Comparison of Compressive and Flexural Strength Among Three Types of Glass Ionomer Cements: An In Vitro Study

Background Glass ionomer cements (GICs) are widely used restorative materials in dental procedures as they release fluorides, chemically adhere to tooth structure, and are biocompatible. Despite these advantages, their mechanical properties vary. Hence, this study aimed to compare the compressive and flexural strengths of three types of GICs, namely, conventional GIC, resin-modified GIC (RMGIC), and zirconia-reinforced GIC (Zirconomer). Methodology An in vitro study was conducted on 120 extracted natural teeth. The 120 specimens were divided into the following three groups of 40 samples: Group A (RMGIC; GC FujiCem; 13.3 g), Group B (conventional GIC; GC Gold Label 2; 15 g powder, 10 mL liquid), and Group C (Zirconomer; SHOFU Zirconomer Improved; 12 g powder, 5 mL liquid). Plastic straws measuring 4 mm in diameter and 6 mm in height were used as molds. Materials were manipulated according to the manufacturer's instructions, with light curing performed for RMGIC. All samples were coated with GIC varnish and stored in deionized water at 37°C for 30 days. Flexural strength was tested using rectangular specimens (4 × 6 × 25 mm) on a Universal Testing Machine after 24 hours of water storage. Compressive strength was measured on cylindrical specimens using an INSTRON E 3000 universal testing machine at a crosshead speed of 1 mm/minute, and values were calculated using the following formula: CS = 4F/πD². Statistical analysis was performed using analysis of variance and Bonferroni post-hoc tests. Results Statistically significant mean measures were seen among all three groups. Group B (conventional GIC) showed the highest compressive and flexural strength, which was statistically significant, compared to the other two groups. Conclusions Within the limits of the study, conventional GIC had higher compressive strength and flexural strength, indicating enhanced durability.