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Cambodia Dentistry Exit Exam study materials
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Cambodia Dentistry Exit Exam practice questions

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Question 1Oral and Maxillofacial Anatomy and Histology

Which permanent tooth normally erupts first into the oral cavity, usually around 6 years of age?

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

Explanation

The mandibular first molar is typically the first permanent tooth to erupt, appearing at about 6 years of age behind the primary second molar and establishing the occlusal key. The permanent incisors follow at roughly 6 to 7 years.

Question 2Oral and Maxillofacial Anatomy and Histology

Enamel is formed by which cell type during amelogenesis?

  1. Ameloblast Correct answer.
  2. Odontoblast
  3. Cementoblast
  4. Osteoclast

Explanation

Ameloblasts are the epithelial cells of the inner enamel epithelium that secrete the enamel matrix and later mineralize it. Odontoblasts form dentin, cementoblasts form cementum, and osteoclasts resorb bone.

Question 3Oral and Maxillofacial Anatomy and Histology

Which muscle elevates the mandible and is considered the principal muscle of mastication?

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

Explanation

The masseter is a powerful elevator of the mandible and, together with the medial pterygoid and temporalis, closes the jaw during chewing. The lateral pterygoid instead protrudes and depresses the mandible.

Question 4Oral and Maxillofacial Anatomy and Histology

The parotid duct (Stensen duct) opens into the oral cavity at which location?

  1. Floor of the mouth beside the lingual frenum
  2. Posterior tonsillar pillar
  3. Lower vestibule opposite the mandibular first molar
  4. Upper vestibule opposite the maxillary second molar Correct answer.

Explanation

Stensen duct traverses the buccinator and opens on the buccal mucosa of the upper vestibule, usually opposite the maxillary second molar. The submandibular duct opens at the sublingual papilla beside the lingual frenum.

Question 5Oral and Maxillofacial Anatomy and Histology

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

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

Explanation

General sensation from the anterior two-thirds of the tongue travels via the lingual nerve, a branch of the mandibular division of the trigeminal nerve. Taste from the same region is carried by the chorda tympani of the facial nerve.

Question 6Oral and Maxillofacial Anatomy and Histology

During root formation, the epithelial root sheath of Hertwig determines root shape and induces which process in the adjacent dental papilla?

  1. Enamel maturation
  2. Dentin formation by odontoblasts Correct answer.
  3. Pulp calcification
  4. Cementum deposition by ameloblasts

Explanation

Hertwig epithelial root sheath grows between the dental papilla and dental follicle and induces papilla cells to differentiate into odontoblasts that lay down root dentin. After dentin forms, the sheath breaks up and cementoblasts deposit cementum.

Question 7Oral and Maxillofacial Anatomy and Histology

A patient has a mandibular fracture through the angle. Which structure is most at risk because it enters the mandible near the lingula on the medial ramus?

  1. Long buccal nerve
  2. Mylohyoid nerve
  3. Chorda tympani
  4. Inferior alveolar nerve Correct answer.

Explanation

The inferior alveolar nerve enters the mandibular canal through the mandibular foramen near the lingula, so fractures of the ramus or angle can injure it and cause lip and chin numbness. The long buccal nerve and chorda tympani are not intraosseous mandibular structures.

Question 8Oral and Maxillofacial Anatomy and Histology

Which type of oral mucosa covers the hard palate and gingiva and is adapted to withstand friction?

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

Explanation

Masticatory mucosa covers the gingiva and hard palate, is keratinized or parakeratinized, and is tightly bound to underlying bone to resist chewing forces. Lining mucosa is nonkeratinized and covers flexible regions such as the buccal mucosa.

Question 9Oral and Maxillofacial Anatomy and Histology

In a histological section of a tooth, which zone lies immediately adjacent to the pulp and contains odontoblast cell bodies?

