ABE Clinical Endodontics 5

Question 1

Which of the following is the MOST reliable method to confirm working length during root canal treatment?

Accepted Answer

Electronic apex locator (EAL) confirmed with periapical radiograph

Answer

Tactile sensation alone with a hand file

Answer

Periapical radiograph with a file in place

Answer

CBCT measurement of root length

Question 2

Sodium hypochlorite accident (extrusion into periapical tissues) is managed initially by:

Accepted Answer

Copious saline irrigation through the canal and cold compresses; supportive management

Answer

Immediate surgical debridement of the affected area

Answer

Prescription of antifungals to prevent secondary infection

Answer

Immediate hospitalization in all cases

Question 3

Vertical root fractures in endodontically treated teeth most commonly present with which radiographic finding?

Accepted Answer

'Halo' or 'J-shaped' radiolucency along the lateral root surface

Answer

Large periapical radiolucency confined to the apex

Answer

Widened periodontal ligament space only at the apex

Answer

Normal radiographic appearance in all early cases

Question 4

The use of chlorhexidine as a final irrigant after sodium hypochlorite is contraindicated primarily because:

Accepted Answer

The combination forms a brown precipitate (parachloroaniline) that may occlude tubules

Answer

Chlorhexidine deactivates the smear layer removal of EDTA

Answer

Chlorhexidine destroys the periapical tissues if extruded

Answer

The two agents neutralize each other's antibacterial effect

Question 5

The primary advantage of nickel-titanium (NiTi) rotary instruments over stainless steel hand files is:

Accepted Answer

Superelasticity allowing better canal centering and reduced transportation in curved canals

Answer

Greater resistance to corrosion in sodium hypochlorite

Answer

Lower cost per instrument allowing more frequent replacement

Answer

Higher cutting efficiency in all canal diameters

Question 6

Which microorganism is most frequently isolated from root-filled teeth with persistent periapical infection?

Accepted Answer

Enterococcus faecalis

Answer

Streptococcus mutans

Answer

Porphyromonas gingivalis

Answer

Fusobacterium nucleatum

Question 7

A mandibular first molar has an additional distal canal (DD configuration). On which surface of the distal root would the second distal canal orifice most likely be located?

Accepted Answer

Lingual to the primary distal canal

Answer

Directly buccal to the primary distal canal

Answer

Mesial to the primary distal canal at the same depth

Answer

At the furcation floor between distal and mesial roots