Impact of dental crowding on the trueness and precision of intraoral scanners: Comparison across different devices and techniques.

Introduction: This study evaluated the impact of dental crowding on the trueness and precision of 6 intraoral scanners (Primescan [Dentsply Sirona], Medit i700 [Medit, Seoul, South Korea], Trios 3 [3Shape, Copenhagen, Denmark], iTero Element 5D [Align Technology, San Jose, Calif], Shining 3D [Shining 3D Technology, Hangzhou, China], and Helios 600 [Changzhou Sifary Medical Technology Co Ltd, Changzhou, China]) and extraoral scans of conventional silicone impressions using 3-dimensional-printed mandibular models with different crowding levels.

Methods: Mandibular models with no, slight, and severe crowding were scanned 5 times with each intraoral scanner and silicone impression. Trueness was assessed by comparing scans to a reference scan using Geomagic Control X, whereas precision was evaluated through intragroup comparisons. Root mean square (RMS) values were analyzed using 2-way analysis of variance and post-hoc least significant difference tests (α = 0.05).

Results: Crowding significantly affected both trueness (P = 0.001) and precision (P <0.05), with severe crowding leading to higher RMS values. Scanner type also influenced results (P <0.001 for trueness; P <0.05 for precision). Silicone impressions showed lower trueness (RMS = 0.1027 mm) and precision (RMS = 0.0788 mm) than intraoral scanners (P <0.001). Among scanners, iTero Element 5D and Trios 3 exhibited the highest precision, whereas Primescan had significantly lower trueness. A significant interaction between the scanning method and crowding (P <0.05) indicated crowding effects that varied by the scanner.

Conclusions: Dental crowding reduces the accuracy of intraoral scanners and silicone impressions, particularly in severe malocclusion. Optimizing scanning strategies and selecting the appropriate scanner is essential for improving outcomes in crowded dentitions.