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Eidgenössisches Examen Zahnmedizin study materials
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Eidgenössisches Examen Zahnmedizin practice questions

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Question 1Caries activity, mineral balance and restorative material mechanisms

What is the micromechanical bonding purpose of enamel acid conditioning in an appropriate resin adhesive system, without specifying one concentration or exposure time for every product?

  1. Selectively dissolving hydroxyapatite crystals to create micro-porosities for resin tag micromechanical retention Correct answer.
  2. Completely dissolving the collagen network within the dentin matrix
  3. Sterilizing the cavity floor to eliminate anaerobic pulp bacteria
  4. Forming a covalent chemical bond between calcium phosphate and composite monomers

Explanation

Acid etching of enamel with 35-37% phosphoric acid selectively dissolves prism cores or prism peripheries, creating high-energy micro-porosities (depth of 10-30 micrometers). Fluid resin bonding agents penetrate these micro-irregularities by capillary action, polymerizing to form micromechanical resin tags.

Question 2Caries activity, mineral balance and restorative material mechanisms

In contemporary adhesive systems, what defines the 'hybrid layer' originally described by Nakabayashi?

  1. The micromechanical interdiffusion zone formed by resin monomers polymerizing within demineralized dentin collagen fibrils Correct answer.
  2. The chemical bond between glass ionomer polyacrylic acid and hydroxyapatite
  3. The layer of residual cutting debris compacted into dentinal tubules (smear plug)
  4. The interface formed between the glass filler particles and silane coupling agent

Explanation

The hybrid layer (zone d'hybridation) is formed when adhesive hydrophilic monomers (e.g., HEMA, Bis-GMA) infiltrate the exposed collagen fibril meshwork produced by acid demineralization of dentin and polymerize in situ, creating a molecular-level mechanical interlocking between tooth structure and restorative resin.

Question 3Caries activity, mineral balance and restorative material mechanisms

During a routine clinical examination under clean, dry conditions with adequate lighting, a clinician observes an opaque, chalky white spot lesion (mancha blanca) on the cervical third of the facial surface of tooth 11. What is the fundamental histological characteristic of this non-cavitated early carious lesion?

  1. Total cavitary collapse of the outer enamel with exposed infected tubular dentin
  2. Subsurface demineralization with an intact, relatively hypermineralized external surface layer Correct answer.
  3. Complete pulp chamber obliteration by secondary reparative dentin
  4. Extensive bacterial colonization of the odontoblastic layer with micro-abscess formation

Explanation

Histologically, the incipient enamel carious lesion (white spot lesion) is characterized by subsurface demineralization (body of the lesion exhibiting 5% to 25% pore volume) beneath a relatively intact and well-mineralized outer surface zone (~30-50 micrometers thick), maintained by constant surface remineralization dynamics from saliva.

Question 4Endodontic diagnosis, disinfection, and structural prognosis

What does a conventional electric pulp test primarily assess?

  1. Neural response rather than direct pulpal blood flow Correct answer.
  2. The amount of calcium in root dentin
  3. The exact number of living pulp cells
  4. The diameter of the apical foramen

Explanation

Electric pulp testing elicits a sensory response and must be interpreted with other findings because it does not directly demonstrate pulpal circulation.

Question 5Endodontic diagnosis, disinfection, and structural prognosis

A recently traumatized immature permanent incisor does not respond to a sensibility test. What is the best interpretation?

  1. The tooth necessarily has a vertical root fracture
  2. Immediate extraction is required in every case
  3. The result proves that apical growth has stopped permanently
  4. One negative test alone does not establish pulp necrosis Correct answer.

Explanation

After trauma and in immature teeth, neural responsiveness may be unreliable; diagnosis should integrate history, serial testing, examination, and imaging.

Question 6Periodontal diagnosis, risk, and long-term stability

What finding most directly distinguishes periodontitis from plaque-induced gingivitis on an otherwise intact periodontium?

  1. Redness limited to the gingival margin
  2. Bleeding after gentle probing alone
  3. Loss of periodontal attachment attributable to periodontal disease Correct answer.
  4. Visible supragingival plaque alone

Explanation

Periodontitis involves destruction of the tooth-supporting attachment apparatus; bleeding and redness alone can occur with reversible gingival inflammation.

Question 7Periodontal diagnosis, risk, and long-term stability

A site has a probing depth of 4 mm and gingival recession of 2 mm from the cementoenamel junction. What is its clinical attachment level?

