Koçak Büyükdere, Ayşe2022-01-272022-01-272021https://doi.org/10.52037/eads.2021.0015http://hdl.handle.net/20.500.12575/77307Purpose: Long-term clinical success is closely related to the internal and marginal adaptation of the restorations. The purpose of this study was to evaluate the internal adaptation of zirconia-based fixed dental prostheses in the posterior region. Materials & Methods: Four-unit porcelain-fused to zirconia fixed dental prostheses were fabricated with CAD-CAM system in 20 patients. For the evaluation of the restorations’ internal fit, conventional silicone replicas were used with the optical microscope. The obtained silicone impression was cut to obtain two cross-sections from buccolingual and 3 from mesiodistal. Fifty different measurements were taken from every tooth by taking 10 from each cross- section; 2 from the margin, 6 from the axial surfaces and 2 from the occlusal by the optical microscope. Results: There were statistically significant differences in internal discrepancy in terms of area and tooth type. The average internal discrepancy on the axial surfaces of the molars was 142.39±47.42µm. In premolars, the mean was 139.53±46.80µm. The average of the internal discrepancy values obtained from occlusal surfaces of the molar teeth was 164.39±53.61µm, whereas the same average for the premolar teeth was 161.92±60.54µm. Conclusion: Within the limitations of this study, restorations fabricated by CAD/CAM and internal and marginal discrepancies were at clinically acceptable intervalsenCAD/CAMmarginal discrepancyinternal discrepancyArticle4802