basement membrane) and a reticular stroma resembling the stellate reticulum.

13. Which syndrome is strongly associated with multiple Odontogenic Keratocysts (OKCs)?

A) Gardner Syndrome

B) Peutz-Jeghers Syndrome

C) Nevoid Basal Cell Carcinoma Syndrome (Gorlin-Goltz Syndrome)

D) Cleidocranial Dysplasia

Answer: C. Explanation: Gorlin-Goltz syndrome (caused by a mutation in the PTCH1 gene) is characterized by multiple OKCs, multiple basal cell carcinomas, palmar/plantar pits, and bifid ribs.

14. The most frequent site for oral squamous cell carcinoma (OSCC) is the:

A) Hard palate

B) Dorsum of the tongue

C) Lateral border and ventral surface of the tongue

D) Buccal mucosa

Answer: C. Explanation: The lateral/ventral tongue and the floor of the mouth are high-risk areas for OSCC because carcinogens pool in these gravity-dependent areas and the mucosa is non-keratinized and highly permeable.

15. A radiopaque lesion attached to the root apex of a vital mandibular first molar, surrounded by a thin radiolucent halo, is most likely a:

A) Cementoblastoma

B) Condensing osteitis

C) Complex odontoma

D) Osteosarcoma

Answer: A. Explanation: Cementoblastomas are benign odontogenic tumors of cementoblasts that fuse to the root of a vital tooth, presenting as a well-defined radiopacity with a radiolucent rim.

16. Which of the following lesions exhibits a "driven snow" appearance on a radiograph?

A) Calcifying Epithelial Odontogenic Tumor (Pindborg Tumor)

B) Ameloblastic Fibroma

C) Adenomatoid Odontogenic Tumor (AOT)

D) Central Ossifying Fibroma

Answer: A. Explanation: The CEOT (Pindborg tumor) often presents with scattered radiopacities within a radiolucent background, classically described as a "driven snow" appearance due to calcified amyloid deposits.

17. The most common benign tumor of the parotid gland is the:

A) Warthin tumor

B) Pleomorphic adenoma

C) Basal cell adenoma

D) Oncocytoma

Answer: B. Explanation: Pleomorphic adenoma (benign mixed tumor) accounts for approximately 80% of all benign parotid tumors.

18. Perineural invasion is a classic histological hallmark and prognostic factor for which salivary malignancy?

A) Mucoepidermoid carcinoma

B) Acinic cell carcinoma

C) Adenoid cystic carcinoma

D) Squamous cell carcinoma

Answer: C. Explanation: Adenoid cystic carcinoma has a strong propensity for perineural invasion, which contributes to pain as a presenting symptom and makes achieving clear surgical margins difficult.

19. A "sunburst" periosteal reaction on a radiograph of the mandible is highly suggestive of:

A) Ewing sarcoma

B) Osteosarcoma

C) Multiple myeloma

D) Chondrosarcoma

Answer: B. Explanation: Osteosarcoma often exhibits a "sunburst" or "sun-ray" appearance radiographically due to osteophytic bone production radiating outward from the cortex.

20. Bence Jones proteins in the urine are a diagnostic marker for:

A) Langerhans Cell Histiocytosis

B) Paget's Disease

C) Multiple Myeloma

D) Osteopetrosis

Answer: C. Explanation: Multiple myeloma is a plasma cell malignancy characterized by punched-out bone lesions and the excretion of monoclonal light chains (Bence Jones proteins) in the urine.

Section 3: Orthognathic Surgery and TMJ

21. The most common post-operative complication of a Bilateral Sagittal Split Osteotomy (BSSO) is:

A) Relapse

B) Condylar resorption

C) Inferior alveolar nerve (IAN) neurosensory deficit

D) Severe hemorrhage

Answer: C. Explanation: Because the sagittal split is performed intimately close to the IAN canal, varying degrees of transient or permanent paresthesia/hypoesthesia are the most frequent complication, approaching 100% transiently in some studies.

