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MDCG Dental Exam practice questions

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Question 1Anatomy and Physiology (Head and Neck)

Which cranial nerve provides general sensory innervation to the anterior two-thirds of the tongue before it passes through the lingual nerve?

  1. Facial nerve (CN VII)
  2. Hypoglossal nerve (CN XII)
  3. Mandibular division of the trigeminal nerve (CN V3) Correct answer.
  4. Glossopharyngeal nerve (CN IX)

Explanation

General sensation from the anterior two-thirds of the tongue travels via the lingual nerve, which is a branch of the mandibular division of the trigeminal nerve. The facial nerve contributes taste to the same region through the chorda tympani but does not carry general sensation. The glossopharyngeal nerve serves the posterior third, and the hypoglossal nerve is motor.

Question 2Anatomy and Physiology (Head and Neck)

A patient cannot protrude the tongue to the left side, and the tongue deviates toward the left on attempted protrusion. Which structure is most likely affected?

  1. Right hypoglossal nerve
  2. Left chorda tympani
  3. Left lingual nerve
  4. Left hypoglossal nerve Correct answer.

Explanation

The genioglossus muscle, innervated by the hypoglossal nerve, protrudes the tongue. When one hypoglossal nerve is damaged, the unopposed contralateral genioglossus pushes the tongue toward the weak side, so a left-sided lesion produces leftward deviation. The lingual nerve and chorda tympani are sensory and would not cause motor deviation.

Question 3Anatomy and Physiology (Head and Neck)

Which muscle of mastication elevates the mandible and is the primary muscle palpated over the ramus of the mandible?

  1. Masseter Correct answer.
  2. Anterior belly of digastric
  3. Medial pterygoid
  4. Lateral pterygoid

Explanation

The masseter runs from the zygomatic arch to the lateral surface of the mandibular ramus and is a powerful elevator of the mandible. It is easily palpated over the ramus when the patient clenches the teeth. The lateral pterygoid depresses and protrudes the mandible, and the anterior digastric depresses it.

Question 4Anatomy and Physiology (Head and Neck)

During wide opening of the mouth, which movement of the temporomandibular joint condyle occurs first?

  1. Pure rotation in the lower compartment Correct answer.
  2. Immediate translation in the upper compartment
  3. Lateral shift of the condyle
  4. Retrusion of the condyle

Explanation

Normal mouth opening begins with rotation of the condyle within the lower joint compartment, followed by translation of the condyle and disc down the articular eminence in the upper compartment. This two-phase pattern reflects the fibrocartilage-lined compartments and the disc dividing them. Lateral shift and retrusion are not the initial opening movement.

Question 5Anatomy and Physiology (Head and Neck)

The articular surfaces of the temporomandibular joint are lined by which tissue?

  1. Hyaline cartilage
  2. Fibrocartilage Correct answer.
  3. Synovial membrane
  4. Elastic cartilage

Explanation

Unlike most synovial joints, the temporomandibular joint is lined by dense fibrous connective tissue and fibrocartilage rather than hyaline cartilage. This adaptation helps the joint withstand heavy loading and shear during mastication. Synovial membrane lines the capsule but does not cover the articular surfaces.

Question 6Anatomy and Physiology (Head and Neck)

Sensory fibres from the lower lip travel to the brainstem primarily through which branch of the trigeminal nerve?

  1. Facial nerve (CN VII)
  2. Mandibular division (V3) Correct answer.
  3. Maxillary division (V2)
  4. Ophthalmic division (V1)

Explanation

The lower lip is innervated by the mental nerve, a terminal branch of the inferior alveolar nerve within the mandibular division of the trigeminal nerve. The maxillary division supplies the upper lip and midface, and the ophthalmic division supplies the forehead and upper face. The facial nerve is motor to the facial muscles and carries taste, not lower lip general sensation.

Question 7Anatomy and Physiology (Head and Neck)

Which salivary gland lies in the floor of the mouth and drains through the submandibular duct (Wharton's duct) at the sublingual papilla?