  1. 8 mm
  2. 6 mm Correct answer.
  3. 4 mm
  4. 2 mm

Explanation

With the gingival margin apical to the cementoenamel junction, clinical attachment loss is the probing depth plus recession.

Question 8Restore function while respecting structure and supporting tissues

How do retention and resistance form differ for a conventional crown preparation?

  1. Retention opposes removal along the path of insertion; resistance opposes other dislodging forces Correct answer.
  2. Retention is the same as pulpal vitality
  3. Both refer only to the shade of ceramic
  4. Resistance means the tooth has no caries

Explanation

Preparation geometry should help resist both withdrawal and functional tipping; these related mechanical requirements are distinct from esthetics or the biological state of the tooth.

Question 9Restore function while respecting structure and supporting tissues

What is the purpose of a ferrule in restoring a structurally compromised endodontically treated tooth?

  1. It makes every root fracture repairable
  2. The ferrule sterilizes the root canal
  3. A band of remaining coronal tooth structure helps resist functional fracture stresses Correct answer.
  4. A post automatically replaces the need for sound tooth structure

Explanation

A ferrule uses remaining tooth structure encircled by the restoration to improve stress management; prognosis still depends on the overall tooth and restorative design.

Question 10Surgical assessment, anatomy, bleeding, and complications

Which sensory deficit most directly suggests inferior alveolar nerve involvement after mandibular surgery?

  1. Altered sensation of the lower lip and chin Correct answer.
  2. Loss of vision in one eye
  3. Loss of shoulder abduction
  4. Isolated numbness of the forehead

Explanation

The inferior alveolar nerve continues through the mental nerve to supply the lower lip and chin, making these areas useful for sensory assessment.

Question 11Surgical assessment, anatomy, bleeding, and complications

Which structure is particularly relevant to altered general sensation of the tongue after lower third-molar surgery?

  1. Phrenic nerve
  2. Greater occipital nerve
  3. Lingual nerve Correct answer.
  4. Optic nerve

Explanation

The lingual nerve supplies general sensation to the anterior tongue and lies near the mandibular third-molar region, creating a recognized surgical risk.

Question 12Describe lesions, construct differentials, and obtain a diagnosis

A persistent indurated ulcer on the lateral tongue has no clear traumatic explanation. What is the most appropriate next diagnostic priority?

  1. Observation indefinitely without documentation
  2. Prompt specialist assessment and biopsy planning Correct answer.
  3. Repeated polishing of adjacent intact teeth as definitive management
  4. Reassurance that all painless ulcers are harmless

Explanation

A persistent unexplained indurated ulcer is a concerning finding; a timely tissue diagnosis or appropriate referral takes priority over unsupported reassurance.

Question 13Describe lesions, construct differentials, and obtain a diagnosis

What does the clinical term leukoplakia describe?

  1. A predominantly white oral patch diagnosed after excluding other definable causes Correct answer.
  2. Any white material that wipes off the mucosa
  3. A guaranteed benign response to spicy food
  4. A histologic diagnosis of invasive carcinoma in every case

Explanation

Leukoplakia is a clinical exclusion diagnosis for a white lesion; histopathology is needed when indicated to evaluate dysplasia or another underlying process.

Question 14Care for the developing dentition with risk-based decisions

Why does the frequency of fermentable carbohydrate exposure matter in caries risk assessment?

  1. Repeated acid challenges can limit the time available for remineralization Correct answer.
  2. Only the color of the food affects caries
  3. Frequency has no effect if total daily intake is unchanged
  4. All carbohydrates permanently sterilize plaque

Explanation

Caries risk reflects the balance of repeated demineralizing challenges and protective factors, so exposure pattern is relevant alongside quantity, fluoride, and biofilm control.

Question 15Care for the developing dentition with risk-based decisions

What is the main anticaries purpose of topical fluoride varnish?

  1. Change primary teeth into permanent teeth
  2. Support remineralization and reduce susceptibility to demineralization Correct answer.
  3. Remove every established cavitated lesion
  4. Replace all need for plaque control

Explanation

Topical fluoride supports mineral balance at the tooth surface, but its use complements risk reduction and does not mechanically restore a cavitated defect.

Question 16Diagnose the cause before selecting mechanics or appliances

What biological process permits orthodontic tooth movement under controlled force?

