Effect of horizontal and vertical intraoral scan bodies on the trueness of complete-arch digital implant impressions: a comparative in vitro study with six implants

Objective: To evaluate the interaction between intraoral scan body (ISB) type, operator, and intraoral scanner (IOS) selection on the trueness of complete-arch digital implant impressions. This study also compared horizontal ISBs (H-ISBs) and vertical ISBs (V-ISBs) across four IOS devices. Material and Methods: Digital impressions of a definitive mandibular cast with six multi-unit analogs were made using four H-ISBs from different manufacturers (denoted as H-NB, H-NS, H-M6, and H-SF), with a V-ISB (V-EA) as the reference. Each ISB was scanned using a desktop scanner and by two operators who scanned each ISB system 10 times using four IOS devices i5D, PS, T3, T4, generating 400 digital impressions. Deviations were measured using root-mean-square (RMS) error (α = 0.05). Results: All independent variables (operator, IOS, ISB) significantly affected trueness (p < 0.05). V-EA with i5D had the lowest trueness (78 [27] μm), while H-NS on PS showed the highest (12 [3] μm). H-M6 maintained high trueness across IOS devices. PS was the most stable IOS, while T4 showed the most variability. Conclusions: Complete-arch digital impressions are influenced by ISBs, IOSs, and operators. H-ISBs demonstrated better trueness and consistency across IOSs and operators.