Effects of liquid scanning-aid material and four variables on the scanning trueness of post space with intraoral scanning.

STATEMENT OF PROBLEM: Current evidence for post space scanning indications is limited. Past studies have focused primarily on opening diameter and depth, overlooking key clinical factors such as adjacent teeth and taper, as well as potential enhancements like scanning-aid material. The combined impact of these variables on scanning trueness remains unclear. PURPOSE: The purpose of this in vitro study was to investigate the effect of liquid scanning-aid material and 4 variables on post space scanning trueness with the TRIOS 5 intraoral scanner. MATERIAL AND METHODS: A standard maxillary dentition model was scanned to obtain data. The right maxillary central incisor was virtually prepared into a residual root post space using a software program, and 4 parameters were set: 2 groups each for post space opening diameter (2.0 mm and 2.5 mm), depth (8.0 mm and 10.0 mm), adjacent tooth status (bilateral adjacent teeth present and absent), and taper (0.04 and 0.08 mm/mm), totaling 16 models. Resin models were fabricated using a high-precision printer. Before and after applying the liquid scanning-aid material, the models were scanned in vitro using the TRIOS 5 scanner (n=10). Trueness was obtained by calculating the average root mean square error (RMSE) through fitting. Two-dimensional cross-sections were constructed to assess the deviation at the bottom of the post space. The Kruskal-Wallis H test was used for univariate analysis, and a mixed-effects model for multifactorial interactions; post hoc pairwise comparisons were performed with the Mann-Whitney U test with Bonferroni correction (α=.05). RESULTS: Without the application of liquid scanning-aid material, the median RMSE ranged from 50.0 to 804.5 μm, and the median bottom deviation values ranged from 0.02 to 4.88 mm; after application, the RMSE ranged from 46.0 to 360.0 μm, and the median bottom deviation values ranged from 0.02 to 3.22 mm. Both the liquid scanning-aid material and the 4 post space parameters significantly affected scanning trueness (P<.05). CONCLUSIONS: With the obstruction of adjacent teeth, the TRIOS 5 scanner could successfully recognize models with a post space opening diameter of 2.5 mm and depth ≤10 mm. In the absence of the obstruction of adjacent teeth, it could additionally successfully identify models with an opening diameter of 2.0 mm and depth ≤8 mm. Liquid scanning-aid material improved the trueness for narrow and deep post spaces.