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Question 1Dental medicine (content domains not enumerated in source)

During a periodontal examination, which clinical parameter best reflects the cumulative destruction of the periodontium caused by past disease activity?

  1. Clinical attachment level Correct answer.
  2. Plaque index
  3. Bleeding on probing
  4. Probing depth

Explanation

Clinical attachment level measures the distance from the cementoenamel junction to the base of the sulcus or pocket, so it records attachment loss accumulated over the patient's lifetime regardless of current inflammation. Probing depth and bleeding on probing describe present status rather than historical destruction.

Question 2Dental medicine (content domains not enumerated in source)

Which local anesthetic is contraindicated in a patient with a documented true allergy to esters and is therefore preferred when ester allergy is suspected?

  1. Procaine
  2. Benzocaine
  3. Amide-type anesthetics such as lidocaine Correct answer.
  4. Articaine

Explanation

True allergy is far more common with ester anesthetics, which are metabolized to para-aminobenzoic acid, a known allergen. Amide anesthetics such as lidocaine are metabolized in the liver and are the safer choice when ester hypersensitivity is documented.

Question 3Dental medicine (content domains not enumerated in source)

A radiograph shows a well-defined radiolucency at the apex of a nonvital maxillary central incisor, continuous with the root canal. Which diagnosis is most consistent with these findings?

  1. Periapical cyst of inflammatory origin Correct answer.
  2. Ameloblastoma
  3. Odontoma
  4. Dentigerous cyst

Explanation

A periapical radiolucency associated with a nonvital tooth and continuous with the canal is characteristic of inflammatory periapical disease, which may be a granuloma or cyst. Dentigerous cysts and odontomas are associated with the crown of an unerupted tooth, and ameloblastoma is typically a multilocular lesion of the posterior mandible.

Question 4Dental medicine (content domains not enumerated in source)

Which tooth surface is most commonly affected by early carious lesions in the permanent dentition because of plaque stagnation?

  1. Occlusal pits and fissures Correct answer.
  2. Labial surface of mandibular incisors
  3. Lingual surface of maxillary incisors
  4. Root surfaces of anterior teeth

Explanation

Pits and fissures of occlusal surfaces retain plaque and are difficult to clean, making them the most frequent site of caries initiation in permanent molars and premolars. Smooth surfaces such as labial and lingual anterior surfaces are more self-cleansing and less often affected early.

Question 5Dental medicine (content domains not enumerated in source)

A patient reports spontaneous, sharp, lancinating pain lasting seconds in the mandibular right quadrant, triggered by touching the lower lip. Which condition should be the leading diagnosis?

  1. Temporomandibular joint arthralgia
  2. Trigeminal neuralgia Correct answer.
  3. Pulpitis of the mandibular right first molar
  4. Atypical odontalgia

Explanation

Brief, electric shock-like pain triggered by light touch in a trigeminal distribution is the classic presentation of trigeminal neuralgia. Pulpal pain is usually provoked by thermal stimuli and persists, while arthralgia is related to joint function.

Question 6Dental medicine (content domains not enumerated in source)

Which instrument is most appropriate for removing supragingival calculus during a routine prophylaxis without injuring the gingival tissue?

  1. Periodontal probe
  2. Universal curette
  3. Explorer
  4. Sickle scaler Correct answer.

Explanation

Sickle scalers have a pointed tip and two cutting edges designed for removing supragingival calculus from crown surfaces. Universal curettes are intended for subgingival scaling, whereas probes and explorers are diagnostic instruments without cutting edges.

Question 7Dental medicine (content domains not enumerated in source)

A 7-year-old child has a mandibular primary second molar with a large carious lesion and irreversible pulpal involvement, and the permanent successor is not expected for several years. Which treatment is most appropriate?

  1. Direct composite restoration only
  2. Extraction without space maintenance
  3. Pulpotomy
  4. Pulpectomy and stainless steel crown Correct answer.

Explanation

When pulpal necrosis or irreversible pulpitis affects a primary molar that must be retained as a space maintainer, pulpectomy followed by a stainless steel crown preserves the tooth until the successor erupts. Simple extraction risks space loss, and a direct restoration cannot address the infected pulp.

Question 8Dental medicine (content domains not enumerated in source)

Which clinical finding is most characteristic of aggressive periodontitis (now classified as a stage of periodontitis with rapid progression) in an adolescent?

