An in vitro study to evaluate the accuracy of different impression techniques of implant supported prosthesis

Statement of the problem: Implant is considered nowadays the first choice for replacing missing teeth and the supported prosthesis is a major part of the treatment plan. The passive fit of the supported prosthesis depends mainly upon the accuracy of the impression. However, there are controversies about the accuracy of different impression techniques of implant supported prosthesis.
Aim of the study: The purpose of this study was to evaluate the accuracy of different impression techniques of implant-supported fixed dental prosthesis.
Methodology: Thirty impressions were made upon a specialized stainless steel mold containing two parallel implant analogues 11.27 mm apart from each other. The impressions were divided into three groups according to implant impression technique used. 10 impressions for closed tray technique, 10 impressions for open tray technique and 10 impressions for splinted open tray technique. After taking impressions, they were poured with type IV dental stone and left for one day before analysis with a stereo microscope. The collected data was statistically analyzed using one way ANOVA followed by T test and the significance level was set at P ≤ 0.05.
Results: Regarding impression accuracy, there was no statistically significant difference between open tray and splinted open tray technique within the master mold while there was statistically significant difference between closed tray technique within the master mold. There was no statistically significant difference between open tray and splinted open tray technique while there was statistically significant difference between closed tray technique within the other two techniques.
Conclusion: Closed tray technique shows more deviation in comparison to the master mold and the other two techniques that affect the final accuracy of multiple implant impression. In comparing open tray technique of both types, splinted and no splinted, it shows no significant difference with the master mold and within each other.