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INI-CET MDS practice questions

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Question 1Dental Anatomy, Oral Histology and Oral Embryology

Which enamel rod (prism) pattern is most characteristic of the inner two-thirds of permanent enamel, where rods run in bundles with alternating directions?

  1. Diazones and parazones Correct answer.
  2. Radial enamel
  3. Hunter-Schreger banding
  4. Gnarled enamel

Explanation

In the inner two-thirds of permanent enamel the rods decussate in alternating groups called diazones and parazones, a pattern that increases resistance to crack propagation. This decussation produces the alternating light and dark bands seen in longitudinal ground sections. Gnarled enamel is the tangled arrangement found beneath cusps and incisal edges, not the general inner pattern.

Question 2Dental Anatomy, Oral Histology and Oral Embryology

During root formation, the epithelial root sheath of Hertwig fragments and leaves small epithelial remnants in the periodontal ligament. These remnants are known as:

  1. Enamel knots
  2. Rests of Malassez Correct answer.
  3. Rests of Serres
  4. Cells of Tomes

Explanation

The rests of Malassez are epithelial remnants of the fragmented Hertwig root sheath that persist in the periodontal ligament throughout life. They can proliferate to form radicular cysts. The rests of Serres are remnants of the dental lamina in the jaw, and cells of Tomes are the ameloblasts that secrete enamel.

Question 3Dental Anatomy, Oral Histology and Oral Embryology

A ground section of a permanent tooth shows incremental lines in dentin that run at right angles to the dentinal tubules. These lines, reflecting the daily rhythm of dentin matrix deposition, are termed:

  1. Lines of Owen
  2. Lines of von Ebner Correct answer.
  3. Neonatal lines
  4. Contour lines of Owen

Explanation

Lines of von Ebner are the daily incremental lines of dentin, running perpendicular to the dentinal tubules and reflecting the rhythmic deposition of dentin matrix. Contour lines of Owen are coarser, less frequent lines marking disturbances in mineralization. The neonatal line is a single accentuated line marking birth.

Question 4Dental Anatomy, Oral Histology and Oral Embryology

Which cell type is responsible for resorbing dentin and bone during physiological root resorption of the deciduous dentition?

  1. Odontoclasts Correct answer.
  2. Osteoblasts
  3. Fibroblasts
  4. Cementoblasts

Explanation

Odontoclasts are multinucleated, ruffled-border cells of the monocyte-macrophage lineage that resorb dentin and cementum during deciduous root resorption. They act in a manner analogous to osteoclasts. Osteoblasts and cementoblasts are formative cells, and fibroblasts are not primarily resorptive.

Question 5Dental Anatomy, Oral Histology and Oral Embryology

In a developing tooth germ, the structure that determines the shape of the future crown by folding and signaling is the:

  1. Dental sac
  2. Dental lamina
  3. Dental papilla
  4. Enamel organ Correct answer.

Explanation

The enamel organ, particularly its inner enamel epithelium and enamel knot signaling centers, folds into the future crown form and drives the shape of the tooth. The dental papilla forms dentin and pulp, while the dental sac forms cementum, periodontal ligament and alveolar bone. The dental lamina is the epithelial band from which the tooth germs arise.

Question 6Dental Anatomy, Oral Histology and Oral Embryology

A patient's maxillary first permanent molar shows a small, extra cusp on the mesiolingual surface. This supernumerary cusp is best termed the:

  1. Dens invaginatus
  2. Talon cusp
  3. Cusp of Carabelli Correct answer.
  4. Dens evaginatus

Explanation

The cusp of Carabelli is a small accessory cusp or ridge on the mesiolingual surface of the maxillary first permanent molar, most often on the first molar. It is a common, usually harmless anatomical variant. Talon cusps occur on the lingual of anterior teeth, and dens evaginatus and dens invaginatus are developmental anomalies of the occlusal or invaginated surfaces.

Question 7Dental Anatomy, Oral Histology and Oral Embryology

Which structure is the first to show evidence of calcification in a developing deciduous tooth?