  1. Remodeling of the periodontal ligament and adjacent alveolar bone Correct answer.
  2. Permanent dissolution of all root cementum
  3. Immediate stretching of enamel into a new shape
  4. Movement of the crown while the root remains fixed forever

Explanation

Orthodontic force produces tissue responses in the periodontal ligament and surrounding bone, allowing movement through coordinated remodeling rather than reshaping enamel.

Question 17Diagnose the cause before selecting mechanics or appliances

What does anchorage describe in orthodontic mechanics?

  1. The color of the brackets
  2. Resistance to unwanted movement of supporting teeth or structures Correct answer.
  3. A guarantee that no tooth will move
  4. The amount of fluoride in a mouth rinse

Explanation

Anchorage planning controls where reaction forces are expressed, helping achieve intended movement while limiting undesirable displacement of the supporting unit.

Question 18Imaging justification, geometry, and responsible interpretation

What is the principal justification for prescribing dental imaging?

  1. Replacement of history taking
  2. A clinical question for which the expected diagnostic benefit outweighs the imaging risk Correct answer.
  3. The patient's request for the largest image volume regardless of need
  4. A fixed need for every possible image at every visit

Explanation

Imaging selection follows clinical assessment and a defined diagnostic purpose, rather than indiscriminate exposure or a belief that more images always improve care.

Question 19Imaging justification, geometry, and responsible interpretation

When CBCT is indicated, what field of view should generally be chosen?

  1. The smallest field sufficient to answer the clinical question Correct answer.
  2. A field that intentionally excludes the lesion
  3. The largest available field for every patient
  4. A field selected only by the patient's height

Explanation

Field selection balances diagnostic coverage against unnecessary exposure, while still including the anatomy required to answer the specific clinical question.

Question 20Read evidence and design programs for the population

What does the prevalence of untreated caries describe in a defined survey population?

  1. Only new cases arising during future follow-up
  2. The probability that treatment will succeed
  3. The number of restorations placed per clinician
  4. The proportion with untreated caries at the specified assessment time Correct answer.

Explanation

Prevalence describes existing disease within a defined population and time frame, so its interpretation depends on the case definition and who was assessed.

Question 21Read evidence and design programs for the population

What does disease incidence measure in a longitudinal study?

  1. All cases ever diagnosed without a time reference
  2. Only the severity of disease at baseline
  3. The percentage of participants satisfied with the clinic
  4. New cases developing among the population at risk over a defined period Correct answer.

Explanation

Incidence concerns the occurrence of new disease over time among people initially at risk, distinguishing it from the burden of existing cases.

Question 22Prevent infection and prepare for physiological deterioration

Why can pulse oximetry alone be insufficient to detect early hypoventilation during sedation?

  1. Oxygen saturation may remain acceptable while ventilation deteriorates, especially with supplemental oxygen Correct answer.
  2. The monitor replaces continuous clinical observation
  3. Pulse oximetry directly measures exhaled carbon dioxide
  4. Normal saturation proves the airway cannot obstruct

Explanation

Oxygenation and ventilation are different physiological functions, so monitoring plans must not assume that a saturation reading provides a complete assessment of breathing.

Question 23Prevent infection and prepare for physiological deterioration

What information does capnography principally provide during procedural sedation?

  1. A direct measurement of pulpal blood flow
  2. The exact depth of dental caries
  3. The total number of viable oral bacteria
  4. Exhaled carbon dioxide patterns that help assess ventilation Correct answer.

Explanation

Capnography provides breath-related carbon dioxide information and waveform trends, supporting recognition of ventilatory problems alongside other monitoring and direct patient assessment.

Question 24Periodontal diagnosis, risk, and long-term stability

A 55-year-old patient presents for maintenance 4 years after receiving an implant-supported crown at site 36. Clinical examination reveals bleeding on gentle probing (BOP) with small amounts of suppuration, a probing depth of 6 mm (increased from 3 mm at baseline prosthesis delivery), and periapical radiography confirms 2.5 mm of progressive marginal bone loss beyond initial remodeling. What is the correct diagnosis according to the 2018 EFP/AAP classification?

  1. Peri-implant health with normal physiological remodeling
  2. Peri-implantitis Correct answer.
  3. Peri-implant mucositis
  4. Implant osseointegration failure requiring immediate trephine explantation

Explanation

Peri-implantitis is characterized by inflammation in the peri-implant mucosa (BOP and/or suppuration), increased probing pocket depths compared to baseline, and progressive marginal bone loss beyond initial biological remodeling. Peri-implant mucositis, in contrast, exhibits mucosal bleeding on probing without any loss of supporting marginal bone.

