ABE Endodontic Materials 4

Question 1

Chlorhexidine gluconate is used as an endodontic irrigant because it provides:

Accepted Answer

Substantivity through prolonged antimicrobial activity

Answer

Chlorhexidine's substantivity (sustained antimicrobial effect after removal) is its key advantage, as it binds to dentinal walls and continues acting for hours.

Question 2

The setting reaction of calcium silicate-based cements (MTA, Biodentine) requires:

Accepted Answer

Water as a reactant to form calcium silicate hydrate and calcium hydroxide

Answer

Calcium silicate cements undergo hydraulic setting, where water reacts with tricalcium and dicalcate silicate to form C-S-H gel and calcium hydroxide.

Question 3

Which property distinguishes resilon from gutta-percha as an obturation material?

Accepted Answer

Ability to bond chemically to resin-based sealers

Answer

Resilon can chemically bond to resin-based sealers like Epiphany, creating a 'monoblock' obturation theoretically improving the apical seal.

Question 4

Sodium hypochlorite at 5.25% concentration injected inadvertently beyond the apex may cause:

Accepted Answer

Severe tissue injury with pain, edema, and possible ecchymosis

Answer

NaOCl accidents cause immediate severe pain, significant edema, and ecchymosis due to the caustic nature of hypochlorite dissolving soft tissue.

Question 5

The primary advantage of using a fiber post over a cast metal post-and-core is:

Accepted Answer

Modulus of elasticity similar to dentin, reducing root fracture risk

Answer

Fiber posts have a modulus of elasticity (approximately 18-40 GPa) closer to dentin (18 GPa), distributing stress more evenly and reducing catastrophic root fractures.

(ABE) American Board of Endodontics Practice Test

(ABE) American Board of Endodontics Practice Test

ABE Endodontic Materials 4