Effects of washing time and method on the surface roughness and translucency of 3D-printed resin materials

Objectives: Three-dimensional (3D) printed resin restorations require a washing process to remove residual surface resin. However, the effects of different washing methods and durations on the properties of these resins remain unclear. This study aimed to investigate the impact of various post-washing methods and durations on the surface roughness and translucency of 3D-printed resin materials. Methods: 3D-printed resin specimens were washed using three methods: ultrasonic bath (U), rotary washer (RW), and manual brushing (MB) (n=12). The control group was rinsed for 10 seconds without further processing, leaving residual resin. All specimens were washed with isopropyl alcohol for 3, 6, 10, or 30 minutes and post-cured for 30 minutes. Surface roughness (SR) was measured using a mechanical profilometer (DR230, Dragon Electronics, Beijing, China), while translucency (TP) was assessed with a spectrophotometer (EasyshadeV, VITAZahnfabrik, Germany) using the CIEDE 2000 system. Statistical analysis was performed with IBM SPSS Statistics 25.0. Results: The washing method and duration had a statistically significant effect on SR and TP. Among all methods, U was the least abrasive across all time intervals. SR was significantly higher in the MB group compared to the RW group (p<0.05). Additionally, TP was highest in the 30-min U group and lowest in the 6-min MB group, with a statistically significant difference (p<0.05). Conclusion: Washing method and duration significantly affect the surface quality and translucency of 3D-printed resins. The ultrasonic bath resulted in the smoothest surface, while manual brushing increased roughness. Longer ultrasonic washing improved translucency, highlighting the need for optimized washing protocols.