Dentist Licensing Examination (Шүдний их эмчийн мэргэжлийн үйл ажиллагаа эрхлэх зөвшөөрлийн шалгалт, Mongolia)

A 32-year-old patient presents with sharp dental pain in the lower right first molar when drinking iced water. The pain subsides within 2 to 3 seconds after the cold stimulus is removed. Electric pulp testing elicits a responsive reading comparable to contralateral control teeth, and periapical radiographs reveal occlusal enamel-dentin radiolucency without periapical changes. What is the most accurate pulpal diagnosis?

• ASymptomatic irreversible pulpitis
• BReversible pulpitis
• CAsymptomatic irreversible pulpitis
• DPulp necrosis

During root canal instrumentation of a maxillary central incisor, the clinician aims to remove the inorganic smear layer produced during mechanical preparation prior to final obturation. Which irrigant is standardly used for this purpose?

• A2.5% Sodium hypochlorite (NaOCl)
• B0.2% Chlorhexidine gluconate
• C17% Ethylenediaminetetraacetic acid (EDTA)
• D3% Hydrogen peroxide (H2O2)

In adhesive restorative dentistry, what histological entity is formed by the micromechanical interdiffusion and polymerization of resin monomers within the acid-demineralized collagen mesh of coronal dentin?

• AThe hybrid layer (hybrid zone)
• BSmear layer plug
• CTertiary reactionary dentin
• DAprismatic enamel boundary

According to G.V. Black's classification of dental caries and cavity preparations, which class designates a carious lesion located on the proximal surface of a premolar or molar?

• AClass I
• BClass II
• CClass III
• DClass IV

An 8-year-old child presents with a non-vital maxillary central incisor following trauma 6 months ago. Radiographs confirm an immature tooth with divergent root walls, thin dentinal walls, and an open blunderbuss apex. Which biologically based treatment modality is currently preferred to promote continued root maturation and thickening of the dentinal walls?

• ATraditional long-term calcium hydroxide apexification
• BImmediate root canal obturation with warm gutta-percha
• CSurgical periapical curettage and retrograde amalgam filling
• DRegenerative endodontic procedure (revascularization)

During endodontic irrigation with 3% sodium hypochlorite using a non-vented needle, the patient experiences sudden excruciating pain, immediate diffuse facial swelling, and rapid ecchymosis of the overlying skin. What is the immediate and most critical in-chair clinical management step?

• AInject additional local anesthetic containing 1:50,000 epinephrine into the apex to cause…
• BTrephine the cortical bone surgically to establish external decompression
• CStop irrigation immediately, gently aspirate, irrigate copiously with sterile saline, and…
• DImmediately place an intracanal calcium hydroxide paste and seal with temporary cement

In operative resin composite restorations, the cavity configuration factor (C-factor) is defined as the ratio of bonded to unbonded restoration surfaces. Which cavity preparation represents the highest C-factor and therefore experiences the greatest polymerization shrinkage stress?

• AClass I occlusal cavity (C-factor about 5: five bonded walls, one free surface)
• BClass II mesio-occluso-distal (MOD) cavity (C-factor about 1)
• CClass IV incisal fracture restoration (C-factor well below 1)
• DDirect resin veneer on a flat labial surface (one bonded surface, C-factor well below 1)

A 40-year-old patient presents for evaluation of a pink discoloration near the cervical margin of tooth #21. Radiographs demonstrate an irregular radiolucency in the cervical third of the root where the root canal outline appears intact and visible through the radiolucency. Thermal pulp testing of tooth #21 gives a normal, vital response. What is the most probable diagnosis?

• AInternal inflammatory root resorption
• BExternal cervical resorption (invasive cervical resorption)
• CInternal replacement resorption
• DCervical root caries

Which bacterial species is most frequently isolated from root canals of previously endodontically treated teeth exhibiting persistent, secondary apical periodontitis, owing to its ability to survive starvation, high alkalinity, and penetrate deeply into dentinal tubules?

• APorphyromonas endodontalis
• BFusobacterium nucleatum
• CStreptococcus mutans
• DEnterococcus faecalis

What is the primary mechanism of adhesion between conventional glass ionomer cements (GIC) and tooth mineral (enamel and dentin)?

