Influence of 3D analysis software on measured deviations of CAD-CAM resin crowns from virtual design file: an in-vitro study.

OBJECTIVES To evaluate a nonmetrology-grade and a metrology-grade 3D analysis software when measuring the deviations of CAD-CAM fabricated crowns from the virtual design file. MATERIALS AND METHODS A right first molar on a mandibular dentate model was prepared and scanned by using an intraoral scanner, i500 (Medit). A complete coverage crown was designed in standard tessellation language format and 20 resin crowns were fabricated by using computer aided design-computer aided manufacturing (CAD-CAM). The crowns were then digitized by using the same intraoral scanner (test-scans). Root mean square (RMS) method was used to evaluate the deviations between the test-scans and the design file of the crowns on 3 surfaces (overall, external, and internal) by using a metrology-grade, Geomagic Control X (3D Systems) and a nonmetrology-grade, Medit Link (Medit) software. The data were analyzed with Welch two-sample t-tests to compare two software for the non-inferiority of the nonmetrology-grade software with a 50 µm threshold and the potential superiority of the metrology-grade software (α = 0.05). RESULTS The Welch two-sample t-tests for the non-inferiority analysis showed that the differences between the nonmetrology-grade and the metrology-grade software were below the threshold of 50 µm for each surface tested (p <.001). The differences between the two-tested software were nonsignificant for each surface analyzed when superiority was considered (p ≥.194). CONCLUSION The nonmetrology-grade software performed similar to the metrology-grade software when analyzing the deviations of CAD-CAM crowns. Therefore, the nonmetrology-grade 3D analysis software may be considered for the deviation measurements of similar restorations. CLINICAL SIGNIFICANCE The trueness of crowns after fabrication may affect their fit, and 3D analysis of trueness prior to the delivery appointment with the tested nonmetrology-grade software after fabrication may facilitate potential clinical adjustments and delivery of the crowns