  1. The cervical region of the root
  2. The dentinoenamel junction area of the incisal edge or cusp tip Correct answer.
  3. The enamel cuticle
  4. The pulp chamber roof

Explanation

In both dentitions, calcification begins at the dentinoenamel junction near the incisal edge or cusp tip and then spreads cervically. The cervical region and pulp chamber roof calcify later. The enamel cuticle is a surface organic layer, not a calcifying front.

Question 8Dental Anatomy, Oral Histology and Oral Embryology

The reduced enamel epithelium that covers the crown of an erupting tooth is derived from which layers of the enamel organ?

  1. Dental papilla and dental sac
  2. Inner enamel epithelium and outer enamel epithelium Correct answer.
  3. Outer enamel epithelium and stellate reticulum
  4. Stellate reticulum and stratum intermedium

Explanation

After enamel formation is complete, the ameloblasts (inner enamel epithelium) and the outer enamel epithelium come together to form the reduced enamel epithelium. It protects the enamel until eruption and later contributes to the epithelial attachment. The stellate reticulum and stratum intermedium regress before this stage.

Question 9Dental Anatomy, Oral Histology and Oral Embryology

Which type of oral mucosa is found on the dorsum of the tongue and is characterized by a keratinized epithelium with specialized papillae?

  1. Masticatory mucosa
  2. Lining mucosa
  3. Specialized mucosa Correct answer.
  4. Reflecting mucosa

Explanation

Specialized mucosa covers the dorsum of the tongue and contains lingual papillae, some with taste buds, with a keratinized or parakeratinized epithelium. Masticatory mucosa covers the gingiva and hard palate, and lining mucosa covers the soft palate, buccal mucosa and floor of the mouth.

Question 10Dental Anatomy, Oral Histology and Oral Embryology

A section of gingiva shows a band of keratinized epithelium attached to the tooth surface by hemidesmosomes and an internal basal lamina. This epithelial attachment is called the:

  1. Oral gingival epithelium
  2. Rete pegs
  3. Sulcular epithelium
  4. Junctional epithelium Correct answer.

Explanation

The junctional epithelium is a nonkeratinized stratified squamous epithelium attached to the tooth by hemidesmosomes and an internal basal lamina, forming the epithelial seal. The sulcular epithelium lines the gingival sulcus, and the oral gingival epithelium is the keratinized outer surface.

Question 11Dental Anatomy, Oral Histology and Oral Embryology

Which of the following is the principal mineral phase of mature enamel and dentin?

  1. Brushite
  2. Hydroxyapatite Correct answer.
  3. Octacalcium phosphate
  4. Whitlockite

Explanation

The principal inorganic phase of enamel and dentin is carbonate-substituted hydroxyapatite. Brushite, whitlockite and octacalcium phosphate are precursor or transient calcium phosphates that may appear during mineralization but do not constitute the bulk of mature hard tissue.

Question 12Dental Anatomy, Oral Histology and Oral Embryology

In the classic description of the periodontium, which fiber group of the periodontal ligament is most responsible for resisting intrusive forces on the tooth?

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

Explanation

Oblique fibers are the most numerous group and are oriented to resist axially directed intrusive forces, converting them into tension on the alveolar bone. Apical fibers resist extrusive forces, and alveolar crest and horizontal fibers resist tipping and horizontal forces.

Question 13Dental Anatomy, Oral Histology and Oral Embryology

Which of the following statements about the dental pulp is correct?

  1. The pulp is avascular and receives nutrition by diffusion from dentin
  2. The pulp contains no nerve fibers in the coronal region
  3. The pulp contains only odontoblasts and no immune cells
  4. The pulp is a loose connective tissue enclosed by dentin and communicates with the periodontium through the apical foramen Correct answer.

Explanation

The pulp is a loose, vascular connective tissue enclosed by dentin and connected to the periodontium through the apical foramen and accessory canals. It contains odontoblasts, fibroblasts, immune cells and a rich nerve and blood supply. It is not avascular, and nerves extend into the coronal pulp.

