Aims: The aim of This study was to compare the marginal and internal adaptation of cores which are fabricated of different materials and systems. Methods: In this experimental study, one Ivorine maxillary right first premolar (A -3 Z; Frasaco, Tettnang, Germany) was prepared for full coverage of zirconium,Nickle chromium and ceramic cores. The tooth was prepared with 1 mm rounded shoulder and 2-5 degrees tapering. Nickle chromium die was prepared for full coverage of upper first premolar, and

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... plicated to produce fifteen resin stone dies.The specimens were devided in to three groups (n=5). Cores were fabricated using NiCr, Empress ceramic, manual Zirconia frame works respectively. Internal space replica technique was used to evaluate the marginal and internal adaptation of the cores using Fit and Bite checker silicone material. The resulted replica of each core was sectioned and the thickness of the black and white silicone layer was measured at marginal and internal points.Data was calculated and compared statistically using Kruskal_Wallis test at p<0.05. Results: There was a significant difference in the internal adaptation of different core materials . Copings fabricated of zirconia material have shown minimum thickness and higher internal adaptability. Conclusions: Zirconia copings have superior marginal adaptability when compared to NiCr and Empress Ceram materials.