**Question:** Toxicity of AH26 sealer is due to the release of

A. formaldehyde
B. ethylene glycol
C. formaldehyde and ethylene glycol
D. other solvents

**Correct Answer:**

**Core Concept:** AH26 sealer is a bioceramic root canal sealer developed by AH Plus sealer manufacturer, Dentsply DeTrey. It is a calcium hydroxide-based sealer that contains calcium hydroxide, tri-calcium silicate, and various organic components.

**Why the Correct Answer is Right:** AH26 sealer is known to release formaldehyde, a known carcinogen, and ethylene glycol, a solvent, into the periradicular tissues upon setting. This release contributes to the sealer's antimicrobial activity and biocompatibility. The presence of formaldehyde and ethylene glycol in AH26 sealer is responsible for the observed toxicity.

**Why Each Wrong Option is Incorrect:**

Option A: Formaldehyde is indeed a component of AH26 sealer, but it is only one part of the sealer's composition. The presence of ethylene glycol is more relevant regarding toxicity due to its release into periradicular tissues.

Option B: Ethylene glycol is a solvent in AH26 sealer, but the release of formaldehyde and the combination of both substances is responsible for the observed toxicity.

Option C: Although formaldehyde is present in AH26 sealer, it is not the sole cause of toxicity. The release of ethylene glycol in combination with formaldehyde is responsible for the observed toxicity.

Option D: Other solvents are present in AH26 sealer, but the release of formaldehyde and ethylene glycol in combination is more relevant to its toxicity.

**Clinical Pearl:** The toxicity of AH26 sealer is primarily due to the release of formaldehyde and ethylene glycol into periradicular tissues, which affects cellular activity and may lead to adverse reactions in the surrounding tissues. Clinicians should be aware of this potential toxicity when selecting and using AH26 sealer for root canal treatment.