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

Explanation

The submandibular gland sits in the submandibular triangle and its duct, Wharton's duct, opens at the sublingual papilla beside the lingual frenum. The parotid drains via Stensen's duct opposite the upper second molar, and the sublingual gland drains through multiple small ducts. This anatomy explains the common presentation of submandibular sialoliths.

Question 8Anatomy and Physiology (Head and Neck)

A stone obstructing the submandibular duct most commonly causes swelling in which location?

  1. Lateral pharyngeal wall
  2. Pre-auricular region
  3. Upper buccal vestibule
  4. Submental and submandibular region Correct answer.

Explanation

The submandibular gland and its duct lie in the submandibular triangle and floor of the mouth, so obstruction produces swelling in the submandibular and submental region, often worsening at mealtimes. Parotid obstruction would cause pre-auricular swelling. Buccal and pharyngeal swelling are unrelated to this duct.

Question 9Anatomy and Physiology (Head and Neck)

Which artery is the principal blood supply to the maxillary teeth?

  1. Inferior alveolar artery
  2. Facial artery
  3. Lingual artery
  4. Superior alveolar arteries Correct answer.

Explanation

The maxillary teeth are supplied by the superior alveolar arteries, branches of the maxillary artery, which run within the maxilla to reach the tooth roots. The inferior alveolar artery supplies the mandibular teeth. The lingual and facial arteries supply the tongue and facial soft tissues respectively.

Question 10Anatomy and Physiology (Head and Neck)

The pterygoid venous plexus is clinically important in dentistry mainly because it communicates with which structure?

  1. Sagittal sinus
  2. Cavernous sinus Correct answer.
  3. Transverse sinus
  4. Straight sinus

Explanation

The pterygoid venous plexus drains through emissary veins that communicate with the cavernous sinus, providing a route for infection from the maxillary molar region to spread intracranially. This is why infections of the posterior maxilla are treated with particular caution. The sagittal, transverse, and straight sinuses are not directly connected through this plexus.

Question 11Anatomy and Physiology (Head and Neck)

Which nerve provides motor innervation to the muscles of facial expression?

  1. Facial nerve Correct answer.
  2. Glossopharyngeal nerve
  3. Trigeminal nerve
  4. Accessory nerve

Explanation

The facial nerve (CN VII) supplies the muscles of facial expression through its temporal, zygomatic, buccal, marginal mandibular, and cervical branches. The trigeminal nerve provides motor supply to the muscles of mastication, not facial expression. This distinction is essential when assessing facial asymmetry after dental procedures.

Question 12Anatomy and Physiology (Head and Neck)

A patient develops sudden unilateral facial droop with inability to close the eye and loss of taste on the anterior tongue after a mandibular block. Which nerve is most likely affected?

  1. Lingual nerve
  2. Facial nerve Correct answer.
  3. Auriculotemporal nerve
  4. Inferior alveolar nerve

Explanation

Facial nerve palsy after a mandibular block can occur when local anaesthetic reaches the nerve as it exits the stylomastoid foramen, producing facial droop, inability to close the eye, and loss of taste via the chorda tympani. The inferior alveolar and lingual nerves are branches of V3 and would cause numbness, not facial weakness. The auriculotemporal nerve carries sensation from the temple and auricle.

Question 13Anatomy and Physiology (Head and Neck)

Which structure passes through the foramen ovale?

  1. Maxillary division of the trigeminal nerve
  2. Mandibular division of the trigeminal nerve Correct answer.
  3. Facial nerve
  4. Hypoglossal nerve

Explanation

The mandibular division of the trigeminal nerve exits the skull through the foramen ovale, accompanied by the motor root and the lesser petrosal nerve. The maxillary division passes through the foramen rotundum, and the facial and hypoglossal nerves exit through the stylomastoid foramen and hypoglossal canal respectively.