Question 25Endodontic diagnosis, disinfection, and structural prognosis

A 35-year-old patient presents with sharp, lingering pain on tooth 47 provoked by cold liquids that persists for more than 30 seconds after stimulus removal. The tooth has a deep occlusal composite restoration with recurrent marginal caries. Percussion test is completely normal and periapical radiography reveals no apical radiolucency. According to the American Association of Endodontists (AAE) diagnostic criteria, what are the pulpal and apical diagnoses?

  1. Pulpal: Symptomatic Irreversible Pulpitis; Apical: Normal Apical Tissues Correct answer.
  2. Pulpal: Reversible Pulpitis; Apical: Symptomatic Apical Periodontitis
  3. Pulpal: Pulp Necrosis; Apical: Asymptomatic Apical Periodontitis
  4. Pulpal: Previously Initiated Therapy; Apical: Acute Apical Abscess

Explanation

The lingering provoked pain and recurrent caries are most consistent with the stated AAE category of symptomatic irreversible pulpitis, while the normal percussion and apical findings support normal apical tissues. Clinical categories organize the working diagnosis; a duration alone does not prove microscopic irreversibility or select every treatment. Integrate the complete assessment and current options.

Question 26Endodontic diagnosis, disinfection, and structural prognosis

A patient presents with severe spontaneous, throbbing pain in the right maxilla localized to tooth 16. The tooth is exquisitely tender to light vertical percussion and palpation over the buccal apex. Sensibility testing to cold (Endo-Ice) and electric pulp testing produce no response. Periapical radiography shows widening of the periodontal ligament space around the mesiobuccal root without a well-defined circular radiolucency. What are the correct AAE pulpal and apical diagnoses?

  1. Pulpal: Normal Pulp; Apical: Chronic Apical Abscess
  2. Pulpal: Pulp Necrosis; Apical: Symptomatic Apical Periodontitis Correct answer.
  3. Pulpal: Symptomatic Irreversible Pulpitis; Apical: Normal Apical Tissues
  4. Pulpal: Reversible Pulpitis; Apical: Condensing Osteitis

Explanation

The combination of absent responses, the clinical history and marked apical tenderness most strongly supports pulp necrosis with symptomatic apical periodontitis among these options. Neural nonresponse alone is not a direct test of blood supply or an infallible confirmation. Compare controls, technical conditions, trauma history and the wider examination before a real treatment decision.

Question 27Endodontic diagnosis, disinfection, and structural prognosis

What is the primary antimicrobial mechanism of non-setting calcium hydroxide (Ca(OH)₂) when used as an interappointment intracanal medicament?

  1. Direct oxidation of bacterial lipids through extreme low acidic pH (pH 2.0)
  2. High alkalinity (pH ~12.5) that releases hydroxyl ions (OH⁻), which damage bacterial cytoplasmic membranes, denature essential enzymes, and neutralize bacterial endotoxins (Lipopolysaccharides [LPS]) Correct answer.
  3. Rapid release of free chlorine gas to chemically vaporize biofilm
  4. Formation of an impermeable gold barrier across the apical third

Explanation

Calcium hydroxide dissociates into calcium and hydroxide ions, producing a strongly alkaline environment. Hydroxide ions are not hydroxyl free radicals. The alkaline chemistry can damage susceptible microbial components and modify relevant endotoxin activity, but it does not guarantee elimination of every organism or compensate for inaccessible anatomy and inadequate infection control.

Question 28Restore function while respecting structure and supporting tissues

A patient is missing teeth 38, 37, 36, 46, 47, and 48, creating bilateral edentulous areas located posterior to the remaining natural teeth. According to Kennedy's Classification of partially edentulous arches, what is this classification?

  1. Kennedy Class IV
  2. Kennedy Class I Correct answer.
  3. Kennedy Class II
  4. Kennedy Class III

Explanation

Kennedy Class I describes bilateral edentulous areas located posterior to the remaining natural standing teeth (bilateral distal extension). Kennedy Class II is a unilateral distal extension; Class III is a unilateral bounded edentulous space; Class IV is a single bounded edentulous area crossing the midline anterior to remaining teeth.

Question 29Restore function while respecting structure and supporting tissues

In digital dentistry and computer-aided design / computer-aided manufacturing (CAD/CAM), what is the function of a 'Scan Body' (scan post) during intraoral optical scanning for implant restorations?

