Gypsum
Pronunciation: JIP-sum
A calcium sulfate-based material used in dental laboratories to fabricate study models, working casts, and dies from dental impressions.
Full Definition
Dental gypsum products are derived from calcium sulfate hemihydrate (CaSO₄·½H₂O) and are classified by the American Dental Association (ADA) and ISO into five types based on expansion, strength, and intended use: plaster of Paris (Type I), model plaster (Type II), dental stone (Type III), die stone (Type IV), and high-strength die stone (Type V). Editors should note that 'plaster', 'stone', and 'gypsum' are not interchangeable and should reflect the specific type described. The setting reaction converts hemihydrate back to dihydrate (CaSO₄·2H₂O). Precise identification of the gypsum type is important in methodology sections.
Usage
Usage note: Do not use 'gypsum', 'plaster', and 'stone' interchangeably. Authors should specify the ADA/ISO type (I–V) in materials and methods sections for reproducibility.
In Context
- "Type IV gypsum was poured within 30 minutes of impression removal to minimise dimensional change." — Laboratory protocol
- "The manuscript incorrectly used 'plaster' and 'dental stone' interchangeably; these were clarified to Type III and Type IV gypsum respectively." — Editorial note