Question 14Dental Anatomy, Oral Histology and Oral Embryology

A developing tooth shows a bell-shaped enamel organ with a clearly defined stratum intermedium and stellate reticulum, and the inner enamel epithelium has begun to elongate. This stage is best described as the:

  1. Cap stage
  2. Bell stage Correct answer.
  3. Dental lamina stage
  4. Bud stage

Explanation

The bell stage is characterized by a bell-shaped enamel organ with distinct stratum intermedium, stellate reticulum and outer and inner enamel epithelia, and by elongation of inner enamel epithelial cells into ameloblasts. The bud stage is a simple epithelial invagination, and the cap stage shows a shallow cap without full differentiation.

Question 15Dental Anatomy, Oral Histology and Oral Embryology

Which of the following is a characteristic feature that distinguishes deciduous from permanent teeth?

  1. Deciduous teeth lack a dentinoenamel junction
  2. Deciduous teeth have no enamel rods
  3. Deciduous molars have more pronounced roots and a thinner enamel layer
  4. Deciduous teeth have a relatively larger pulp chamber and thinner enamel Correct answer.

Explanation

Deciduous teeth typically have thinner enamel and dentin, relatively larger pulp chambers and more slender roots, features relevant to cavity preparation and endodontics. They do contain enamel rods and a dentinoenamel junction, as do permanent teeth.

Question 16Dental Anatomy, Oral Histology and Oral Embryology

In a histological section of a tooth, a layer of unmineralized organic matrix is seen at the pulpal surface of dentin, adjacent to the odontoblast layer. This layer is the:

  1. Predentin Correct answer.
  2. Interglobular dentin
  3. Sclerotic dentin
  4. Tomes granular layer

Explanation

Predentin is the unmineralized organic matrix secreted by odontoblasts at the pulpal surface of dentin, which subsequently mineralizes. Interglobular dentin is a hypomineralized area in the circumpulpal dentin, and Tomes granular layer is a region near the cementum.

Question 17Dental Anatomy, Oral Histology and Oral Embryology

Which of the following best explains why enamel cannot repair itself after a carious lesion destroys its structure?

  1. Ameloblasts migrate into the pulp after eruption
  2. Ameloblasts are lost after eruption and enamel has no cells to secrete new matrix Correct answer.
  3. Enamel is replaced by cementum after eruption
  4. Enamel contains no mineral and cannot remineralize

Explanation

Ameloblasts are lost during eruption when the reduced enamel epithelium is shed, so enamel has no cellular capacity for matrix secretion or repair. Enamel is highly mineralized and can undergo limited remineralization from saliva, but it cannot regenerate lost structure. Cementum and pulp cells do not replace enamel.

Question 18Dental Anatomy, Oral Histology and Oral Embryology

A ground section of a tooth shows a narrow, highly mineralized zone at the dentinoenamel junction that is less permeable to dyes than adjacent dentin. This zone is best identified as:

  1. Dead tracts
  2. The mantle dentin Correct answer.
  3. Tomes granular layer
  4. Interglobular dentin

Explanation

Mantle dentin is the first-formed, outermost layer of dentin, slightly less mineralized than circumpulpal dentin, and near the dentinoenamel junction it forms a narrow, relatively impermeable zone. Interglobular dentin and Tomes granular layer are hypomineralized regions, and dead tracts are empty tubules.

Question 19Dental Anatomy, Oral Histology and Oral Embryology

Which of the following accurately describes the pattern of eruption of the permanent dentition in a typical child?

  1. Permanent first molars erupt before the permanent incisors Correct answer.
  2. Permanent canines erupt before the first molars
  3. All permanent teeth erupt simultaneously after the deciduous teeth are lost
  4. Permanent incisors erupt before the first molars

Explanation

The permanent first molars typically erupt before the permanent incisors, around age 6, and are often called the six-year molars. The permanent incisors follow, then premolars and canines. Eruption is sequential, not simultaneous.

