Dental Gypsum Products | American Dental Association

Dental Gypsum Products

ANSI/ADA Standard No. 25 Executive Summary

What is ANSI/ADA Standard No. 25 about?

This standard gives requirements and test methods for acceptable physical and chemical properties of dental gypsum products. It also gives the requirements for what information needs to be provided to the consumer on the labeling and packaging of the products for informed decision making.

What are the requirements I should know about for dental gypsum products?

ANSI/ADA Standard No. 25 sets requirements for the five types of gypsum products used in dentistry to ensure safety for use by the consumer. The five types are: 1) Dental plaster for impressions; 2) Dental plaster for mounting and models; 3) Dental stone for models; 4) High strength/low expansion dental stone for CAD/CAM dies; and 5) High strength/high expansion dental stone for dental restoration dies. The requirements are:

  • Quality
    A homogeneous mix, uniform and free from foreign matter and lumps
  • Fluidity at pouring time (Type 1 materials only)
    Equal to or greater than 70 mm
  • Setting time
    Setting time of type 1 materials shall be in the range of 2.5 min to 5.0 min and the setting time of all material types shall be within 20 % of the value claimed by the manufacturer

What’s the bottom line?

ANSI/ADA Standard No. 25 sets quality, fluidity, setting time, expansion and strength requirements for the various types of gypsum products used in dentistry.