ABSTRACT
Statement of the Problem: Precision of the impression taken from implant positions significantly determines accurate fit of implant-supported prostheses. An imprecise impression may produce prosthesis misfit
Purpose: This study aimed to evaluate the accuracy of four impression-making techniques for angulated implants by stereomicroscope through measuring the vertical marginal gaps between the cemented metal framework and the implant analog
Materials and Method: A definitive cast with two 15° mesially angulated implants served as the standard reference for making all the impressions and later for accuracy evaluation. Four groups of five samples were evaluated: [1] closed-tray snap-fit transfer, [2] open-tray nonsplinted impression coping, [3] metal splinted impression coping, and [4] fabricated acrylic resin transfer cap. A gold-palladium framework was fabricated over the angulated implant abutments, the fit of which was used as reference. The gaps between the metal framework and the implant analogs were measured in sample groups. Corresponding means for each technique and the definitive cast were compared by using ANOVA and post hoc tests
Results: The mean marginal gap was 38.16+/-0um in definitive cast, 89+/-19.74um in group 1, 78.66+/-20.63um in group 2, 54.16+/-24.29um in group 3, and 55.83+/- 18.30um in group 4. ANOVA revealed significant differences between the definitive cast and groups 1 and 2, but not with groups 3 and 4 [p< 0.05]
Conclusion: Vertical gap measurements showed that metal splinted impression coping and fabricated acrylic resin transfer cap techniques produced quite more accurate impressions than closed-tray snap-fit transfer and open-tray nonsplinted impression coping techniques do
The fabricated acrylic resin transfer cap tech-nique seems to be a reliable impression-making method