Question 20Dental Anatomy, Oral Histology and Oral Embryology

Which structure forms the epithelial lining of the oral cavity and is derived from the ectoderm and, in part, from the endoderm?

  1. Alveolar bone
  2. Dental papilla
  3. Oral epithelium Correct answer.
  4. Periodontal ligament

Explanation

The oral epithelium is derived largely from ectoderm, with contributions from endoderm in the pharyngeal region, and forms the epithelial lining of the oral cavity. The dental papilla, alveolar bone and periodontal ligament are of mesenchymal (neural crest) origin.

Question 21Oral Pathology and Oral Microbiology

A 45-year-old man has a well-demarcated, velvety, red plaque on the floor of the mouth that has persisted for eight months and does not rub off. He has never smoked or chewed betel quid. Which diagnosis is most consistent with this presentation?

  1. Chemical burn from aspirin placement
  2. Hairy leukoplakia
  3. Erythroplakia Correct answer.
  4. Linea alba

Explanation

A persistent, non-removable, velvety red patch with no identifiable benign cause is by definition erythroplakia, a lesion with a high risk of severe dysplasia or carcinoma in situ. Its classic site is the floor of the mouth and ventral tongue, and the absence of a clear irritant strengthens the diagnosis. Biopsy is mandatory because clinical appearance cannot exclude invasive carcinoma.

Question 22Oral Pathology and Oral Microbiology

Which organism is the principal causative agent of acute necrotizing ulcerative gingivitis?

  1. Streptococcus mutans
  2. Actinomyces israelii
  3. Prevotella intermedia Correct answer.
  4. Porphyromonas gingivalis

Explanation

Acute necrotizing ulcerative gingivitis is a fusospirochetal infection in which Prevotella intermedia is one of the key cultivable organisms, acting with Fusobacterium and Treponema species in a synergistic anaerobic consortium. The clinical picture is punched-out, crater-like interdental papillae with a pseudomembrane, foul odour and severe pain.

Question 23Oral Pathology and Oral Microbiology

A 30-year-old woman presents with multiple small, shallow, recurrent ulcers on the non-keratinized mucosa that heal within ten days without scarring. Which term best describes this condition?

  1. Herpes simplex labialis
  2. Behçet syndrome
  3. Major aphthous ulceration
  4. Recurrent aphthous stomatitis, minor type Correct answer.

Explanation

Minor recurrent aphthous stomatitis produces ulcers under 1 cm on non-keratinized mucosa that heal within 7 to 10 days without scarring. Major aphthous ulcers are larger than 1 cm, persist for weeks and frequently heal with scarring, while Behçet syndrome requires additional systemic features.

Question 24Oral Pathology and Oral Microbiology

Which cell is the principal target of Epstein-Barr virus infection in oral hairy leukoplakia?

  1. Salivary acinar cell
  2. Langerhans cell
  3. Plasma cell
  4. Epithelial keratinocyte of the tongue Correct answer.

Explanation

Epstein-Barr virus replicates lytically within the epithelial keratinocytes of the lateral border of the tongue, producing the corrugated white plaque of hairy leukoplakia. The lesion reflects latent virus reactivation, usually with immunosuppression such as HIV infection.

Question 25Oral Pathology and Oral Microbiology

Which feature most reliably distinguishes a ranula from a true cyst of the floor of the mouth on histopathology?

  1. Presence of cholesterol clefts
  2. Presence of a stratified squamous epithelial lining
  3. Absence of an epithelial lining with a connective tissue wall Correct answer.
  4. Presence of a lymphoid aggregate

Explanation

A ranula is a pseudocyst caused by extravasation of mucus from the sublingual gland, so it lacks a true epithelial lining and is bounded only by granulation tissue and fibrous connective tissue. A true cyst, such as an epidermoid or dermoid cyst, would show a recognizable epithelial lining.

