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Mongolia Dentist Licensing Exam study materials
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Mongolia Dentist Licensing Exam practice questions

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Question 1Oral and Maxillofacial Anatomy, Histology, and Physiology

Which permanent tooth typically erupts first in the oral cavity?

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

Explanation

The mandibular first molar is normally the earliest permanent tooth to erupt, appearing at about 6 years of age and often called the '6-year molar'. Central incisors follow shortly afterward, so the molar precedes them in most children.

Question 2Oral and Maxillofacial Anatomy, Histology, and Physiology

Enamel is formed by which cell type during amelogenesis?

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

Explanation

Ameloblasts are the specialized epithelial cells of the inner enamel epithelium that secrete enamel matrix and later mineralize it. Odontoblasts form dentin, and cementoblasts form cementum, so each hard tissue has a distinct secretory cell.

Question 3Oral and Maxillofacial Anatomy, Histology, and Physiology

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

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

Explanation

General sensation from the anterior two-thirds of the tongue travels via the lingual nerve, a branch of V3. Taste from the same region is carried by the chorda tympani of CN VII, which travels with the lingual nerve but serves a different modality.

Question 4Oral and Maxillofacial Anatomy, Histology, and Physiology

Which salivary gland secretion is predominantly serous and rich in amylase?

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

Explanation

The parotid gland is almost entirely serous and produces amylase-rich saliva delivered through Stensen's duct. The sublingual gland is predominantly mucous, and minor glands such as palatal and labial glands are mostly mucous as well.

Question 5Oral and Maxillofacial Anatomy, Histology, and Physiology

Which muscle elevates the mandible and is considered a primary elevator of the jaw?

  1. Geniohyoid
  2. Masseter Correct answer.
  3. Digastric anterior belly
  4. Lateral pterygoid

Explanation

The masseter is one of the four muscles of mastication and acts as a powerful elevator of the mandible. The lateral pterygoid protrudes and depresses the mandible, while the digastric and geniohyoid assist in depression.

Question 6Oral and Maxillofacial Anatomy, Histology, and Physiology

The temporomandibular joint is best described as which type of joint?

  1. Primary cartilaginous joint
  2. Fibrous synchondrosis
  3. Bicondylar synovial joint with an articular disc Correct answer.
  4. Pure hinge synovial joint

Explanation

The TMJ is a bilateral synovial joint in which two condyles articulate with the temporal bone through a fibrocartilaginous disc, allowing both hinge and gliding movements. Its disc divides the joint into upper and lower compartments with distinct functions.

Question 7Oral and Maxillofacial Anatomy, Histology, and Physiology

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

  1. Palatoglossus muscle
  2. Soft palate Correct answer.
  3. Epiglottis
  4. Uvula alone

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, so its role is separate.

Question 8Oral and Maxillofacial Anatomy, Histology, and Physiology

Which statement about dentin permeability is most accurate?

  1. Dentin is more permeable than enamel because of its tubular structure. Correct answer.
  2. Dentin is impermeable because of its high mineral content.
  3. Dentin contains no organic matrix and therefore no fluid movement.
  4. Dentin permeability is highest in the outer mantle dentin.

Explanation

Dentin is traversed by dentinal tubules containing odontoblast processes and fluid, making it far more permeable than enamel. This tubular structure explains dentin sensitivity and the rapid spread of caries through dentin.

Question 9Oral and Maxillofacial Anatomy, Histology, and Physiology

A patient reports loss of sensation over the lower lip and chin after a difficult mandibular third molar extraction. Which nerve is most likely injured?

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

Explanation

The inferior alveolar nerve supplies sensation to the mandibular teeth and, through its mental branch, to the lower lip and chin. Its close relation to the roots of the third molar makes it vulnerable during surgical extraction.

Question 10Oral and Maxillofacial Anatomy, Histology, and Physiology

Which cells are responsible for resorbing bone during orthodontic tooth movement and root resorption?