  1. It serves as a permanent titanium abutment that remains in the mouth permanently
  2. It dissolves the surrounding gingiva to expose the alveolar bone for photography
  3. It delivers local anesthetic directly to the implant fixture during scanning
  4. It is a precision-engineered geometric marker attached to the implant fixture that allows the CAD software to accurately identify the 3D spatial position, depth, and rotational orientation of the implant Correct answer.

Explanation

A scan body is a prefabricated polymer, titanium, or PEEK landmark attached to the implant during intraoral or laboratory optical scanning. Its precisely calibrated geometric surfaces and height enable the CAD software's library alignment algorithm to calculate the exact three-dimensional spatial coordinates, depth, angulation, and hex rotation of the underlying implant platform.

Question 30Describe lesions, construct differentials, and obtain a diagnosis

A routine panoramic radiograph of a 17-year-old patient reveals a well-circumscribed, unilocular, pericoronal radiolucency attached symmetrically to the cementoenamel junction (CEJ) of an impacted mandibular third molar (tooth 48). The follicle measures 5 mm in width. What is the most likely diagnosis?

  1. Radicular cyst attached to a non-vital tooth
  2. Stafne bone defect of the mandibular body
  3. Dentigerous (follicular) cyst originating from the accumulation of fluid between the reduced enamel epithelium and the crown of an unerupted tooth Correct answer.
  4. Malignant osteosarcoma of the mandible

Explanation

A Dentigerous (follicular) cyst is the second most common odontogenic cyst, developing from fluid accumulation between the inner/outer layers of the reduced enamel epithelium and the crown of an unerupted tooth. It presents radiographically as a well-defined unilocular radiolucency attached precisely at the cementoenamel junction (CEJ) of an impacted tooth (follicular space > 3–4 mm).

Question 31Describe lesions, construct differentials, and obtain a diagnosis

What fundamental pathophysiological and histopathological differences distinguish Pemphigus Vulgaris from Mucous Membrane Pemphigoid (Cicatricial Pemphigoid)?

  1. Pemphigus vulgaris is an allergic reaction to latex, while pemphigoid is a bacterial infection of bone
  2. Pemphigus vulgaris is characterized by IgG autoantibodies targeting desmoglein 3 within desmosomes, causing intraepithelial acantholysis and flaccid blisters with a positive Nikolsky sign; Mucous Membrane Pemphigoid involves autoantibodies targeting hemidesmosomes (e.g., BP180) in the basement membrane zone, causing subepithelial detachment and tense blisters that heal with scarring Correct answer.
  3. Pemphigus vulgaris involves subepithelial blistering only on the skin, while pemphigoid affects exclusively the enamel crystals
  4. Pemphigus vulgaris is a fungal disease, whereas pemphigoid is an autosomal dominant skeletal dysplasia

Explanation

Pemphigus vulgaris is an intraepithelial autoimmune disease where IgG autoantibodies attack desmoglein 3 (and desmoglein 1) in desmosomes, causing loss of keratinocyte cohesion (acantholysis), suprabasilar clefting, and fragile, flaccid blisters that rupture quickly (positive Nikolsky sign). Mucous membrane pemphigoid involves autoantibodies against basement membrane antigens (BP180, laminin 332 in hemidesmosomes), creating subepithelial clefts beneath an intact full-thickness epithelium, resulting in tense blisters that frequently scar (e.g., ocular symblepharon).

Question 32Describe lesions, construct differentials, and obtain a diagnosis

A 23-year-old patient presents with three painful, shallow, round ulcerations of 3–5 mm diameter on the non-keratinized labial and buccal mucosa. The ulcers have a grayish-yellow necrotic base surrounded by a prominent erythematous halo. The patient has a history of similar recurrent episodes that heal spontaneously within 7–10 days without scarring. What is the diagnosis?

  1. Major aphthous ulcers (Sutton's disease)
  2. Herpetic gingivostomatitis with secondary syphilis
  3. Minor Recurrent Aphthous Stomatitis (Minor RAS / Mikulicz aphthae) Correct answer.
  4. Carcinoma in situ of the lip

Explanation

Minor Recurrent Aphthous Stomatitis (Minor RAS / Mikulicz aphthae) is the most common form of aphthae (accounting for ~80% of cases). It is characterized by 1–5 shallow, round or oval ulcers < 10 mm in diameter on non-keratinized mobile mucosa (labial, buccal, ventral tongue) covered by a fibrinous yellow-gray slough with a distinct red halo, which heal spontaneously in 7–14 days without scarring.