22. Which orthognathic procedure is considered the "gold standard" for correcting a transverse maxillary deficiency?

A) Le Fort I osteotomy with segmentalization

B) Surgically Assisted Rapid Palatal Expansion (SARPE)

C) Anterior maxillary osteotomy (Wassmund procedure)

D) Genioplasty

Answer: B. Explanation: For skeletally mature patients with transverse discrepancies greater than 5mm, SARPE provides stable expansion by surgically releasing the closed facial sutures prior to utilizing an orthodontic expander.

23. During a Le Fort I osteotomy, the descending palatine artery is encountered. Through which anatomical structure does it pass?

A) Pterygomaxillary fissure

B) Sphenopalatine foramen

C) Greater palatine canal

D) Incisive foramen

Answer: C. Explanation: The descending palatine artery runs through the greater palatine canal to emerge on the hard palate as the greater palatine artery, which supplies the anterior segment in multi-piece maxillas.

24. The primary blood supply to the maxilla after a complete Le Fort I down-fracture is maintained by the:

A) Descending palatine artery

B) Ascending pharyngeal artery

C) Ascending palatine branch of the facial artery and the anterior branch of the ascending pharyngeal artery

D) Sphenopalatine artery

Answer: C. Explanation: When the descending palatine vessels are ligated or compromised during a Le Fort I, the maxilla survives on a collateral mucosal pedicle, primarily from the ascending palatine artery and ascending pharyngeal artery via the soft palate.

25. Wilkes Staging is used to classify disorders of the:

A) Salivary glands

B) Temporomandibular Joint (TMJ) internal derangement

C) Trigeminal neuralgia

D) Cleft lip and palate

Answer: B. Explanation: The Wilkes staging system (Stages I-V) classifies TMJ internal derangement based on clinical, radiographic, and anatomical/surgical findings, ranging from early clicking (Stage I) to severe degenerative joint disease (Stage V).

26. The superior joint space of the TMJ is primarily responsible for which movement?

A) Rotation

B) Translation

C) Lateral excursion

D) Elevation

Answer: B. Explanation: The TMJ is a ginglymoarthrodial joint. The lower joint compartment allows for hinge-like rotation, while the upper joint compartment allows for translation (gliding).

27. What is the most common direction of articular disc displacement in TMJ internal derangement?

A) Posterior

B) Lateral

C) Medial

D) Anteromedial

Answer: D. Explanation: Due to the pull of the superior belly of the lateral pterygoid muscle, the disc is most commonly displaced in an anteromedial direction.

28. An orthognathic patient requires a 10mm mandibular advancement. To minimize the risk of condylar sag and relapse, what is the best intraoperative step?

A) Stripping the masseter muscle aggressively

B) Proper seating of the condyle in the glenoid fossa prior to rigid fixation

C) Extracting the third molars simultaneously

D) Over-advancing the mandible by 3mm

Answer: B. Explanation: Failing to properly seat the proximal (condyle-bearing) segment in the centric position within the glenoid fossa during fixation leads to condylar sag, which results in immediate postoperative malocclusion and relapse.

29. The "V-Y" closure technique during a Le Fort I mucosal incision is utilized primarily to:

A) Prevent postoperative infection

B) Maintain the width of the attached gingiva

C) Prevent shortening and thinning of the upper lip

D) Provide better access for rigid fixation

Answer: C. Explanation: A continuous Le Fort I incision can cause widening of the alar base and thinning/shortening of the vermilion border. The V-Y vestibular closure helps maintain lip fullness and vertical height.

30. True bony ankylosis of the TMJ is most successfully managed surgically by:

A) Arthrocentesis

B) High condylectomy with no interpositional graft

C) Gap arthroplasty with an interpositional graft (e.g., temporalis fascia) and aggressive physiotherapy

D) Prolonged maxillomandibular fixation

Answer: C. Explanation: Resection of the ankylotic mass (gap arthroplasty) combined with an interpositional material (temporalis muscle/fascia, auricular cartilage) prevents re-fusion. Immediate, aggressive physiotherapy is strictly required.

Section 4: Dentoalveolar Surgery & Anesthesia

31. The maximum safe dose of 2% Lidocaine with 1:100,000 epinephrine for a healthy 70kg adult is approximately:

A) 300 mg

B) 500 mg

C) 700 mg

D) 900 mg

Answer: B. Explanation: The maximum dose for Lidocaine with epinephrine is generally accepted as 7 mg/kg. For a 70kg adult, 70 x 7 = 490 mg (safely rounded to 500 mg).

