An In Vitro Evaluation of the Effect of Nanoparticle Graphene Oxide on Compressive Strength of Conventional and Resin-Modified Glass Ionomer Cements (GICs)

Introduction: Conventional glass ionomer cements (CGICs) exhibit favorable properties, including chemical adhesion and fluoride release, but demonstrate limited mechanical strength, restricting their use in posterior stress-bearing restorations. Resin-modified glass ionomer cements (RMGICs) offer improved mechanical performance, yet remain inferior to resin composites. Nanotechnology, particularly graphene oxide incorporation, has emerged as a promising strategy to enhance the mechanical properties of dental cements. This in vitro study evaluated the effect of 2 wt% nanographene oxide (nGO) on the compressive strength of CGIC and RMGIC. Material and methods: Eighty cylindrical specimens (6 mm × 4 mm) were fabricated and allocated to four groups (n = 20): CGIC control, CGIC + 2 wt% nGO, RMGIC control, and RMGIC + 2 wt% nGO. nGO powder was blended with cement powders at 2 wt% concentration and homogenized using an amalgamator. Specimens were stored at 37°C and 100% relative humidity for 24 hours. Compressive strength was measured using a universal testing machine at a crosshead speed of 1.0 mm/min. Data were analyzed using one-way ANOVA followed by Tukey's post hoc test (p < 0.05). Results: ANOVA revealed significant differences among groups (p < 0.001, η² = 0.59). RMGIC + nGO demonstrated the highest mean compressive strength (104.10 ± 42.3 MPa), followed by RMGIC control (95.91 ± 36.69 MPa), CGIC + nGO (36.73 ± 10.27 MPa), and CGIC control (29.00 ± 6.11 MPa). RMGIC groups exhibited significantly higher compressive strength than CGIC groups (p < 0.001). However, within each material type, nGO incorporation did not yield statistically significant improvements (CGIC: p = 0.829; RMGIC: p = 0.802). Conclusion: Incorporation of 2 wt% nGO did not significantly enhance compressive strength in either CGIC or RMGIC. RMGIC demonstrated substantially superior compressive strength compared to CGIC regardless of nGO modification. Further investigation with varied concentrations and long-term aging studies is warranted to optimize nGO reinforcement.