Relationship Between pH Changes and Dimensional Stability in Irreversible Hydrocolloid Impression Material During Setting

This study investigated the relationship between pH changes and dimensional stability during setting of irreversible hydrocolloid impression materials. Twelve specimens of seven irreversible hydrocolloid materials were used; pH readings for 20 minutes and dimensional (mass and linear) measurements for a 24-hour period were taken after mixing. The study of the curves and the comparison between them in range and in variance, together with the application of the t test, showed that pH changes were strongly related to the linear and mass changes derived fro the variety and the chemistry of the included components and their amounts.