Abstract
Objective. The purpose of this ex vivo study was to compare the trueness of traditional and digital workflows and to analyze the interfacial fit of CAD/CAM restorations on gypsum and 3D-printed casts (3DC). Methods: Forty patients underwent indirect posterior adhesive restorations. After tooth preparation, both traditional and chairside procedures were followed. Obtained models were scanned to generate STL files of the intraoral impression (IOS), the conventional cast (RS), and the 3D-printed cast (3DCS). Superimposition of the casts was performed to evaluate trueness. Then, for each preparation, two identical CAD/CAM restorations were milled and luted on RS and 3DC. Micro-CT scan was performed to evaluate 3D interfacial fit. Results. Surface trueness analysis showed no significant differences among groups (p > 0.05), with average trueness ranging from 11.56 to 17.01 µm. Micro-CT analysis showed significant differences between gypsum casts (average ranging from 135.78 to 212.31 µm) and 3DC (average ranging from 57.63 to 144.55 µm) for both marginal and internal fit. Conclusions. In adhesive restorations manufacturing, digital and conventional procedures generate casts that are not significantly different. Marginal fit of adhesive restorations is similar to conventional crown design and clinically acceptable. It is assumable that a direct digital workflow could benefit from the usage of 3DC.
Highlights
Computer-assisted design/manufacturing (CAD/CAM) systems have made single tooth indirect restoration easier, faster, and more predictable [1,2]
The CAD-CAM workflow could be implemented thanks to the possibility to export the stereolithography (STL) file of the intraoral scan and produce 3D printed casts (3DCs), which could be useful to clinicians and technicians for material characterization, contact points, and occlusion checks [4,5]
Obtained results showed no significant differences in terms of surface trueness between tested scans and reference scan (RS), so the first null hypothesis was accepted
Summary
Computer-assisted design/manufacturing (CAD/CAM) systems have made single tooth indirect restoration easier, faster, and more predictable [1,2]. The CAD-CAM workflow could be implemented thanks to the possibility to export the stereolithography (STL) file of the intraoral scan and produce 3D printed casts (3DCs), which could be useful to clinicians and technicians for material characterization, contact points, and occlusion checks [4,5]. The use of these materials presents the risk of distortion, expansion, or shrinkage due to numerous steps involved. They need large storage spaces and there is a risk of damage during time [15,16]
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