A study on the machining accuracy of dental digital method focusing on dental inlay

PURPOSE. The purpose of this study was to compare the cutting method and the lamination method to investigate whether the CAD data of the proposed inlay shape are machined correctly. MATERIALS AND METHODS. The Mesial-Occlusal shape of the inlay was modeled by changing the stereolithography (STL). Each group used SLS (metal powder) or SLA (photocurable resin) in the additive method, and wax or zirconia in the subtractive method (n=10 per group, total n=40). Three-dimensional (3D) analysis program (Geomagic Control X inspection software; 3D systems) was used for the alignment and analysis. The root mean square (RMS) in the 2D plane state was measured within 50 mu m radius of eight comparison measuring points (CMP). Differences were analyzed using one-way analysis of variance and post-hoc Tukey's test were used (alpha=.05). RESULTS. There was a significant difference in RMS only in SLA and SLS of 2D section (P<.05). In CMP mean, CMP 4 (-5.3 +/- 46.7 mu m) had a value closest to 0, while CMP 6 (20.1 +/- 42.4 mu m) and CMP 1 (-89.2 +/- 61.4 mu m) had the greatest positive value and the greatest negative value, respectively. CONCLUSION. Since the errors obtained from the study do not exceed the clinically acceptable values, the lamination method and the cutting method can be used clinically.