Impact of crown and inlay size variations on the accuracy of various digital impression techniques

Accurate digital impressions are crucial in modern dentistry, particularly for capturing fine details of various dental preparations. This study aimed to evaluate the effect of variations in the sizes of crown and inlay specimen on the accuracy of three digital impression techniques. Nine crown and nine inlay specimens were fabricated according to American Dental Association Standard No. 132. Gold standard measurements were obtained using a coordinate-measuring machine. Digitized files were generated using three impression techniques (n = 10): intraoral scanner (IOS), extraoral scanner with alginate (EOS-A), and extraoral scanner with silicone rubber (EOS-S). Digital models from EOSs served as reference sets for three-dimensional (3D) fitting analysis. Statistical analysis was conducted using one-way analysis of variance and Tukey's post-hoc test. Specimen size variations significantly affected the accuracy of all impression techniques (p < 0.05). IOS exhibited superior accuracy across all specimens, with most trueness values falling within the clinical threshold. EOS-S demonstrated moderate trueness, meeting the threshold for most indexes, except the r_a index in A₂ and C₁ crowns. EOS-A met the threshold only for A₃ crown. All techniques achieved clinical precision thresholds, except for the r_d index of A₁ in the EOS-A inlay specimens, for which a slight exceedance was observed. Additionally, 3D fitting analysis revealed more pronounced deviations in the EOS-A group. The accuracy of digital impressions technique is influenced by variations in the size of crowns and inlays. This study highlights the significant impact of specimen size on the accuracy of digital impression techniques, providing valuable insights for enhancing restorative dentistry outcomes.