Question 26Oral Pathology and Oral Microbiology

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 (periapical) cyst is the most common odontogenic cyst, arising from epithelial rests of Malassez in a periapical inflammatory environment. It is usually attached to the apex of a non-vital tooth and lined by non-keratinized stratified squamous epithelium with inflammation.

Question 27Oral Pathology and Oral Microbiology

A 60-year-old chronic smoker has a firm, indurated ulcer with rolled everted margins on the lateral border of the tongue and a fixed, hard submandibular node. Which diagnosis is most likely?

  1. Tuberculous ulcer
  2. Syphilitic chancre
  3. Squamous cell carcinoma Correct answer.
  4. Traumatic ulcer

Explanation

An indurated ulcer with rolled margins on the lateral tongue of an older smoker, together with a hard fixed cervical node, is the classic presentation of oral squamous cell carcinoma with nodal metastasis. The lateral border of the tongue is a high-risk site because of pooling of carcinogens in saliva.

Question 28Oral Pathology and Oral Microbiology

In the pathogenesis of dental caries, which property of Streptococcus mutans most directly promotes its cariogenicity on smooth surfaces?

  1. Production of glucosyltransferase for insoluble glucan synthesis Correct answer.
  2. Presence of catalase
  3. Production of coagulase
  4. Ability to form spores

Explanation

Streptococcus mutans expresses glucosyltransferases that convert sucrose into insoluble glucans, which mediate firm adherence to the pellicle and enable plaque biofilm formation. Combined with acidogenicity and aciduricity, this drives demineralization of enamel.

Question 29Oral Pathology and Oral Microbiology

A 25-year-old man has a firm, dome-shaped swelling at the junction of the hard and soft palate, slightly to one side of the midline. Which lesion should be considered first?

  1. Pleomorphic adenoma of a minor salivary gland Correct answer.
  2. Papillary cystadenoma lymphomatosum
  3. Nasopalatine duct cyst
  4. Mucoepidermoid carcinoma

Explanation

Pleomorphic adenoma is the most common benign tumour of minor salivary glands and classically arises at the junction of the hard and soft palate as a firm, painless, slowly growing submucosal swelling. The palate is the most frequent intraoral site for minor salivary gland tumours.

Question 30Oral Pathology and Oral Microbiology

Which microscopic finding is characteristic of an ameloblastoma?

  1. Ghost cells with calcification
  2. Odontogenic epithelium with amyloid deposits
  3. Clear cells with glycogen
  4. Reverse polarity of basal cells with subnuclear vacuolization Correct answer.

Explanation

Ameloblastoma shows islands of odontogenic epithelium with peripheral palisaded columnar cells exhibiting reverse polarity, meaning nuclei displaced away from the basement membrane, and subnuclear vacuolization. The central cells resemble the stellate reticulum of the enamel organ.

Question 31Oral Pathology and Oral Microbiology

A patient on long-term phenytoin therapy develops marked gingival overgrowth. Which mechanism best explains this finding?

  1. Autoimmune destruction of the junctional epithelium
  2. Deposition of amyloid in the gingival lamina propria
  3. Direct bacterial invasion of gingival connective tissue
  4. Increased fibroblast proliferation and collagen synthesis with reduced collagenase activity Correct answer.

Explanation

Drug-induced gingival overgrowth from phenytoin results from a direct effect on fibroblasts, with increased proliferation and collagen production together with reduced matrix metalloproteinase activity, so collagen accumulates. Plaque-induced inflammation amplifies the response, which is why meticulous oral hygiene improves the lesion.

Question 32Oral Pathology and Oral Microbiology

Which feature best differentiates a periapical granuloma from a radicular cyst radiographically and histologically?

  1. Presence of foamy macrophages
  2. Presence of an epithelial-lined cavity in the cyst Correct answer.
  3. Presence of chronic inflammatory cells in the granuloma
  4. Presence of cholesterol clefts

Explanation

A radicular cyst is defined by an epithelial-lined lumen, whereas a periapical granuloma is a mass of granulation tissue with chronic inflammation and no epithelial cavity. Radiographs alone cannot reliably distinguish the two, so histopathology is required.