• AMechanical retention via macro-undercuts and dovetails
• BMicromechanical interlocking into phosphoric acid-etched microporosities
• CChemical chelation between carboxyl groups of polyacrylic acid and calcium ions in hydrox…
• DCovalent cross-linking between bis-GMA and type I collagen fibrils

A 55-year-old patient presents with mild biting discomfort on an endodontically treated mandibular first molar with a cast post and crown placed 5 years ago. Periodontal probing reveals an isolated, narrow 9 mm pocket on the mid-buccal root surface with all other pocket depths measuring 2 to 3 mm. Radiographs show a characteristic 'halo' or 'J-shaped' radiolucency extending from the lateral root surface around the apex. What is the definitive diagnosis and recommended management?

• AVertical root fracture; tooth extraction is indicated
• BSecondary occlusal trauma; perform selective occlusal adjustment
• CEndodontic-periodontal combined lesion; perform periodontal flap debridement and systemic…
• DPeriapical cyst recurrence; perform surgical root-end resection and MTA retrofilling

During deep caries excavation on an asymptomatic mandibular molar in a 20-year-old patient, a mechanical pin-point pulp exposure (<1 mm) occurs in a completely isolated, clean field with bleeding controlled within 2 minutes. Which material is considered the gold standard for direct pulp capping to stimulate dentin bridge formation with minimal pulpal inflammation?

• AZinc oxide-eugenol (ZOE) cement
• BPolycarboxylate cement
• CAcid-etched resin bonding adhesive
• DMineral trioxide aggregate (MTA) or hydraulic calcium silicate

When shaping curved root canals with engine-driven nickel-titanium (NiTi) rotary instruments, separation of a file occurring without visible unwinding or plastic deformation after rotating in a severe curvature is primarily caused by:

• ATorsional stress exceeding the ultimate shear strength
• BExcessive apical push force binding the tip in the canal
• CCyclic fatigue (flexural fatigue)
• DCorrosion from prolonged immersion in sodium hypochlorite

In the internal 'walking bleach' technique for non-vital discolored endodontically treated teeth, what critical safety step must be performed prior to placing the bleaching paste to prevent external invasive cervical resorption?

• APlacing a 2 mm barrier of glass ionomer or resin-modified glass ionomer cement over the g…
• BEtching the internal dentin walls with 37% phosphoric acid for 60 seconds
• CSoaking the pulp chamber with 10% sodium ascorbate solution
• DSealing the access with gutta-percha directly flush with the incisal edge

A clinical examination of a 16-year-old patient reveals a chalky, opaque white spot lesion along the gingival margin of the facial surface of tooth #11. Tactile assessment reveals a rough, matte surface that retains dental plaque. How should this lesion be classified regarding disease activity and management?

• AArrested caries lesion; no treatment or fluoride needed
• BDevelopmental enamel hypoplasia; requires immediate porcelain veneer
• CSevere dentinal decay; requires immediate Class V cavity preparation and composite filling
• DActive non-cavitated caries lesion; indicated for remineralization therapy, biofilm contr…

Bioceramic (calcium silicate-based) root canal sealers have gained widespread use in single-cone obturation techniques. What unique physicochemical property of bioceramic sealers facilitates this approach compared to conventional epoxy-resin sealers?

• ASignificant volumetric contraction upon setting that draws gutta-percha tightly against t…
• BComplete dissolution within 6 months to allow osseous tissue ingrowth into the canal
• CRapid setting within 30 seconds upon contact with endodontic EDTA
• DHydrophilic setting reaction with slight volumetric expansion and bioactivity producing h…

A 24-year-old patient presents with asymptomatic deep occlusal caries on a mandibular molar. Radiographs show caries penetrating into the inner third of the dentin with an intact pulpal barrier and no periapical pathology. Pulp sensibility is normal. According to current minimally invasive consensus, what is the recommended excavation strategy to avoid pulp exposure?

• ANon-selective excavation to hard dentin across the entire cavity floor
• BImmediate prophylactic pulpotomy followed by stainless steel crown
• CSelective removal to soft or firm dentin over the pulp wall, leaving leathery/soft cariou…
• DComplete excavation followed by temporary zinc phosphate cement placement

What is the detrimental consequence of moisture (saliva or water) contamination of zinc-containing dental amalgam alloys during trituration or condensation?

