AIXFit- A Virtual Fitchecker

Objectives: The aim was to test the accuracy of an innovative non-destructive, digital method for evaluating the marginal and internal fit of dental restorations.
Methods: Twelve monolithic crowns made of zirconia were fabricated on phantom dies. In order to be able to compare values achieved from a saw cut method [2D] with digitally obtained data [3D] in a mutual reference system, each die was fixed in a stand obtaining landmarks. An intraoral scanner (True Definition, 3M, Seefeld, Germany) was used to achieve a 3D stl-data set of the inner surface of the crown and of the die inclusively the landmarks. The AIXFIT [3D] software was used as a specially developed best fit algorithm to match digitally the intaglio surface of the crown with the surface of the preparation. The measurement of distances from 0 to +X µm between the die and the crown was possible all over the intaglio surface of the crown. For verifying the accuracy of the [3D] application a [2D] reference method was applied: the restoration was fixed with superglue on its die and separated into four pieces by a diamond band-saw. The marginal cement gap of each specimen was examined under a light microscope (x200). By the aid of a specific Blender software (Blender Foundation, Amsterdam) it was possible to compare the corresponding values achieved by [3D] and [2D].
Results: For a total of 48 measurements for the marginal gap the mean difference between [3D] and [2D] was 19 µm (SD:32 µm). T-Test showed a weak significant difference between [3D] and [2D] (p<0,05).
Conclusions: Regarding the clinically relevant range, the results confirm that the AIXFIT software is able to measure reasonable results showing the advantage to get an analysis over the entire intaglio surface.