Question 33Oral Pathology and Oral Microbiology

Which organism is most strongly implicated in the initiation of root caries?

  1. Actinomyces viscosus Correct answer.
  2. Streptococcus sanguinis
  3. Veillonella parvula
  4. Capnocytophaga gingivalis

Explanation

Root caries involves Gram-positive filamentous organisms, with Actinomyces viscosus and Actinomyces naeslundii being strongly implicated in initiating lesions on exposed dentine. Streptococcus mutans also contributes once the lesion progresses, but Actinomyces species dominate early root surface colonization.

Question 34Oral Pathology and Oral Microbiology

A 50-year-old woman has bilateral white, striated plaques on the buccal mucosa with a lacy Wickham pattern and a history of painful erosions. Which diagnosis is most likely?

  1. Lupus erythematosus
  2. Leukoplakia
  3. Candidiasis
  4. Oral lichen planus Correct answer.

Explanation

Bilateral lacy white striae on the buccal mucosa with erosive areas is the classic presentation of oral lichen planus, an immune-mediated interface mucositis. The bilateral symmetry and Wickham striae help distinguish it from homogeneous leukoplakia.

Question 35Oral Pathology and Oral Microbiology

Which radiographic feature is most characteristic of a dentigerous cyst?

  1. Multilocular radiolucency with soap-bubble appearance
  2. Well-defined radiolucency at the apex of a non-vital tooth
  3. Ground-glass radiopacity of the affected jaw
  4. Well-defined radiolucency attached at the cementoenamel junction of an unerupted tooth Correct answer.

Explanation

A dentigerous cyst encloses the crown of an unerupted tooth and attaches at the cementoenamel junction, producing a well-defined radiolucency around the crown. This attachment point distinguishes it from a hyperplastic follicle and from a radicular cyst.

Question 36Oral Pathology and Oral Microbiology

A 35-year-old woman has a bluish, fluctuant swelling of the lower lip that recurs after several excisions and contains mucus on aspiration. Which mechanism best explains this lesion?

  1. Proliferation of glandular acini with atypia
  2. Extravasation of saliva from a ruptured minor salivary gland duct Correct answer.
  3. Obstruction by a calculus in the submandibular duct
  4. Dilation of a retained duct with an epithelial lining

Explanation

A mucocele of the lower lip is a pseudocyst caused by extravasation of saliva from a traumatized minor salivary gland duct into surrounding connective tissue, eliciting a granulation tissue reaction. Because there is no epithelial lining, simple excision must include the feeding gland to prevent recurrence.

Question 37Oral Pathology and Oral Microbiology

Which statement about the oral manifestations of HIV infection is most accurate?

  1. Oral candidiasis and hairy leukoplakia may be the earliest clinical indicators of HIV infection Correct answer.
  2. Linear gingival erythema is pathognomonic of HIV infection
  3. Oral hairy leukoplakia resolves permanently with topical antifungals
  4. Kaposi sarcoma of the oral cavity occurs most often on the buccal mucosa

Explanation

Oropharyngeal candidiasis, particularly pseudomembranous and erythematous types, and oral hairy leukoplakia often appear early in HIV disease and can be the first sign of infection or of immune deterioration. Their presence should prompt HIV testing and CD4 monitoring.

Question 38Oral Pathology and Oral Microbiology

Which histological feature best distinguishes an odontogenic keratocyst from other odontogenic cysts?

  1. Non-keratinized epithelium with prominent rete ridges and inflammation
  2. Ciliated columnar epithelium with goblet cells
  3. Uniform parakeratinized epithelium with a corrugated surface and palisaded basal cells Correct answer.
  4. Stratified squamous epithelium with numerous mucous cells

Explanation

The odontogenic keratocyst is lined by a thin, uniform parakeratinized stratified squamous epithelium with a corrugated keratin surface and a well-defined palisaded basal layer. These features explain its high recurrence rate and its association with the PTCH1 gene and nevoid basal cell carcinoma syndrome.

