AFK Quiz – Endo & Radio

The plexus of Raschkow is a network of sensory nerve fibers located in the cell-free zone (zone of Weil) just beneath the odontoblasts, allowing pain transmission from dentin.

The main reason for fracture is loss of pre-cervical dentin, which weakens tooth structure far more than dehydration or canal preparation.

Chlorhexidine has good antimicrobial action but cannot dissolve organic tissue, unlike sodium hypochlorite—this is its major limitation in endodontics.

Most persistent apical radiolucencies are periapical granulomas, characterized histologically by chronic inflammatory cells and granulation tissue, not cysts.

Early coronal sealing is critical to prevent microleakage and reinfection; delaying restoration increases endodontic failure risk.

Apical patency involves gently passing a small file (e.g., #8 or 10) slightly beyond the foramen to prevent debris accumulation and apical blockage.

In curved canals, repeated tension–compression cycles lead to cyclic fatigue, the most common cause of unexpected Ni-Ti file separation.

Over-use on the danger zone (distal root of mandibular molars) can thin the inner root wall, leading to strip perforation.

A full mucoperiosteal flap provides adequate access, visibility, and blood supply, making it the preferred flap for apical surgery.

The crown-down approach allows early coronal flaring, better solvent penetration, improved debris removal, and reduced apical extrusion.

Correct: indirect pulp capping
MTA is used for apexification, perforation repair, root-end filling, and revascularization—but indirect pulp capping is usually managed with calcium hydroxide and RMGI.

After trauma, pulpal nerves may be temporarily non-responsive even if the pulp is still vital, leading to a false-negative EPT result.

Correct: Tricalcium silicate
Tricalcium silicate–based materials (e.g., MTA/bioceramics) provide an excellent long-term seal and stimulate reparative dentin formation, making them superior to calcium hydroxide in immature permanent teeth.

Correct: Negative vitality test results
An acute apical abscess arises from a necrotic pulp; therefore, a negative pulp vitality test is essential to confirm the diagnosis, whereas radiographic changes may be absent early.

Correct: Condensing osteitis
Condensing osteitis is a bone reaction to chronic low-grade irritation and may occur adjacent to either a vital or nonvital pulp, unlike other apical pathoses.

Correct: to heat
Cracked teeth are typically sensitive to cold and biting/release, but heat sensitivity is uncommon, helping differentiate from irreversible pulpitis.

Transportation refers to deviation of the canal path caused by preferential dentin removal on the outer curvature of a curved canal during instrumentation.

Correct: inability to dissolve necrotic tissue
Chlorhexidine has good antimicrobial activity but cannot dissolve organic tissue, which limits its effectiveness compared to sodium hypochlorite.

Correct: lingual to the mesiobuccal canal
The MB2 canal is most commonly found lingual and slightly mesial to the MB1 orifice along the mesial groove of the pulpal floor.

Correct: Acute apical abscess
Spontaneous pain, vestibular swelling, tenderness, and a periapical radiolucency indicate pus formation from a necrotic pulp, consistent with an acute apical abscess.

Correct: loss of coronal tooth structure
Endodontically treated teeth fracture mainly due to loss of coronal dentin and marginal ridges, not because they are more brittle or dehydrated.

Correct: lower second molars
C-shaped canals are most frequently found in mandibular second molars, especially in certain populations.

Correct: slight resistance to removal at length (tug-back)
Proper master cone selection requires tug-back at working length, indicating good apical adaptation and seal before obturation.

Correct: low modulus of elasticity
Posts should ideally have a modulus similar to dentin;

Correct: 3 mm
Resecting 3 mm of the apex removes the majority of apical ramifications and lateral canals, improving surgical success.

Correct: Reaction to pulpal inflammation
A diffuse periapical radiopacity adjacent to a heavily restored tooth is characteristic of condensing osteitis, which represents a sclerotic bone response to chronic pulpal inflammation, not an idiopathic finding.

Correct: Use a small pre-curved file to bypass the ledge
Ledges are best managed by bypassing with small, pre-curved hand files, allowing re-establishment of the original canal path without removing excessive dentin.

Correct: Ledge formation
A ledge causes the file to deviate from the original canal curvature, producing loss of apical binding and a false canal path on radiographs.

Correct: Master gutta-percha cone at the apical third
“Tug back” indicates snug apical fit of the master cone at working length, confirming proper apical preparation and cone selection.

Correct: Barium sulphate
Barium sulphate is added to gutta-percha as a radiopacifier, allowing visualization on radiographs.