  1. Uniform horizontal bone loss around all teeth
  2. Painless gingival enlargement limited to the palate
  3. Rapid attachment loss and severe bone loss on first molars and incisors with minimal local factors Correct answer.
  4. Generalized heavy calculus with mild bone loss

Explanation

Rapid attachment loss affecting first molars and incisors with amounts of plaque and calculus inconsistent with the severity of destruction is a hallmark of this pattern of periodontitis. Heavy calculus with mild bone loss suggests chronic disease, and uniform horizontal loss is not typical of the localized aggressive pattern.

Question 9Dental medicine (content domains not enumerated in source)

Which material is most appropriate as a direct pulp-capping agent to promote reparative dentin formation?

  1. Amalgam
  2. Calcium hydroxide Correct answer.
  3. Zinc oxide eugenol
  4. Glass ionomer luting cement

Explanation

Calcium hydroxide creates an alkaline environment that induces a zone of necrosis and stimulates odontoblast-like cells to form a dentin bridge. Zinc oxide eugenol is irritating to pulp tissue, amalgam has no biologic sealing capacity, and luting cement is not designed for pulp contact.

Question 10Dental medicine (content domains not enumerated in source)

A patient with a history of infective endocarditis requires a dental extraction. Which regimen is consistent with standard antibiotic prophylaxis before the procedure?

  1. Amoxicillin given 24 hours after the procedure
  2. Clindamycin given only after bleeding begins
  3. Amoxicillin given 30 to 60 minutes before the procedure Correct answer.
  4. No prophylaxis is ever required for extractions

Explanation

Standard prophylaxis for high-risk cardiac patients consists of a single dose of amoxicillin taken 30 to 60 minutes before the procedure to achieve adequate serum levels at the time of bacteremia. Postoperative-only dosing does not protect during the procedure.

Question 11Dental medicine (content domains not enumerated in source)

Which radiographic projection best demonstrates the entire mandibular arch and is commonly used for a general survey in an edentulous patient?

  1. Panoramic radiograph Correct answer.
  2. Lateral cephalometric radiograph
  3. Periapical radiograph of a single tooth
  4. Bitewing radiograph

Explanation

A panoramic radiograph captures the maxilla and mandible, including the temporomandibular joints and sinuses, in a single image and is useful for broad surveys. Bitewings and periapicals cover limited regions, and cephalometric films are used for growth and orthodontic assessment.

Question 12Dental medicine (content domains not enumerated in source)

A patient presents with a firm, painless, sessile nodule on the buccal mucosa that has been present for years and is the same color as surrounding mucosa. Which diagnosis is most likely?

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

Explanation

A longstanding, firm, asymptomatic, mucosa-colored nodule on the buccal mucosa is typical of an irritation fibroma, a reactive fibrous hyperplasia. Squamous cell carcinoma is usually ulcerated and indurated, a mucocele is fluctuant and bluish, and a hemangioma blanches on pressure.

Question 13Dental medicine (content domains not enumerated in source)

Which occlusal concept describes the contact of the mesiobuccal cusp of the maxillary first molar with the buccal groove of the mandibular first molar in ideal occlusion?

  1. Class II division 1 relationship
  2. Class I occlusal relationship Correct answer.
  3. Class III relationship
  4. Anterior open bite

Explanation

In a Class I molar relationship, the mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first molar. Class II and Class III relationships describe distal and mesial positions of the mandibular molar relative to the maxillary molar, respectively.

Question 14Dental medicine (content domains not enumerated in source)

A patient on warfarin with an INR of 3.5 requires a simple extraction. Which management approach is most appropriate?

  1. Proceed with local hemostatic measures and consider INR-guided timing in consultation with the physician Correct answer.
  2. Double the warfarin dose before the procedure
  3. Refer for extraction only after INR falls below 1.0
  4. Discontinue warfarin 5 days before extraction without consultation

Explanation

Most simple extractions can be performed with an INR within therapeutic range using local measures such as sutures, pressure, and hemostatic agents, and the physician should be consulted regarding timing. Abrupt discontinuation risks thromboembolism, and an INR below 1.0 is not required for routine dental surgery.

Question 15Dental medicine (content domains not enumerated in source)

Which tooth is most frequently impacted in the permanent dentition?

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

Explanation

Mandibular third molars are the most commonly impacted teeth because of limited arch space and late eruption timing. Maxillary canines are the second most common impaction but occur less frequently than third molars.