  1. Predentin
  2. Odontoblast layer Correct answer.
  3. Granular layer of Tomes
  4. Hyaline layer

Explanation

The odontoblast layer is the palisade of cells lining the pulp surface, with their processes extending into dentinal tubules. Predentin is the unmineralized matrix between the odontoblasts and mineralized dentin.

Question 10Oral and Maxillofacial Anatomy and Histology

Which artery is the principal blood supply to the maxillary teeth and the deep structures of the face?

  1. Maxillary artery Correct answer.
  2. Facial artery
  3. Superficial temporal artery
  4. Lingual artery

Explanation

The maxillary artery, a terminal branch of the external carotid, gives off the inferior alveolar, posterior superior alveolar, and greater palatine branches that supply maxillary teeth and deep facial structures. The facial artery mainly supplies superficial soft tissues.

Question 11Oral and Maxillofacial Anatomy and Histology

A developing tooth shows a bell-shaped enamel organ with differentiated ameloblasts and odontoblasts and the beginning of hard tissue formation. Which stage is this?

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

Explanation

The late bell stage is marked by differentiation of ameloblasts and odontoblasts and the onset of dentin and enamel apposition at the dentinoenamel junction. Bud and cap stages precede cytodifferentiation and hard tissue formation.

Question 12Oral and Maxillofacial Anatomy and Histology

Which periodontal ligament fiber group is oriented to resist intrusive forces on the tooth?

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

Explanation

The oblique fibers run from bone coronally to cementum apically and are the most numerous group, converting axial (intrusive) loading into tension and thus resisting intrusive forces. The apical group resists extrusive forces.

Question 13Oral and Maxillofacial Anatomy and Histology

Which feature distinguishes the mandibular first premolar from the mandibular second premolar in most patients?

  1. The second premolar has a single cusp and no lingual cusp
  2. The first premolar has three cusps and a Y-shaped central groove
  3. The first premolar has a prominent buccal cusp with a small or absent lingual cusp and a mesial marginal groove Correct answer.
  4. The second premolar has a larger buccal cusp and no central fossa

Explanation

The mandibular first premolar typically has a large buccal cusp and a much smaller lingual cusp, with a mesial marginal groove crossing the mesiolingual marginal ridge. The second premolar usually has two or three well-developed cusps and a more centrally placed lingual cusp.

Question 14Oral and Maxillofacial Anatomy and Histology

Which structure forms the anterior boundary of the pterygomandibular space, an important landmark for inferior alveolar nerve block?

  1. Posterior border of the mylohyoid muscle
  2. Anterior border of the masseter
  3. Medial surface of the mandibular ramus Correct answer.
  4. Lateral pterygoid plate

Explanation

The pterygomandibular space is bounded anteriorly by the medial surface of the mandibular ramus, medially by the medial pterygoid and lateral pterygoid plate, and laterally by the ramus and buccinator region. The needle in an inferior alveolar block passes through this space toward the mandibular foramen.

Question 15Oral and Maxillofacial Anatomy and Histology

A biopsy of a gingival lesion shows parakeratinized stratified squamous epithelium with elongated rete ridges and dense chronic inflammatory infiltrate in the connective tissue. Which diagnosis is most consistent?

  1. Normal masticatory mucosa
  2. Ameloblastoma
  3. Odontogenic keratocyst
  4. Chronic inflammatory gingival hyperplasia Correct answer.

Explanation

Parakeratinized epithelium with elongated rete pegs and a dense chronic inflammatory infiltrate in the lamina propria is the histological picture of chronic inflammatory gingival hyperplasia. Normal masticatory mucosa lacks the heavy inflammatory infiltrate and prominent rete elongation.

Question 16Oral and Maxillofacial Anatomy and Histology

Which anatomical relationship explains why infection from a mandibular third molar can spread to the submandibular space?

