Evaluation of the accuracy of direct digital impressions versus conventional silicone impressions for post-and-core with different root space diameters: a preliminary study in vitro

Direct intraoral scanning is a viable option for post spaces with a diameter ≥ 1.5 mm and depth ≤ 7 mm. Its application is strictly limited in narrow canals (≤ 1.5 mm). For deep preparations (9 mm), a minimum diameter of 2.0 mm allows data capture but with poor reliability, whereas a diameter ≥ 2.5 mm ensures acceptable and predictable accuracy. Clinical adoption requires careful consideration of these diameter- and depth-dependent performance boundaries.