Question 16Dental medicine (content domains not enumerated in source)

Which mechanism best explains the anticaries effect of topical fluoride applied to erupted teeth?

  1. Mechanical sealing of pits and fissures
  2. Systemic incorporation into developing enamel
  3. Direct bactericidal elimination of all oral flora
  4. Promotion of remineralization and inhibition of demineralization Correct answer.

Explanation

Topical fluoride enhances remineralization by forming fluorapatite, inhibits demineralization, and reduces bacterial acid production. Its action is local, not systemic, and it does not sterilize the oral cavity or mechanically seal fissures.

Question 17Dental medicine (content domains not enumerated in source)

A patient has a maxillary complete denture with poor retention and a flat residual alveolar ridge. Which factor most directly limits retention in this situation?

  1. Insufficient atmospheric pressure seal due to reduced denture base adaptation Correct answer.
  2. Excessive vertical dimension of occlusion
  3. Increased salivary flow
  4. Presence of natural mandibular teeth

Explanation

Retention of a maxillary complete denture depends on an adequate border seal and intimate adaptation to the palate, which allows atmospheric pressure and adhesion to hold the prosthesis. A flat ridge reduces support and stability, but loss of the peripheral seal most directly compromises retention.

Question 18Dental medicine (content domains not enumerated in source)

Which nerve block is indicated for anesthesia of the mandibular molars and the buccal soft tissue on the same side?

  1. Inferior alveolar nerve block with buccal nerve block Correct answer.
  2. Greater palatine nerve block
  3. Nasopalatine nerve block
  4. Mental nerve block

Explanation

The inferior alveolar nerve block anesthetizes the mandibular molars and premolars, and the buccal nerve block anesthetizes the buccal soft tissues and periosteum. Palatal blocks anesthetize palatal mucosa, and a mental nerve block affects only anterior soft tissues.

Question 19Dental medicine (content domains not enumerated in source)

Which clinical feature distinguishes a gingival abscess from a periodontal abscess?

  1. Gingival abscess always causes tooth mobility
  2. Periodontal abscess resolves without treatment
  3. Periodontal abscess affects only the attached gingiva
  4. Gingival abscess is confined to the marginal gingiva and does not involve the periodontal ligament Correct answer.

Explanation

A gingival abscess is localized to the marginal or interdental gingiva and does not involve the periodontal ligament or alveolar bone, whereas a periodontal abscess involves deeper periodontal structures and often causes mobility. Both require treatment, and mobility is more typical of periodontal abscess.

Question 20Dental medicine (content domains not enumerated in source)

Which impression material is most appropriate for a final impression of a prepared tooth when dimensional accuracy and detail reproduction are required?

  1. Zinc oxide eugenol paste
  2. Alginate
  3. Impression compound
  4. Addition silicone (polyvinyl siloxane) Correct answer.

Explanation

Addition silicones provide excellent dimensional stability, detail reproduction, and elastic recovery, making them suitable for final impressions of prepared teeth. Alginate is dimensionally unstable, impression compound is rigid and used for border molding, and zinc oxide eugenol paste is not used for final crown impressions.

Question 21Dental medicine (content domains not enumerated in source)

A patient reports a burning sensation on the tongue and angular cheilitis. Which nutritional deficiency is most likely?

  1. Vitamin D deficiency
  2. Iron excess
  3. Vitamin B complex deficiency Correct answer.
  4. Vitamin C deficiency

Explanation

Burning tongue, glossitis, and angular cheilitis are classic signs of B vitamin deficiency, particularly riboflavin, niacin, and B12. Vitamin C deficiency causes scurvy with bleeding gums, vitamin D deficiency causes rickets, and iron excess is unrelated to these findings.

Question 22Dental medicine (content domains not enumerated in source)

Which principle of cavity preparation requires that the gingival margin of a proximal box be placed clear of the adjacent tooth to allow proper restoration contour?

  1. Outline form Correct answer.
  2. Convenience form
  3. Resistance form
  4. Retention form

Explanation

Outline form defines the external boundaries of the preparation, including extension of proximal margins to self-cleansing areas and clearance from adjacent teeth. Convenience form improves access, resistance form resists fracture, and retention form prevents displacement of the restoration.

Question 23Dental medicine (content domains not enumerated in source)

A 45-year-old patient has generalized gingival enlargement with a history of nifedipine use. Which management step is most appropriate initially?