  1. The masseter muscle inserts into the third molar socket
  2. The lingual cortex of the posterior mandible is thin and perforated above the mylohyoid line Correct answer.
  3. The buccal cortex is uniformly thick and impermeable in the molar region
  4. The submandibular duct directly communicates with the follicle

Explanation

The lingual cortical plate of the posterior mandible is thin and often perforated above the mylohyoid line, so infection from a mandibular third molar can enter the sublingual and then submandibular spaces. Buccal spread occurs when the infection tracks laterally instead.

Question 17Oral Pathology and Oral Medicine

A 24-year-old patient has a painless, fluctuant swelling at the floor of the mouth that transilluminates and elevates the tongue. Which lesion is most likely?

  1. Hemangioma
  2. Pleomorphic adenoma
  3. Dermoid cyst
  4. Ranula Correct answer.

Explanation

A ranula is a mucocele arising from the sublingual gland that extravasates mucus into the floor of the mouth, producing a bluish, fluctuant, transilluminating swelling that lifts the tongue. Because it contains fluid rather than solid tissue, it classically transilluminates, which helps separate it from solid neoplasms.

Question 18Oral Pathology and Oral Medicine

Which organism is most strongly associated with the initiation of dental caries on smooth enamel surfaces?

  1. Porphyromonas gingivalis
  2. Streptococcus mutans Correct answer.
  3. Treponema denticola
  4. Candida albicans

Explanation

Streptococcus mutans is a highly acidogenic and aciduric organism that adheres to enamel and produces the localized acid demineralization that starts smooth-surface caries. It also synthesizes glucans from sucrose, which promotes plaque formation and bacterial adherence.

Question 19Oral Pathology and Oral Medicine

A patient reports recurrent, painful, shallow ulcers with a yellow pseudomembrane and a red halo on non-keratinized mucosa, healing in about 10 days without scarring. What is the most likely diagnosis?

  1. Herpangina
  2. Recurrent aphthous stomatitis Correct answer.
  3. Squamous cell carcinoma
  4. Oral lichen planus

Explanation

Recurrent aphthous stomatitis produces shallow, painful ulcers with a yellow-grey center and erythematous halo on non-keratinized mucosa, and minor ulcers heal within about 7 to 14 days without scarring. The recurrent pattern and lack of scarring distinguish it from other ulcerative conditions.

Question 20Oral Pathology and Oral Medicine

Which clinical finding is most characteristic of a radicular cyst?

  1. A multilocular radiolucency of the posterior mandible
  2. Diffuse widening of the periodontal ligament of a vital tooth
  3. A well-defined radiolucency at the apex of a non-vital tooth Correct answer.
  4. A well-defined radiopacity at the apex of a vital tooth

Explanation

A radicular cyst arises from epithelial rests of Malassez in a periapical granuloma of a non-vital tooth, producing a well-defined periapical radiolucency with loss of the lamina dura. The tooth is non-vital, which is a key diagnostic feature.

Question 21Oral Pathology and Oral Medicine

A 6-year-old child has a painful, rapidly enlarging swelling of the anterior maxilla with a bluish hue and displacement of developing teeth. What is the most likely diagnosis?

  1. Odontogenic keratocyst
  2. Dentigerous cyst
  3. Eruption cyst Correct answer.
  4. Ameloblastoma

Explanation

An eruption cyst is a soft-tissue cyst overlying an erupting tooth, often bluish and painful, and is common in children in the anterior maxilla. It resolves with eruption and is distinct from intraosseous cysts.

Question 22Oral Pathology and Oral Medicine

Which vitamin deficiency classically causes swollen, bleeding, spongy gingiva with delayed wound healing?

  1. Vitamin K
  2. Vitamin B12
  3. Vitamin D
  4. Vitamin C Correct answer.

Explanation

Vitamin C is required for collagen synthesis and maintenance of the periodontal tissues, so deficiency (scurvy) causes swollen, hemorrhagic, spongy gingiva and poor wound healing. The gingival changes are a direct consequence of defective collagen.

