Effect of heat-treatment duration on accuracy of castable resin patterns for denture frameworks fabricated by digital light processing in the vacuum-sealed method: An in vitro study.

内容摘要

The combined application of the vacuum-sealing method and heat treatment has been suggested to be effective in minimizing the deformation of 3-dimensionally (3D) printed castable resin patterns during denture framework fabrication. The duration of the optimum heat-treatment remains unclear. This study aimed to evaluate the effect of heat-treatment duration on the trueness and precision of castable resin patterns for denture frameworks printed by digital light processing (DLP). A simplified major connector design was created digitally on a definitive cast simulating the maxillary palate. Thirty-five specimens were printed using a DLP printer and were divided into 5 groups (n=7). In the control group, the specimens were rinsed, vacuum-sealed with a cast, and postpolymerized. In the experimental groups, the specimens were rinsed, vacuum sealed with the cast, and then subjected to heat treatment in 90 &#xb0;C water for 5, 10, 15, or 20 minutes, followed by postpolymerization. The specimens were scanned to obtain digital data for evaluating trueness and precision based on the calculation of root mean square (RMS) values. The 1-way analysis of variance (ANOVA) and Games-Howell post hoc tests were used to assess differences between groups for trueness (&#x3b1;=.05). The pairwise RMS values for precision were summarized at the group level by calculating the mean and standard deviation. Regarding trueness, the control group showed significantly higher RMS values than the 5-, 10-, 15-, and 20-minute groups (all P<.001). Moreover, the 5-minute group exhibited significantly higher RMS values compared with the 10- (P=.008), 15- (P=.013), and 20-minute (P=.011) groups. For precision, the 10-minute group showed the lowest mean RMS value. Heat treatment combined with the vacuum-sealing method significantly improved the trueness of the DLP printed resin patterns. Heat treatments of 10, 15, and 20&#x202f;minutes demonstrated better trueness than the control and 5-minute groups. In addition, the 10-minute heat treatment yielded the lowest mean RMS value for precision among the tested conditions. These results suggest that a 10-minute heat treatment may represent a favorable postprocessing duration under the conditions evaluated.