The Accuracy of Printing and milling Zirconia Crowns

Abstract Purpose: The dental prosthesis required stability, esthetic and accurate marginal fit. The excellent marginal fit is the most important reason for the prosthesis to succeed. Poor marginal fit leads to microleakage, recurrent caries, and cement dissolution. To decrease the complication, it is important to minimize the marginal gaps and choose the right material restoration for longevity and esthetic. Thus, this study will evaluate the accuracy of printed and milled zirconia crowns. Material and methods: 20 models for mandibular first molar prepared 6-degree taper and it has a 1.5 mm chamfer finish line. These teeth were digitized by using a laboratory scanner (D2000, 3Shape; Blue LED Multi-line; 5 – 8 μm accuracy). Full coverage restorations were made by Dental Designer Software (3Shape). The master file of the designed restoration (.stl file) used to milled and printed zirconia crowns (“milling”, DS1300, DentaSwiss) and ( printer machine name). Geomagic software (Geomagic Control X, 3D systems) used to superimpose the digitized file representing each fabricated crown over the master design file. (Software-defined best-fit algorithms) used to analyze the three-dimensional accuracy of fabricated crowns relative to the master design. Result: RMS values were found lower with printed zirconia crowns compare to milled zirconia crowns. Significant differences were found between milling and printed zirconia crowns. Conclusion: 3D printed zirconia crown gives us better accuracy both in Best fit and Marginal alignment. 3D printing has better color and shade, less manufacturing time, no exposure to drilling bits and less probability to fractures, less zirconia waste, no limitation by cutting instrument for accuracy.

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