32. According to Winter's classification, which mandibular third molar impaction is statistically the most difficult to extract?

A) Mesioangular

B) Vertical

C) Distoangular

D) Horizontal

Answer: C. Explanation: In the mandible, distoangular impactions are the most difficult because the tooth's withdrawal pathway is obstructed by the ascending ramus, and surgical access is restricted.

33. The most common severe complication associated with the extraction of a maxillary third molar is:

A) Fracture of the maxillary tuberosity

B) Damage to the lingual nerve

C) Fracture of the zygomatic arch

D) Subcutaneous emphysema

Answer: A. Explanation: Due to the thin bone of the posterior maxilla, forceful elevation can fracture the maxillary tuberosity, potentially creating an oroantral communication.

34. A patient experiences prolonged numbness in the anterior two-thirds of the tongue following the surgical extraction of tooth 38 (FDI). Which nerve is injured?

A) Inferior alveolar nerve

B) Long buccal nerve

C) Lingual nerve

D) Hypoglossal nerve

Answer: C. Explanation: The lingual nerve supplies general and special sensation to the anterior two-thirds of the tongue and lies close to the lingual plate of the mandible near the third molar.

35. Which specific elevator principle is utilized when using a Cryer elevator to remove a retained mandibular molar root?

A) Lever

B) Wedge

C) Wheel and Axle

D) Pulley

Answer: C. Explanation: The Cryer elevator operates on the wheel and axle principle, where the handle acts as the wheel and the working tip acts as the axle, providing rotational mechanical advantage.

36. You create an oroantral communication (OAC) of 4mm during a molar extraction. The gold standard immediate management is:

A) Buccal advancement flap

B) Buccal fat pad flap

C) Figure-of-eight suture and sinus precautions

D) No treatment, leave it to heal by secondary intention

Answer: C. Explanation: For OACs between 2mm and 6mm in a healthy sinus, establishing a blood clot with a figure-of-eight suture over the socket, placing Gelfoam, and advising sinus precautions is usually sufficient.

37. Local anesthetics block nerve conduction by:

A) Depolarizing the nerve membrane

B) Blocking voltage-gated sodium channels from the inside of the cell

C) Opening potassium channels

D) Inhibiting acetylcholinesterase

Answer: B. Explanation: Local anesthetics exist in a non-ionized form to cross the lipid membrane, then ionize inside the cell to bind to and block the intracellular portion of voltage-gated sodium channels.

38. Which condition is an absolute contraindication to the use of nitrous oxide-oxygen conscious sedation?

A) Hypertension

B) Asthma

C) First trimester of pregnancy

D) Diabetes mellitus

Answer: C. Explanation: Nitrous oxide interferes with vitamin B12 metabolism and folate, posing a teratogenic risk during the first trimester (organogenesis).

39. Flumazenil is a specific reversal agent for:

A) Opioids

B) Local anesthetic toxicity

C) Benzodiazepines

D) Barbiturates

Answer: C. Explanation: Flumazenil is a competitive antagonist at the GABA-A receptor, used specifically to reverse the effects of benzodiazepines (e.g., midazolam).

40. The optimal flap design for the surgical removal of a palatally impacted maxillary canine is a:

A) Semilunar flap

B) Full-thickness palatal envelope flap extending from premolar to premolar

C) Buccal mucoperiosteal flap

D) Submarginal (Ochsenbein-Luebke) flap

Answer: B. Explanation: A palatal envelope flap provides excellent access and preserves the greater palatine vessels, which are contained within the full-thickness reflection.

Section 5: Infections, Anatomy & Medical Emergencies

41. Ludwig's angina is defined as a rapidly spreading bilateral cellulitis involving which fascial spaces?

A) Submandibular, submental, and sublingual spaces

B) Pterygomandibular, masseteric, and temporal spaces

C) Lateral pharyngeal and retropharyngeal spaces

D) Canine and buccal spaces

Answer: A. Explanation: Ludwig's angina is a life-threatening, bilateral brawny induration of the submandibular, sublingual, and submental spaces, most often resulting from a mandibular molar infection. It severely compromises the airway.

