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NMCLE Dental practice questions

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Question 1Oral Anatomy, Histology and Embryology

Which permanent tooth normally erupts first into the oral cavity?

  1. Maxillary central incisor
  2. Mandibular central incisor
  3. Mandibular first molar Correct answer.
  4. Mandibular lateral incisor

Explanation

The mandibular first molar is typically the earliest permanent tooth to erupt, appearing at roughly 6 years of age, often before any permanent incisor. It erupts distal to the primary second molar without replacing a deciduous tooth, which is why it is sometimes mistaken for a primary tooth. The permanent incisors follow shortly afterward in the 6 to 7 year window.

Question 2Oral Anatomy, Histology and Embryology

Enamel rods (prisms) are oriented in which principal direction within the crown?

  1. Perpendicular to the long axis of the tooth in the cervical third only
  2. Radially from the dentinoenamel junction toward the surface Correct answer.
  3. Parallel to the dentinoenamel junction throughout their length
  4. Tangentially around the pulp chamber

Explanation

Enamel rods extend from the dentinoenamel junction outward toward the enamel surface, generally running at right angles to the dentin surface. Near the surface they may become more vertical or gnarled (the striae of Retzius and rodless enamel), but the overall course is radial. This orientation reflects the direction of ameloblast migration during apposition.

Question 3Oral Anatomy, Histology and Embryology

Which structure is a remnant of the epithelial root sheath of Hertwig and may persist in the periodontal ligament?

  1. Rests of Serres
  2. Enamel pearls
  3. Oxytalan fibers
  4. Rests of Malassez Correct answer.

Explanation

After the epithelial root sheath of Hertwig fragments during root development, residual epithelial cells persist in the periodontal ligament as the epithelial rests of Malassez. These clusters can proliferate to form radicular cysts. They are distinct from the rests of Serres, which are remnants of the dental lamina in the gingiva.

Question 4Oral Anatomy, Histology and Embryology

The greater palatine foramen is located in which bone?

  1. Sphenoid bone
  2. Zygomatic bone
  3. Maxilla
  4. Palatine bone Correct answer.

Explanation

The greater palatine foramen lies in the palatine bone at the junction of its horizontal and perpendicular plates, near the posterolateral corner of the hard palate. It transmits the greater palatine nerve and vessels. The incisive foramen, by contrast, is in the maxilla.

Question 5Oral Anatomy, Histology and Embryology

Which muscle elevates the mandible and is innervated by the mandibular division of the trigeminal nerve?

  1. Geniohyoid
  2. Platysma
  3. Masseter Correct answer.
  4. Digastric (anterior belly)

Explanation

The masseter is a primary elevator of the mandible and receives motor innervation from the masseteric branch of the mandibular nerve (V3). The anterior digastric depresses the mandible and is also V3-innervated, but it does not elevate. Geniohyoid is supplied by C1 via the hypoglossal nerve and assists depression.

Question 6Oral Anatomy, Histology and Embryology

Which dental tissue is derived primarily from the neural crest-derived ectomesenchyme?

  1. Dentin Correct answer.
  2. Enamel
  3. Ameloblasts
  4. Reduced enamel epithelium

Explanation

Dentin is secreted by odontoblasts, which differentiate from ectomesenchymal cells of neural crest origin within the dental papilla. Enamel, in contrast, is a product of ectodermally derived ameloblasts. This ectodermal-ectomesenchymal interaction at the bell stage governs the histodifferentiation of both tissues.

Question 7Oral Anatomy, Histology and Embryology

A patient has a maxillary first molar with five canals. Which canal configuration is most commonly reported in such cases?

  1. Two mesiobuccal, one distobuccal, two palatal
  2. Two mesiobuccal, two distobuccal, one palatal Correct answer.
  3. Two mesiobuccal, one distobuccal, one palatal plus a separate distopalatal
  4. One mesiobuccal, two distobuccal, two palatal

Explanation

When a maxillary first molar has five canals, the most frequently described pattern is two mesiobuccal canals (MB1 and MB2), two distobuccal canals (DB1 and DB2), and a single palatal canal. The second mesiobuccal canal is the most common supernumerary canal overall. Additional palatal canals are far less frequent.