• AComplete loss of radiopacity on follow-up radiographs
• BInstantaneous dissolution of the mercury-alloy matrix
• CDelayed expansion (secondary expansion) caused by hydrogen gas generation
• DPremature conversion of gamma-1 phase into pure silver crystals

A 48-year-old patient reports brief, sharp pain when biting down on crusty bread on their maxillary first molar, which has a moderate MOD amalgam restoration. Thermal testing is normal, and no periapical radiolucency is seen. Pain is sharply elicited upon the sudden release of biting pressure on an individual cusp using a Tooth Slooth. What is the most likely condition?

• AAcute apical periodontitis
• BTrigeminal neuralgia
• CCemental tear
• DCracked tooth syndrome

Which rubber dam clamp design is specifically engineered for partially erupted or irregularly shaped molars, featuring subgingivally directed jaws that seat apical to the cervical constriction?

• AClamp #9 (butterfly clamp with flat jaws)
• BWingless clamp with festooned, subgingival jaws (e.g., W8A)
• CClamp #00 (small flat-jawed clamp for small premolars)
• DClamp #212 (dual-bow cervical retraction clamp for Class V)

In surgical exodontia, which physical mechanical principle is primarily utilized by a straight dental elevator (e.g., Coupland or Bein elevator) when inserted perpendicularly or wedged into the periodontal ligament space between the alveolar bone crest and the root?

• AWedge principle and first-class lever principle
• BWheel-and-axle principle exclusively
• CTensile elongation principle
• DThird-class lever principle

A panoramic radiograph shows an impacted mandibular third molar whose crown is partly covered by the anterior border of the ramus (the space between the ramus and the second molar is smaller than the third molar's mesiodistal width). The highest point of the impacted tooth lies below the occlusal plane but above the cervical line of the second molar. How is this impaction classified under Pell and Gregory?

• AClass I, Position A
• BClass III, Position C
• CClass II, Position B
• DClass II, Position C

A 35-year-old patient presents to the emergency department with severe dysphagia, drooling, trismus, elevated 'woody' bilateral submandibular swelling, and superior-posterior elevation of the tongue causing stridor. Which fascial space infection (Ludwig's angina) is this, and what is the immediate life-saving priority?

• AUnilateral buccal space abscess; immediate outpatient extraction under local anesthesia
• BRapidly spreading bilateral cellulitis of the submandibular, sublingual, and submental sp…
• CCanine space infection; needle aspiration and outpatient prescription of oral amoxicillin
• DPeritonsillar abscess; cold saline gargles and discharge home

A 28-year-old female smoker presents 3 days after an uncomplicated extraction of tooth #38 with throbbing, foul-tasting, severe pain radiating to her ear. Clinical examination reveals an empty extraction socket devoid of a blood clot, exposed sensitive bone walls, and halitosis without fever or swelling. What is the standard management for this condition (alveolar osteitis)?

• AVigorously curette the socket walls to stimulate new bleeding and bone formation
• BPerform surgical flap elevation, socket decortication, and primary closure
• CPrescribe high-dose prophylactic IV clindamycin and hospitalize the patient
• DGently irrigate the socket with warm physiological saline, place an analgesic dressing (e…

During the extraction of a deeply seated maxillary first molar, a root tip is removed and the clinician notes a small 3 mm oroantral communication (OAC) with healthy, non-infected sinus mucosa. What is the appropriate clinical management?

• APlace a collagen sponge or hemostatic gelatin sponge in the socket, stabilize with a figu…
• BPerform an immediate Caldwell-Luc surgical procedure to obliterate the maxillary sinus
• CPack the socket tightly with non-resorbable petroleum gauze and leave for 4 weeks
• DInstruct the patient that no action is necessary and encourage vigorous nose-blowing to c…

A healthy 60 kg adult requires surgical extraction of multiple teeth. You are administering 2% lidocaine with 1:100,000 epinephrine. Based on the maximum recommended dose (MRD) of 7.0 mg/kg (up to an absolute ceiling of 500 mg), what is the maximum number of standard 1.8 mL cartridges that can be safely administered to this patient?

• A7 cartridges
• B11 cartridges
• C16 cartridges
• D20 cartridges

When administering a conventional inferior alveolar nerve block (IANB) using the Halsted technique, where should the needle be inserted relative to anatomical landmarks?