Question 14Anatomy and Physiology (Head and Neck)

The greater palatine foramen is located in which bone?

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

Explanation

The greater palatine foramen lies at the junction of the palatine bone and maxilla but is primarily a feature of the palatine bone, transmitting the greater palatine nerve and vessels. It is a key landmark for palatal anaesthesia. The maxilla forms the anterior palate but the foramen belongs to the palatine bone.

Question 15Anatomy and Physiology (Head and Neck)

Which muscle forms the bulk of the soft palate and is responsible for tensing the soft palate during swallowing?

  1. Levator veli palatini
  2. Musculus uvulae
  3. Tensor veli palatini Correct answer.
  4. Palatoglossus

Explanation

The tensor veli palatini arises from the medial pterygoid plate and auditory tube and tenses the soft palate, also opening the pharyngotympanic tube during swallowing. The levator veli palatini elevates the palate, while palatoglossus and musculus uvulae have different actions. This distinction matters when assessing velopharyngeal function.

Question 16Anatomy and Physiology (Head and Neck)

The nasopalatine nerve enters the oral cavity through which foramen?

  1. Incisive foramen Correct answer.
  2. Lesser palatine foramen
  3. Infraorbital foramen
  4. Greater palatine foramen

Explanation

The nasopalatine nerve descends through the incisive canal and emerges at the incisive foramen on the anterior hard palate, supplying sensation to the anterior palatal mucosa. The greater and lesser palatine foramina transmit the palatine nerves posteriorly, and the infraorbital foramen is on the facial skeleton.

Question 17Anatomy and Physiology (Head and Neck)

Which lymph node group is the primary drainage site for the tip of the tongue?

  1. Supraclavicular nodes
  2. Deep cervical nodes at level II
  3. Submental nodes Correct answer.
  4. Retropharyngeal nodes

Explanation

Lymph from the tip of the tongue drains first to the submental nodes, which lie in the submental triangle. The lateral tongue drains to submandibular and deep cervical nodes, and the posterior tongue drains to deeper cervical nodes. Knowing this pattern guides examination for metastatic spread.

Question 18Anatomy and Physiology (Head and Neck)

A dental abscess in the mandibular first molar spreads to the submandibular space. Which fascial space is most directly contiguous and at risk of involvement?

  1. Buccal space
  2. Sublingual space
  3. Parapharyngeal space
  4. Masticator space Correct answer.

Explanation

The roots of the mandibular molars lie below the mylohyoid attachment, so infection spreads into the submandibular space and can extend to the masticator space via the ramus. The sublingual space is above the mylohyoid and more typical of anterior tooth infections. The parapharyngeal space may be involved secondarily but is not the most direct contiguous space from this molar.

Question 19Anatomy and Physiology (Head and Neck)

The buccinator muscle is innervated by which nerve?

  1. Mandibular division of the trigeminal nerve
  2. Hypoglossal nerve
  3. Maxillary division of the trigeminal nerve
  4. Facial nerve Correct answer.

Explanation

The buccinator is a muscle of facial expression and is innervated by the facial nerve through its buccal branches. Although it lies near the buccal branch of the mandibular nerve, that branch is sensory. The maxillary division is sensory to the midface and the hypoglossal nerve is motor to the tongue.

Question 20Anatomy and Physiology (Head and Neck)

Which paranasal sinus is most closely related to the roots of the maxillary posterior teeth?

  1. Frontal sinus
  2. Ethmoid sinus
  3. Sphenoid sinus
  4. Maxillary sinus Correct answer.

Explanation

The maxillary sinus floor lies close to the apices of the maxillary posterior teeth, and in some cases roots project into the sinus. This relationship explains sinusitis-like symptoms from posterior maxillary infections and the risk of oroantral communication during extraction. The other sinuses are distant from the dental arches.

Question 21Anatomy and Physiology (Head and Neck)

Which cranial nerve supplies the carotid body and the stylopharyngeus muscle?