  1. Osteoblasts
  2. Cementoblasts
  3. Osteocytes
  4. Osteoclasts Correct answer.

Explanation

Osteoclasts are multinucleated cells that resorb bone on the pressure side of a moving tooth, allowing the tooth to translate through the alveolus. Osteoblasts then deposit bone on the tension side, coupling resorption with formation.

Question 11Oral and Maxillofacial Anatomy, Histology, and Physiology

Which feature distinguishes primary (deciduous) teeth from permanent teeth on a radiograph?

  1. Complete absence of roots
  2. Thinner enamel and more bulbous crowns with marked cervical constriction Correct answer.
  3. Presence of a radicular cyst
  4. Absence of a pulp chamber

Explanation

Primary teeth have thinner enamel, relatively larger pulp chambers, bulbous crowns, and a pronounced cervical constriction compared with permanent teeth. These features help identify retained primary teeth and plan exodontia.

Question 12Oral and Maxillofacial Anatomy, Histology, and Physiology

Which statement about the maxillary sinus and posterior maxillary teeth is correct?

  1. The sinus is lined by stratified squamous epithelium.
  2. The roots of posterior maxillary teeth may project into or lie close to the sinus floor. Correct answer.
  3. The sinus drains through the nasolacrimal duct.
  4. The sinus floor is always well above the apices of the posterior teeth.

Explanation

The maxillary sinus floor often lies close to or between the roots of the posterior maxillary teeth, which can lead to oroantral communication during extraction. The sinus is lined by ciliated pseudostratified columnar respiratory epithelium and drains via the middle meatus.

Question 13Oral and Maxillofacial Anatomy, Histology, and Physiology

A patient has difficulty protruding the mandible and shows deviation toward the affected side on opening. Which structure is most likely impaired?

  1. Right medial pterygoid
  2. Right masseter
  3. Left temporalis
  4. Left lateral pterygoid Correct answer.

Explanation

The lateral pterygoid protrudes the mandible and, acting with the disc-condyle complex, assists in opening; weakness causes deviation toward the affected side. A left lateral pterygoid deficit would therefore produce deviation to the left on opening.

Question 14Oral and Maxillofacial Anatomy, Histology, and Physiology

Which periodontal structure provides the main anchorage of the tooth to alveolar bone?

  1. Principal fibers of the periodontal ligament Correct answer.
  2. Junctional epithelium
  3. Gingival sulcular epithelium
  4. Cementoenamel junction

Explanation

The principal fibers of the periodontal ligament insert into cementum and alveolar bone, suspending the tooth and transmitting occlusal forces. The junctional epithelium provides a seal but not mechanical anchorage.

Question 15Oral and Maxillofacial Anatomy, Histology, and Physiology

Which nerve carries taste from the posterior third of the tongue?

  1. Glossopharyngeal nerve (CN IX) Correct answer.
  2. Lingual nerve
  3. Vagus nerve (CN X)
  4. Chorda tympani

Explanation

Taste from the posterior third of the tongue is carried by the glossopharyngeal nerve, which also provides general sensation there. The chorda tympani serves taste from the anterior two-thirds, and the vagus serves taste from the epiglottis and pharynx.

Question 16Oral and Maxillofacial Anatomy, Histology, and Physiology

Which feature of enamel explains its low reparative capacity after caries or trauma?

  1. It is continuously secreted by ameloblasts throughout life.
  2. It has a high collagen content that remodels rapidly.
  3. It is avascular and acellular and loses its ameloblasts after eruption. Correct answer.
  4. It contains abundant odontoblast processes.

Explanation

Enamel is acellular and avascular, and ameloblasts are lost after tooth eruption, so no new enamel can be deposited. Repair is therefore limited to remineralization and restorative intervention rather than cellular regeneration.

Question 17Oral and Maxillofacial Anatomy, Histology, and Physiology

A patient develops a hematoma in the floor of the mouth after a mandibular implant procedure. Which vessel is most likely injured?

  1. Lingual artery Correct answer.
  2. Maxillary artery in the pterygopalatine fossa
  3. Facial artery
  4. Superficial temporal artery

Explanation

The lingual artery runs in the floor of the mouth deep to the hyoglossus and supplies the tongue and floor of the mouth; injury can cause a rapidly expanding sublingual hematoma that threatens the airway. The facial artery crosses the mandible more superficially, and the other options are distant from the floor of the mouth.

