Effect of PH changes in some irreversible hydrocolloids on surface qualities of dental stone casts

ABSTRACT

Irreversible hydrocolloid [alginate] is the impression material used most commonly in making dental casts for diagnosis, treatment and fabrication of prostheses. The aim of this study was to evaluate the effects of pH value of four alginate impression materials on dimensional accuracy, surface roughness and surface hardness of dental stone casts. Samples were prepared from each irreversible hydrocolloid and pH values were measured after 5, 10, 15 and 20 minutes from mixing. Five specimens of dental stone from each alginate impression material were obtained and evaluated as regards dimensional accuracy, surface roughness and surface hardness. The results have shown nonsignificant correlation between pH changes of different alginates and dimensional accuracy and surface hardness of dental stone casts when compared with each other. The stone casts showed greater surface roughness with alkaline pH value