Evaluation of trueness and precision of stereolithography-fabricated photopolymer-resin dentures under different postpolymerization conditions: An in vitro study

Stereolithography (SLA) additive manufacturing (AM) technologies have become popular for the fabrication of complete dentures; however, the trueness and precision of the dentures under different postpolymerization conditions remain unclear.The purpose of this in vitro study was to investigate the effect of different postpolymerization times and temperatures on the trueness and precision of SLA dentures.Specimens simulating maxillary complete dentures were fabricated by SLA 3D printing. They were polymerized for 15 minutes or 30 minutes at different temperatures (40 °C, 60 °C, and 80 °C). The intaglio surface trueness of the specimens was evaluated by superimposing the postpolymerization standard tessellation language (STL) file on the original STL file for each specimen via a best-fit method (n=10). The precision was measured across specimens by superimposing the postpolymerization STL file from each specimen group and using the combination formula (n=45). Subsequently, root-mean-square estimates (RMSEs) and color map data were obtained, and a normality test was conducted on the obtained data. The results indicated that the distributions were not normal; therefore, nonparametric Kruskal-Wallis and Mann-Whitney tests were used to analyze the data (α=.05).For trueness, the lowest RMSE corresponded to the postpolymerization time of 30 minutes and a temperature of 40 °C. This result was significantly different from specimens those of the 15-minute and 60 °C, 15-minute and 80 °C, and 30-minute and 80 °C specimens (P.001). For precision, the median of the lowest RMSE corresponded to the 30-minute and 40 °C specimens. This median value was significantly different from those of other specimens (P.001). The findings indicate that the postpolymerization condition of 30 minutes and 40 °C affords the highest trueness and precision and the most favorable intaglio surface adaptation of the denture.The postpolymerization conditions influenced the RMSE values of the trueness and precision of a clear photopolymer resin. The RMSE and color map data associated with the 30-minute and 40 °C condition corresponded to the greatest trueness and precision of all the SLA denture specimens considered.