  1. Trigeminal nerve
  2. Vagus nerve
  3. Glossopharyngeal nerve Correct answer.
  4. Facial nerve

Explanation

The glossopharyngeal nerve provides motor innervation to the stylopharyngeus and carries afferent fibres from the carotid body and carotid sinus. The vagus nerve supplies most other pharyngeal muscles and thoracic and abdominal viscera. The facial and trigeminal nerves do not innervate the stylopharyngeus.

Question 22Anatomy and Physiology (Head and Neck)

Which muscle of the soft palate is the only one innervated by the mandibular division of the trigeminal nerve?

  1. Palatopharyngeus
  2. Tensor veli palatini Correct answer.
  3. Levator veli palatini
  4. Palatoglossus

Explanation

All palatal muscles are supplied by the pharyngeal plexus via the vagus nerve except the tensor veli palatini, which is innervated by the mandibular division of the trigeminal nerve. This exception is important when evaluating palatal function in trigeminal lesions. The levator, palatopharyngeus, and palatoglossus are supplied through the vagus.

Question 23Anatomy and Physiology (Head and Neck)

The parotid gland is enclosed within which fascia?

  1. Superficial cervical fascia
  2. Prevertebral fascia
  3. Investing layer of deep cervical fascia Correct answer.
  4. Pretracheal fascia

Explanation

The parotid gland is enclosed by the investing layer of deep cervical fascia, which forms the parotid capsule and tethers the gland during swelling. The pretracheal fascia encloses the thyroid and trachea, and the prevertebral fascia covers the vertebral column. This arrangement explains the tense, painful swelling typical of parotitis.

Question 24Anatomy and Physiology (Head and Neck)

Which nerve is most at risk of injury during surgical removal of a mandibular third molar, leading to altered sensation of the lower lip?

  1. Lingual nerve
  2. Mylohyoid nerve
  3. Inferior alveolar nerve Correct answer.
  4. Buccal nerve

Explanation

The inferior alveolar nerve runs in the mandibular canal close to the apices of the third molar, and injury during extraction can cause numbness of the lower lip and chin. The lingual nerve is also at risk but produces tongue numbness. The buccal and mylohyoid nerves do not supply the lower lip.

Question 25Oral Anatomy, Histology, and Embryology

Which permanent tooth typically erupts first into the oral cavity?

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

Explanation

The mandibular first molar normally erupts at about 6 years of age, earlier than any other permanent tooth, and it does so distal to the primary second molar without replacing a deciduous tooth. The permanent incisors follow at roughly 6 to 7 years.

Question 26Oral Anatomy, Histology, and Embryology

Enamel is formed by which cell type?

  1. Ameloblasts Correct answer.
  2. Odontoblasts
  3. Cementoblasts
  4. Fibroblasts of the periodontal ligament

Explanation

Ameloblasts are the specialized epithelial cells of the inner enamel epithelium that secrete enamel matrix and later mineralize it. Odontoblasts, derived from dental papilla ectomesenchyme, produce the underlying dentin instead.

Question 27Oral Anatomy, Histology, and Embryology

The dental lamina develops from which embryonic tissue?

  1. Endoderm of the foregut
  2. Neural crest-derived ectomesenchyme
  3. Mesoderm of the first pharyngeal arch
  4. Surface ectoderm of the stomodeum Correct answer.

Explanation

The dental lamina arises as a thickening of the oral epithelium, which is surface ectoderm lining the stomodeum. The underlying ectomesenchyme condenses to form the dental papilla and follicle but does not give rise to the lamina itself.

Question 28Oral Anatomy, Histology, and Embryology

Which tissue covers the root surface of a fully formed tooth and anchors periodontal ligament fibers?

  1. Dentin
  2. Pulp
  3. Enamel
  4. Cementum Correct answer.

Explanation

Cementum is the mineralized tissue covering the root dentin, and its extrinsic collagen fibers interdigitate with periodontal ligament Sharpey fibers to attach the tooth to alveolar bone. Enamel is confined to the crown.