Question 18Oral and Maxillofacial Anatomy, Histology, and Physiology

Which structure must be identified to avoid injury when making a crestal incision in the anterior mandible for an implant?

  1. Greater palatine nerve
  2. Incisive canal
  3. Mental nerve and its mental foramen Correct answer.
  4. Nasopalatine nerve

Explanation

The mental nerve exits the mental foramen in the premolar region and supplies sensation to the lower lip and chin, so its position must be identified before anterior mandibular surgery. The incisive canal and nasopalatine nerve are in the maxilla.

Question 19Oral and Maxillofacial Anatomy, Histology, and Physiology

Which statement best explains why enamel rods are oriented perpendicular to the dentinoenamel junction in the inner enamel but become more complex near the surface?

  1. Enamel rods are randomly oriented throughout their length.
  2. Ameloblasts migrate and change direction during secretion, producing decussating rods. Correct answer.
  3. Odontoblasts deposit enamel from the pulp outward.
  4. Enamel is formed by cementoblasts after eruption.

Explanation

As ameloblasts secrete enamel, they migrate outward and change direction, producing rod decussation and gnarled enamel near the surface. This arrangement increases fracture resistance of the enamel cap.

Question 20Oral and Maxillofacial Anatomy, Histology, and Physiology

Which physiologic mechanism explains referred pain from the mandibular molars to the ear?

  1. Shared blood supply of the molar and auricular regions
  2. Convergence of trigeminal and cervical afferents in the trigeminocervical complex Correct answer.
  3. Lymphatic drainage from the molar to the ear
  4. Direct spread of inflammation through the external auditory canal

Explanation

Nociceptive afferents from the mandibular molars and from the auricular region converge on second-order neurons in the trigeminocervical complex, so the brain may mislocalize the source. This convergence underlies referred dental and auricular pain.

Question 21Oral Pathology and Oral Medicine

Which organism is the principal causative agent of acquired immune deficiency syndrome-related Kaposi sarcoma of the oral cavity?

  1. Human papillomavirus type 16
  2. Cytomegalovirus
  3. Human herpesvirus 8 Correct answer.
  4. Epstein-Barr virus

Explanation

Kaposi sarcoma, including the oral mucosal form seen in HIV infection, is consistently associated with human herpesvirus 8 (HHV-8), also called Kaposi sarcoma-associated herpesvirus. Detection of the virus in spindle cells supports the diagnosis. Other herpesviruses and papillomaviruses are not the causative agent of this lesion.

Question 22Oral Pathology and Oral Medicine

A painless, fluctuant, bluish swelling of the lower lip that empties and blanches on pressure, then refills when pressure is released, is most consistent with which diagnosis?

  1. Mucocele
  2. Fibroma
  3. Hemangioma Correct answer.
  4. Pleomorphic adenoma

Explanation

Among these options, a hemangioma best fits a bluish vascular lesion that empties and blanches under pressure, then refills. This response reflects compression of blood-filled vascular spaces. A mucocele can be soft and bluish on the lower lip, but pooled mucus does not produce vascular blanching and refilling.

Question 23Oral Pathology and Oral Medicine

Which clinical feature most strongly suggests oral lichen planus rather than lichenoid drug reaction?

  1. Bilateral symmetric white striae on the buccal mucosa Correct answer.
  2. Lesion confined to the gingiva
  3. Association with a new antihypertensive drug
  4. Unilateral ulceration of the lateral tongue

Explanation

Oral lichen planus typically produces bilateral, roughly symmetric reticular white striae (Wickham striae) on the buccal mucosa. Lichenoid drug reactions tend to be unilateral, more erosive, and temporally related to a culprit medication. Symmetry and striae therefore favor idiopathic lichen planus.

Question 24Oral Pathology and Oral Medicine

A 60-year-old man has a nontender, indurated ulcer with rolled borders on the lateral border of the tongue. Which is the most appropriate immediate step?

