Fitness of the Nano-composite CAD/CAM Restorations

Objectives: To compare the marginal and internal fit of the nano-composite CAD-CAM restorations with a full veneer crown and a mesio-occlusal-distal (MOD) inlay with a one-cusp-cap design
Methods: A full veneer crown and an mesio-occluso-distal (MOD) inlay cavity prepared and scanned. CAD-CAM restorations were milled using different nano-composite CAD/CAM blocks under the same milling parameters by using CEREC system. To assess the marginal and internal gap, each restorations-abutment assembly was scanned with micro computed tomography for gap measurement, and each restoration-replica assembly was embedded in acrylic mold for sectioning at 0.5-mm intervals. The measured data were pooled according to block type and measuring point for statistical analysis.
Results: Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000). Gap data were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001).
Conclusions: The marginal and internal fit of the nano-composite CAD/CAM blocks differed according to the measuring point. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data.