Evaluation of mechanical properties of new elastomer material applicable for dental 3D printer

Purpose: Digital technology has advanced and changed clinical dentistry. The utility of various thermoplastic materials for 3D dental printing has not been thoroughly explored. The aim of this study was to evaluate mechanical properties of a new thermoplastic elastomer material applicable for a dental 3D printer. Material & method: Three thermoplastic elastomers: ABS, PLA and an acrylic block copolymer (KUR) and a dental self-curing resin (PMMA) were used in this study. Physical properties were evaluated by measuring water sorption (WS), dimensional accuracy (DA), ultimate tensile strength (UTS) and shear bond strength (SBS) to PMMA. For WS and DA, specimens were measured by weight and length, respectively after desiccation and immersion in 37 degrees C distilled water for 1 day, 1 week and 1 month. For UTS, the specimens were prepared according to ISO 527-2-5A and loaded to test the UTS at a crosshead speed of 5 mm/min after storage in 37 degrees C distilled water for 24 h and 1 month. For SBS, MMA self-curing resin was filled in a Teflon ring which was mounted onto polished specimens to make the adhesive area. The prepared specimens were tested for SBS after storage in 37 degrees C distilled water for 24 h and 37 degrees C distilled water for 24 h followed by 10000 times thermal cycling. The data were analyzed by repeated measures ANOVA, two-way ANOVA and t-test with Bonferroni correction at 95% confidence level. Result: The WS value of PMMA was significantly higher than those of the other materials after 1 day (p < 0.05), while the WS values of KUR were significantly higher than those of the other materials after 1 week and 1 month (p < 0.05). The DA values were influenced by water storage periods except for KUR. There were no significant differences among ABS, PLA and PMMA in SBS before thermal cycling (p > 0.05). The SBS of KUR was the lowest among the materials before thermal cycling (p < 0.05). However, there was no significant difference between PMMA and KUR after thermal cycling (p > 0.05). Conclusion: The acrylic block copolymer demonstrated acceptable physical properties, suggesting the potential to be a material to make provisional restorations for a dental 3D printer.