  1. Immediate gingivectomy without hygiene therapy
  2. Extraction of all affected teeth
  3. Consultation with the physician regarding alternative medication plus meticulous oral hygiene Correct answer.
  4. Antibiotic therapy alone

Explanation

Drug-influenced gingival enlargement often improves after physician consultation to substitute the medication and after meticulous plaque control. Surgical reduction is considered only after inflammation is controlled and if enlargement persists.

Question 24Dental medicine (content domains not enumerated in source)

Which developmental anomaly is characterized by a small, pointed cusp on the lingual surface of a maxillary incisor that may cause occlusal interference?

  1. Fusion
  2. Enamel pearl
  3. Dens invaginatus
  4. Talon cusp Correct answer.

Explanation

A talon cusp is an accessory cusp on the lingual surface of anterior teeth, most often maxillary incisors, and can interfere with occlusion and trap plaque. Dens invaginatus is an infolding of enamel, an enamel pearl is a nodule of enamel on a root, and fusion is the union of two teeth.

Question 25Dental medicine (content domains not enumerated in source)

Which factor most strongly increases the risk of osteoradionecrosis after extraction in a patient who received head and neck radiation?

  1. Patient's blood type
  2. Presence of a single restored tooth
  3. Use of local anesthetic without vasoconstrictor
  4. Radiation dose and time since therapy Correct answer.

Explanation

The risk of osteoradionecrosis is related to the total radiation dose and the interval since radiotherapy, with higher doses and recent treatment increasing risk. Blood type, vasoconstrictor use, and a single restoration do not determine this risk.

Question 26Dental medicine (content domains not enumerated in source)

During a crown preparation on a vital tooth, which local anesthetic property is most desirable to minimize pulpal irritation from the vasoconstrictor?

  1. Absence of vasoconstrictor Correct answer.
  2. Intrinsic vasodilating activity
  3. High lipid solubility
  4. Low pKa

Explanation

Vasoconstrictors such as epinephrine reduce bleeding and prolong anesthesia but can decrease pulpal blood flow and potentially irritate a vital pulp. For crown preparations where pulpal health is a concern, an anesthetic without vasoconstrictor (e.g., mepivacaine 3% plain or articaine 4% plain) is often preferred. The other properties affect onset, duration, or potency but do not directly address pulpal irritation from vasoconstriction.

Question 27Dental medicine (content domains not enumerated in source)

Which radiographic feature best differentiates a periapical cyst from a periapical granuloma?

  1. Well-defined sclerotic border and size greater than 1 cm Correct answer.
  2. Presence of internal calcifications
  3. Rapid growth over 6 months
  4. Ill-defined margins and association with a nonvital tooth

Explanation

A periapical cyst typically shows a well-circumscribed radiolucency with a sclerotic border and is often larger than 1 cm, whereas a granuloma tends to have less distinct margins and is usually smaller. Both are associated with nonvital teeth, so vitality testing alone cannot reliably distinguish them. Definitive diagnosis requires histopathologic examination.

Question 28Dental medicine (content domains not enumerated in source)

Which analgesic regimen is most appropriate for a patient with a history of peptic ulcer disease who requires post-extraction pain control?

  1. Ibuprofen 400 mg every 6 hours
  2. Naproxen 500 mg twice daily
  3. Acetaminophen 1000 mg every 6 hours Correct answer.
  4. Aspirin 650 mg every 4 hours

Explanation

Acetaminophen is preferred for patients with peptic ulcer disease because it lacks the gastrointestinal mucosal toxicity associated with NSAIDs. NSAIDs such as ibuprofen, naproxen, and aspirin inhibit cyclooxygenase and can exacerbate ulcer disease or cause bleeding. Acetaminophen provides adequate analgesia for many post-extraction scenarios when dosed appropriately.

Question 29Dental medicine (content domains not enumerated in source)

Which feature is most characteristic of a benign migratory glossitis (geographic tongue) on clinical examination?

  1. White, adherent plaques on the buccal mucosa
  2. Firm, painless nodule on the lateral border of the tongue
  3. Vesicles along the vermilion border
  4. Depapillated red patches with serpiginous white borders on the dorsum of the tongue Correct answer.

Explanation

Benign migratory glossitis presents as areas of depapillation on the dorsal tongue, appearing red with a white, serpiginous border that changes location over time. These lesions are often asymptomatic but may cause mild discomfort with spicy foods. The other options describe different oral mucosal conditions.