  1. Incisional biopsy of the lesion Correct answer.
  2. Prescribe a topical corticosteroid and review in two weeks
  3. Prescribe an antifungal mouth rinse
  4. Reassure and review in six months

Explanation

An indurated ulcer with rolled borders on the lateral tongue in an older adult is highly suspicious for squamous cell carcinoma. Incisional biopsy provides histopathologic confirmation and grading before definitive treatment. Empirical steroid or antifungal therapy risks delaying cancer diagnosis.

Question 25Oral Pathology and Oral Medicine

Which finding is characteristic of oral hairy leukoplakia?

  1. A firm submucosal nodule of the buccal mucosa
  2. A white pseudomembrane that wipes off leaving an erythematous base
  3. A pigmented macular lesion of the hard palate
  4. Vertical corrugated white plaques on the lateral tongue that cannot be wiped off Correct answer.

Explanation

Oral hairy leukoplakia presents as corrugated, vertically oriented white plaques on the lateral border of the tongue and is caused by Epstein-Barr virus in immunocompromised patients. The plaques are adherent and cannot be wiped off. This distinguishes them from candidal pseudomembranes.

Question 26Oral Pathology and Oral Medicine

Which radiographic and clinical pattern best fits dentinogenesis imperfecta type I?

  1. Normal tooth color with enlarged pulp chambers and taurodontism
  2. Enamel hypoplasia with pitted surfaces and normal dentin
  3. Yellow-brown teeth with normal crowns and no systemic disease
  4. Opalescent teeth with bulbous crowns and obliterated pulp chambers, occurring with osteogenesis imperfecta Correct answer.

Explanation

Dentinogenesis imperfecta type I occurs in patients with osteogenesis imperfecta and shows opalescent blue-brown teeth, bulbous crowns, cervical constriction, and obliterated pulp chambers. The association with a systemic connective tissue disorder defines type I. Isolated dentinogenesis imperfecta without osteogenesis imperfecta is type II.

Question 27Oral Pathology and Oral Medicine

A patient reports recurrent episodes of unilateral burning pain with a vesicular eruption on the hard palate that heals without scarring. Which diagnosis is most likely?

  1. Recurrent aphthous stomatitis
  2. Recurrent intraoral herpes simplex infection Correct answer.
  3. Herpes zoster of the maxillary division
  4. Erythema multiforme

Explanation

Recurrent intraoral herpes simplex typically affects keratinized mucosa such as the hard palate and appears as clusters of small vesicles that rupture into shallow ulcers and heal without scarring. Herpes zoster follows a dermatome but is usually unilateral and may scar. Aphthous ulcers are nonvesicular and favor nonkeratinized mucosa.

Question 28Oral Pathology and Oral Medicine

Which is the most common site of oral leukoplakia with the highest risk of malignant transformation?

  1. Hard palate
  2. Floor of the mouth and lateral tongue Correct answer.
  3. Attached gingiva
  4. Dorsal tongue

Explanation

Leukoplakia of the floor of the mouth and lateral tongue is associated with the highest malignant transformation risk because these sites are bathed in saliva and exposed to carcinogens. Nonhomogeneous lesions, especially in these high-risk sites, warrant biopsy. Palatal and gingival leukoplakia have lower transformation rates.

Question 29Oral Pathology and Oral Medicine

Which feature distinguishes pemphigus vulgaris from mucous membrane pemphigoid on direct immunofluorescence?

  1. Granular IgA deposits in the dermal papillae
  2. Linear IgG deposition along the basement membrane
  3. Intercellular IgG deposition in the epithelium Correct answer.
  4. Negative immunofluorescence in all cases

Explanation

Pemphigus vulgaris shows intercellular IgG deposition within the epithelium, reflecting autoantibodies against desmogleins. Mucous membrane pemphigoid shows linear IgG and complement along the basement membrane zone. Direct immunofluorescence is therefore essential for distinguishing these vesiculobullous diseases.

Question 30Oral Pathology and Oral Medicine

A patient with a long-standing history of tobacco and alcohol use develops a painless, nonhealing ulcer on the floor of the mouth. Which risk factor combination is most strongly associated with oral squamous cell carcinoma?