Question 8Oral Anatomy, Histology and Embryology

During development, which structure gives rise to the dental papilla?

  1. Ectomesenchyme of the dental papilla region Correct answer.
  2. Stellate reticulum
  3. Dental follicle
  4. Outer enamel epithelium

Explanation

The dental papilla forms from ectomesenchymal condensation beneath the enamel organ and becomes the pulp and odontoblasts. The dental follicle, also ectomesenchymal, surrounds the enamel organ and gives rise to cementum, periodontal ligament, and alveolar bone. The enamel organ derivatives are epithelial.

Question 9Oral Anatomy, Histology and Embryology

Which feature best distinguishes primary from permanent teeth on a radiograph?

  1. Primary molars have more divergent roots and a more constricted cervical region Correct answer.
  2. Primary teeth lack a pulp chamber
  3. Permanent teeth have thinner enamel than primary teeth
  4. Permanent molars have shorter, more flared roots

Explanation

Primary molars show slender, widely divergent roots that accommodate the developing permanent premord, and their crowns are markedly constricted at the cervical line. Enamel and dentin in primary teeth are thinner than in permanent teeth, not thicker. These features help the clinician distinguish dentitions radiographically.

Question 10Oral Anatomy, Histology and Embryology

Which salivary gland secretion is predominantly serous and contributes most of the resting salivary flow?

  1. Parotid gland
  2. Minor palatal glands
  3. Sublingual gland
  4. Submandibular gland Correct answer.

Explanation

The submandibular gland is mixed but predominantly serous and provides the majority of unstimulated salivary flow, roughly two-thirds. The parotid is almost entirely serous but contributes mainly to stimulated flow. The sublingual gland is predominantly mucous.

Question 11Oral Anatomy, Histology and Embryology

The temporomandibular joint disc is primarily composed of which tissue?

  1. Dense regular collagenous tissue
  2. Fibrocartilage Correct answer.
  3. Hyaline cartilage
  4. Elastic cartilage

Explanation

The articular disc of the temporomandibular joint consists mainly of fibrocartilage, with dense collagen bundles and few chondrocytes. This contrasts with hyaline cartilage in most synovial joints and reflects the functional demands of the joint. The disc divides the joint into upper and lower compartments.

Question 12Oral Anatomy, Histology and Embryology

Which cranial nerve provides general sensation to the anterior two-thirds of the tongue?

  1. Facial nerve
  2. Hypoglossal nerve
  3. Lingual nerve branch of the mandibular nerve Correct answer.
  4. Glossopharyngeal nerve

Explanation

General sensation from the anterior two-thirds of the tongue travels via the lingual nerve, a branch of the mandibular division of the trigeminal nerve. Taste from the same region is carried by the chorda tympani branch of the facial nerve. The glossopharyngeal nerve supplies general and taste sensation to the posterior third.

Question 13Oral Anatomy, Histology and Embryology

Which statement about the striae of Retzius is correct?

  1. They are artifacts produced during decalcification
  2. They represent incremental growth lines reflecting rhythmic enamel apposition Correct answer.
  3. They indicate areas of dentin resorption
  4. They are found only in the primary dentition

Explanation

Striae of Retzius are incremental lines in enamel that record rhythmic apposition by ameloblasts, often accentuated by environmental or systemic disturbances. When they reach the surface, they may produce perikymata. They occur in both primary and permanent enamel and are not decalcification artifacts.

Question 14Oral Anatomy, Histology and Embryology

A developing tooth shows a bell-shaped enamel organ with distinct stratum intermedium and stellate reticulum, and the dental lamina is beginning to break up. Which stage is this?

  1. Late bell stage (apposition) Correct answer.
  2. Early bell stage
  3. Bud stage
  4. Cap stage

Explanation

In the late bell stage, the enamel organ is fully shaped, the dental lamina disintegrates, and hard tissue apposition begins at the dentinoenamel junction. The stratum intermedium and stellate reticulum are well developed earlier, but the onset of matrix deposition marks the appositional phase. The early bell stage precedes actual mineralization.

Question 15Oral Anatomy, Histology and Embryology

Which fibers of the periodontal ligament are principally responsible for resisting intrusive forces?

