Comparative effect of polishing and coatings on the surface properties of 3D-printed denture-base resin and teeth: an in vitro study
Abstract
Background The surface properties of three-dimensional (3D)-printed resins remain an area requiring further improvement. Therefore, this study aimed to evaluate the effects of different polishing and coating protocols on the surface roughness and hardness of 3D-printed denture base resins (DBRs) and denture teeth. Methods Two 3D printed resins (ASIGA and NextDent) for DBRs and denture teeth were used to fabricate disk-shaped (15 ×2 mm) specimens. Per resin, 96 specimens (48 for denture base and 48 for teeth) were divided into 4 groups (n=12) according to surface treatment: no polishing-coating (NP-C), conventional polishing (CP), Optiglaze (OG) coating, and PRIZMA seal (PS) coating. Surface roughness (Ra) and hardness were measured using a profilometer and Vickers hardness tester, respectively. The data was analyzed using one & two-way ANOVA, and post-hoc Tukey’s tests (α=0.05). Results For both DBR materials, polished and coated groups showed a significant decrease (p<0.001) in Ra compared to the unpolished group (ASIGA: 1.6±0.36 µm; NextDent: 1.13±0.17 µm). Coated groups had lower roughness than the polished group (p<0.05). Similarly, for both printed tooth resins, the unpolished group recorded the highest Ra values and differed significantly from the polished and coated groups (p<0.001). CP showed significantly higher Ra than OG and PS (p<0.001), with no significant difference between the two coated groups. Regarding hardness, no significant differences were found among unpolished, polished, and coated DBR groups (p>0.05), except for the OG group, which showed significantly higher hardness than other groups (p<0.001). Between the two resins, NextDent showed significantly higher hardness than ASIGA only in the OG group (p=0.009). The same trend was observed for printed teeth, where OG coating yielded the highest hardness values. Conclusion Surface roughness of 3D printed DBR and denture teeth decreased after polishing and coatings. Coating using OG resin improved the hardness of DBR and denture teeth.