In vitro accuracy of digital versus conventional implant impressions for the all on four concept

Aim: To compare, in vitro, the three-dimensional accuracy of digital and conventional impression techniques for the All-on-Four concept. Methods: A metal reference cast was fabricated to simulate an All-on-Four concept scenario. The cast was scanned using a contact scanner to serve as a control image. Subsequently, two extraoral scanners (Ceramill Lab Scanner, DS Lab Scanner) and one intraoral scanner (Trios IO) were employed to digitize the reference cast, generating STL images (n = 10) for accuracy comparison. Additionally, ten conventional casts were produced from the reference cast and scanned with a contact scanner to compare accuracy between conventional and digital techniques. Data were processed using Rhino3D software. Overlapping of the images generated by each scanner onto the control image was conducted. Discrepancies among the abutments were quantified along axes X, Y, and Z. A three-way ANOVA test, followed by Tukey’s post hoc test, was performed at a significance level of α = 5%. Results: The Z-axis demonstrated greater deviations compared to the X-axis (p=0.312) and the Y-axis (p=0.002). Abutment D exhibited larger deviations relative to abutments A (p=0.131), B (p<0.001), and C (p<0.001). The Ceramill lab scanner produced the most accurate results, followed by Trios IO (p=0.003), the conventional method (p<0.001), and the DS lab scanner (p<0.001). Conclusions: Abutment D and the Z-axis exhibited the most substantial deviations. The Ceramill laboratory scanner provided the most precise results. Conventional impressions demonstrated considerable deviations when compared to intraoral scanning methods.