  1. Alveolar crest fibers
  2. Apical fibers
  3. Horizontal fibers
  4. Oblique fibers Correct answer.

Explanation

Oblique fibers run from alveolar bone apically to cementum coronally and are the most numerous group, converting intrusive and vertical loads into tension on bone. Apical fibers resist extrusive forces, while alveolar crest and horizontal fibers resist tipping and horizontal movement. This arrangement distributes occlusal stress efficiently.

Question 16Oral Anatomy, Histology and Embryology

The mandibular condyle grows by which mechanism?

  1. Chondroid tissue that never mineralizes
  2. Intramembranous ossification only
  3. Appositional growth of hyaline cartilage without replacement
  4. Endochondral ossification at the condylar cartilage Correct answer.

Explanation

The condylar cartilage of the mandible functions as a growth center where endochondral ossification produces the lengthening condyle and ramus. This differs from the cranial vault, which grows by intramembranous ossification. The condylar cartilage is secondary cartilage and is replaced by bone during growth.

Question 17Oral Anatomy, Histology and Embryology

Which permanent tooth most commonly shows a dens invaginatus (dens in dente) anomaly?

  1. Mandibular canine
  2. Mandibular first molar
  3. Maxillary lateral incisor Correct answer.
  4. Maxillary central incisor

Explanation

Dens invaginatus occurs most often in the maxillary lateral incisor, where an infolding of the enamel organ creates a blind pouch lined by enamel. This anomaly predisposes the tooth to early pulpal infection because the invagination can communicate with the oral cavity. It is far less frequent in other permanent teeth.

Question 18Oral Anatomy, Histology and Embryology

A clinician notes a small supernumerary tooth located in the midline between the maxillary central incisors. This structure is best termed a:

  1. Paramolar
  2. Distomolar
  3. Supplemental premolar
  4. Mesiodens Correct answer.

Explanation

A mesiodens is a supernumerary tooth situated in the maxillary midline between the central incisors, often conical and sometimes inverted. Paramolars and distomolars are supernumerary teeth located buccally or distally to molars. Recognizing the location is key to correct terminology and management.

Question 19Oral Anatomy, Histology and Embryology

Which cell type is responsible for the resorption of primary tooth roots during exfoliation?

  1. Fibroblast
  2. Odontoblast
  3. Ameloblast
  4. Osteoclast lineage (odontoclast) Correct answer.

Explanation

Odontoclasts, which belong to the osteoclast lineage, resorb the roots of primary teeth during exfoliation. They are multinucleated cells that create resorption lacunae on the root surface. Odontoblasts and ameloblasts are formative cells and do not resorb dental hard tissue.

Question 20Oral Anatomy, Histology and Embryology

In a maxillary first molar, the mesiobuccal root typically shows which curvature pattern that complicates instrumentation?

  1. Straight with a wide apical foramen
  2. Dilacerated at the cervical third
  3. Curved mesially with a single canal
  4. Curved distally and often with a second canal Correct answer.

Explanation

The mesiobuccal root of the maxillary first molar generally curves distally and frequently contains two canals (MB1 and MB2). The curvature and the second canal make thorough cleaning and shaping difficult. The palatal root is the largest and most often straight.

Question 21Oral Pathology and Oral Medicine

A 24-year-old patient has a painless, fluctuant swelling of the lower lip that has recurred twice after being drained. The lesion is bluish and blanches on pressure. What is the most likely diagnosis?

  1. Squamous cell carcinoma
  2. Mucocele
  3. Hemangioma Correct answer.
  4. Fibroma

Explanation

A bluish, fluctuant lesion that blanches on pressure suggests a vascular lesion because pressure displaces blood from its vessels. Among the listed choices, hemangioma best fits this specific sign. Lower-lip location and recurrence after drainage can suggest mucocele, but they do not outweigh true blanching.

Question 22Oral Pathology and Oral Medicine

Which organism is the primary etiologic agent of acute necrotizing ulcerative gingivitis?

