Comparative Evaluation of the Stress of High- and Low-Viscosity Glass Ionomer Filling Materials in Class I and Class II Cavities in Primary Molars Using Finite Element Analysis

Objective: Dental caries remains highly common among children, indicating a growing need for durable and biocompatible restorative materials. Glass ionomer cements (GICs) are amongst the most commonly used restorative materials because they provide fluoride release, chemical bonding, biocompatibility, and versatility in clinical applications. Materials and Methods: A finite element analysis was performed using a 3D micro-CT-derived model of a primary mandibular first molar. Six models were created, including Class I and Class II cavities restored with high- and low-viscosity GIC, plus two control models. Material properties were based on literature. A 100-N vertical load was applied, and von Mises stress and deformation were analyzed using ANSYS. The materials were assumed to be homogeneous, isotropic, and linearly elastic. Results: High-viscosity GIC showed lower stress than low-viscosity GIC in both cavity types. In Class I cavities, the stresses were 17.65 MPa versus 22.28 MPa, and in Class II cavities, 27.10 MPa versus 32.49 MPa. Class II cavities showed higher stress and deformation than Class I cavities. Unrestored models showed the highest stress values. Conclusion: Material stiffness and cavity design significantly affected stress distribution in primary molars. High-viscosity GIC demonstrated more favorable biomechanical behavior than low-viscosity GIC. Class II cavities generated higher stresses than Class I cavities under static loading.