Question 29Oral Anatomy, Histology, and Embryology

In the FDI two-digit system, which tooth is designated 36?

  1. Mandibular right first molar
  2. Mandibular left first molar Correct answer.
  3. Maxillary left first molar
  4. Maxillary right first molar

Explanation

In FDI notation the first digit indicates the quadrant and the second the tooth position from the midline. Quadrant 3 is the mandibular left, and position 6 is the first permanent molar, so 36 is the mandibular left first molar.

Question 30Oral Anatomy, Histology, and Embryology

Which salivary gland secretion is predominantly mucous and enters the oral cavity via the sublingual caruncle region?

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

Explanation

The sublingual gland is a mixed gland with predominantly mucous acini, and its ducts open along the sublingual fold, with some joining the submandibular duct near the sublingual caruncle. The parotid is almost entirely serous.

Question 31Oral Anatomy, Histology, and Embryology

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

  1. Facial nerve (CN VII)
  2. Glossopharyngeal nerve (CN IX)
  3. Lingual nerve branch of mandibular division of trigeminal (CN V3) Correct answer.
  4. Hypoglossal nerve (CN XII)

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 chorda tympani fibers of the facial nerve.

Question 32Oral Anatomy, Histology, and Embryology

Which muscle of mastication is the primary depressor of the mandible during opening?

  1. Temporalis
  2. Medial pterygoid
  3. Lateral pterygoid Correct answer.
  4. Masseter

Explanation

The lateral pterygoid, particularly its inferior head, protrudes the mandible and assists in depressing it during opening, working with the suprahyoid muscles. The masseter, temporalis, and medial pterygoid are elevators.

Question 33Oral Anatomy, Histology, and Embryology

Which type of dentin forms the initial layer secreted before the odontoblast has fully differentiated?

  1. Circumpulpal dentin
  2. Tertiary dentin
  3. Secondary dentin
  4. Mantle dentin Correct answer.

Explanation

Mantle dentin is the first-formed dentin layer, deposited by newly differentiated odontoblasts just beneath the dentinoenamel junction, and it contains larger, less mineralized collagen fibers. Circumpulpal dentin forms later and constitutes most of the dentin thickness.

Question 34Oral Anatomy, Histology, and Embryology

The epithelial root sheath of Hertwig is responsible for which developmental event?

  1. Development of the periodontal ligament blood supply
  2. Determination of root shape and initiation of dentin and cementum formation Correct answer.
  3. Formation of the dental pulp chamber
  4. Formation of the enamel organ

Explanation

Hertwig epithelial root sheath is a bilayer of inner and outer enamel epithelium that grows from the cervical loop to map the root outline. It induces adjacent papilla cells to become odontoblasts, and its subsequent fragmentation allows cementoblasts to reach the root surface.

Question 35Oral Anatomy, Histology, and Embryology

Which enamel structure represents the path traveled by an ameloblast during enamel formation?

  1. Hunter-Schreger band
  2. Neonatal line
  3. Enamel rod Correct answer.
  4. Perikymata

Explanation

Each enamel rod is the product of a single ameloblast and reflects the cell's path as it retreats outward during appositional growth. Hunter-Schreger bands are optical alternations of rod direction, and perikymata are surface manifestations of incremental lines.

Question 36Oral Anatomy, Histology, and Embryology

Which primary tooth morphology feature most clearly distinguishes primary molars from permanent molars?

  1. Presence of accessory cusps
  2. Presence of an enamel pearl
  3. Marked cervical constriction and bulbous crown Correct answer.
  4. Absence of a pulp chamber

Explanation

Primary teeth generally show a pronounced cervical constriction, bulbous crowns, and relatively thin enamel, which together give them their characteristic shape. Permanent molars are less constricted and have more parallel proximal walls.

