EVALUATION OF EFFECT OF NATURAL BIO-CALCIUM SOURCES AND COMMERCIAL REINFORCEMENTS ON THE COMPRESSIVE STRENGTH AND MICROHARDNESS OF GLASS IONOMER CEMENT – AN INVITRO STUDY

Background: Glass ionomer cement (GIC) is widely used in restorative dentistry due to its fluoride release and chemical bonding to tooth structure, but its mechanical limitations restrict its use in high-stress bearing areas. Reinforcement with natural bio-calcium sources and commercial additives has been explored to enhance its performance. Aim: To evaluate and compare the compressive strength and microhardness of conventional GIC, GIC modified with chicken eggshell powder, GIC modified with seashell powder, Zirconomer, and Miracle Mix. Materials and Methods: One hundred specimens were prepared and randomly divided into five groups (n = 20 each): Group 1—Conventional GIC; Group 2—GIC + Chicken eggshell powder; Group 3—GIC + Seashell powder; Group 4—Zirconomer; Group 5—Miracle Mix. Each group was further subdivided into two subgroups (n = 10) for compressive strength and microhardness testing. Compressive strength was measured using a universal testing machine, and microhardness was assessed with a Vickers microhardness tester. Data were analyzed using one-way ANOVA and post hoc pairwise comparisons (p < 0.05). Results: Both natural bio-calcium additives (Groups 2 and 3) significantly improved compressive strength and microhardness compared to conventional GIC (p < 0.05). Zirconomer (Group 4) exhibited the highest values, followed closely by Miracle Mix (Group 5). Post hoc analysis confirmed significant differences between reinforced groups and the control, with no significant difference between Zirconomer and Miracle Mix (p > 0.05). Conclusion: Addition of natural bio-calcium sources such as eggshell and seashell powder enhances the mechanical properties of conventional GIC. However, commercial reinforcements, especially Zirconomer, remain superior. Bio-calcium modification represents a promising, cost-effective, and eco-friendly approach, but further long-term clinical studies are warranted.