Influence of the fabrication technique on the marginal and internal adaptation of ceramic onlays
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This study aimed to evaluate the marginal and internal adaptation of partial coverage crowns (ceramic onlays) fabricated with Press, CEREC BlueCam, and CEREC OmniCam systems, using two preparation designs and evaluating the internal discrepancies at different locations. Two phantom maxillary premolars (master teeth) received different preparation designs, with (BX) and without (NB) a modified occlusal box with round internal angles. Sixty IPS e-max ceramic restorations were fabricated with three systems: Press (n=20), CEREC BlueCam (n=20), and CEREC OmniCam (n=20). Both marginal and internal discrepancy width were measured by using a stereomicroscope at 325 magnification. The data were evaluated statistically using analysis of variance followed by Tukey's Honestly Significant Difference test (a=0.05). The ceramic restorations fabricated with the Press system presented significantly smaller marginal and internal disadaptations than the BlueCam and OmniCam CEREC systems (p,0.0001). Regarding the preparation designs, preparation BX presented the smallest marginal discrepancies for all fabrication systems and larger internal discrepancies than for restorations fabricated with the Press system. The occlusal location presented a larger internal discrepancy compared with the axial locations. Although the three systems resulted in the fabrication of restorations within a clinically acceptable adaptation with marginal discrepancies below 100 lm, the Press system presented the smallest marginal and internal discrepancies. An improved marginal adaptation was observed in the preparation design with a modified occlusal box with rounded internal angles.