Question 37Oral Anatomy, Histology, and Embryology

During swallowing, which structure prevents food from entering the nasopharynx?

  1. Soft palate Correct answer.
  2. Epiglottis
  3. Palatoglossal arch
  4. Uvula

Explanation

During the pharyngeal phase of swallowing, the soft palate elevates and tenses to seal the nasopharynx and prevent nasal regurgitation. The epiglottis protects the laryngeal inlet instead.

Question 38Oral Anatomy, Histology, and Embryology

Which cell layer of the junctional epithelium provides the epithelial attachment to the tooth surface?

  1. Stratum basale cells with hemidesmosomes Correct answer.
  2. Rete peg extensions into connective tissue
  3. Keratinized superficial cells
  4. Melanocytes in the basal layer

Explanation

The junctional epithelium attaches to the tooth via an internal basal lamina, and its cells form hemidesmosomes that anchor them to this lamina. This epithelial attachment seals the gingival sulcus from the underlying connective tissue.

Question 39Oral Anatomy, Histology, and Embryology

Which developmental defect results from incomplete fusion of the palatal shelves and presents as a midline opening of the hard palate?

  1. Bifid uvula only
  2. Cleft lip
  3. Macrostomia
  4. Cleft palate Correct answer.

Explanation

Cleft palate arises when the palatal shelves fail to meet and fuse in the midline, leaving a communication between oral and nasal cavities. Cleft lip instead results from failure of fusion of the medial nasal and maxillary processes.

Question 40Oral Anatomy, Histology, and Embryology

Which periodontal ligament fiber group is oriented to resist tipping forces and extends from the cervical cementum apically to the alveolar crest?

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

Explanation

Alveolar crest fibers run from the cementum just below the epithelial attachment to the alveolar crest and resist horizontal and tipping forces. Oblique fibers, by contrast, are the main group resisting axial occlusal loads.

Question 41Oral Anatomy, Histology, and Embryology

A patient has a localized developmental defect in which enamel and dentin are both invaginated into the pulp chamber on the lingual of a maxillary lateral incisor. Which anomaly is this?

  1. Dens evaginatus
  2. Enamel pearl
  3. Dens invaginatus Correct answer.
  4. Taurodontism

Explanation

Dens invaginatus results from infolding of the enamel organ before mineralization, creating a channel lined by enamel and dentin that can communicate with the pulp. It most commonly affects maxillary lateral incisors and predisposes to pulpal infection.

Question 42Oral Anatomy, Histology, and Embryology

Which statement best explains why the mandibular first molar frequently develops caries soon after eruption?

  1. It has the thinnest enamel of any permanent tooth
  2. Its occlusal surface has deep pits and fissures that retain plaque during a period of incomplete mineralization Correct answer.
  3. It erupts before salivary glands become functional
  4. It lacks a periodontal ligament until root completion

Explanation

The mandibular first molar erupts early and its occlusal fissures are deep and narrow, creating stagnation areas for plaque while post-eruptive enamel maturation is still occurring. This combination makes it highly susceptible to fissure caries.

Question 43Oral Anatomy, Histology, and Embryology

Which feature of the temporomandibular joint allows the mandible to translate forward during opening?

  1. A fibrocartilaginous disc dividing the joint into upper and lower compartments Correct answer.
  2. Absence of a joint capsule
  3. Presence of a synovial membrane only in the lower compartment
  4. Complete bony separation of the joint into two cavities

Explanation

The temporomandibular joint contains a fibrocartilaginous articular disc that divides it into upper and lower synovial compartments. The lower compartment permits rotation, while the upper compartment permits translation of the condyle and disc forward during opening.

Question 44Oral Anatomy, Histology, and Embryology

Which developmental process directly produces the reduced enamel epithelium that later fuses with oral epithelium during eruption?