Question 39Oral Pathology and Oral Microbiology

Which molecular event is most consistently associated with the development of oral squamous cell carcinoma?

  1. Inactivation of the APC gene
  2. Activation of the RET proto-oncogene
  3. Fusion of EWSR1 with FLI1
  4. Inactivation of TP53 with loss of heterozygosity at 17p Correct answer.

Explanation

Loss of function of the tumour suppressor TP53, often through mutation with loss of heterozygosity at 17p, is one of the most frequent early events in oral squamous cell carcinoma. It impairs apoptosis and cell cycle arrest after DNA damage, allowing accumulation of further genetic alterations driven by tobacco and alcohol exposure.

Question 40Oral Pathology and Oral Microbiology

In the context of periodontal disease pathogenesis, which statement best reflects the role of the host immune response?

  1. Antibody production is irrelevant to disease progression
  2. Neutrophil deficiency protects against attachment loss
  3. Bacterial lipopolysaccharide directly degrades collagen fibres
  4. Tissue destruction results largely from host inflammatory mediators rather than direct bacterial toxicity Correct answer.

Explanation

Most periodontal tissue destruction is collateral damage from the host inflammatory and immune response, including matrix metalloproteinases and cytokines released by neutrophils and macrophages, rather than from direct bacterial enzymes. This explains why disease severity is modified by host factors such as diabetes and smoking.

Question 41Oral Medicine, Oral Radiology and Oral Diagnosis

A 24-year-old woman reports a burning sensation of the tongue and buccal mucosa that is absent on waking but worsens through the day and is relieved by eating. Examination is normal. Which diagnosis best fits this pattern?

  1. Oral candidiasis
  2. Burning mouth syndrome Correct answer.
  3. Oral lichen planus
  4. Erythema migrans

Explanation

Burning mouth syndrome classically produces intraoral burning in a patient with clinically normal mucosa, typically absent on waking, worsening over the day, and paradoxically relieved by eating. The absence of visible lesions and the characteristic temporal pattern distinguish it from mucosal disease.

Question 42Oral Medicine, Oral Radiology and Oral Diagnosis

Which radiographic appearance is most characteristic of a simple bone cyst (traumatic bone cyst) of the mandible?

  1. A ground-glass radiopacity with loss of the lamina dura
  2. A diffuse radiolucency with sun-ray periosteal reaction
  3. A multilocular radiolucency with cortical expansion and root resorption
  4. A well-defined radiolucent cavity that scallops between the roots without root resorption Correct answer.

Explanation

A simple bone cyst appears as a well-circumscribed radiolucency that typically scallops upward between the roots of vital teeth and does not cause root resorption or significant cortical expansion. It is usually an incidental finding in the mandible of young patients.

Question 43Oral Medicine, Oral Radiology and Oral Diagnosis

Which clinical finding most reliably differentiates a gingival fibroma from a pyogenic granuloma of the gingiva?

  1. A bright red, friable surface
  2. Rapid growth over a few weeks
  3. Firm, pale, non-bleeding consistency with a sessile base Correct answer.
  4. A history of bleeding on gentle probing

Explanation

A fibroma is a firm, pale, fibrous lesion that does not bleed readily and typically has a sessile base, reflecting its collagenous composition. Pyogenic granuloma, by contrast, is soft, red, friable and bleeds easily because of its vascular proliferation.

Question 44Oral Medicine, Oral Radiology and Oral Diagnosis

A patient with a suspected parotid duct obstruction is examined. Which manoeuvre best assesses the patency of the parotid duct orifice?

  1. Transilluminating the buccal mucosa with a light source
  2. Massaging the parotid gland while observing the orifice for saliva flow Correct answer.
  3. Palpating the submandibular gland bimanually
  4. Percussing the gland over the masseter

Explanation

Milking or massaging the parotid gland from posterior to anterior while observing the duct orifice on the buccal mucosa demonstrates whether saliva flows freely. Reduced or absent flow from the orifice suggests obstruction such as a sialolith or stricture.