42. Which muscle separates the sublingual space from the submandibular space?

A) Geniohyoid

B) Anterior belly of digastric

C) Mylohyoid

D) Platysma

Answer: C. Explanation: The mylohyoid muscle forms the floor of the mouth. Infections originating from tooth apices above the mylohyoid line enter the sublingual space; those below enter the submandibular space.

43. The classic clinical presentation of an infection involving the masseteric space is:

A) Uvular deviation

B) Severe trismus

C) Swelling of the lower eyelid

D) Dysphagia

Answer: B. Explanation: The masseteric (submasseteric) space is located between the lateral aspect of the mandibular ramus and the masseter muscle. Inflammation here causes intense spasm of the masseter, resulting in severe trismus.

44. A patient in the dental chair suddenly complains of crushing chest pain radiating to the left arm and jaw, which is not relieved by nitroglycerin. The most likely diagnosis is:

A) Angina pectoris

B) Myocardial infarction

C) Pulmonary embolism

D) Gastroesophageal reflux

Answer: B. Explanation: Chest pain that is severe, radiating, and unresponsive to standard doses of sublingual nitroglycerin strongly indicates an acute myocardial infarction rather than stable angina.

45. What is the definitive first-line medication for the treatment of severe anaphylaxis?

A) Intravenous diphenhydramine

B) Intramuscular epinephrine (1:1,000)

C) Intravenous hydrocortisone

D) Albuterol inhaler

Answer: B. Explanation: IM Epinephrine (0.3 to 0.5 mg of 1:1,000 solution) injected into the anterolateral thigh is the gold standard, life-saving treatment for anaphylaxis to reverse cardiovascular collapse and bronchospasm.

46. Osteoradionecrosis (ORN) of the jaws is primarily caused by:

A) Bacterial infection of irradiated bone

B) Fungal osteomyelitis

C) Hypoxia, hypovascularity, and hypocellularity of the bone

D) Autoimmune destruction of osteoblasts

Answer: C. Explanation: According to Marx's theory, radiation induces an endarteritis that leaves the bone hypocellular, hypovascular, and hypoxic (the "3 Hs"), severely compromising its ability to heal.

47. Hyperbaric oxygen (HBO) therapy prior to extracting teeth in heavily irradiated bone aims to stimulate:

A) Osteoblast proliferation

B) Angiogenesis

C) Bacterial lysis

D) Nerve regeneration

Answer: B. Explanation: HBO increases tissue oxygen tension, stimulating the formation of new capillaries (angiogenesis) and fibroplasia in the hypoxic bone tissue.

48. In the management of actinomycosis of the cervicofacial region, the hallmark clinical sign is:

A) Rapid, painful, fluctuant swelling

B) Multiple draining sinuses discharging yellow "sulfur granules"

C) Unilateral facial paralysis

D) Profound trismus with no swelling

Answer: B. Explanation: Actinomyces israelii (a gram-positive anaerobic bacterium) causes a chronic, granulomatous infection characterized by woody fibrosis and sinus tracts that exude colonies of bacteria called sulfur granules.

49. Cavernous sinus thrombosis is a lethal complication most frequently arising from an infection in the:

A) Mandibular third molar

B) Maxillary anterior teeth (canine space)

C) Parotid gland

D) Floor of the mouth

Answer: B. Explanation: Infections from the "danger triangle of the face" (e.g., canine space) can spread via the valveless angular and ophthalmic veins directly retrograde into the cavernous sinus.

50. The triad of deep facial pain, ipsilateral rectus muscle paralysis (abducens nerve palsy), and altered sensation in the ophthalmic division of the trigeminal nerve is known as:

A) Frey's Syndrome

B) Trotter's Syndrome

C) Gradenigo's Syndrome

D) Horner's Syndrome

Answer: C. Explanation: Gradenigo's syndrome results from apical petrositis (inflammation of the petrous apex of the temporal bone), affecting cranial nerves V and VI.