  1. Chronic candidiasis
  2. Betel quid chewing alone
  3. Tobacco smoking and alcohol consumption Correct answer.
  4. Human papillomavirus type 6 infection

Explanation

Tobacco smoking and alcohol consumption act synergistically to increase the risk of oral squamous cell carcinoma, especially in the floor of the mouth and lateral tongue. This combination is the strongest established risk factor for oral cavity cancer. Betel quid is associated with oral submucous fibrosis and cancer in specific populations.

Question 31Oral Pathology and Oral Medicine

Which condition is characterized by progressive fibrosis of the oral submucosa with restricted mouth opening and is strongly associated with areca nut chewing?

  1. Radiation-induced fibrosis
  2. Scleroderma
  3. Oral submucous fibrosis Correct answer.
  4. Oral lichen planus

Explanation

Oral submucous fibrosis results from areca nut chewing and produces progressive juxtaepithelial fibrosis, leading to restricted mouth opening, blanching, and burning. It is a potentially malignant disorder. Scleroderma and radiation fibrosis cause similar stiffness but have different causes.

Question 32Oral Pathology and Oral Medicine

Which clinical presentation best fits geographic tongue (benign migratory glossitis)?

  1. Migratory areas of depapillation with a white border on the dorsal tongue Correct answer.
  2. Diffuse gingival enlargement
  3. Fixed white plaque on the lateral tongue
  4. Painful vesicular eruption of the palate

Explanation

Geographic tongue shows irregular, migratory areas of filiform papilla loss with a slightly raised white border, producing a map-like appearance on the dorsal tongue. Lesions change location over time. It is usually asymptomatic but may cause burning with acidic foods.

Question 33Oral Pathology and Oral Medicine

Which feature is most characteristic of fibrous dysplasia of the jaws?

  1. Multiple punched-out radiolucencies
  2. Ground-glass radiographic appearance with blending into surrounding bone Correct answer.
  3. Well-defined radiolucency with a sclerotic border
  4. Sunburst periosteal reaction

Explanation

Fibrous dysplasia produces a ground-glass or orange-peel radiographic pattern as normal bone is replaced by fibro-osseous tissue, and the lesion blends imperceptibly with adjacent bone. Margins are not well demarcated. This distinguishes it from encapsulated fibro-osseous lesions such as ossifying fibroma.

Question 34Oral Pathology and Oral Medicine

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

  1. Nasopalatine duct cyst
  2. Radicular cyst Correct answer.
  3. Dentigerous cyst
  4. Odontogenic keratocyst

Explanation

The radicular cyst, also called periapical cyst, is the most common odontogenic cyst and arises from epithelial rests of Malassez in a periapical granuloma. It is associated with a nonvital tooth. Dentigerous and odontogenic keratocysts are less common.

Question 35Oral Pathology and Oral Medicine

A 25-year-old woman has a well-defined multilocular radiolucency in the posterior mandible with a soap-bubble appearance and a history of a similar lesion treated previously. Which diagnosis is most likely?

  1. Central giant cell granuloma
  2. Ameloblastoma Correct answer.
  3. Osteosarcoma
  4. Odontogenic keratocyst

Explanation

Ameloblastoma classically presents as a multilocular soap-bubble radiolucency in the posterior mandible and has a high recurrence rate after conservative treatment. Its locally aggressive behavior and multilocular appearance help distinguish it from a unilocular cyst. Odontogenic keratocysts are usually unilocular and grow along the bone.

Question 36Oral Pathology and Oral Medicine

Which feature best distinguishes a periapical granuloma from a radicular cyst?

  1. Association with root canal infection
  2. Location at the apex of a nonvital tooth
  3. Presence of chronic inflammatory cells
  4. Presence of an epithelial-lined cavity Correct answer.

Explanation

Both periapical granuloma and radicular cyst occur at the apex of a nonvital tooth and contain chronic inflammation. The defining difference is the presence of a stratified squamous epithelial lining enclosing a cavity in a radicular cyst. Without an epithelial-lined lumen, the lesion is a granuloma.