Question 45Oral Medicine, Oral Radiology and Oral Diagnosis

On a panoramic radiograph, which structure appears as a radiolucent band crossing the mandibular ramus just above the mandibular foramen?

  1. The submandibular fossa
  2. The mandibular canal Correct answer.
  3. The incisive canal
  4. The mental foramen

Explanation

The mandibular canal is seen as a radiolucent band with corticated borders running within the mandible and opening at the mental foramen. It carries the inferior alveolar nerve and vessels and is an important landmark for surgical and implant planning.

Question 46Oral Medicine, Oral Radiology and Oral Diagnosis

Which statement correctly describes the diagnostic criterion for a definitive diagnosis of oral lichen planus?

  1. Presence of circulating antinuclear antibodies
  2. Positive direct immunofluorescence for intercellular IgG
  3. Clinical features alone are sufficient in all cases
  4. Clinical features plus histopathology showing a band-like lymphocytic infiltrate at the epithelial-connective tissue interface Correct answer.

Explanation

Definitive diagnosis of oral lichen planus requires correlation of the clinical picture with histopathology, typically a band-like subepithelial lymphocytic infiltrate with basal cell degeneration. Clinical features alone can be suggestive but are not sufficient for a definitive diagnosis.

Question 47Oral Medicine, Oral Radiology and Oral Diagnosis

A 45-year-old man has a firm, non-tender swelling in the floor of the mouth that is fluctuant on bimanual palpation and transilluminates. Which diagnosis is most likely?

  1. Dermoid cyst
  2. Submandibular sialolith
  3. Pleomorphic adenoma of the sublingual gland
  4. Ranula Correct answer.

Explanation

A ranula is a mucous extravasation cyst arising from the sublingual gland, presenting as a soft, fluctuant, bluish swelling in the floor of the mouth that transilluminates. Bimanual palpation confirms its cystic nature within the floor of the mouth.

Question 48Oral Medicine, Oral Radiology and Oral Diagnosis

Which radiographic feature best distinguishes a radicular cyst from a periapical granuloma on conventional radiography?

  1. The granuloma is always larger than 1 cm
  2. Both are indistinguishable radiographically, and histopathology is required Correct answer.
  3. The cyst causes root resorption while the granuloma does not
  4. The cyst shows a corticated margin while the granuloma does not

Explanation

Radicular cysts and periapical granulomas cannot be reliably distinguished on conventional radiographs because both appear as periapical radiolucencies of variable size. Definitive differentiation requires histopathological examination of the lesion.

Question 49Oral Medicine, Oral Radiology and Oral Diagnosis

A patient reports pain on opening the mouth that is worse in the morning and associated with clicking. Which finding on examination most supports a diagnosis of temporomandibular joint disc displacement with reduction?

  1. Crepitus on lateral excursion
  2. Limitation of opening to 10 mm with no click
  3. A single late opening click without deviation
  4. A reciprocal click with deviation on opening that reduces with a later click Correct answer.

Explanation

Disc displacement with reduction typically produces a reciprocal click, one on opening as the disc reduces and one on closing as it displaces again, often with deviation of the mandible. The pattern of clicking with reduction distinguishes it from displacement without reduction.

Question 50Oral Medicine, Oral Radiology and Oral Diagnosis

Which laboratory finding is most characteristic of primary Sjögren syndrome?

  1. Positive anti-Ro/SSA and anti-La/SSB antibodies Correct answer.
  2. Positive anti-mitochondrial antibodies
  3. Elevated serum angiotensin-converting enzyme
  4. Positive anti-double-stranded DNA antibodies

Explanation

Primary Sjögren syndrome is characterised by autoantibodies against Ro/SSA and La/SSB, along with keratoconjunctivitis sicca and xerostomia. These antibodies support the diagnosis when combined with clinical and histopathological findings.