Question 30Dental medicine (content domains not enumerated in source)

Which parameter is most important to evaluate when assessing the risk of root caries in an older adult with exposed root surfaces?

  1. Fluoride concentration in drinking water
  2. Number of restored teeth
  3. Salivary flow rate and buffering capacity Correct answer.
  4. Toothbrushing frequency

Explanation

Root caries risk is strongly influenced by salivary flow and buffering capacity, which affect the clearance of fermentable carbohydrates and the neutralization of acids. Reduced salivary flow, often due to medications or systemic disease, increases caries risk. While hygiene and fluoride exposure are relevant, salivary parameters are particularly critical in older adults with exposed roots.

Question 31Dental medicine (content domains not enumerated in source)

Which design feature of a removable partial denture framework helps direct functional forces along the long axes of the abutment teeth?

  1. Rest seats Correct answer.
  2. Denture base
  3. Major connector
  4. Clasp retentive arms

Explanation

Rest seats are prepared to provide a positive seat for the framework and to direct occlusal forces along the long axis of the abutment teeth, minimizing torque. Retentive clasp arms provide retention but do not primarily direct forces axially. Major connectors and denture bases distribute forces but are not the primary feature for axial loading.

Question 32Dental medicine (content domains not enumerated in source)

Which cell type is primarily responsible for the resorption of bone during orthodontic tooth movement?

  1. Chondrocytes
  2. Osteoblasts
  3. Fibroblasts
  4. Osteoclasts Correct answer.

Explanation

Osteoclasts are multinucleated cells that resorb bone on the pressure side of a tooth undergoing orthodontic movement. Their activity is regulated by cytokines and the RANK/RANKL/OPG system. Osteoblasts form bone on the tension side, while fibroblasts and chondrocytes are not primarily involved in bone resorption.

Question 33Dental medicine (content domains not enumerated in source)

Which statement best describes the rationale for using a fluoride varnish in a patient with active white spot lesions?

  1. It removes the demineralized enamel layer to allow remineralization.
  2. It neutralizes oral acids immediately upon application.
  3. It seals the lesions and prevents further bacterial colonization.
  4. It provides a sustained reservoir of fluoride that promotes remineralization and inhibits demineralization. Correct answer.

Explanation

Fluoride varnish adheres to the tooth surface and releases fluoride over time, enhancing remineralization and reducing enamel solubility. It does not seal lesions, immediately neutralize acids, or remove enamel. Its main benefit is the sustained local fluoride effect.

Question 34Dental medicine (content domains not enumerated in source)

Which suture technique is most appropriate for closing a large extraction socket after surgical removal of a mandibular third molar to approximate the flaps without tension?

  1. Continuous locking suture
  2. Simple interrupted suture Correct answer.
  3. Horizontal mattress suture
  4. Figure-of-eight suture

Explanation

Simple interrupted sutures are commonly used to approximate flaps after third molar surgery because they provide adequate closure with minimal tension and allow for easy removal. Figure-of-eight and horizontal mattress sutures can be used but may cause more tissue compression. Continuous locking sutures are less suitable for small intraoral sites.

Question 35Dental medicine (content domains not enumerated in source)

Which microorganism is most commonly associated with the initiation of dental caries?

  1. Candida albicans
  2. Porphyromonas gingivalis
  3. Actinomyces viscosus
  4. Streptococcus mutans Correct answer.

Explanation

Streptococcus mutans is a key cariogenic bacterium because it adheres to enamel, produces acids from fermentable carbohydrates, and synthesizes glucans from sucrose. Porphyromonas gingivalis is a periodontal pathogen, Actinomyces viscosus is associated with root caries but is not the primary initiator, and Candida albicans is a fungus.

Question 36Dental medicine (content domains not enumerated in source)

A patient with a history of angina reports chest pain during a dental appointment. After stopping treatment and administering sublingual nitroglycerin, the pain persists. Which action is most appropriate next?

  1. Administer epinephrine intramuscularly
  2. Place the patient in a supine position and monitor
  3. Give the patient aspirin and resume dental treatment
  4. Administer a second dose of nitroglycerin and call emergency services Correct answer.

Explanation

Persistent chest pain after one dose of nitroglycerin may indicate an acute myocardial infarction. A second dose can be given, but emergency medical services should be activated immediately. Aspirin may be advised by emergency personnel, but resuming treatment is inappropriate. Supine positioning may worsen symptoms, and epinephrine is not indicated.

