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

Abbass Fallah Tafti, Mahnaz Hatami, Foroughsadat Razavi, Behnaz Ebadian


Background: 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.
Materials and Methods: 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).
Results: 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.
Conclusion: 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.
Key Words: Accuracy, dental implants, dental impression techniques

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