Accuracy of crowns based on digital intraoral scanning compared to conventional impression-a split-mouth randomised clinical study

Objectives The aim of this prospective in vivo study was to evaluate the accuracy of the marginal and internal fit of crowns based on conventional impression (CI) or intraoral scan (IOS) in a randomised, split-mouth set-up. Materials and methods Nineteen patients needing full coverage crowns, fitting a split-mouth design, were provided with two lithium disilicate crowns: one based on a CI and one based on an IOS. The marginal and internal accuracy of the crowns were assessed with the replica technique and clinically using a modified California Dental Association (CDA) quality evaluation system. Results At the preparation margin, the median gap was 60 mu m for IOS and 78 mu m for CI. For the other points, the median gap ranged from 91 to 159 mu m for IOS and 109 to 181 mu m for CI. The accuracy of the IOS was statistically significantly better at all point except at the cusp tip. All crowns where rated R or S at both the 6- and 12-month follow-up appointments. The results for the clinical evaluation with CDA for marginal integrity showed no statistically significant difference between the two impression methods at both the 6- and 12-month evaluations. Conclusions Crowns based on IOS show statistically significantly better marginal and internal adaptation before cementation compared to conventional impression. However, the clinical evaluation showed similar marginal adaptation.