Himdani dual (heavy/light body) impression technique (in vitro) cross-sectional comparative study

Aim: To evaluate the accuracy of the modified Himdani one-step impression technique compared with the conventional two-step technique. Detailed objectives: To measure dimensional changes in each impression type; To compare the effect of partial putty setting on the final impression accuracy; To determine whether the scanning process influences dimensional measurements.

Materials and Methods: An in vitro design using 20 casts was employed in this study, comprising 10 casts from each of the two impression techniques. The two-step and modified single-step impression techniques were used in groups A and B, respectively. A putty was used for 1 minute of polymerization relined with light body on and around the teeth inside the putty impression. The putty was then re-seated until both were fully seated before removal. Each cast virtual model was superimposed on the arch virtual model using Exocad Dental DB software for matching. The buccal, lingual, mesial, distal, and occlusal aspects of both teeth 24 and 26, as well as the interabutment distance between the distal surface of tooth 24 and the mesial surface of tooth 26, were measured for each sample, revealing the maximum discrepancy in these nine areas.

Results: The modified one-step technique demonstrated significantly lower dimensional discrepancies across all measured surfaces compared with the twostep technique (p<0.001).

Conclusions: The modified technique demonstrated numerous advantages over the conventional technique, with greater accuracy in capturing dental impressions for dental prostheses. It was also simple and easy to apply in dentistry, which can replace the traditional impression technique.