Trueness of High-Resolution Function in Intraoral Scanners: in Vitro Study

Introduction and aims Although digital impression systems are widely used in modern restorative dentistry, scan resolution settings may influence data accuracy. This study compared the trueness of 3-dimensional (3D) impressions and finish line preparations obtained using high-resolution (HR) and standard-resolution (SR) settings across 5 intraoral scanners (IOS) for a single-unit tooth preparation. Methods A maxillary right first molar on a typodont was prepared according to conventional guidelines and scanned using 5 IOS: Trios 5, Helios 500, Helios 680, AlliedStar 200E, and Aoralscan 3. Sixteen digital impressions were acquired per scanner (8 HR and 8 SR). Standard tessellation language datasets were superimposed onto a reference model using Geomagic Control X software. Trueness of the 3D impressions was assessed using root mean square deviation analysis. Marginal discrepancy was evaluated at 100 evenly distributed points along the finish line, divided into buccal, mesial, palatal, and distal sections. Data were analysed using 2-way analysis of variance and post-hoc tests (α = 0.05). Results HR mode generally improved 3D impression trueness compared with SR mode, with a significant difference observed only for the Helios 680 scanner ( P = .0014). In contrast, SR scans demonstrated significantly greater finish line trueness than HR scans for most scanners, whereas no significant difference was found for the Helios 500 ( P > .05). Trueness was influenced by tooth surface, with SR scans showing lower marginal discrepancies at the buccal and mesial sections ( P < .05). Conclusion Within the limitations of this in vitro study, HR settings were not universally advantageous. Although they may improve overall 3D impression trueness in certain IOS devices, they do not consistently enhance finish line trueness. Clinical relevance Selection of scan resolution settings should be based on the clinical objective, balancing overall scan trueness with the marginal detail required for restorative procedures.