Abstract
Objectives
To assess and compare the trueness (dimensional discrepancy and degree of deviation)
of various methods of impressions for All-on-4 implants.
Materials and Methods
This investigation employed a single-piece artificial mandibular jaw with four implants
arranged in an All-on-4 configuration. Three impression methods were compared: one
open-tray conventional impression digitized after pouring, and two intraoral scanners,
TRIOS 5 and Runyes 3DS 3.0. A reference scan (control) was conducted with a laboratory-based
scanner. All scans were performed using scan bodies and exported as Standard Tessellation
Language (STL) files. A total of 30 STL scans were produced (n = 10). The dimensional discrepancy (along the X, Y, and Z axes) and the overall degree of deviation in the position were assessed. Data analysis
was conducted using Brown–Forsythe one-way analysis of variance and Tamhane's post
hoc tests (p < 0.05).
Results
The mean degree of deviation for scan bodies was as follows: TRIOS 5 (1.11 ± 0.06 mm),
Runyes 3DS (1.02 ± 0.05 mm), and conventional (0.82 ± 0.16 mm). Statistically significant
differences were found among all impression methods (p < 0.05). While the conventional method showed the highest trueness, it had the greatest
standard deviation (SD, 0.16), which was the least consistent among them. The Runyes
3DS scans displayed the highest precision with the degree of deviation of 0.05 (± SD).
Dimensional discrepancies mainly occur on the Z-axis across all three impression methods. Conventional impressions showed statistically
significant discrepancies in the Y- and Z-axes, while TRIOS 5 images had statistically significant discrepancies in the X- and Z-axes. Runyes 3DS readings were statistically significantly discrepant in the Z-axis.
Conclusion
While both conventional methods and digital scans have their merits, traditional impression
methods may offer improved trueness in full-arch implant cases. Utilizing the open-tray
system with suitable materials and methods can enhance precision and lead to more
reliable outcomes.
Keywords
degree of deviation - All-on-4 - trueness - intraoral scan - precision - accuracy
