[Improved method for combined agar/alginate hydrocolloid impression. Bond strength of combination agar-gel/alginate]

The authors have been developing an improved method that an alginate mix is applied to gelled agar to obtain precise impressions. In the present study, the bond strength of the improved method was investigated. Thirty-one agar impression materials and thirteen alginate impression materials were used. The tensile-bond strength between an alginate (VAd) and various agars (exp. 1), and between an agar (DBRS) and various alginates (exp. 2), was measured by means of the Instron Testing Machine (model 1123) operated at a cross-head speed of 500 mm/min. The bond strength varied with the combinations of the products of agar and alginate. The bond strength of some combinations was higher than the stress in removing impressions from the mouth. Comparing the products of the same manufacture, the bond strength varied with the different colors (composition) of agar, but didn't vary with the different types of cartridge++ or syringe. The result suggested that the bond strength between agar and alginate depended, not only on the agar, but also on the alginate.