Dentsply Sirona Dycal is a rigid, self-setting calcium hydroxide composition used in dentistry primarily as a cavity liner and for direct/indirect pulp capping. It forms a protective barrier beneath restorative materials and cements, stimulating secondary dentin formation while protecting the dental pulp.

Composition & Chemical Breakdown

Dycal is supplied as a two-paste system (Base Paste and Catalyst Paste) mixed in an equal proportion:

Base Paste1,3-Butylene Glycol Disalicylate / Glycol Salicylate: Reacts with calcium hydroxide to form the hard-setting matrix

.Calcium Tungstate: Provides radiopacity, allowing clear visibility on dental X-rays.

Calcium Sulfate & Zinc Oxide: Serve as inorganic fillers to impart strength, stability, and control setting times.

Catalyst Paste

Calcium Hydroxide ($\text{Ca(OH)}_2$): The primary active ingredient providing high alkaline pH ($\approx 11$–$12$), which antimicrobial action and stimulates dentinogenesis.

Zinc Oxide & Titanium Dioxide: Active fillers and opacifiers for consistency and color match (Ivory or Dentin shades).

Sulfonamide plasticizers & Inert Fillers: Provide smooth handling properties during paste mixing.

Key Performance Properties

Ratio: 1:1 paste-to-paste mix ratio ($1.17\text{ g base} : 1.0\text{ g catalyst}$).

Working Time: ~2 minutes 20 seconds.

Setting Time: ~2.5 to 3.5 minutes.

Biological Effect: High alkaline pH neutralizes acidic threats from restoratives and aids pulp vitality.

Radiopacity: Visually distinguishable from dentin and secondary caries under radiograph inspection.