  1. Fusobacterium nucleatum with spirochetes Correct answer.
  2. Candida albicans
  3. Actinomyces israelii
  4. Streptococcus mutans

Explanation

Acute necrotizing ulcerative gingivitis is a polymicrobial anaerobic infection in which fusiform bacteria such as Fusobacterium nucleatum together with spirochetes predominate. The other organisms cause caries, actinomycosis, and candidiasis respectively.

Question 23Oral Pathology and Oral Medicine

A patient reports recurrent episodes of unilateral severe headache with ipsilateral tearing and nasal congestion lasting 15 to 180 minutes. Which diagnosis best fits this presentation?

  1. Cluster headache Correct answer.
  2. Temporomandibular joint disorder
  3. Migraine with aura
  4. Trigeminal neuralgia

Explanation

Cluster headache is characterized by severe unilateral periorbital pain with ipsilateral autonomic features such as lacrimation, rhinorrhea, and ptosis, lasting 15 to 180 minutes. Trigeminal neuralgia produces brief electric-shock-like pain triggered by touch, and TMJ disorder pain is related to jaw function.

Question 24Oral Pathology and Oral Medicine

Which clinical feature most reliably distinguishes a benign irritational fibroma from a peripheral ossifying fibroma?

  1. Soft consistency on palpation
  2. Histologic presence of calcified deposits within the fibrous mass Correct answer.
  3. Location on the buccal mucosa
  4. History of less than one month

Explanation

Peripheral ossifying fibroma contains calcified or ossifying deposits within a fibrous proliferation, which distinguishes it histologically from a purely fibrous irritational fibroma. Location, consistency, and short duration are not reliable discriminators.

Question 25Oral Pathology and Oral Medicine

Which of the following is the most common odontogenic cyst of the jaws?

  1. Dentigerous cyst
  2. Radicular cyst Correct answer.
  3. Lateral periodontal cyst
  4. Odontogenic keratocyst

Explanation

The radicular cyst, also called periapical cyst, is the most common odontogenic cyst and arises from inflammatory stimulation of epithelial rests at the apex of a nonvital tooth. Dentigerous cysts are the most common developmental odontogenic cyst but are less frequent overall.

Question 26Oral Pathology and Oral Medicine

A patient has a painless, sessile, white plaque on the buccal mucosa that cannot be wiped off. Which diagnosis is most consistent with this finding?

  1. Geographic tongue
  2. Chemical burn
  3. Oral candidiasis
  4. Leukoplakia Correct answer.

Explanation

A white plaque that cannot be wiped off and has no identifiable cause is termed leukoplakia, a clinical diagnosis of exclusion with potential for dysplasia. Candidiasis and chemical burns can usually be removed or resolve after removing the cause, and geographic tongue is red with white borders.

Question 27Oral Pathology and Oral Medicine

Which vitamin deficiency classically produces angular cheilitis, glossitis, and a magenta-colored tongue?

  1. Vitamin K
  2. Vitamin C
  3. Riboflavin (B2) Correct answer.
  4. Vitamin D

Explanation

Riboflavin deficiency causes angular cheilitis, glossitis, and a magenta or purplish tongue as part of the classic orofacial manifestations. Vitamin C deficiency causes scurvy with bleeding gums, while vitamins D and K do not produce these mucosal signs.

Question 28Oral Pathology and Oral Medicine

A 45-year-old patient presents with a firm, fixed submandibular mass. Which diagnostic step is most appropriate next?

  1. Fine-needle aspiration cytology Correct answer.
  2. Observation for six months
  3. Topical corticosteroid application
  4. Incision and drainage

Explanation

A firm fixed submandibular mass raises concern for malignancy, and fine-needle aspiration cytology provides a minimally invasive initial tissue diagnosis. Incision and drainage is appropriate for abscess, observation delays diagnosis, and topical steroids have no role.

Question 29Oral Pathology and Oral Medicine

Which feature is most characteristic of oral lichen planus?

  1. Bilateral white reticular striae on the buccal mucosa Correct answer.
  2. Unilateral ulceration of the lateral tongue
  3. Punched-out interdental papillae
  4. Yellowish nodules on the hard palate

Explanation

Oral lichen planus classically presents as bilateral symmetrical white reticular striae, often called Wickham striae, on the buccal mucosa. Unilateral ulceration, necrotic papillae, and yellow nodules suggest other diagnoses.

