Accuracy of a titanium maxillary complete denture baseplate fabricated by using the electron beam melting technique: An in vitro study

Statement of problem. Electron beam melting (EBM) is a promising additive manufacturing technique for fabricating denture baseplates; however, studies evaluating its accuracy are sparse. Purpose. The purpose of this in vitro study was to compare the fit accuracy of titanium maxillary complete denture baseplates fabricated by using the EBM technique with those fabricated by using the conventional casting technique and to evaluate the dimensional accuracy of the EBM baseplate by using a 3-dimensional inspection software program. Material and methods. Definitive casts of an edentulous maxilla were prepared. After the casts were optically scanned, computer-aided designs for the EBM baseplate were created by using a software program for standard tessellation language file editing. The EBM baseplates were fabricated with an EBM machine by using a Grade II titanium powder as the raw material. The cast baseplates were fabricated with a lost-wax casting technique by using refractory casts duplicated from the definitive casts. After fitting the EBM and cast baseplates to their corresponding definitive cast, they were embedded in a Type IV stone. The embedded baseplates on the casts were sectioned at 3 regions: posterior palatal seal, molar, and premolar. The maximum gaps between the baseplate and definitive cast were measured in these 3 regions. The virtual casts obtained by scanning the EBM baseplate were superimposed on the computer-aided design to evaluate the dimensional accuracy. Distribution color maps were then generated, and the mean absolute deviations and root mean square deviations were calculated. One-way analysis of variance and t tests were used for statistical analysis (alpha=.05). Results. No significant differences in the maximum gaps among the 3 regions were found in the cast or EBM baseplate groups (P>.05). The EBM baseplate group showed significantly lower values than the cast baseplate group in all regions (premolar: P=.008; molar: P=.003; posterior palatal seal: P=.004). The mean maximum gap for the 3 regions in the cast baseplates was 168.0 mm and that in the EBM baseplates was 60.7 mm. The distribution color map of the EBM baseplate showed a favorable dimensional accuracy. The mean absolute deviation value was 19.7 mm, and the root mean square deviation value was 25.1 mu m. Conclusions. The EBM baseplates had a significantly higher fit accuracy than the cast baseplates. Thus, the fit accuracy of the EBM technique is suitable for fabricating metal baseplates.