Question 23Oral Pathology and Oral Medicine

Which site is the most common location for oral squamous cell carcinoma?

  1. Gingiva
  2. Hard palate
  3. Lateral border of the tongue Correct answer.
  4. Buccal mucosa

Explanation

The lateral border and ventral surface of the tongue are the most frequent sites for oral squamous cell carcinoma, followed by the floor of the mouth. These areas are exposed to pooled saliva and carcinogens from tobacco and alcohol.

Question 24Oral Pathology and Oral Medicine

A patient has a firm, non-tender, freely movable mass in the buccal mucosa that has been slowly enlarging for years. Which diagnosis should be considered first?

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

Explanation

Pleomorphic adenoma is the most common benign salivary gland tumor and typically presents as a slow-growing, firm, painless, mobile mass, often in the palate or buccal minor glands. Its long indolent course and mobility favor a benign neoplasm.

Question 25Oral Pathology and Oral Medicine

Radiographs show multiple impacted supernumerary teeth and numerous odontogenic keratocysts in a young patient with palmar pits. Which syndrome is most likely?

  1. Cleidocranial dysplasia
  2. Gorlin syndrome Correct answer.
  3. Gardner syndrome
  4. Treacher Collins syndrome

Explanation

Gorlin syndrome (nevoid basal cell carcinoma syndrome) is characterized by multiple odontogenic keratocysts, palmar and plantar pits, basal cell carcinomas, and skeletal anomalies. The combination of keratocysts and palmar pits is highly suggestive.

Question 26Oral Pathology and Oral Medicine

Which feature best distinguishes oral hairy leukoplakia from other white lesions?

  1. Bilateral buccal striae that wipe off with gauze
  2. A homogeneous plaque on the floor of the mouth
  3. Vertical corrugations on the lateral tongue in an HIV-positive patient Correct answer.
  4. A painful ulcer with a yellow base

Explanation

Oral hairy leukoplakia presents as corrugated, vertically oriented white plaques on the lateral border of the tongue and is associated with Epstein-Barr virus in immunocompromised patients, especially HIV infection. It does not wipe off, unlike candidiasis.

Question 27Oral Pathology and Oral Medicine

A patient on long-term phenytoin therapy presents with generalized gingival enlargement. Which mechanism explains this finding?

  1. Vitamin C deficiency
  2. Drug-induced fibroblast proliferation and collagen accumulation Correct answer.
  3. Autoimmune destruction of the basement membrane
  4. Direct bacterial infection of the gingiva

Explanation

Phenytoin, like cyclosporine and calcium channel blockers, induces gingival fibroblast proliferation and increased collagen synthesis, causing generalized fibrous gingival enlargement. Plaque control influences severity but the primary mechanism is drug-induced fibrosis.

Question 28Oral Pathology and Oral Medicine

Which clinical presentation is most typical of oral lichen planus?

  1. Black pigmentation of the attached gingiva
  2. Unilateral indurated ulcer with rolled margins
  3. Yellowish nodules on the soft palate
  4. Bilateral white reticular striae on the buccal mucosa Correct answer.

Explanation

Oral lichen planus classically presents with bilateral, symmetrical white reticular striae (Wickham striae) on the buccal mucosa, often with erosive areas. The bilateral symmetry and reticular pattern are characteristic.

Question 29Oral Pathology and Oral Medicine

A patient develops fever, widespread oral erosions, and a skin rash after starting carbamazepine. Which diagnosis is most likely?

  1. Herpes labialis
  2. Nicotinic stomatitis
  3. Erythema multiforme Correct answer.
  4. Recurrent aphthous stomatitis

Explanation

Erythema multiforme is an acute immune-mediated reaction often triggered by drugs or infections, producing target skin lesions and widespread oral erosions with hemorrhagic crusts. The temporal relation to a new drug and systemic symptoms supports this diagnosis.

Question 30Oral Pathology and Oral Medicine

Which radiographic feature is most suggestive of an ameloblastoma of the posterior mandible?

