Evaluation of Marginal Microleakage in Posterior Teeth using Different Restorative Materials under Stereomicroscope – An In-Vitro Study

Abstract

Introduction :-

Marginal microleakage is a common cause of marginal staining, secondary caries, and pulpal pathology, often leading to restoration replacement. Conventional glass ionomer cement (GIC), introduced by Wilson and Kent in 1972, provides chemical adhesion and fluoride release but has limitations such as low fracture toughness, brittleness, and poor wear resistance. Silver-reinforced GIC (cermet cement) was developed to improve mechanical properties, though its metallic appearance limits esthetics. In contrast, nanohybrid composite resins offer improved strength, wear resistance, polishability, and superior esthetics due to the incorporation of nanometer-sized fillers.

Objectives:

1. To evaluate the marginal microleakage between tooth and conventional GIC (Type IX).


2. To evaluate the marginal microleakage between tooth and silver-reinforced GIC.


3. To evaluate the marginal microleakage between tooth and nanofilled zirconium composite resin.


4. To compare the marginal microleakage among the three restorative materials.

Methods:

Thirty freshly extracted human premolars free of caries, cracks, and restorations will be selected. Standardized Class I cavities measuring 1.5 × 2 × 2 mm will be prepared and restored with GC Fuji Type IX GIC (Group 1), Pyrax silver-reinforced GIC (Group 2), and nanohybrid zirconium composite resin (Group 3), according to manufacturers’ instructions. The samples (n=10 per group) will be stored in saline for 24 hours, mounted in acrylic, and subjected to thermocycling for 500 cycles between 5 °C and 55 °C. Two coats of nail varnish will be applied leaving a 1 mm margin around the restorations, and roots will be sealed with acrylic before immersion in methylene blue dye. Each specimen will then be sectioned buccolingually and examined under a stereomicroscope (40×). The maximum extent of dye penetration will be scored on a 0–3 scale (0 = no leakage, 3 = penetration to cavity floor). Data will be tabulated and statistically analyzed using Chi-square and Kruskal–Wallis tests.

Results :

The extent of marginal microleakage among the three groups will be compared. Final conclusions will be drawn after statistical evaluation.

Conclusion:-

Within study limits, Nanofill composite showed the least microleakage, followed by Type IX GIC, and Silver-impregnated GIC with the highest leakage. The composite demonstrated significantly better marginal sealing (p < 0.001), confirming its suitability for Class I restorations