Trueness of a device for intraoral scanning to capture the angle and distance between implants in edentulous mandibular arches

摘要

Statement of problem. The digitalization of completely edentulous arches presents limitations because of the lack of anatomic structures for best -fit alignment during the image generation process of the scanner's software program.Purpose. The purpose of this clinical study was to evaluate a new device for intraoral scanning and to analyze its usefulness in capturing the 3-dimensional (3D) position of implants in edentulous mandibular arches.Material and methods. The 3D positions of 40 implants in 10 participants with fixed interim mandibular prostheses were evaluated by comparing 3 scanning techniques. Images were generated in 2 experimental groups, with digital scan bodies (group SC) and with the scanning device (group SD) and in a control group (group CT) in which images were obtained by laboratory scanning of casts produced from splinted impression copings. The standard tessellation language (STL) files were superimposed by using a reverse engineering software program to measure the 3D coordinate system. Variations in implant linear displacements (Ax, p ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Ay, and Az), total 3D displacement ( Dx2+Dy2+Dz2), and angle projections (AqXY, AqXZ, and AqYZ) were statistically analyzed (a=.05). The distances between the implants were also measured. The Spearman correlation coefficient (a=.05) was used to find the correlation between the 3D coordinates and the distances between the implants.Results. Group SD had lower values for linear displacement than group SC; however, this difference was not statistically significant except for implant #2. The overall evaluation showed a significant difference with better accuracy for group SD. Concerning angular displacements, group SD showed lesser angular variation for the 3 projection planes. For the distances between the implants, significant differences were only observed for the "all" assessment in which group SD behaved similarly to group CT, while group SC showed the highest values (P<.05). No correlation was detected between the axes (x, y, and z) and the distances between the implants.Conclusions. The evaluated scanning device led to improved trueness for linear, angular displacements, and distances between implants in mandibular edentulous arches.