RESUMO
Statement of Problem: Various impression techniques have different effects on the accuracy of final cast dimensions. Meanwhile; there are some controversies about the best technique
Purpose: This study was performed to compare two kinds of implant impression methods [open tray and closed tray] on 15 degree angled implants
Materials and Method: In this experimental study, a steel model with 8 cm in diameter and 3 cm in height were produced with 3 holes devised inside to stabilize 3 implants
The central implant was straight and the other two implants were 15° angled. The two angled implants had 5 cm distance from each other and 3.5 cm from the central implant
Dental stone, high strength [type IV] was used for the main casts. Impression trays were filled with poly ether, and then the two impression techniques [open tray and closed tray] were compared. To evaluate positions of the implants, each cast was analyzed by CMM device in 3 dimensions [x,y,z]. Differences in the measurements obtained from final casts and laboratory model were analyzed using t-Test
Results: The obtained results indicated that closed tray impression technique was significantly different in dimensional accuracy when compared with open tray method. Dimensional changes were 129 +/= 37? and 143.5 +/= 43.67? in closed tray and open tray, while coefficient of variation in closed- tray and open tray were reported to be 27.2% and 30.4%, respectively
Conclusion: Closed impression technique had less dimensional changes in comparison with open tray method, so this study suggests that closed tray impression technique is more accurate