Crown preparations by undergraduate dental students: A comparison of conventional versus digital assessment via an intraoral scanner

This study aims to assess the effectiveness of the 3Shape TRIOS intraoral scanner (IOS) in student crown preparation evaluation. Students were tasked to perform a full metal crown preparation on the upper left first molar on a patient simulator within 45 minutes. Marginal Width, Occlusal Reduction, Presence of Undercuts, Taper, Planes of Reduction, Line Angles, Conformity to Gingival Contour, and Smoothness were evaluated via 3 assessment modes: (a) Conventional assessment by 2 supervisors; (b) Conventional assessment by students; (c) Digital assessment by students. Agreement between assessment modes was investigated using Kappa (κ), with a threshold set at κ > 0.4. Effectiveness of IOS for objective parameters was determined via physical verification, while that for subjective parameters was defined by agreement with the stricter supervisor grade. Substantial agreement (κ = 0.631) was found between IOS measurement of Marginal Width and physical verification. Two of 5 subjective parameters met κ > 0.4 for agreement between IOS and the stricter supervisor grade. Agreement between supervisors ranged from slight (κ = 0.103) for Occlusal Reduction to Fair (κ = 0.399) for Marginal Width. Agreement between conventional assessments of supervisors and students ranged from less than chance (κ = −0.142) for Occlusal Reduction to moderate (κ = 0.577) for Line Angles. Agreement between conventional assessments of supervisors and digital assessments of students ranged from slight (κ = 0.130) for Planes of Reduction to moderate (κ = 0.538) for Line Angles. IOS may be used to overcome limitations in conventional assessment of objective parameters and some subjective parameters. Digital assessment of crown preparations cannot completely replace conventional assessment.