Objective: To compare the accuracy of alginate substitute with polyvinyl siloxane (PVS) impression materials for both single and multiple implant restorations using open- and closed-tray techniques placed unilaterally in a partially edentulous maxillary Typodont model.
Methods: Two maxillary typodont hard models, two impression materials and two impression techniques were used in this study. A total of 80 impressions were made for both models simulating clinical scenario for single and multiple implant restorations, 10 impressions for each subgroup. Accuracy was assessed by measuring three dimensions (Anteroposterior, cross arch and vertical) on stone models obtained from impressions of the typodont models. Each dimension was measured three times and the mean value was calculated. The data were analyzed using independent samples t-test and Mann- Whitney U Test.
Results: In group 1 (single implant), significant differences were found only in the vertical dimension between alginate substitute and monophase PVS impression materials when using an open-tray technique (mean diff.= 0.17; P= 0.003), and between closed- and open-tray techniques when using alginate substitute impression material (mean diff.= -0.24; P= 0.008). In group 2 (multiple implants), significant differences were found only in the horizontal cross-arch and vertical dimensions between open and closed-tray techniques when using alginate substitute impression material (P= 0.049 and P≤ 0.01, respectively).
Conclusion: The results obtained showed that the stone dies fabricated using monophase PVS and alginate substitute impression materials were comparable to those of the typodont models. Overall discrepancies of the monophase PVS were smaller than those of the alginate substitute but not statistically significant.
