Standardized Digital Volumetric Evaluation of Removed Tooth Structure: A New Technique

This study aimed to quantify tooth structure removed during full crown preparation and test a method to evaluate preparation proximity to the pulp chamber using a digital approach.

To obtain 10 digital central upper incisors, five. STL and five Dicom files, achieved for clinical purposes, were matched in a dedicated software (RealGuide 5.0, 3DIEMME). The volume of each tooth was extrapolated with real shapes and dimensions. Moreover, the volume of pulp chambers was segmented and subtracted from the final volume. The virtual teeth were uploaded in a dental CAD software (DentalCAD, Exocad GmbH) and digital preparations were performed. Four preparation types with definite parameters were simulated: knife edge, chamfer, light chamfer, and knife edge with differentiated thicknesses. Data were analyzed using one-way ANOVA (a=0.05) and Tukey Test (a=0.05).

Statistical analysis showed a significant difference among preparations: light chamfer preparation was more conservative compared to chamfer (P=0.002) and knife edge (P=0.001) preparations. Knife edge preparation removed more tooth substance compared to knife edge preparation with differentiated thicknesses (p= 0.040).

With the limitations of an in vitro study, it could be asserted that the tested digital technique can be considered a possible option to measure the total amount of tooth structure removed during a dental preparation. Moreover, it was possible to calculate the residual thicknesses of tooth structure with respect to the pulp chamber. This technique could be used to evaluate different types of preparations, like partial crowns, inlays, onlays, overlays, and laminate veneers.