Correct: Barium sulphate
Barium sulphate is added to gutta-percha as a radiopacifier, allowing visualization on radiographs.

Correct: Using the file in a dry canal
Lack of lubrication increases friction and torsional stress, significantly raising the risk of Ni-Ti file separation.

Correct: Apply root canal sealer
Lentulo spirals are designed to evenly distribute sealer داخل the canal, especially in the apical and lateral spaces.

Correct: Calcified canals
Calcification affects instrument negotiation, not the electrical principles of apex locators; fluids, resorption, and metal restorations affect accuracy more.

Correct: Size 60
Larger-diameter Ni-Ti files experience greater cyclic tensile–compressive stress in curved canals, making them more fracture-prone.

Correct: Enterococcus faecalis
E. faecalis is highly resistant, survives harsh canal conditions, and is most commonly isolated from failed or previously treated root canals.

Correct: Over-filling
Over-filling refers specifically to a solid obturation material (e.g., gutta-percha) extending beyond the apical foramen, whereas over-extension usually describes sealer extrusion alone.

Correct: Limited field-of-view CBCT
Vertical root fractures are often not visible on 2D radiographs; a small FOV CBCT provides the highest diagnostic accuracy by eliminating superimposition.

Correct: Copious irrigation with chlorhexidine
CHX should not be used after NaOCl extrusion due to chemical interaction and tissue toxicity; saline irrigation, cold compresses, and antibiotics are appropriate.

Correct: Thermal test
Electric pulp testing is unreliable through crowns; cold testing applied to the cervical area is the most dependable method for assessing pulp responsiveness.

Correct: Watch-winding
Watch-winding involves small back-and-forth rotational movements with light pressure to negotiate canals, especially during initial canal scouting.

C fibers are unmyelinated, slow-conducting nerves responsible for dull, aching, and persistent pain, typical of irreversible pulpitis.

Correct: 17% EDTA
EDTA chelates calcium ions, effectively removing the inorganic component of the smear layer, unlike NaOCl which removes organic tissue only.

Correct: Using Step-back technique
The step-back technique is a hand-instrumentation method and does not reduce Ni-Ti rotary file separation; glide path, torque control, and coronal flaring do.

Glide paths must be created with small hand or rotary files; Gates-Glidden drills are too aggressive and unsafe for glide-path creation.

Correct: Cleaning apical debris
Recapitulation prevents apical blockage by removing dentin debris from the apical third, maintaining patency during progressive enlargement.

Correct: Within 2 mm of the radiographic apex
In lateral compaction, the master cone should reach near the radiographic apex with tug-back to ensure proper apical seal before adding accessory cones.

Correct: Osteoradionecrosis
Deterministic effects have a dose threshold and severity increases with dose. Osteoradionecrosis is a classic deterministic effect, unlike cancers or genetic mutations which are stochastic.

Correct: Two posterior bitewing images
For a caries-free adolescent with good oral hygiene, posterior bitewings every 24–36 months are recommended to monitor interproximal caries.

Correct: Submentovertex (SMV)
The SMV (jug-handle) view best visualizes the zygomatic arches without superimposition, making it ideal for detecting arch fractures.

Correct: Increased exposure time
Paralleling technique increases source-to-receptor distance, requiring longer exposure time to maintain image density.

Correct: Reducing the exposure time
Children are more radiosensitive and have smaller structures; reducing exposure time minimizes radiation dose while maintaining diagnostic quality.

Correct: Size 2
Size 2 receptors are designed to capture crowns of maxillary and mandibular teeth simultaneously in adult bitewing radiographs.

Correct: Sialolith
Sialoliths commonly appear as round or oval radiopacities superimposed near the mandible or condylar region on panoramic images.

Correct: Between the x-ray source and the center of rotation
Objects in this zone are projected twice, creating a magnified, blurred ghost image on the opposite side of the panoramic image.

Correct: Calcified lymph node
Calcified lymph nodes have a lobulated or cauliflower appearance, typically located near the inferior border of the mandible.

Correct: Decrease the vertical angulation
Reducing vertical angulation moves the zygomatic process superiorly, minimizing overlap with maxillary molar roots.

Correct: Zirconia
Zirconia has a very high atomic number and density, making it more radiopaque than enamel, composite, or porcelain.

Correct: Elongation
If the central ray is perpendicular to the tooth but not perpendicular to the receptor, the image appears elongated.

Correct: Decreasing kilovoltage
Lower kVp produces high-contrast images with fewer shades of gray, resulting in a short gray scale.