Effect of incorporating various concentrations of reduced Graphene Oxide (rGO) nanoparticles on the Shore D hardness of 3D-printed denture base resin: An in vitro Study

Abstract

Background: Three-dimensional (3D) printing is increasingly used for denture base fabrication; however, concerns remain regarding various mechanical properties of 3D-printed denture materials. To address these limitations, nanotechnology has been explored as a promising approach for enhancing material properties. In this context, reduced graphene oxide (rGO), owing to its favourable mechanical properties, has been used for various biomedical applications.

Aim: To evaluate the surface hardness of a 3D-printed denture base resin incorporating different concentrations of rGO.

Materials and methods: A total of 25 standardized disc-shaped specimens were fabricated using a 3D-printing process and divided into five groups with 5 in each. The groups included a control (0 wt%) and four experimental groups containing 0.005 wt%, 0.01 wt%, 0.1 wt%, and 0.25 wt% reduced graphene oxide (rGO), respectively. Specimens were designed using CAD software and fabricated using a DLP-based 3D-printer. Raman spectroscopy was performed to confirm the characteristic peaks of rGO within the resin matrix. Shore D hardness was measured using a manual analogue durometer in accordance with ASTM D2240 standards. Statistical analysis was performed using one-way ANOVA, followed by post hoc tests.

Results: An increase in Shore D hardness was observed in Group 2a (0.005 wt%) and Group 2b (0.01 wt%), both significantly higher than the control, whereas a decrease was noted in Group 2c (0.1 wt%) and Group 2d (0.25 wt%), which were significantly lower than the control. All intergroup comparisons were statistically significant (p < 0.0001).

Conclusion: The findings indicate that the effect of rGO incorporation on shore D hardness is concentration-dependent, but shows an inverse relationship, where lower concentrations result in greater improvement, while higher concentrations lead to reduced performance. The optimal concentrations were found to be 0.005 wt% and 0.01 wt%.