Question 33Describe lesions, construct differentials, and obtain a diagnosis

A 10-year-old child presents with all primary and permanent teeth displaying an opalescent, amber, translucent brown-blue discoloration. The enamel flakes off easily from the underlying soft dentin, leading to severe attrition. Radiographs show bulbous crowns with marked cervical constriction and complete obliteration of all dental pulp chambers and root canals by abnormal dentin. What is the diagnosis?

  1. Amelogenesis imperfecta (Hypoplastic type)
  2. Dental fluorosis (Dean's severe index)
  3. Tetracycline staining of enamel
  4. Dentinogenesis Imperfecta (Type II / Hereditary Opalescent Dentin) Correct answer.

Explanation

Dentinogenesis Imperfecta Type II (hereditary opalescent dentin, caused by mutations in the DSPP gene) is an autosomal dominant disorder affecting both dentitions. Characteristic features include opalescent amber/blue-brown tooth discoloration, bulbous crowns with sharp cervical constrictions, rapid enamel loss due to a defective dentino-enamel junction, and progressive obliteration of pulp chambers and root canals by irregular dysplastic dentin.

Question 34Diagnose the cause before selecting mechanics or appliances

What dental and incisor characteristics differentiate an Angle Class II Division 1 malocclusion from an Angle Class II Division 2 malocclusion?

  1. Division 1 features crossbite of all posterior teeth, while Division 2 features an anterior open bite with Class III molars
  2. Division 1 has Class I molars with lingually tipped canines, while Division 2 has Class III molars with bimaxillary protrusion
  3. Class II Division 1 features proclined maxillary central incisors with an increased positive overjet (excessive horizontal overlap), whereas Class II Division 2 features retroclined maxillary central incisors, proclined/labially tipped lateral incisors, a deep bite (excessive vertical overlap), and normal or minimal overjet Correct answer.
  4. Class II Division 1 is exclusively found in primary dentition, while Division 2 only occurs in edentulous adults

Explanation

Both Class II divisions feature a distal relationship of the mandibular first molar relative to the maxillary first molar (mesiobuccal cusp of maxillary first molar occluding anterior to the buccal groove of mandibular first molar). Division 1 is characterized by proclined maxillary central incisors and increased overjet. Division 2 is characterized by palatally retroclined central incisors, labially flared lateral incisors, and an exaggerated deep overbite.

Question 35Diagnose the cause before selecting mechanics or appliances

In standard lateral cephalometric analysis (Steiner analysis), what is the clinical interpretation of an ANB angle of +7° (normal mean: 2°–4°), where SNA is 82° and SNB is 75°?

  1. Skeletal Class III malocclusion due to mandibular prognathism
  2. Normal orthognathic skeletal Class I relationship
  3. Bimaxillary protrusion with normal mandible
  4. Skeletal Class II malocclusion due to mandibular retrognathism (retrognathic mandible relative to cranial base) Correct answer.

Explanation

The ANB angle reflects the anteroposterior sagittal skeletal relationship between the maxilla (A point) and mandible (B point) relative to the anterior cranial base (Sella-Nasion line). A normal ANB is ~2°–4°. An increased ANB of +7° indicates a Skeletal Class II relationship. Because SNA is normal (82°) and SNB is decreased (75° vs normal 80°), the discrepancy is caused by mandibular retrognathism.

Question 36Care for the developing dentition with risk-based decisions

A 3-year-old child presents with rampant, extensive carious demineralization affecting the labial, palatal, and proximal surfaces of all four maxillary primary incisors, while the mandibular primary incisors remain caries-free. The parents report that the child falls asleep every night nursing on a bottle containing sweetened fruit juice or milk. What is the diagnosis and the anatomical reason why the mandibular incisors are spared?

  1. Early Childhood Caries (ECC / Nursing bottle caries); mandibular incisors are protected by the physical barrier of the tongue during suckling and constant cleansing by saliva from the submandibular and sublingual ducts Correct answer.
  2. Amelogenesis imperfecta; mandibular incisors are genetically immune to enamel defects
  3. Fluorosis of the primary dentition; caused by swimming in chlorinated pools
  4. Congenital syphilis (Hutchinson teeth)

Explanation

Early Childhood Caries (ECC / 'nursing bottle caries') is characterized by rampant caries on teeth that erupt early and are bathed in pool liquids during nocturnal bottle feeding (maxillary incisors and primary first molars). The mandibular incisors are typically spared because the child's tongue covers them during suckling and they receive constant salivary flow from the submandibular and sublingual glands.