Question 30Oral Pathology and Oral Medicine

Which radiographic feature best supports a diagnosis of ameloblastoma of the mandible?

  1. Unilocular radiolucency around the crown of an impacted tooth
  2. Ground-glass appearance of the bone
  3. Multilocular soap-bubble radiolucency with cortical expansion Correct answer.
  4. Sunburst periosteal reaction

Explanation

Ameloblastoma classically produces a multilocular soap-bubble radiolucency with cortical expansion, most often in the posterior mandible. A pericoronal radiolucency suggests dentigerous cyst, ground-glass bone suggests fibrous dysplasia, and sunburst reaction suggests osteosarcoma.

Question 31Oral Pathology and Oral Medicine

A patient on warfarin requires an extraction with an INR of 4.0. What is the most appropriate management?

  1. Defer the procedure and consult the physician regarding warfarin adjustment Correct answer.
  2. Give vitamin K intravenously and extract immediately
  3. Proceed with extraction without modification
  4. Increase the warfarin dose before surgery

Explanation

An INR of 4.0 exceeds the generally accepted threshold for routine outpatient extraction, so the procedure should be deferred and the physician consulted about dose adjustment. Proceeding risks severe hemorrhage, and vitamin K is a physician-directed reversal agent.

Question 32Oral Pathology and Oral Medicine

Which finding is most suggestive of oral squamous cell carcinoma rather than a traumatic ulcer?

  1. Ulcer with a soft, non-indurated border
  2. Indurated, non-healing ulcer persisting beyond three weeks Correct answer.
  3. Ulcer appearing after biting the lip
  4. Ulcer that resolves after removing a sharp cusp

Explanation

Induration and persistence beyond two to three weeks despite removal of local trauma are red flags for malignancy and warrant biopsy. Traumatic ulcers are soft, painful, and heal after the cause is eliminated.

Question 33Oral Pathology and Oral Medicine

Which condition is characterized by episodic, brief, lancinating pain triggered by light touch to the face?

  1. Myofascial pain
  2. Atypical odontalgia
  3. Burning mouth syndrome
  4. Trigeminal neuralgia Correct answer.

Explanation

Trigeminal neuralgia produces brief electric-shock-like paroxysms triggered by light tactile stimuli in the distribution of the trigeminal nerve. Atypical odontalgia is a persistent dull pain, burning mouth syndrome is bilateral burning, and myofascial pain is related to muscle trigger points.

Question 34Oral Pathology and Oral Medicine

A patient has a smooth, red, velvety patch on the floor of the mouth. What is the most appropriate management?

  1. Incisional biopsy Correct answer.
  2. Topical antifungal therapy
  3. Observation with no follow-up
  4. Reassurance and review in one year

Explanation

An erythroplakia is a red velvety patch with a high risk of dysplasia or carcinoma and requires biopsy for histologic diagnosis. Antifungal therapy is appropriate only if candidiasis is confirmed, and prolonged observation is unsafe.

Question 35Oral Pathology and Oral Medicine

Which drug class is most commonly associated with gingival overgrowth?

  1. Proton pump inhibitors
  2. Calcium channel blockers Correct answer.
  3. Selective serotonin reuptake inhibitors
  4. Beta blockers

Explanation

Calcium channel blockers such as nifedipine, along with phenytoin and cyclosporine, are the classic drugs causing gingival overgrowth. Beta blockers, proton pump inhibitors, and SSRIs are not typically implicated.

Question 36Oral Pathology and Oral Medicine

A patient reports a sudden onset of unilateral facial paralysis with inability to close the eye and loss of the nasolabial fold. Which diagnosis is most likely?

  1. Myasthenia gravis
  2. Trigeminal neuralgia
  3. Bell palsy Correct answer.
  4. Temporomandibular joint dislocation

Explanation

Acute unilateral lower motor neuron facial paralysis with inability to close the eye is characteristic of Bell palsy, a peripheral facial nerve disorder. Trigeminal neuralgia causes pain, and myasthenia gravis produces fatigable weakness rather than acute unilateral paralysis.

