Do Type and Shape of Scan Bodies Affect Accuracy and Time of Digital Implant Impressions?

Reports concerning the accuracy of intraoral digital impression systems are limited. This study aimed to assess the effects of scan body types and shapes on digital impression accuracy and scanning time in all-on-four restorations.This in vitro study was conducted with two acrylic maxillary models. Two implant systems with different connection types (internal trilobe and external hexagon connection) were inserted according to the all-on-four design. Scanning was performed using Doowon, NT-Trading, and DESS scan bodies. Changes in implants' positions (ΔR) and angulation (ΔA), and the implants' distance from the reference pin (ΔD) compared with the actual model were determined. Scanning times were also measured and compared.The effects of implant connections and scan bodies on ΔR and ΔA were significant (p ⟨0.05). Implant angulation could also affect ΔA (p=0.019). ΔD was only affected by scan body (p ⟨0.001). The three scan bodies were significantly different in terms of scanning time (p=0.001).The results showed that scan body type and shape, and implant connection and angulation could affect digital impression accuracy in all-on-four restorations. For both internal and external connections, the NT-Trading and DESS scan bodies had the shortest and longest scanning times, respectively.