• ADirectly into the retromolar trigone at the level of the maxillary occlusal plane
• B1 cm inferior to the mandibular occlusal plane along the anterior border of the ramus
• CIn the pterygomandibular depression, approximately 6 to 10 mm above the mandibular occlus…
• DMedial to the palatoglossal arch pointing directly toward the uvula

A 42-year-old male presents with painless swelling of the posterior mandibular body and angle. Panoramic radiograph reveals a large, well-defined, multilocular radiolucency with a 'soap-bubble' appearance causing cortical expansion, thinning, and root resorption of adjacent molars. What is the most likely diagnosis, and what is the definitive surgical approach?

• AConventional ameloblastoma; en bloc resection with 1 to 1.5 cm clear bony margins
• BTraumatic simple bone cyst; surgical curettage to stimulate bleeding
• CPeriapical granuloma; non-surgical root canal treatment
• DDentigerous cyst; simple decompression and marsupialization

An odontogenic keratocyst (OKC) is known for its aggressive clinical behavior and high recurrence rate. Histologically, which characteristic feature distinguishes an OKC from other odontogenic cysts?

• ANon-keratinized stratified squamous epithelium with mucous-secreting goblet cells and cil…
• BAbundant cholesterol clefts surrounded by multinucleated foreign body giant cells in the…
• CThick fibrovascular wall containing prominent Rushton bodies without basal cell palisading
• DA uniform parakeratinized stratified squamous epithelial lining 6 to 8 cells thick, with…

A patient experiences continuous capillary oozing from an extraction socket 2 hours post-operatively. What is the immediate first-line clinical measure to control the hemorrhage in the dental chair?

• AAdminister an intravenous transfusion of fresh frozen plasma
• BPlace a folded damp gauze pack directly over the socket and have the patient bite down fi…
• CInject 1:1,000 epinephrine directly into the marrow bone of the socket
• DCauterize the entire alveolar bone crest using an electrocautery loop

When designing a mucoperiosteal flap for surgical removal of an impacted tooth or periapical surgery, which principle must be strictly adhered to prevent flap necrosis and dehiscence?

• AThe base of the flap must be narrower than the free gingival margin to permit stretching
• BVertical releasing incisions must be placed directly across the mid-radicular prominence…
• CThe base of the flap must be wider than the apex to ensure adequate microvascular perfusi…
• DThe flap must split the periosteum so that only mucosa is elevated

According to the American Association of Oral and Maxillofacial Surgeons (AAOMS) guidelines, which diagnostic criterion defines Medication-Related Osteonecrosis of the Jaw (MRONJ)?

• AExposed necrotic bone or an intraoral/extraoral fistula probing to bone in the maxillofac…
• BAcute bone infection presenting with fever and sequestrum formation within 7 days of star…
• CExposed alveolar bone following radiation therapy to the jaws exceeding 60 Gy in the abse…
• DAny painful extraction socket in an oncology patient regardless of bone exposure

A patient with an untreated canine space abscess secondary to maxillary anterior tooth infection develops severe periorbital edema, exophthalmos (proptosis), ptosis, dilated sluggish pupils, and paralysis of extraocular eye movements. Which life-threatening intracranial venous complication has developed?

• ASuperior sagittal sinus thrombosis
• BTransverse sinus thrombophlebitis
• CAcute subarachnoid hemorrhage
• DCavernous sinus thrombosis

Why is the use of high-speed air-turbine dental handpieces strictly contraindicated during surgical tooth sectioning and alveolar bone guttering?

• AThe diamond burs dull too rapidly when cutting cortical bone
• BExhaust air propelled into the surgical wound can cause life-threatening tissue emphysema…
• CThe rotational speed is insufficient to penetrate tooth enamel
• DAir turbines generate electrical fields that interfere with ECG monitors

What is the tissue of origin for the epithelial lining of a radicular (periapical) cyst?

• AReduced enamel epithelium
• BDental lamina remnants (rests of Serres)
• CEpithelial rests of Malassez in the periodontal ligament
• DNasopalatine duct remnant epithelium

During the extraction of an asymptomatic, non-infected mandibular second molar, a 2.5 mm root tip fractures deep in the socket. The pre-operative radiograph demonstrates that the root tip is in direct contact with the superior cortical border of the inferior alveolar canal. After 15 minutes of unsuccessful gentle closed retrieval, what is the most appropriate management strategy?