  1. Degeneration of the stellate reticulum and fusion of ameloblast layers after enamel completion Correct answer.
  2. Apoptosis of the dental papilla
  3. Mineralization of the dental follicle
  4. Formation of the epithelial root sheath

Explanation

After enamel maturation, the ameloblasts, stratum intermedium, stellate reticulum, and outer enamel epithelium collapse into the reduced enamel epithelium. Its fusion with the oral epithelium creates an eruption pathway for the crown.

Question 45Oral Pathology and Oral Medicine

A 7-year-old child has a well-demarcated, painless, sessile nodule on the buccal mucosa that has been present for several months. Excisional biopsy shows a proliferation of spindle cells with numerous mast cells. Which diagnosis is most consistent with these findings?

  1. Mucocele
  2. Neurofibroma Correct answer.
  3. Irritation fibroma
  4. Traumatic neuroma

Explanation

A painless, slow-growing mucosal spindle cell lesion containing numerous mast cells in a child is characteristic of a solitary neurofibroma. Mast cells are a recognized feature of neurofibromas and help distinguish them from other spindle cell proliferations. The location and chronicity fit a benign neural tumor rather than a reactive fibrous or salivary lesion.

Question 46Oral Pathology and Oral Medicine

Which mucosal lesion is characterized histologically by a band-like lymphocytic infiltrate hugging the epithelial-connective tissue interface with basal cell liquefactive degeneration?

  1. Candidal leukoplakia
  2. Pemphigus vulgaris
  3. Oral lichen planus Correct answer.
  4. Leukoplakia with mild dysplasia

Explanation

Oral lichen planus classically shows a dense band-like lymphocytic infiltrate at the interface, basal cell liquefactive degeneration, and saw-tooth rete ridges. These interface changes reflect a T-cell-mediated attack on basal keratinocytes. The other entities lack this specific interface pattern.

Question 47Oral Pathology and Oral Medicine

A patient reports recurrent episodes of unilateral facial paralysis, facial edema, and fissured tongue. Which condition best unifies these findings?

  1. Sjögren syndrome
  2. Melkersson-Rosenthal syndrome Correct answer.
  3. Bell palsy
  4. Trigeminal neuralgia

Explanation

The triad of recurrent facial paralysis, orofacial edema (often lip swelling), and fissured tongue defines Melkersson-Rosenthal syndrome. Noncaseating granulomatous inflammation is the characteristic histologic finding. Bell palsy alone does not include lip edema or fissured tongue.

Question 48Oral Pathology and Oral Medicine

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

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

Explanation

The radicular (periapical) cyst is the most common odontogenic cyst, arising from epithelial rests of Malassez in response to pulpal necrosis. It is inflammatory in origin and typically occurs at the apex of a nonvital tooth. Other odontogenic cysts are developmental and less frequent.

Question 49Oral Pathology and Oral Medicine

A 45-year-old tobacco user has a chronic nonhealing ulcer on the lateral tongue with rolled, indurated borders. Which feature most strongly raises suspicion for squamous cell carcinoma rather than a traumatic ulcer?

  1. Presence of a necrotic center
  2. Association with a sharp carious tooth
  3. Pain on palpation
  4. Induration of the ulcer base and margins Correct answer.

Explanation

Induration reflects tumor infiltration into underlying tissue and is a key clinical sign of malignancy in a chronic oral ulcer. Traumatic ulcers are typically soft and resolve after the cause is removed. Pain, necrosis, and association with a sharp tooth can occur in benign traumatic ulcers as well.

Question 50Oral Pathology and Oral Medicine

Which virus is most strongly associated with the development of oral hairy leukoplakia?

  1. Epstein-Barr virus Correct answer.
  2. Herpes simplex virus type 1
  3. Human papillomavirus type 16
  4. Cytomegalovirus

Explanation

Oral hairy leukoplakia is caused by Epstein-Barr virus replication within the tongue epithelium, usually in immunocompromised patients such as those with HIV. It presents as corrugated white plaques on the lateral tongue border. Other herpesviruses and HPV are not implicated in this lesion.