Question 37Dental medicine (content domains not enumerated in source)

Which local anesthetic is most appropriate for a patient with a known allergy to ester-type anesthetics?

  1. Benzocaine
  2. Procaine
  3. Tetracaine
  4. Lidocaine Correct answer.

Explanation

Lidocaine is an amide-type local anesthetic and is appropriate for patients allergic to ester anesthetics because cross-reactivity between esters and amides is rare. Procaine, benzocaine, and tetracaine are all ester-type anesthetics and should be avoided in a patient with ester allergy.

Question 38Dental medicine (content domains not enumerated in source)

Which factor most increases the risk of bisphosphonate-related osteonecrosis of the jaw (BRONJ) after a dental extraction?

  1. Concomitant use of calcium supplements
  2. Oral bisphosphonate therapy for less than 1 year
  3. Intravenous bisphosphonate therapy for malignancy Correct answer.
  4. History of periodontal disease

Explanation

Intravenous bisphosphonates, especially in cancer patients, are associated with a much higher risk of BRONJ than oral bisphosphonates. The potency, route, and duration of therapy are key risk factors. Calcium supplements and periodontal disease are not primary risk factors for BRONJ.

Question 39Dental medicine (content domains not enumerated in source)

Which feature best distinguishes a gingival cyst of the adult from a lateral periodontal cyst?

  1. Gingival cyst of the adult occurs in the soft tissue, whereas lateral periodontal cyst is intraosseous. Correct answer.
  2. Gingival cyst of the adult is derived from odontogenic epithelium.
  3. Lateral periodontal cyst is always associated with a nonvital tooth.
  4. Lateral periodontal cyst is more common in the anterior mandible.

Explanation

Gingival cyst of the adult is a soft tissue cyst on the gingiva, while lateral periodontal cyst is an intraosseous lesion typically found in the lateral periodontal region of the mandibular premolar area. Both are odontogenic, and lateral periodontal cyst is usually associated with a vital tooth. Location (soft tissue vs. bone) is the key distinguishing feature.

Question 40Dental medicine (content domains not enumerated in source)

Which statement about the use of a mouthguard in sports dentistry is most accurate?

  1. Mouthguards are only necessary for contact sports such as boxing.
  2. Mouthguards should be worn only during competition, not practice.
  3. Custom-fabricated mouthguards provide better fit and protection than stock mouthguards. Correct answer.
  4. Stock mouthguards are as effective as custom-made guards.

Explanation

Custom-fabricated mouthguards, made from a dental impression, offer superior fit, comfort, and protection compared with stock or boil-and-bite types. They help absorb and distribute impact forces, reducing the risk of dental and orofacial injuries. Mouthguards are recommended for both contact and many non-contact sports, during practice and competition.

Question 41Dental medicine (content domains not enumerated in source)

Which principle best explains why a bevel is placed on the cavosurface margin of a Class III composite restoration?

  1. To increase the surface area for bonding and improve esthetics Correct answer.
  2. To reduce the need for enamel etching
  3. To allow for a thicker layer of composite
  4. To provide a butt joint for strength

Explanation

Beveling the cavosurface margin in enamel increases the surface area for etching and bonding, improves the blending of composite for esthetics, and creates a gradual transition. A butt joint is used in amalgam preparations, not typically for composite. Beveling does not reduce the need for etching or allow a thicker composite layer.

Question 42Dental medicine (content domains not enumerated in source)

Which cephalometric measurement is most commonly used to assess the anteroposterior relationship of the maxilla to the mandible?

  1. ANB angle Correct answer.
  2. Facial angle
  3. SNB angle
  4. SNA angle

Explanation

The ANB angle is the difference between the SNA and SNB angles and indicates the anteroposterior skeletal relationship between the maxilla and mandible. A positive ANB suggests a Class II skeletal pattern, while a negative ANB suggests Class III. SNA and SNB assess the position of the maxilla and mandible relative to the cranial base, respectively.

Question 43Dental medicine (content domains not enumerated in source)

Which condition is most likely to cause a generalized widening of the periodontal ligament space on a periapical radiograph?

  1. Dental caries
  2. Occlusal trauma Correct answer.
  3. Pulp stones
  4. Periapical abscess

Explanation

Occlusal trauma can lead to a generalized widening of the periodontal ligament space due to increased forces on the tooth. Dental caries does not typically cause PDL widening unless it leads to pulpal pathology. Periapical abscess causes a localized widening or radiolucency at the apex, and pulp stones are calcifications within the pulp chamber.

