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
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