Micro-computed Tomography Evaluation of Film Thickness of Veneers and Crowns Made with Conventional and 3D Printed Provisional Materials

Objectives: Evaluate the film thickness of veneers and crowns made with different provisional materials, through mCT.
Methods: A veneer and a crown preparation were performed on a central incisor and a second molar of a dental model, respectively, scanned with an intra-oral scanner, and the .STL files were exported to an LCD-based SLA 3D-Printer. Twenty-four preparations were 3D-printed for each veneer and crown and divided into 4 groups (n=6/group):1-Acrylic resin (Acrílico Marche);2-Bisacrylic resin (Protemp 4);3- PMMA CAD-CAM (Vipiblock); and 4-3D-printed resin for provisional restorations (Raydent C&B for temporary crown and bridge). Veneers and crowns restorations were performed and cemented with a flowable composite. Each specimen was scanned with a m-CT apparatus, files were imported for data analysis, and film thickness was quantitatively measured. Data were analyzed by 2-way ANOVA and Tukey post-hoc tests (α=.05).
Results: For all materials, crowns presented a thicker cementation film than veneers (P<.05).The bisacrylic resin showed the smallest veneer film thickness, similar to the acrylic resin (P=.151), which was not significantly different than the PMMA CAD/CAM material (P=.153). The 3D printed provisional material showed the thicker film, different than all other materials (P<.05). The bisacrylic resin showed a film thickness with a high number of voids in its surface. For crowns cementation, the 3D printed provisional material showed the thicker cementation film, different than all other materials (P<.05).
Conclusions: Different provisional materials present different film thickness. The 3D printed provisional material showed the highest veneer and crown film thicknesses. Veneers film thicknesses were smaller than crowns for all provisional materials.