A Comparison of Two Commonly Employed Impression Methods for Multiple Splinted Implants in Completely Edentulous Patients - An In vitro Study.

Background: Accurate impressions of implants are required for transferring position of implants to master cast so no additional stresses are placed on the implants through final restorations. Various impression materials, types of trays and their combinations have been described for the clinicians to choose from.

Aim: This study aimed to compare the accuracy of the commonly employed impression technique to another recommended technique, for multiple splinted implants.

Materials and methods: This in vitro , comparative, experimental study consisted of 10 master casts prepared by 10 secondary impressions which were made by 2 different impression techniques i.e., polyvinyl siloxane with open stock tray and polyether with an open custom tray, which are routinely used by clinicians in daily practice. The inter-implant distance was measured by the coordinate measuring machine. Data was collected and analyzed statistically to obtain the result.

Results: The values of coordinates that were significant (1 and 2, 3 and 4, 1 and 4, and 2 and 4) were selected to measure the accuracy of the material used for the impression and tray type employed. The accuracy of the impressions was analyzed by using Scheffé's method. Mostly non-significant differences were observed between the centroids using the two techniques.

Conclusion: The results suggested that both polyether and polyvinyl siloxane impression materials have nearly equally precise dimensional accuracy and are comparable to each other. Although not statistically significant, polyvinyl siloxane showed slightly higher accuracy than polyether. Both the trays used with their respective impression materials provided clinically acceptable results and hence may be used interchangeably.