Question 37Oral Pathology and Oral Medicine

Which medication class is most commonly associated with gingival enlargement?

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

Explanation

Calcium channel blockers such as nifedipine and amlodipine are well-known causes of drug-induced gingival enlargement. Phenytoin and cyclosporine are also classic culprits. Beta blockers, proton pump inhibitors, and SSRIs are not typically associated with this effect.

Question 38Oral Pathology and Oral Medicine

A patient on cyclosporine after renal transplantation develops generalized gingival enlargement. Which additional factor most increases the severity of this enlargement?

  1. Low calcium intake
  2. Increased vitamin C intake
  3. Regular use of fluoride mouthwash
  4. Poor plaque control Correct answer.

Explanation

Cyclosporine-induced gingival enlargement is worsened by plaque accumulation and poor oral hygiene, which potentiate the fibrotic response. Meticulous plaque control and periodontal therapy reduce the severity. Dietary calcium, fluoride, and vitamin C are not major modifiers of this drug effect.

Question 39Oral Pathology and Oral Medicine

Which is the most common salivary gland malignancy in the oral cavity?

  1. Adenoid cystic carcinoma
  2. Acinic cell carcinoma
  3. Mucoepidermoid carcinoma Correct answer.
  4. Pleomorphic adenoma

Explanation

Mucoepidermoid carcinoma is the most common malignant salivary gland tumor of the oral cavity, especially in the palate and minor salivary glands. Pleomorphic adenoma is the most common benign tumor but is not malignant. Adenoid cystic carcinoma is less common but notable for perineural invasion.

Question 40Oral Pathology and Oral Medicine

Which clinical finding is most suggestive of oral candidiasis in a patient using inhaled corticosteroids?

  1. Fluctuant bluish swelling of the lower lip
  2. White plaques on the palate and buccal mucosa that can be wiped off Correct answer.
  3. Blue-black macular pigmentation of the gingiva
  4. Deep indurated ulcer with rolled borders

Explanation

Inhaled corticosteroids suppress local immunity and can predispose to oral candidiasis, which presents as wipeable white plaques on the palate and buccal mucosa. Rinsing the mouth after inhaler use reduces risk. The other options describe malignancy, pigmentation, or a mucocele.

Question 41Oral Pathology and Oral Medicine

Which feature is characteristic of necrotizing ulcerative gingivitis?

  1. Multiple flaccid bullae on the gingiva
  2. Diffuse white striae on the buccal mucosa
  3. Punched-out, crater-like interdental papillae with pseudomembrane and foul odor Correct answer.
  4. Generalized painless gingival enlargement

Explanation

Necrotizing ulcerative gingivitis presents with painful, punched-out ulceration of the interdental papillae, a gray pseudomembrane, foul breath, and bleeding. It is associated with fusospirochetal organisms and risk factors such as stress, smoking, and immunosuppression.

Question 42Oral Pathology and Oral Medicine

A patient reports recurrent, shallow, painful ulcers with a yellow-white center and erythematous halo on the nonkeratinized mucosa, healing without scarring. Which is the most likely diagnosis?

  1. Oral squamous cell carcinoma
  2. Recurrent aphthous stomatitis Correct answer.
  3. Pemphigus vulgaris
  4. Hairy leukoplakia

Explanation

Recurrent aphthous stomatitis produces shallow, painful ulcers with a yellow-white pseudomembrane and erythematous halo on nonkeratinized mucosa such as the buccal mucosa and vestibule. Lesions heal without scarring in minor aphthae. This clinical pattern is distinct from vesicular and neoplastic diseases.

Question 43Oral Pathology and Oral Medicine

Which radiographic feature is most characteristic of an ameloblastoma?

  1. Multilocular radiolucency with a soap-bubble pattern in the posterior mandible Correct answer.
  2. Ground-glass opacity with blending margins
  3. Sunburst periosteal reaction
  4. Well-defined unilocular radiolucency around an impacted crown

Explanation

Ameloblastoma typically produces a multilocular radiolucency with a soap-bubble or honeycomb pattern in the posterior mandible or ramus. It is locally aggressive and tends to recur after enucleation. The other patterns suggest fibrous dysplasia, osteosarcoma, or a dentigerous cyst.