  1. Sunburst periosteal reaction
  2. Well-defined unilocular radiolucency around a crown
  3. Diffuse ground-glass opacity
  4. Multilocular soap-bubble radiolucency with root resorption Correct answer.

Explanation

Ameloblastoma typically appears as a multilocular, soap-bubble or honeycomb radiolucency in the posterior mandible and may cause root resorption and cortical expansion. These features reflect its locally aggressive, benign epithelial nature.

Question 31Oral Pathology and Oral Medicine

A patient has unilateral facial paralysis, dry eye, and a vesicular rash in the external auditory canal. Which diagnosis is most likely?

  1. Trigeminal neuralgia
  2. Ramsay Hunt syndrome Correct answer.
  3. Sjogren syndrome
  4. Bell palsy

Explanation

Ramsay Hunt syndrome results from varicella-zoster virus reactivation in the geniculate ganglion, causing facial palsy, ear pain with vesicles, and sometimes hearing loss or dry eye. The vesicular rash in the auricular distribution distinguishes it from Bell palsy.

Question 32Oral Pathology and Oral Medicine

Which oral mucosal change is most strongly associated with smokeless tobacco use?

  1. White, wrinkled plaque at the site of tobacco placement Correct answer.
  2. Geographic tongue
  3. Bilateral reticular striae
  4. Median rhomboid glossitis

Explanation

Smokeless tobacco keratosis appears as a white, wrinkled or corrugated plaque at the site where tobacco is held, usually the mandibular vestibule. It represents a site-specific mucosal reaction to chronic chemical irritation.

Question 33Oral Pathology and Oral Medicine

A patient with poorly controlled diabetes develops a tender, indurated swelling of the submandibular region with pus expressed from the duct. What is the most likely diagnosis?

  1. Pleomorphic adenoma
  2. Mucocele
  3. Suppurative sialadenitis Correct answer.
  4. Sialolithiasis without infection

Explanation

Suppurative sialadenitis presents with a painful, indurated gland, pus from the duct, and systemic signs, and is favored by reduced salivary flow such as in uncontrolled diabetes. Stasis plus bacterial infection produces the suppurative picture.

Question 34Oral Pathology and Oral Medicine

Which finding is most consistent with median rhomboid glossitis?

  1. Painful ulcers on the ventral tongue
  2. White striae on the buccal mucosa
  3. Erythematous, depapillated area in the midline of the dorsal tongue Correct answer.
  4. Multiple vesicles along the lateral tongue

Explanation

Median rhomboid glossitis is a rhomboid erythematous, depapillated area in the midline of the dorsal tongue, anterior to the foramen cecum, and is associated with candidal infection. Loss of filiform papillae produces the smooth red appearance.

Question 35Oral Pathology and Oral Medicine

A patient with a history of heavy alcohol and tobacco use has a painless, indurated ulcer with everted margins on the floor of the mouth. Which step is most appropriate?

  1. Incisional biopsy of the lesion Correct answer.
  2. Observation for 6 months
  3. Topical corticosteroid application
  4. Topical antifungal therapy

Explanation

An indurated, non-healing ulcer in a high-risk patient is suspicious for oral squamous cell carcinoma and requires prompt incisional biopsy for histopathologic confirmation. Delay or empirical topical treatment can allow progression of malignancy.

Question 36Oral Pathology and Oral Medicine

A 50-year-old woman has bilateral facial swelling, dry mouth, and dry eyes with anti-Ro antibodies. Which diagnosis is most likely?

  1. Sarcoidosis
  2. Scleroderma
  3. Systemic lupus erythematosus
  4. Sjogren syndrome Correct answer.

Explanation

Sjogren syndrome is an autoimmune exocrinopathy causing dry mouth and dry eyes with lymphocytic infiltration of the lacrimal and salivary glands, often with anti-Ro/SSA antibodies. Bilateral parotid enlargement is common.

