Effects of auxiliary devices for intraoral scanning on the accuracy of scan bodies and implant positioning accuracy for prosthetic design

PURPOSE: This study evaluated the effects of auxiliary devices on the scanning accuracy of scan bodies and implant positioning accuracy for dental prosthetic design. METHODS: Four implants were placed in an edentulous maxillary model and fitted with scan bodies. Two types of removable auxiliary devices were designed and 3D-printed for intraoral scanning, categorized into three groups: non-auxiliary device (NAD), geometric-shaped device (GAD), and tooth-shaped device (TAD) groups. Scanning was performed using three intraoral scanners (i700, i500, and Primescan), with ten scans acquired per group. The scanning accuracy of scan bodies was assessed using 3D inspection software (Zeiss Inspect; Zeiss), whereas implant positioning accuracy after scan body library alignment was analyzed using Geomagic Control X (3D Systems) and Zeiss Inspect. Statistical analyses were performed using one-way and two-way ANOVA followed by Tukey HSD tests to compare the performance among the three groups (α = 0.05). RESULTS: The TAD group demonstrated significantly lower linear discrepancy in the anterior and posterior scan body distance for the i700 and i500 (P < 0.001). However, in terms of implant position accuracy after scan body library alignment, the NAD group with the i700 system showed significantly lower root mean square (RMS) values (P = 0.001) and also demonstrated significantly lower deviation in the apical region (P = 0.005). CONCLUSIONS: The use of auxiliary devices for intraoral scanning improved the accuracy of the scan body; however, these devices had little or even a detrimental effect on implant positioning accuracy after scan body library alignment in the CAD process.