Surface and linear scan accuracy of intraoral and extraoral photogrammetry systems: An in vitro study.

Statement Of Problem Digital photogrammetry systems have the potential to simplify implant recording procedures and improve accuracy. Nevertheless, the surface and linear scan accuracy of these systems, particularly those using intraoral photogrammetry technology, compared with that of conventional impressions, has not been fully established.Purpose The purpose of this in vitro study was to evaluate the surface and linear scan accuracy (trueness and precision) of intraoral and extraoral photogrammetry systems by comparing them with conventional polyvinyl siloxane impressions for complete arch mandibular implant-supported prostheses.Material And Methods An edentulous master mandibular stone cast with 6 implants was digitized with an industrial-grade scanner to generate its reference standard tessellation language (R-STL) file. Digital scans of the master cast were made using intraoral (Aoralscan Elite, AE) and extraoral photogrammetry systems (Icam4D, IC; OxoFit, OX), while stone casts obtained from conventional polyvinyl siloxane impressions of the master cast (CNV) were digitized with a laboratory scanner (n=20). The R-STL file and the STL files of all recordings were imported into an analysis software program to calculate the surface and linear deviations of the recording methods. While the surface deviations were analyzed with the Welch analysis of variance and Tamhane T2 tests, the linear deviations were assessed with Kruskal-Wallis and Bonferroni-adjusted post hoc tests. Precision was defined as the average of how much each measurement differed from the overall mean and was statistically analyzed with Kruskal-Wallis and Bonferroni-adjusted post hoc tests (α=.05).Results OX recordings had the highest surface deviations, while CNV impressions had the lowest linear deviations (P≤.009). In addition, OX led to lower linear deviations than IC (P=.002). Regardless of the outcome, IC led to the lowest values when the precision of the measured deviations was considered (P<.001).Conclusions Although the tested recording methods showed significant differences in scan accuracy, the magnitude of deviations was small, and the deviations were within clinically acceptable thresholds.