Abstract
AIM AND BACKGROUND: The quest for optimal restorative material balancing function, biocompatibility, and durability is ongoing. Among these materials, glass ionomer cement (GIC) remains unique due to its fluoride release property and chemical adhesion to the tooth. To address its mechanical limitations, this study explores the incorporation of micro- and nano-hydroxyapatite (HA) into GC Hybrid to improve tensile strength, shear bond strength, and microleakage. MATERIALS AND METHODS: Thirty-three extracted human primary molars free of caries, defects, or previous restorations were collected and stored in saline. The control group (GC Hybrid), group 1 (GC Hybrid + micro-HA), and group 2 (GC Hybrid + nano-HA) underwent tensile strength, shear bond strength, and microleakage tests. For bonding strength, 27 teeth were prepared, treated, and tested for bonding failure using a universal testing machine. Tensile strength was evaluated on 27 cylindrical specimens using the diametral tensile strength (DTS) test. Microleakage was assessed on 6 molars restored with each material, analyzed under a stereomicroscope. Data were subjected to statistical analysis. RESULTS: Group 2 showed significantly higher tensile (8.46 ± 1.42, p 0.00) and shear bond strength (9.19 ± 1.82, p 0.01), followed by group 1, and least in the control group. Microscopic evaluation revealed no microleakage in group 2, reduced microleakage in group 1, and high in the control group. CONCLUSION: GC Hybrid with nano-HA demonstrated highest DTS and shear bond strength with no microleakage. In contrast, the control group exhibited lowest values with high microleakage, while GC Hybrid with micro-HA showed moderate improvements, indicating nano-HA significantly enhances bonding and mechanical properties of GC Hybrid. CLINICAL SIGNIFICANCE: Incorporation of nano-HA into GC Hybrid significantly improves the bonding and mechanical properties, reduces microleakage, and lowers the risk of secondary caries, making it superior to GC Hybrid alone or with micro-HA. HOW TO CITE THIS ARTICLE: Banu N, Arali V, Gunasekaran S, et al. A Comparative Evaluation of Bonding Strength, Tensile Strength, and Microleakage of GC Hybrid Cement with Micro- and Nano-hydroxyapatite: An In Vitro Study. Int J Clin Pediatr Dent 2025;18(6):660-665.