Question 37Oral Pathology and Oral Medicine

Which feature most reliably differentiates an odontogenic keratocyst from other odontogenic cysts on histopathology?

  1. A non-keratinized lining with numerous goblet cells
  2. A thick stratified squamous lining with rete ridges
  3. A lining with ciliated columnar epithelium
  4. A parakeratinized corrugated epithelial lining with a palisaded basal layer Correct answer.

Explanation

Odontogenic keratocysts are lined by a thin, uniform parakeratinized epithelium with a corrugated surface and a palisaded, hyperchromatic basal layer. These features explain their high recurrence rate and aggressive behavior.

Question 38Oral Pathology and Oral Medicine

A patient with a known primary malignancy develops multiple painful oral ulcers with a violaceous border and a history of recent chemotherapy. Which diagnosis is most likely?

  1. Erythema migrans
  2. Oral candidiasis
  3. Drug-induced mucositis Correct answer.
  4. Recurrent aphthous stomatitis

Explanation

Chemotherapy-induced mucositis produces diffuse, painful oral ulceration with erythematous or violaceous borders and occurs during or shortly after cytotoxic therapy. It reflects direct mucosal toxicity and immunosuppression rather than a recurrent idiopathic process.

Question 39Oral Pathology and Oral Medicine

A biopsy of a white palatal plaque shows hyperkeratosis, acanthosis, and a band of inflammatory cells with a history of reverse smoking. Which diagnosis is most likely?

  1. Nicotinic stomatitis Correct answer.
  2. Candidiasis
  3. Leukoplakia with dysplasia
  4. Lichen planus

Explanation

Nicotinic stomatitis is a reactive keratosis of the palate associated with smoking, especially reverse smoking, showing hyperkeratosis and acanthosis with inflammation of the minor salivary gland ducts. The clinical history of reverse smoking is key.

Question 40Oral Pathology and Oral Medicine

Which mechanism best explains the association between human papillomavirus and oropharyngeal squamous cell carcinoma?

  1. Autoimmune destruction of the tonsillar epithelium
  2. Viral E6 and E7 proteins inactivate p53 and retinoblastoma protein Correct answer.
  3. Direct bacterial invasion of the tonsillar crypts
  4. Chronic mechanical trauma from dentures

Explanation

High-risk HPV types, especially HPV-16, express E6 and E7 proteins that degrade p53 and inactivate retinoblastoma protein, disrupting cell cycle control and promoting malignant transformation. This mechanism underlies the distinct clinical behavior of HPV-positive oropharyngeal carcinoma.

Question 41Restorative Dentistry and Endodontics

Which instrument is used in endodontics to determine the working length of a root canal before obturation?

  1. A Gates-Glidden drill
  2. An electronic apex locator Correct answer.
  3. A periodontal probe
  4. A rubber dam clamp

Explanation

An electronic apex locator measures the impedance between the file and the apical tissues to locate the apical constriction and establish working length. It is used before cleaning and shaping and before obturation to define the preparation limit.

Question 42Restorative Dentistry and Endodontics

What is the main purpose of applying a rubber dam during root canal treatment?

  1. To speed up the setting of the sealer
  2. To isolate the tooth from saliva and prevent irrigant swallowing Correct answer.
  3. To improve access to the pulp chamber
  4. To reduce the need for local anesthesia

Explanation

The rubber dam isolates the operating field from oral fluids and soft tissues, maintaining a clean field and protecting the patient from aspiration or swallowing of instruments and irrigants such as sodium hypochlorite. Access and anesthesia are unrelated to its purpose.

Question 43Restorative Dentistry and Endodontics

Which irrigant is most widely used in root canal therapy for its antimicrobial action and tissue-dissolving capacity?

