Digitale Vermessung und 3D-Analyse von Kronen im Rahmen der klinischen Studie "Vergleichende klinische Untersuchung zwischen drei Herstellungsverfahren für keramisch verblendete Kronen hinsichtlich ihrer marginalen und internen Passung"

Abstract

Objectives: The aim of this study was to investigate three additive manufacturing processes for the production of single crown copings in terms of their marginal and internal fit using an all-optical and a combined mechanical/optical three-dimensional non-destructive analysis system. In addition the influence on the internal fit of copings by adapting and veneering the crown frameworks was investigated. Material and Method: The posterior teeth of ten patients were prepared with a chamfer. From each prepared tooth one master and three gypsum duplicate dies were produced. A crown was fabricated on each die from the materials: (1) densely sintered zirconia (ZrO2) ceramics (ce.novation GmbH, GER), (2) conventional produced non-precious alloy (Dental Laboratory Flemming Dental, GER), (3) non-precious alloy in the laser sintering process (infiniDent, Sirona Dental Systems, GER). The determination of the internal fit was implemented using two different methods. Results: Depending on the production average deviations between 0.0931 mm (SD 0.0211 mm) and 0.1431 mm (SD 0.0511 mm) were shown. Regarding the internal fit, both research methods revealed no significant difference (p = 0.969). In contrast, production of a coping (p < 0.001) and the respective tooth shape (p = 0.003) showed significant differences with respect to the internal fit. The adaption and the veneering of the crown frameworks had no significant influence on the internal fit. Regarding the marginal analysis, mean deviations of the absolute marginal discrepancy of 0.2356 mm (SD 0.1023) for (1), 0.1854 mm (SD 0.0940) for (3) and 0.1816 mm (SD 0.1061) for (3) occurred. Discussion: In respect to precision, both methods can be applied equivalently for the 3D-analysis of the internal fit. All crown frameworks were clinically appropriate. The CAD/CAM method may provide an advantage in accuracy, but not necessarily. Moreover, the tooth shape affects the internal fit regardless of the way it was manufactured.