• ALeave the root tip in situ, inform the patient, document the event, and arrange radiograp…
• BUse a surgical bur aggressively down the socket to pulverize the root tip without visual…
• CDrive a straight elevator forcefully with a mallet into the periodontal space
• DImmediately schedule a submandibular extraoral approach to resect the mandibular angle

Comparing oral leukoplakia and oral erythroplakia, which statement accurately reflects their clinical significance and malignant transformation risk?

• ALeukoplakia has a higher rate of dysplasia and malignant transformation than erythroplakia
• BErythroplakia is always benign and represents simple candida infection
• CBoth lesions carry an identical 5% risk of malignant transformation
• DErythroplakia has a substantially higher risk of severe epithelial dysplasia, carcinoma i…

A 22-year-old patient presents with acute trismus, halitosis, and severe localized pain surrounding a partially erupted mandibular left third molar. The operculum is erythematous, edematous, and purulent exudate is expressed upon palpation, but there is no facial swelling or systemic fever. What is the immediate treatment of choice?

• AImmediate surgical extraction of the tooth under local anesthesia despite acute inflammat…
• BGentle debridement and irrigation of the sub-opercular space with warm saline or 0.12% ch…
• CImmediate radical laser excision of the entire retromolar pad
• DIntravenous administration of triple antibiotic therapy in a hospital ward

A 65-year-old female presents with severe, unilateral, lancinating, 'lightning-bolt' pain across her right cheek and lower jaw. The episodes last only 5 to 10 seconds and are reliably triggered by light mechanical touch, such as brushing her teeth, applying makeup, or a light breeze. All teeth test vital with no radiographic pathology. What is the diagnosis and initial first-line medical therapy?

• AAtypical odontalgia; prescribe high-dose opioids
• BMyofascial pain dysfunction; place a stabilization occlusal splint
• CTrigeminal neuralgia (tic douloureux); initiate carbamazepine therapy
• DTemporal arteritis; administer intravenous heparin

In which major salivary gland and duct does the overwhelming majority (80% to 90%) of salivary calculi (sialolithiasis) occur, and why?

• ASubmandibular gland (Wharton's duct), due to uphill salivary flow, higher mucin content,…
• BParotid gland (Stensen's duct), due to purely serous secretions and acidic pH
• CSublingual gland (Bartholin's duct), due to its small diameter and absence of ductal bran…
• DMinor salivary glands of the lower lip, due to frequent biting trauma

According to the Kennedy classification of partially edentulous dental arches, how is an arch characterized that presents with bilateral edentulous areas located posterior to the remaining natural teeth?

• AKennedy Class II
• BKennedy Class I
• CKennedy Class III
• DKennedy Class IV

What is the minimum required vertical height of the floor of the mouth (distance between the active lingual sulcus and the free gingival margin) to utilize a conventional mandibular lingual bar major connector?

• A3 mm
• B5 mm
• C7 to 8 mm
• D12 to 14 mm

In a Kennedy Class I removable partial denture (RPD), where should indirect retainers be positioned to most effectively neutralize rotational dislodging forces around the primary fulcrum line when the patient eats sticky foods?

• AAs far anterior to and perpendicular to the primary fulcrum line as possible
• BDirectly on the distal occlusal rests of the primary abutment molars
• CAs far posterior to the fulcrum line on the distal extension saddles as possible
• DOn the lingual surfaces of the most posterior molar abutments

When preparing a posterior tooth for an all-ceramic (lithium disilicate or zirconia) full-coverage crown, which finish line configuration is recommended to minimize stress concentration and provide adequate material bulk?

• AKnife-edge (feather-edge) finish line
• BBeveled shoulder finish line with a 45-degree metal collar
• CUndercut groove finish line
• DRounded deep chamfer or radial shoulder with rounded internal line angles

What is the anatomical definition and average combined vertical dimension of the 'biological width' (supracrestal tissue attachment) described by Gargiulo et al.?

• ADepth of the gingival sulcus alone; approximately 0.5 mm
• BThickness of attached keratinized gingiva; approximately 3.5 mm
• CDistance between the cementoenamel junction and the mucogingival junction; approximately…
• DCombined dimension of the junctional epithelium (~0.97 mm) and supracrestal connective ti…

Which elastomeric dental impression material exhibits the highest dimensional stability, allowing delayed pouring or multiple accurate stone casts to be poured days after impression taking without significant distortion?

• AIrreversible hydrocolloid (alginate)
• BPolysulfide (rubber base)
• CAddition silicone (polyvinyl siloxane / PVS)
• DCondensation silicone