  1. Chlorhexidine 2%
  2. Sodium hypochlorite Correct answer.
  3. Saline
  4. Hydrogen peroxide 3%

Explanation

Sodium hypochlorite is the standard irrigant because it dissolves necrotic pulp tissue and is broadly antimicrobial, though it does not remove the smear layer. Chlorhexidine is antimicrobial but lacks tissue-dissolving ability, and saline has no antimicrobial action.

Question 44Restorative Dentistry and Endodontics

In a Class II cavity preparation, which surface of the tooth is involved in addition to the occlusal surface?

  1. The proximal surface Correct answer.
  2. The lingual surface
  3. The cervical third of the root
  4. The incisal edge

Explanation

A Class II lesion involves the proximal surfaces of posterior teeth, so the preparation includes an occlusal component and a proximal box. Class III and IV involve proximal surfaces of anterior teeth, while Class V involves the cervical third.

Question 45Restorative Dentistry and Endodontics

What is the primary function of a matrix band when placing a Class II amalgam restoration?

  1. To sterilize the cavity
  2. To provide pulpal anesthesia
  3. To polish the restoration surface
  4. To restore the proximal contour and contain the material Correct answer.

Explanation

A matrix band supports the restorative material, confines it within the preparation, and helps reproduce the proximal contour and contact. It does not sterilize the cavity or affect anesthesia.

Question 46Restorative Dentistry and Endodontics

Which pulp diagnosis describes a tooth with provoked pain that persists after the stimulus is removed, indicating irreversible inflammation?

  1. Normal pulp
  2. Irreversible pulpitis Correct answer.
  3. Pulpal necrosis
  4. Reversible pulpitis

Explanation

Irreversible pulpitis is characterized by lingering pain after thermal or mechanical stimulation, indicating that the pulp cannot heal and root canal treatment is required. Reversible pulpitis produces sharp pain that resolves promptly when the stimulus is removed.

Question 47Restorative Dentistry and Endodontics

What does the term 'working length' refer to in endodontic treatment?

  1. The diameter of the largest file used
  2. The total length of the root measured on a radiograph
  3. The distance from a coronal reference point to the apical constriction Correct answer.
  4. The length of the irrigation needle used

Explanation

Working length is the distance from a stable coronal reference point to the apical constriction, where instrumentation and obturation should terminate. It is shorter than the radiographic root length because the apical constriction lies short of the radiographic apex.

Question 48Restorative Dentistry and Endodontics

Which material is a direct esthetic restorative commonly used for anterior Class III cavities?

  1. Gutta-percha
  2. Amalgam
  3. Zinc phosphate cement
  4. Composite resin Correct answer.

Explanation

Composite resin is bonded directly to enamel and dentin, allowing a tooth-colored restoration with good esthetics in anterior Class III preparations. Amalgam is not esthetic, zinc phosphate is a luting cement, and gutta-percha is an endodontic filling material.

Question 49Restorative Dentistry and Endodontics

A patient reports sharp pain in a molar that lasts only a few seconds after drinking cold water and disappears when the cold is removed. What is the most appropriate diagnosis?

  1. Reversible pulpitis Correct answer.
  2. Asymptomatic apical periodontitis
  3. Pulpal necrosis
  4. Irreversible pulpitis

Explanation

Sharp pain provoked by cold that resolves immediately after removal of the stimulus is the classic presentation of reversible pulpitis, and the pulp may recover if the cause is removed. Lingering pain would suggest irreversible pulpitis, while a nonresponsive tooth suggests necrosis.

Question 50Restorative Dentistry and Endodontics

During access preparation on a maxillary first molar, which canal is often the smallest and most difficult to locate?

  1. The palatal canal
  2. The second mesiobuccal canal Correct answer.
  3. The mesiobuccal canal
  4. The distobuccal canal

Explanation

The maxillary first molar frequently has a second mesiobuccal canal (MB2) located under the dentinal shelf between the MB1 and palatal orifices, and it is narrow and commonly missed. The palatal canal is the largest, and the distobuccal canal is usually straightforward to find.