Accuracy and bond strength of combination agar/alginate hydrocolloid impression materials

The accuracy and bond strength of several combinations of agar and alginate hydrocolloid impression materials were assessed. In general, there was little difference in accuracy among agar hydrocolloids. Of the alginate hydrocolloids, products J and CA produced the most accurate casts in combination with any of the agar hydrocolloids. For all product combinations, however, distortion of the diameter of the improved stone die was evident. The buccal-lingual diameter was 0.32% larger, whereas the mesial-distal diameter was only 0.06% larger. Regarding bond strength, alginate hydrocolloids P, CA, and VA in combination with agar hydrocolloids DB and DG produced the best results of all combinations tested. Thus, considering both bond strength and accuracy, product CA in combination with either DB or DG produced the best overall results.