scope:

This Technical Specification specifies a test method using a constraint-variable instrument, designed based on first principles of mechanics for the necessary accuracy and sensitivity of the instrument to the presence of shrinkage[1], for the measurement of polymerization shrinkage stress (PSS) of external- or internal-energy activated polymer-based restorative materials such as composites and core materials. The instrument provides the measurement carried out under various instrumental compliances that are comparable to the compliances of clinically prepared tooth cavities.