Comparative evaluation of fracture strength of all ceramic zirconia based crown cemented with glass ionomer cement and resin modified glass ionomer cement for posterior semi permanent restoration of second deciduous molar An in vitro study

Introduction: Zirconia crowns are increasingly preferred for restoring primary molars due to their strength and esthetics. The longevity of such restorations depends not only on crown material but also on the luting cement. This in-vitro study aimed to compare the fracture strength of zirconia-based crowns cemented with Glass Ionomer Cement (GIC) and Resin-Modified Glass Ionomer Cement (RMGIC) for semi-permanent restoration of second deciduous molars. Methodology: Sixty-four mandibular second deciduous molar typodont teeth were selected and randomly divided into two groups (n=32). Standardized tooth preparation included 1.5–2 mm occlusal reduction, 0.5–1 mm axial reduction, 4°–8° taper, and a 0.5 mm chamfer margin. Group I crowns were cemented with GIC (Fuji I), while Group II crowns were bonded with RMGIC (Ionoseal, Voco). Following thermocycling, fracture strength testing was performed using a Universal Testing Machine by applying vertical compressive load at 1 mm/min until fracture occurred. Data were analyzed using an unpaired t-test with significance set at p<0.05. Results: Group I (GIC) exhibited a mean fracture strength of 1158.3 ± 88.0 N, whereas Group II (RMGIC) showed significantly higher strength at 1625.0 ± 58.5 N. The difference between the groups was highly significant (p=0.001). Conclusion: Zirconia crowns cemented with RMGIC demonstrated significantly greater fracture resistance compared to GIC. Within the limitations of this study, RMGIC appears to be the preferred luting cement for enhancing the durability and longevity of zirconia crowns in posterior semi-permanent restorations of deciduous molars.