Agar/Alginate Combined Impression Systems : Improvement of Compatibility of Impressions with Gypsums by Fixing the Impression Surface with Weak Acid Solutions

Abstract

To improve the compatibility of reversible hydrocolloid (agar) or agar/alginate combined impressions with dental stones, the surfaces of impressions were fixed with 5% solutions of weak acids (acetic, lactic, citric, tartaric, phosphoric and oxalic acid) for 30 seconds. Surface roughness and hardness of the stone models obtained from the control or fixed impressions were measured. The stone surfaces were also observed with a scanning electron microscope (SEM). Weak acids, except citric, effectively improved the compatibility of agar impression materials with dental stones. The fixing of agar or combined impressions with the phosphoric acid solution is recomended.