Question 37Care for the developing dentition with risk-based decisions

According to the European Academy of Paediatric Dentistry (EAPD), what are the clinical diagnostic criteria and typical presentation of Molar-Incisor Hypomineralization (MIH)?

  1. Generalized loss of all enamel across the entire primary dentition due to trauma at birth
  2. Bilateral Hutchinson notched incisors caused by Treponema pallidum infection
  3. Excessive wear of canine teeth caused solely by nocturnal bruxism
  4. Systemically determined developmental hypomineralization affecting 1 to 4 permanent first molars, frequently associated with affected permanent incisors, presenting as demarcated enamel opacities (white, yellow, or brown) with post-eruptive enamel breakdown, severe hypersensitivity, and rapid atypical caries Correct answer.

Explanation

Molar-Incisor Hypomineralization (MIH) is defined by the EAPD as a qualitative developmental enamel defect of systemic origin affecting one or more permanent first molars, frequently involving permanent incisors. Clinically, it presents as well-demarcated opacities (creamy-white or yellow-brown) with reduced mineral density, prone to rapid post-eruptive breakdown under mastication, severe dentinal hypersensitivity, and bonding difficulties.

Question 38Prevent infection and prepare for physiological deterioration

A 20-year-old anxious patient suddenly turns pale, complains of lightheadedness, nausea, and visual dimming during local anesthetic injection, followed by brief loss of consciousness lasting 15 seconds. The radial pulse is slow (bradycardia, 45 bpm) and blood pressure drops to 85/50 mmHg. The patient recovers consciousness immediately upon being placed in the supine position with legs elevated. What is the diagnosis?

  1. Acute myocardial infarction
  2. Vasovagal syncope (neurocardiogenic reflex / psychogenic fainting) Correct answer.
  3. Anaphylactic shock to articaine
  4. Severe hypoglycemia with diabetic ketoacidosis

Explanation

The trigger, pallor, bradycardia, transient hypotension and rapid recovery described are most consistent with vasovagal syncope. Any collapse still requires prompt assessment of airway, breathing, circulation and possible alternative causes. Supine positioning with suitable leg elevation is different from prescribing a head-down Trendelenburg tilt for every patient; individual breathing and medical circumstances matter.

Question 39Imaging justification, geometry, and responsible interpretation

In dental panoramic radiography and Cone Beam Computed Tomography (CBCT), what causes 'beam hardening' artifacts and 'ghost images' (phantom images), respectively?

  1. Beam hardening is an optical distortion of the computer monitor; ghost images are caused by dirty sensor glass
  2. Beam hardening is caused by patient movement during the scan; ghost images are caused by chemical developer contamination
  3. Beam hardening occurs when low-energy photons are preferentially absorbed by high-density objects (e.g., metal crowns, implants), creating dark streaks and cupping artifacts; Ghost images on panoramic radiographs are caused by dense anatomical objects (such as the contralateral mandible or earrings) located between the X-ray source and the rotation center, projected higher, blurred, and magnified on the opposite side Correct answer.
  4. Beam hardening occurs only in film-based radiography; ghost images occur only in ultrasound

Explanation

In polychromatic X-ray beams, 'beam hardening' occurs when a high-density metallic object (implant, amalgam, metal post) absorbs the softer (low-energy) photons, causing the remaining high-energy beam to produce dark streak bands and cupping artifacts between dense objects. A 'ghost image' on a rotational panoramic radiograph is created when a radiodense structure located between the X-ray tube and the center of rotation is projected onto the contralateral side of the image in a higher, blurred, and horizontally magnified position.

Question 40Endodontic diagnosis, disinfection, and structural prognosis

Why should adjacent and contralateral teeth sometimes be tested during endodontic diagnosis?

  1. They eliminate the need to test the symptomatic tooth
  2. They provide comparison and help localize referred or poorly identified pain Correct answer.
  3. They establish that all nearby teeth require treatment
  4. They make a radiograph unnecessary in every case

Explanation

Comparative testing helps calibrate the patient's responses and discriminate a localized pulpal problem from referred pain or another source.

Question 41Endodontic diagnosis, disinfection, and structural prognosis

What is the principal function of an electronic apex locator?

  1. Measure crown shade
  2. Estimate the position of the canal terminus during working-length determination Correct answer.
  3. Determine the exact histologic status of the pulp
  4. Sterilize the apical third of the canal

Explanation

An apex locator contributes to working-length determination, which is integrated with anatomy, radiographic information, and a controlled instrumentation strategy.

