Transferring Occlusal Anatomy From Worn Temporary Crowns To Zirconium Oxide Crowns

Purpose/Aim: To evaluate the accuracy of transferring the occlusal anatomy of provisional crowns to monolithic zirconium oxide crowns. Materials and Methods: From a prepared typodont-tooth (# 36), ten CAD/CAM provisional polymethylethacrylate crowns were fabricated with the E4D system. Each provisional crown had its occlusion adjusted. They were scanned (E4D) and the .stl files of the crown preparations were merged with the files from the adjusted crowns (3 shape software) to produce ten polished monolithic zirconium oxide crowns. For comparison, provisional and monolithic zirconium oxide crowns were scanned (True-Definition scanner), the .stl files aligned, converted into a normalized 76x76-matrix, analyzed with ANOVA with repeated measures and Tukey's test. To generate deviation distribution tables and difference plots, .stl files (provisional crowns and monolithic zirconium oxide crowns) were merged with Geomagic software. Results: There were significant differences between provisional crowns and monolithic zirconium oxide crowns. The differences were manly in the fissure area. 86% of the calculated deviations were between + 0.06mm and - 0.04mm, 42.4% of all data points were within +/- 0.022mm with a SD of 0.005mm. The main differences were in the fissures, requiring clinically none or only minimal occlusal adjustments for these zirconium oxide crowns.