dimensional accuracy of three impression materials by one-step and two-step impression techniques: an in- vitro study

Introduction: an accurate impression is essential to create a well-fitted dental prosthesis. this study aimed to compare the dimensional accuracy of three elastomeric materials using one-step and two-step impression techniques. methods: in this study, 20 impressions were fabricated for each vinyl siloxane ether (identium), condensation silicone (speedex), and additional silicone (panasil) impression materials by the one-step and two-step impression techniques using perforated metal trays. the one-step impression technique was simultaneously performed with heavy body/light-body materials. in the two-step impression technique, acrylic copings with 2-mm thickness were placed on the abutments to obtain similar spacing for the light-body material. the dimensional accuracy of different impression materials and techniques were measured using distance differences of the stone dies from the master cast; subsequently, the results were compared with the reference model. data were analyzed using a one-way analysis of variance and dunnett’s tests (α=0.05). results: all impression materials demonstrated an acceptable clinical accuracy. identium (vinyl siloxane ether) displayed the most accuracy in both the one-step and two-step impression techniques (p>0.05). the best accuracy for panasil (additional silicone) was found to be the two-step impression technique (p>0.05), and the best accuracy for speedex (condensation silicone) was reported as the one-step impression technique (p>0.05). furthermore, the one-step impression technique was highly accurate in diameter dimension, as compared to the two-step impression technique. conclusion: as evidenced by the results, the accuracy of impression is affected by the impression materials. moreover, identium (vinyl siloxane ether) demonstrated the most accuracy in both one-step and two-step impression techniques.