Question 42Endodontic diagnosis, disinfection, and structural prognosis

Why is dental dam isolation essential during root canal treatment?

  1. It limits contamination and helps protect against ingestion of instruments or chemicals Correct answer.
  2. It makes access cavity design irrelevant
  3. It guarantees that every canal will be located
  4. It allows irrigant to be injected under unlimited pressure

Explanation

Dental dam isolation supports asepsis and protects the patient, but it does not replace careful irrigation, anatomical assessment, or sound operative technique.

Question 43Endodontic diagnosis, disinfection, and structural prognosis

Which property makes sodium hypochlorite particularly useful as an endodontic irrigant?

  1. Direct measurement of pulpal blood circulation
  2. Antimicrobial activity together with dissolution of organic tissue Correct answer.
  3. Reliable removal of all inorganic smear layer by itself
  4. Permanent strengthening of every instrumented root

Explanation

Sodium hypochlorite is valued for antimicrobial action and organic tissue dissolution; it must be delivered carefully to avoid injury beyond the root canal.

Question 44Endodontic diagnosis, disinfection, and structural prognosis

What is the main endodontic role of EDTA irrigation?

  1. Creation of an adhesive coronal restoration
  2. Chelation of inorganic components of the smear layer Correct answer.
  3. Replacement of all mechanical canal preparation
  4. Reliable dissolution of necrotic soft tissue as its primary action

Explanation

EDTA chelates mineral components and helps manage the inorganic smear layer, while cleaning the canal system still requires complementary mechanical and chemical measures.

Question 45Endodontic diagnosis, disinfection, and structural prognosis

Which irrigation practice reduces the risk of forcing sodium hypochlorite into periapical tissues?

  1. Inject forcefully whenever resistance increases
  2. Avoid binding the needle and use controlled delivery short of the canal terminus Correct answer.
  3. Ignore the working length after shaping begins
  4. Wedge the needle tightly at the apex

Explanation

A freely positioned needle and gentle, controlled irrigation reduce hydraulic pressure; working-length knowledge and awareness of root anatomy remain important safety measures.

Question 46Endodontic diagnosis, disinfection, and structural prognosis

When may limited-field CBCT be justified in endodontic assessment?

  1. For every tooth before any examination
  2. When a specific unresolved diagnostic question cannot adequately be answered by lower-dose information Correct answer.
  3. To guarantee identification of all microbial species
  4. To replace the medical history

Explanation

Three-dimensional imaging should address a defined diagnostic need and be justified by the expected benefit rather than ordered routinely without a clinical question.

Question 47Endodontic diagnosis, disinfection, and structural prognosis

A root-filled tooth has an isolated narrow deep probing defect. What important differential diagnosis should be considered?

  1. Vertical root fracture Correct answer.
  2. A benign color variation of enamel
  3. Dental fluorosis alone
  4. Normal physiological sulcus depth in every case

Explanation

An isolated narrow periodontal defect can occur with a vertical root fracture, although diagnosis requires integration with symptoms, imaging, and other clinical findings.

Question 48Endodontic diagnosis, disinfection, and structural prognosis

Sharp pain on release after biting a cusp raises suspicion for which condition?

  1. Generalized gingivitis as the sole explanation
  2. A normally exfoliating primary tooth in every adult
  3. An incidental missing third molar
  4. A cracked tooth Correct answer.

Explanation

A crack can allow cusp movement under load and produce pain on release; diagnosis requires targeted testing and assessment of crack extent.

Question 49Endodontic diagnosis, disinfection, and structural prognosis

Why may a sinus tract be traced with an appropriate radiopaque point during diagnosis?

  1. To help identify the source of drainage Correct answer.
  2. To mechanically seal the tract permanently
  3. To measure the patient's salivary flow rate
  4. To prove that the nearest tooth is the source without imaging

Explanation

Tracing a draining tract can help localize its origin because the opening may be distant from the causative tooth or lesion.

Question 50Endodontic diagnosis, disinfection, and structural prognosis

A previously treated tooth has persistent apical radiolucency. What should guide the next step?

  1. Automatic extraction regardless of symptoms or prognosis
  2. The color of the rubber dam used previously
  3. The assumption that every radiolucency is a cyst
  4. Clinical findings, healing history, technical factors, and restorability Correct answer.

Explanation

Persistent disease needs a reasoned assessment of possible causes and management options; radiographic appearance alone does not establish histology or mandate one treatment.