Question 44Oral Pathology and Oral Medicine

Which systemic condition is most strongly associated with oral candidiasis resistant to topical therapy?

  1. Hypothyroidism
  2. Iron deficiency anemia
  3. HIV infection with low CD4 count Correct answer.
  4. Well-controlled hypertension

Explanation

Advanced HIV infection with low CD4 counts predisposes to severe and recurrent oral candidiasis that may be resistant to topical antifungals and require systemic therapy. The immune defect impairs mucosal defense against Candida. Hypertension, iron deficiency, and hypothyroidism are not strongly linked to resistant candidiasis.

Question 45Cariology and Restorative Dentistry (Operative Dentistry)

Which bur is the most appropriate for removing infected dentin while preserving affected dentin during caries excavation?

  1. A polymer or ceramic round bur at low speed Correct answer.
  2. A long tapered diamond bur at high speed
  3. A fine-grit diamond fissure bur at high speed
  4. A tungsten carbide round bur at high speed

Explanation

Polymer and ceramic burs are designed to cut selectively: they remove softened, infected dentin efficiently but leave harder, leathery affected dentin that can be remineralized. This supports minimally invasive cavity preparation and reduces the risk of pulp exposure.

Question 46Cariology and Restorative Dentistry (Operative Dentistry)

In a patient with high caries risk, which radiograph is the standard initial tool for detecting proximal caries in posterior teeth?

  1. Bitewing radiograph Correct answer.
  2. Panoramic radiograph
  3. Periapical radiograph with a 40-degree distal angulation
  4. Occlusal radiograph

Explanation

Bitewing radiographs show the crowns of posterior teeth in both arches at near-orthogonal incidence, making early proximal demineralization visible. They are the accepted first-line radiographic method for proximal caries detection and monitoring.

Question 47Cariology and Restorative Dentistry (Operative Dentistry)

Which instrument is used to evaluate the hardness of dentin during caries excavation?

  1. Periodontal probe
  2. Dental explorer Correct answer.
  3. Articulating paper
  4. Dental mirror

Explanation

A sharp explorer transmits tactile feedback about tissue hardness, allowing the clinician to distinguish soft infected dentin from firm affected dentin. This tactile criterion remains a practical guide for deciding when excavation is complete.

Question 48Cariology and Restorative Dentistry (Operative Dentistry)

What is the primary purpose of beveling the enamel margin of a Class III composite restoration?

  1. To remove unsupported enamel and widen the cavity for access
  2. To reduce the need for a matrix band
  3. To increase the bulk of composite at the cavosurface
  4. To expose enamel rods so they can be etched and bonded for a better seal Correct answer.

Explanation

A bevel cuts across enamel rods and creates a broader etched surface, improving micro-mechanical bonding and marginal adaptation of composite. It also improves the esthetic transition between restoration and tooth.

Question 49Cariology and Restorative Dentistry (Operative Dentistry)

Which factor most strongly determines the initial adhesion of a resin composite to enamel?

  1. Phosphoric acid etching of enamel Correct answer.
  2. Use of a filled flowable composite
  3. Application of a dentin bonding primer
  4. Placement of a glass ionomer liner

Explanation

Etching enamel with phosphoric acid dissolves hydroxyapatite and creates microporosities into which resin tags form, which is the basis of enamel adhesion. Without adequate etching, enamel bonding is weak regardless of the composite chosen.

Question 50Cariology and Restorative Dentistry (Operative Dentistry)

Which material is indicated for a Class V lesion in a patient with root caries and poor plaque control?

  1. Amalgam
  2. Microfilled composite
  3. Feldspathic ceramic inlay
  4. Glass ionomer cement Correct answer.

Explanation

Glass ionomer bonds chemically to dentin and enamel and releases fluoride, which benefits patients with active root caries and limited hygiene. Its lower esthetic quality is an acceptable trade-off in this situation.