In Vitro Evaluation of Accuracy and Reliability of Tooth Shade Selection Using Different Digital Instruments

Introduction Managing tooth shade is a significant challenge in aesthetic dentistry, especially for anterior restorations. Accurate shade assessment, combined with tailored treatment strategies and effective communication, is crucial. To improve the precision and reliability of aesthetic dental treatments, new shade-matching technologies have emerged. Current clinical methods for determining tooth shade utilize both visual assessments and instrumental techniques. The current study aimed to assess and compare the reliability and accuracy of four digital methods of tooth shade matching. Materials and methods This study utilized a 3D-printed resin upper arch model with tooth preparation done on tooth 11. An intraoral scanner was employed to scan and design the tooth, followed by the fabrication of 30 zirconia crowns using computer-aided design and computer-assisted manufacturing (CAD/CAM). The assessment of shade matching involved four digital photometric methodologies (group 1: twin flash + digital single-lens reflex (DSLR) camera (DT), group 2: ring flash + DSLR camera (DR), group 3: smartphone camera (SMART), group 4: intraoral scanner (IOS)) with Commission Internationale de l'Eclairage (CIEL*a*b*) values determined through Adobe Photoshop transformation. Accuracy (ΔE) was calculated and a specific shade using Vitablocs Mark II 3D-Master served as the standard. CIEL*a*b* data (where L = lightness, a and b = chromaticity coordinates) from four cohorts were analyzed in SPSS 26.0 for reliability, with intraclass correlation. The Kruskal-Wallis test and Spearman's correlation assessed reliability, while a one-sample t-test assessed accuracy, comparing values to clinical thresholds (p<0.05). Results The intraclass correlation revealed noteworthy variations in the L*, a*, and b* values, spanning from 0.730 to 0.994, 0.885 to 0.992, and 0.881 to 0.997, respectively. Intraoral scanners demonstrated high accuracy (ΔE = 5.8), while the SMART method showed the lowest precision (ΔE = 12.09). Twin flash with DSLR (TF+DSLR) and ring flash with DSLR (RF+DSLR) displayed comparable precision, with ΔE values of 10.90 and 10.97 respectively. Conclusion The smartphone exhibited the least precision, displaying notable discrepancies in all CIEL*a*b* metrics when compared to the manufacturer-specified shades. Conversely, the intraoral scanner demonstrated higher accuracy and reliability compared to the other groups, with no discernible variation in any of the CIEL*a*b* values from the manufacturer's standard.