Question 44Dental medicine (content domains not enumerated in source)

Which dietary factor is most strongly associated with the development of dental erosion?

  1. Use of fluoride toothpaste
  2. High intake of dairy products
  3. Consumption of fibrous vegetables
  4. Frequent consumption of carbonated soft drinks Correct answer.

Explanation

Dental erosion is primarily caused by intrinsic or extrinsic acids. Carbonated soft drinks are a major extrinsic source of acid and, when consumed frequently, can lead to enamel demineralization. Dairy products and fibrous vegetables are not erosive, and fluoride toothpaste is protective.

Question 45Dental medicine (content domains not enumerated in source)

Which local anesthetic is most appropriate for a patient with a known allergy to amide-type anesthetics?

  1. Articaine
  2. Mepivacaine
  3. Lidocaine
  4. Procaine Correct answer.

Explanation

Procaine is an ester-type local anesthetic and can be used in patients allergic to amide anesthetics because cross-reactivity is rare. Lidocaine, mepivacaine, and articaine are all amide-type anesthetics and should be avoided. Allergy to amide anesthetics is uncommon but requires careful selection.

Question 46Dental medicine (content domains not enumerated in source)

Which statement best describes the mechanism of action of chlorhexidine gluconate as an adjunctive periodontal therapy?

  1. It promotes osteoblast differentiation and bone formation.
  2. It inhibits collagenase activity in the gingival crevicular fluid.
  3. It neutralizes endotoxins produced by periodontal pathogens.
  4. It binds to oral tissues and releases over time, disrupting bacterial cell membranes. Correct answer.

Explanation

Chlorhexidine is a cationic bisbiguanide that binds to negatively charged surfaces in the oral cavity and is released slowly, providing substantivity. It disrupts bacterial cell membranes, leading to bacterial death. It does not primarily inhibit collagenase, neutralize endotoxins, or promote bone formation.

Question 47Dental medicine (content domains not enumerated in source)

Which factor is most important in determining the prognosis of a tooth with a horizontal root fracture?

  1. Patient's age
  2. Presence of a restoration in the crown
  3. Type of trauma
  4. Location of the fracture relative to the alveolar crest Correct answer.

Explanation

The prognosis of a horizontal root fracture is best when the fracture is located in the apical third, as it is farther from the gingival sulcus and has a better blood supply. Coronal third fractures have a poorer prognosis due to communication with the oral cavity and increased risk of infection. The other factors are less predictive.

Question 48Dental medicine (content domains not enumerated in source)

Which feature is most characteristic of a dentigerous cyst on a radiograph?

  1. Ill-defined radiolucency at the apex of a nonvital tooth
  2. Well-defined radiolucency attached to the cementoenamel junction of an unerupted tooth Correct answer.
  3. Multilocular radiolucency with soap-bubble appearance
  4. Sunburst periosteal reaction

Explanation

A dentigerous cyst appears as a well-circumscribed radiolucency that surrounds the crown of an unerupted tooth and attaches at the cementoenamel junction. It is the most common developmental odontogenic cyst. The other options describe different lesions such as periapical granuloma, ameloblastoma, or osteosarcoma.

Question 49Dental medicine (content domains not enumerated in source)

Which principle of smile design is most important when selecting the width of maxillary anterior teeth for a fixed prosthesis?

  1. Bizygomatic width
  2. Golden proportion Correct answer.
  3. Incisal display
  4. Interpupillary distance

Explanation

The golden proportion (approximately 1.618:1) is often used as a guideline to determine the relative widths of maxillary anterior teeth to achieve an esthetically pleasing smile. Interpupillary distance and bizygomatic width can provide general guides but are less specific. Incisal display relates to tooth length and lip dynamics.

Question 50Dental medicine (content domains not enumerated in source)

Which is the most likely cause of a localized area of gingival recession on the facial aspect of a mandibular canine?

  1. Vitamin C deficiency
  2. Systemic antibiotic use
  3. Insufficient attached gingiva and thin buccal bone Correct answer.
  4. Fremitus from occlusal trauma

Explanation

Localized gingival recession on a mandibular canine is often due to a thin buccal bone plate and inadequate attached gingiva, which predispose to recession, especially with toothbrushing trauma. Occlusal trauma can contribute but is less commonly the primary cause of localized recession. Systemic factors and vitamin C deficiency typically cause more generalized effects.