Comparative Evaluation of Flexural Strength, Modulus of Elasticity, and Microleakage of Three Different Glass Ionomer Restorative Materials in Class V Preparations – An In vitro Study

Abstract

Aims: Flexural strength, modulus of elasticity, and microleakage evaluation of three glass ionomer restorative materials in class V preparations. Materials and Methods: Twenty bar-shaped specimens each of Type-II glass-ionomer cement (GIC), Zirconomer and Type-IX GIC were prepared by inserting freshly mixed cements into 25 mm × 2 mm × 2 mm polyvinylacetate moulds followed by storage in artificial saliva for 24 h at 37°C. Samples were then rinsed, polished, and tested in autograph universal testing machine for flexural strength and modulus of elasticity using three-point bending test. Standardized Class V cavities in 60 extracted human premolars of dimensions 3 mm × 2 mm × 1.5 mm were prepared, divided at random into three groups of twenty each and restorations were done using Type-IX GIC, Type-II GIC, and Zirconomer. Teeth were immersed in 1%wt Rhodamine-B dye after thermocycling for 24 h, split bucco-lingually in longitudinal section and evaluated for microleakage under a stereomicroscope. Results: Flexural strength evaluation showed that Zirconomer had the highest and Type-II GIC had the lowest flexural strengths that was statistically significant (P < 0.05; analysis of variance [ANOVA]-Tukey Honestly Significant Difference [HSD]). Analysis of modulus of elasticity revealed that Type-IX GIC had the highest and Type-II GIC had the lowest modulus and the difference was significant statistically (P < 0.05; ANOVA-Tukey HSD). Occlusal microleakage was the highest in samples restored with Zirconomer (50% of the teeth), whereas samples restored with Type IX GIC showed no microleakage. At the gingival margins, 60% of both Type-IX GIC and Zirconomer restored samples exhibited no microleakage and 55% of Type-II GIC restored samples showed no microleakage. Conclusion: Within the limitations of this study, Type IX GIC exhibited good flexural strength, low modulus of elasticity, and least microleakage followed by Type II GIC and Zirconomer.