E5906583FFECT OF DIFFERENT DIGITAL IMPRESSION TECHNIQUES ON MARGINAL FIT OF ZIRCONIA CROWNS

Purpose: This study was performed to evaluate the effect of different methods of digital impression techniques on the marginal adaptation of monolithic zircon crown restorations. Three groups of zirconia crowns, Materials and Methods: 10 crowns in each group, were as follows:1)First group (G1) :Optical scanningof the stainless steel die (represent the natural tooth) using Zirkonzahn S600 ARTI®.optical scanner after it is sprayed with scanning spray gave us an optical impression from which we fabricated zirconium crowns directly. 2)Second group (G2): Polyvinylsiloxane impression material was used for fabrication of the conventional impression then digitized by optical scanning, then CAD/CAM was used to get zirconium crowns. 3)Third group (G3): Dental stone die, was scanned to produce the zirconium crowns. Results: The marginal gap (M ± S.D., µm) of zirconia crowns fabricated using the digital impression for the master die (G1) was 21.62 ± 9.62, those fabricated from scanning the conventional impression (G2) was 22.13 ± 8.48, and those fabricated from scanning the stone die (G3) was 18.30 ± 7.18. A one-way ANOVA test was used to compare the marginal gaps of the three groups, where the P value was 0.09. It was considered that there is no-significant difference between them. While there was no significant difference, the highest marginal gap was observed in the crowns fabricated from conventional impression scanning (Group II), and the lowest gap was observed in the crowns fabricated from stone die scanning (Group III). HO: There is no difference in the marginal fit of the three groups of crown Research hypotheses: restorations. HA: There is a difference in the marginal fit of the three groups.