The dimensional accuracy of polyvinyl siloxane impression materials using two different impression techniques: An in vitro study

AIM OF THE STUDY: To evaluate and compare the linear dimensional changes of the three representative polyvinyl siloxane (PVS) impression materials and to compare the accuracy of single mix with double mix impression technique. METHODOLOGY: A study mold was prepared according to revised American Dental Association specification number 19 for nonaqueous elastic dental impression materials. Three PVS impression materials selected were Elite-HD, Imprint(™) II Garant, Aquasil Ultra Heavy. Two impression techniques used were single mix and double mix impression technique. A total of 60 specimens were made and after 24 h the specimens were measured using profile projector. STATISTICAL ANALYSIS: The data were analyzed using one-way analyses of variance analysis and significant differences were separated using Student's Newman–Keul's test. RESULTS: When all the three study group impression materials were compared for double mix technique, the statistically significant difference was found only between Imprint(™) II Garantand Elite-HD (P < 0.05). Similarly, using single mix technique, statistically significant difference were found between Elite-HD and Imprint(™) II Garant (P < 0.05) and also between Aquasil Ultra Heavy and Elite-HD (P < 0.05). When the linear dimensional accuracy of all three impression material in double mix impression technique and single mix impression technique were compared with the control group, Imprint(™) II Garant showed the values more nearing to the values of master die, followed by Aquasil Ultra Heavy and Elite-HD respectively. CONCLUSION: Among the impression materials Imprint(™) II Garant showed least dimensional change. Among the impression techniques, double mix impression technique showed the better results.