Question 37Oral Pathology and Oral Medicine

Which histologic finding is characteristic of an odontogenic keratocyst?

  1. Stratified squamous epithelium with prominent rete ridges
  2. Ciliated columnar epithelium
  3. Corrugated parakeratinized epithelium with a palisaded basal layer Correct answer.
  4. Giant cells within a fibrous stroma

Explanation

Odontogenic keratocyst shows a thin corrugated parakeratinized epithelial lining with a palisaded, hyperchromatic basal layer. Rete ridges, ciliated epithelium, and giant cells are features of other cystic or reactive lesions.

Question 38Oral Pathology and Oral Medicine

A patient with HIV presents with a persistent white, corrugated plaque on the lateral border of the tongue. Which condition should be suspected?

  1. Oral hairy leukoplakia Correct answer.
  2. Leukoplakia
  3. Nicotinic stomatitis
  4. Oral lichen planus

Explanation

Oral hairy leukoplakia, caused by Epstein-Barr virus, appears as a corrugated white plaque on the lateral tongue in immunocompromised patients, especially those with HIV. Lichen planus is bilateral and reticular, and nicotinic stomatitis affects the palate.

Question 39Oral Pathology and Oral Medicine

Which of the following is the most appropriate first-line treatment for a localized recurrent aphthous ulcer?

  1. Topical corticosteroid Correct answer.
  2. Antiviral therapy
  3. Surgical excision
  4. Systemic antibiotics

Explanation

Topical corticosteroids reduce inflammation and pain in recurrent aphthous ulcers and are first-line for localized lesions. Antibiotics, excision, and antivirals are not indicated for aphthous ulceration.

Question 40Oral Pathology and Oral Medicine

A patient has a unilateral swelling of the parotid gland that increases during meals and then subsides. What is the most likely cause?

  1. Salivary duct obstruction by a sialolith Correct answer.
  2. Parotid malignancy
  3. Mumps infection
  4. Sjögren syndrome

Explanation

Mealtime swelling that subsides after eating is typical of salivary duct obstruction, often by a sialolith, causing intermittent enlargement. Malignancy produces a fixed mass, Sjögren syndrome causes bilateral dryness, and mumps causes bilateral acute swelling.

Question 41Oral Pathology and Oral Medicine

Which radiographic appearance is most characteristic of fibrous dysplasia of the jaws?

  1. Sunburst periosteal reaction
  2. Ground-glass opacification blending with surrounding bone Correct answer.
  3. Multilocular soap-bubble radiolucency
  4. Well-defined unilocular radiolucency

Explanation

Fibrous dysplasia produces a ground-glass opacification that blends with adjacent bone and often causes expansion of the affected jaw. Unilocular radiolucency, sunburst reaction, and soap-bubble appearance correspond to other bone lesions.

Question 42Oral Pathology and Oral Medicine

Which feature best distinguishes a periapical cemento-osseous dysplasia from a periapical granuloma?

  1. Size of the radiolucency
  2. Presence of pain
  3. Vitality of the associated tooth Correct answer.
  4. Patient age

Explanation

Periapical cemento-osseous dysplasia occurs in vital teeth, whereas a periapical granuloma is associated with a nonvital pulp. Size, pain, and age are less reliable, and pulp vitality testing is the key discriminator.

Question 43Oral Pathology and Oral Medicine

A patient develops a rapidly enlarging, fluctuant swelling with crepitus and fever after a dental extraction. What is the most urgent concern?

  1. Development of a mucocele
  2. Spread of odontogenic infection to fascial spaces Correct answer.
  3. Formation of a dentigerous cyst
  4. Onset of trigeminal neuralgia

Explanation

Rapid swelling with crepitus and fever after extraction suggests a gas-forming odontogenic infection spreading through fascial spaces, which can threaten the airway and requires urgent management. Mucocele, dentigerous cyst, and trigeminal neuralgia do not present this way.

Question 44Oral Pathology and Oral Medicine

Which statement best explains why odontogenic keratocysts have a high recurrence rate after enucleation?

  1. Presence of a thick keratinized lining resistant to removal
  2. Association with impacted third molars
  3. Rapid malignant transformation of the lining
  4. Thin friable lining with satellite daughter cysts in the capsule Correct answer.

