Effect of different impression materials and techniques on the dimensional accuracy of implant defi nitive casts

Abstract

Background: Different factors such as impression techniques and materials can affect the

passive fi t between the superstructure and implant. The aim of this study was to determine the

effect of different impression materials and techniques on the dimensional accuracy of implant

defi nitive casts.

Materials and Methods: Four internal hex implants (Biohorizons Ø4 mm) were placed on a

metal maxillary model perpendicular to the horizontal plane in maxillary lateral incisors, right

canine and left fi rst premolar areas. Three impression techniques including open tray, closed tray

using ball top screw abutments and closed tray using short impression copings and two impression

materials (polyether and polyvinyl siloxane) were evaluated (n = 60). The changes in distances

between implant analogues in mediolateral (x) and anteroposterior (y) directions and analogue

angles in x/z and y/z directions in the horizontal plane on the defi nitive casts were measured by

coordinate measuring machine. The data were analyzed by multivariate two-way analysis of variance

and one sample t-test (α = 0.05).

Results: No statistical signifi cant differences were observed between different impression

techniques and materials. However, deviation and distortion of defi nitive casts had a signifi cant

difference with the master model when short impression copings and polyvinyl siloxane

impression material were used (P < 0.05). In open tray technique, there was a signifi cant

difference in the rotation of analogs compared with the master model with both impression

materials (P < 0.05).

Conclusion: There was no difference between open and closed tray impression techniques;

however, less distortion and deviation were observed in the open tray technique. In the closed tray

impression technique, ball top screw was more accurate than short impression copings.

Key Words: Dental implants, dental impression materials, dental impression techniques,

dental models