The accuracy of direct digital impressions of post spaces with different diameters and depths scanned by a wireless intraoral scanner

Abstract

Objectives

To assess the accuracy of a wireless intraoral scanner (IOS) in scanning post spaces with different diameters and depths.

Methods

Six maxillary central incisors underwent endodontic treatment and tooth preparation. Post space preparation was performed using a #4 or #6 post drill to depths of 6, 8, and 10 mm, respectively. Direct digital impressions of the post spaces were scanned using an IOS (Trios 5, 3Shape, Copenhagen, Denmark) ten times as test data. Conventional impressions were also taken and subsequently scanned using a laboratory scanner to serve as reference data. The accuracy of the test data was evaluated through both 3D and 2D comparisons against the reference data. Statistical analysis was performed using analysis of variance (α=0.05).

Results

As post space depth increased or diameter decreased, 3D root mean square (RMS) values increased, ranging from 65.7 μm to 82.8 μm (p < 0.001), while the proportion of green region (indicating a deviation within 0.1 mm) decreased from 90.05 % to 76.38 % (p < 0.001). 2D RMS values gradually decreased from the cervical to the apical region. Except for the apical region in the #4 drill group with a 10 mm depth, all 3D and 2D RMS values remained below 100 μm. Furthermore, only the post space with a 10 mm depth in the #4 drill group exhibited a proportion of green region <80 %.

Conclusions

The accuracy of the wireless IOS in post space scanning was significantly affected by both depth and diameter, and decreased with increasing depth or decreasing diameter. Furthermore, the accuracy diminished as the scan approached the apical region.

Clinical significance

When the depth of post space prepared with a 1.9 mm diameter drill is ≤8 mm or when prepared with a 2.25 mm diameter drill is ≤10 mm, Trios 5 is suitable for direct digital impressions.