Comparison of the accuracy of open-tray and snap-on impression techniques of implants with different angulations

A precise transfer of the position of an implant to the working cast is particularly important to achieve an optimal fit of the final restoration. Different variables affect the accuracy of implant impression. The purpose of the present study is to compare the accuracy of open-tray and snap-on impression techniques in implants with different angulations.

In this experimental study: A reference acrylic resin model of the mandible was fabricated. Four implants were positioned with the angles of 0°, 10°, 15°, and 25° in the model. Ten impressions were prepared with open-tray technique and ten impressions were made using snap-on technique. All impressions were made from vinyl polysiloxane impression material. Linear (Δx, Δy, and Δr) and angular displacements (Δθ) of implants were evaluated using a coordinate measuring machine. Measured data were then analyzed using two-way analysis of variance and Tukey's test (α = 0.05).

The results showed that the accuracy of open-tray impression technique is significantly different from snap-on technique in Δx (P = 0.003), Δy (P = 0.000), Δr (P = 0.000), and Δθ (P = 0.000). Implants with 25° angulation are significantly less accurate than 0°, 10°, and 15° implants in Δx, Δy, Δr, and Δθ. Fifteen-degree implants are less accurate than 0° and 10° ones in Δθ.

Regarding the findings of this study, it can be concluded that snap-on technique is less accurate than open-tray technique, and the accuracy of 25° implant is less than that of 0°, 10°, and 15° implants.