Flexural Strength of Different Restorative Materials Used for Direct Restoration in Pediatric Dentistry: An In Vitro Study

Abstract

Background: Preservation of tooth structure is a key principle in pediatric dentistry, where restorative materials must balance mechanical strength with the preservation of pulp vitality and minimally invasive techniques. The aim of this in vitro study, as it relates to pediatric dentistry, was to investigate the flexural strength of common composite resins, glass ionomer cements, and resin-modified glass ionomer cement within standardized and homogeneous laboratory conditions. Methods: This study evaluated the flexural strength of seven restorative materials: four composites (Filtek™ Z250, Filtek™ Supreme XT, Gradia, Premise), two GICs (Ketac™ Molar Easymix, GC Fuji IX GP), and one RMGIC (Vitremer). Standardized specimens were prepared and tested using a three-point bending protocol with a universal testing machine (Zwick-Roell Z005). A total of 49 specimens were fabricated and analyzed. Statistical analysis was performed with a one-way ANOVA followed by Tukey’s post hoc test. Results: The flexural strength value of composite resins was significantly greater than that of the glass ionomer and resin-modified glass ionomer cements (p < 0.001). Filtek™ Z250 had the highest flexural strength, and Vitremer, a resin-modified glass ionomer cement, exhibited intermediate performance. Ketac™ Molar Easymix had the lowest values among conventional glass ionomer cements, whilst the flexural strength values obtained for GC Fuji IX GP were similar to some composite materials but with higher variability. Conclusions: Composite resins remain the most durable option for pediatric restorations in stress-bearing areas, whereas RMGICs provide a compromise between mechanical performance and biological advantages such as fluoride release and biocompatibility. Conventional GICs, despite their lower flexural strength, retain clinical relevance in low-load sites and for patients at a high risk of caries. Material selection in pediatric dentistry should therefore be tailored to the child’s age, tooth location, and functional demands to ensure long-lasting, minimally invasive restorations. This study involved only mechanical properties alone, and biological aspects, such as fluoride release and biocompatibility, were not considered. Material selection in pediatric dentistry should therefore take into account mechanical requirements, restorative location, and clinical environment.