148 - Post-curing of 3D printed resin using dental light curing unit.

3D printing products are progressively being utilized in the dental field and for achieving suitable mechanical properties. The post-curing process is essential after fabricating a restoration using 3D printed resin. This study aimed to evaluate the potential use of a handheld multiwavelength light-emitting diode (LED) dental light-curing unit (LCU) for post-curing of 3D printed resin by measuring the microhardness and biaxial strength of the post-cured resin. 1-mm and 2-mm thick resin discs (n=6, each) were 3D printed using a DLP printer (Zenith L2; Dentis). After rinsing with ethyl alcohol, the discs were further post-cured by a dental LCU (VALO; Ultradent) for 3 seconds per cycle at 3,200 mW/cm2. Post-curing was repeated either on one side from the top surface: 2 cycles (V2S), 4 cycles (V4S), 8 cycles (V8S); or on both sides from the top and bottom surface: 1 cycle (V1D), 2 cycles (V2D), 4 cycles (V4D) for each side. Afterwards, microhardness and biaxial strengths of the discs were compared to those post-cured by conventional desktop curing units (Cure Box; ODS [DCB] and Zenith Cure; Dentis [DZC]) (n=6, each) and those without post-curing (NC) (n=6). Data were analyzed using One-way ANOVA, Tukey HSD Test for multiple comparisons, and independent t-test to compare the values between the 1-mm-thick and 2-mm-thick discs (α=0.05). Microhardness of the discs varied between the 1-mm and 2-mm-thick discs and between the top and bottom surfaces, depending on the post-curing methods. In both thicknesses, V8S and V4D provided microhardness values of the top surface comparable to the control group, while DCB and V4D obtained the highest microhardness on the bottom surface (P< 0.05). The 1-mm-thick discs showed greater biaxial strength than the 2-mm-thick discs, except for NC and DZC. V4D provided the highest biaxial strength in both thicknesses (P< 0.05) that were comparable to the conventional desktop curing units (P> 0.05). The dental LCU showed increased microhardness and biaxial strength of the post-cured 3D printed discs, particularly with multiple curing cycles from both sides. The handheld multiwavelength LCU has the potential to be used as a viable alternative to conventional desktop curing units. [ABSTRACT FROM AUTHOR]