Explanation

The keratocyst lining is thin and friable, and satellite daughter cysts within the capsule remain after simple enucleation, explaining the high recurrence rate. Malignant transformation is uncommon, and impacted third molars are not the mechanism of recurrence.

Question 45Oral and Maxillofacial Surgery

A 24-year-old patient has a mandibular third molar with a radiolucency around the crown and a history of two episodes of pericoronitis in the past year. Which finding is the strongest indication for extraction of this tooth?

  1. Asymptomatic partial eruption with no soft tissue coverage
  2. Presence of the tooth in the arch with a normal follicular space
  3. Radiographic presence of the tooth with a fully formed apex
  4. Recurrent pericoronitis with a follicular space suggestive of a dentigerous cyst Correct answer.

Explanation

Recurrent pericoronitis together with a widened follicular space raises concern for a developing dentigerous cyst and is an accepted indication for removal of a mandibular third molar. Asymptomatic, disease-free third molars are generally managed by observation rather than prophylactic surgery.

Question 46Oral and Maxillofacial Surgery

Which local anesthetic property best explains why 2% lidocaine with 1:100,000 epinephrine provides hemostasis during a mandibular surgical extraction?

  1. Vasoconstriction that reduces local blood flow Correct answer.
  2. Direct activation of clotting factor VII
  3. Reversible blockade of sodium channels in the motor end plate
  4. Rapid hepatic metabolism of the amide bond

Explanation

Epinephrine produces local vasoconstriction, which reduces bleeding in the surgical field and prolongs the anesthetic effect. Sodium channel blockade produces anesthesia but does not itself provide hemostasis.

Question 47Oral and Maxillofacial Surgery

During a difficult mandibular third molar extraction, a patient suddenly develops trismus and deviation of the mandible to the opposite side. Which structure is most likely injured?

  1. Marginal mandibular branch of the facial nerve
  2. Lingual nerve
  3. Temporomandibular joint capsule Correct answer.
  4. Inferior alveolar nerve

Explanation

Sudden trismus with deviation of the mandible away from the affected side suggests injury or dislocation involving the temporomandibular joint rather than a sensory nerve. Nerve injuries to the lingual or inferior alveolar nerves produce sensory disturbance, not mandibular deviation.

Question 48Oral and Maxillofacial Surgery

A patient sustains a blow to the chin with bilateral fractures of the anterior mandible. Which clinical sign most reliably suggests a bilateral parasymphyseal fracture?

  1. Anterior open bite with posterior displacement of the fractured segments Correct answer.
  2. Unilateral swelling over the body of the mandible
  3. Trismus limited to 10 mm of opening
  4. Numbness of the lower lip on one side only

Explanation

Bilateral parasymphyseal fractures allow the genial segments to displace posteriorly and inferiorly, producing an anterior open bite. Unilateral swelling or unilateral numbness points to a single-sided injury rather than a bilateral one.

Question 49Oral and Maxillofacial Surgery

Which antibiotic regimen is appropriate for a healthy adult with a localized dentoalveolar abscess who has not yet received any antibiotics?

  1. Amoxicillin 500 mg orally every 8 hours for 5 to 7 days Correct answer.
  2. Metronidazole alone for 14 days
  3. Vancomycin intravenously for 10 days
  4. No antibiotics are ever needed for dentoalveolar abscess

Explanation

For a healthy adult with a localized dentoalveolar infection, amoxicillin is a first-line oral agent, and the mainstay of treatment remains drainage of the source. Antibiotics are adjunctive and should not replace removal of the cause.

Question 50Oral and Maxillofacial Surgery

Which radiographic view is best for evaluating a suspected fracture of the mandibular condyle?

  1. Occlusal radiograph of the maxilla
  2. Panoramic radiograph with a reverse Towne view Correct answer.
  3. Bitewing radiograph
  4. Periapical radiograph of the lower incisors

Explanation

Condylar fractures are best assessed with a panoramic radiograph combined with a reverse Towne view, which shows the condylar neck and medial displacement. Bitewing and periapical views do not image the condyle adequately.