Effect of scan body geometric configuration and library design on digital implant impression accuracy

The purpose of this in vitro study was to evaluate how variations in scan body geometry, specifically body height and the length of the flat indexing surface (FIS), affect linear and angular accuracy when combined with truncated or full-geometry library files.

Nine scan body geometries were fabricated by combining three body heights (4, 5, and 6 mm) with three FIS lengths (1, 2, and 3 mm). Digital impressions were superimposed onto truncated or full-geometry library files. Linear deviation (ΔD) and angular deviation (ΔA) were calculated by comparing aligned scan bodies with coordinate measuring machine references. Linear and angular deviations were compared between library types using the Mann-Whitney U test, and differences among body heights and FIS lengths were evaluated using the Kruskal-Wallis test with Dunn's post-hoc test (α = .05).

Linear deviation remained within a comparable range, and most geometry-library comparisons did not show a significant difference from body height, FIS length, or library morphology (P > .05). Angular deviation demonstrated geometry-dependent behavior, increasing only in the 4-mm body paired with larger FIS lengths, particularly when full-geometry libraries were used. No significant angular differences were observed in the 5-mm or 6-mm body groups.

Digital implant registration remained stable across most configurations. Shortened scan bodies performed reliably when FIS dimensions were preserved. Angular accuracy was more sensitive to geometry-library interactions, with truncated libraries improving stability.