Micro-CT Analysis of Cement Layer Volume and Interfacial Gap in CAD/CAM and 3D-Printed Occlusal Veneers

AIM The aim of the present study is to evaluate the different thicknesses of the cement film layer, with the null hypotheses that the cement interface is not influenced by the occlusal veneer material and a qualitative assessment of the margins of cyclically fatigued restorations using SEM does not demonstrate any significant differences related to the material type. METHODS 48 models of a standardized occlusal veneer preparation are prepared. The specimens are scanned, and a standardized occlusal veneer is designed through CAD software. All the restorations are milled or 3D printed, according to the material tested. For the present study two different CAD/CAM and two 3D printed material are selected: 1. 3D printed Irix Plus, DWS, Italy. 2. 3D printed Irix Max, DWS, Italy. 3. CAD/CAM Grandio Blocs, Voco, Cuxhaven, Germany. 4. Lithium disilicate, GC Initial, LiSi Block, Japan. All specimens are submitted to an initial scan with microCT to detect the cement layer interface. Then, specimens are subjected to an accelerated fatigue cycling protocol using a universal machine; microCT scans are repeated after fatigue cycle and the interface is analyzed with SEM. Data will be statistically analyzed with ANOVA test and pair-wise comparisons as test post-hoc. RESULTS Statistical analysis revealed that Grandio Blocs and LiSi Block are both significantly different from Irix Max and Irix Plus, with (p<0.01). Across all analyses, central gap values exhibited significantly poorer performance compared to marginal gap values (p<0.01). CONCLUSION The study demonstrated that various production techniques have a significant impact on the thickness of the cement layer in the internal adaptation of different restorative materials. 3D printed restorations show better results.