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The traditional method of evaluating student tooth preparations in preclinical courses has relied on the judgment of experienced clinicians primarily utilizing visual inspection. At times, certain aids such as reduction matrices or reduction instruments of known dimension are used to assist the evaluator in determining the grade. Despite the skill and experience of the evaluator, there is still a signiicant element of uncertainty and inconsistency in these methods. Students may perceive this inconsistency as a form of subjective, arbitrary, and empirical evaluation, which often results in students' focusing more on the grade than the actual learning or developing skills necessary to accomplish the preparation properly. Perceptions of favoritism, discrimination, and unfairness (whether verbalized or not) may interfere with the learning process. This study reports the use of a new experimental scanning and evaluation software program (E4D Compare) that can consistently and reliably scan a student's tooth preparation and compare it to a known (faculty-determined) standardized preparation. An actual numerical evaluation is generated by the E4D Compare software, thereby making subjective judgments by the faculty unnecessary. In this study, the computer-generated result was found to be more precise than the hand-graded method.

Interest in intraoral scanners (IOSs) has increased in dentistry since the introduction of the CEREC system in 1984. 1 The rapid pace of innovation in digital scanners has increased the indications for use to include more complicated completearch prostheses, removable prostheses, extensive implantsupported prostheses, and orthodontic aligners. 2-6 Intraoral digital scans are now acceptable for complete arch prostheses supported by nonparallel implants, which is a testament to how far the technology has advanced. 7 These expanded indications combined with an increase in the ease of use have increased the adoption of digital workflows. This results in increased patient comfort, shortened treatment time, and the potential for decreased overhead, all while maintaining the quality of conventional systems. 8-11 Additionally, intraoral Declaration of Interest: A.M. and W.R. have lectured for Planmeca at CE events and received honoraria. M.L. has lectured for Dentsply Sirona at CE events and received honoraria.

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Objective This in vitro study compares the newest generation of intraoral scanners to their older counterparts, and tests whether material substrates affect the trueness and precision of intraoral scanners (IOS). Material and methods A custom model, used as the reference standard, was fabricated with teeth composed of different dental materials. The reference standard scan was obtained using a three‐dimensional (3D) optical scanner, the ATOS III. Experimental scans were obtained using eight different IOS, operated by experienced clinicians, using the manufacturer's recommended scanning strategy. A comprehensive metrology program, Geomagic Control X, was used to compare the reference standard scan with the experimental scans. Results For all scanners tested, except Trios3, the substrate does influence the trueness and precision of the scan. Furthermore, differences exist when comparing the same substrate across different scanners with some of the latest generation scanners clearly leaping ahead of the older generation regarding both trueness and precision. Conclusions Substrate type affects the trueness and precision of a scan. Active Triangulation scanners are more sensitive to substrate differences than their parallel confocal counterparts. Some scanners scan certain substrates better, but in general the new generation of scanners outperforms the old, across all substrates. Clinical significance The substrates being scanned play an import role in the trueness and precision of the 3D model. The new generation of scanners is remarkably accurate across all substrates and for complete‐arch scanning.