Introduction

Resin-based composite materials have become the restorative material of choice in modern dentistry because of their excellent esthetic properties, compatibility with adhesive bonding techniques that enable durable attachment to tooth structure, and support for minimally invasive cavity preparation [1]. Continuous advancements in composite technology have focused on improving the mechanical performance and longevity of restorations, while maintaining superior esthetics. These developments have led to modifications in resin matrix composition, filler characteristics, and polymerization systems, resulting in materials with enhanced clinical performance [2].

Among the various generations of resin composites, nanohybrid composites represent significant advancements in restorative dentistry. These materials combine nanosized filler particles with conventional microfillers, enabling a higher filler loading, improved polish retention, reduced polymerization shrinkage, and enhanced wear resistance. The incorporation of nanotechnology has also contributed to better mechanical properties and color stability by improving the stress distribution within the resin matrix and strengthening the filler-matrix interface. Consequently, nanohybrid composites are widely recommended for both anterior and posterior restorations, where esthetics and mechanical durability are equally important [3,4]. Although these restorative materials are collectively classified as nanohybrid composites, they are not compositionally identical. Commercially available nanohybrid composites differ in filler type, filler particle size and distribution, filler loading (by weight and volume), resin matrix composition, silane coupling chemistry, photoinitiator systems, and manufacturing processes. These variations may substantially influence their physical and mechanical properties, indicating that materials within the same classification should not be assumed to exhibit equivalent clinical or laboratory performance.

The long-term clinical success of composite restorations largely depends on their physical and mechanical properties. Tensile strength, flexural strength, compressive strength, and surface hardness are critical indicators of a material's ability to withstand functional occlusal forces, resist fractures, and maintain dimensional stability during service [5]. However, despite belonging to the same material category, commercially available nanohybrid composites differ considerably in terms of filler composition, particle size, filler loading, resin chemistry, and manufacturing processes [6]. These variations may result in significant differences in mechanical behavior, making evidence-based comparisons essential for appropriate material selection by clinicians.

Therefore, the present in vitro study was conducted to compare the physical and mechanical properties of four commercially available nanohybrid composite resins. This study aimed to evaluate and compare the tensile strength, flexural strength, compressive strength, and Barcol hardness of Ivoclar Tetric N-Ceram, Prevest Fusion Universal, Dentgist NanoCom, and Waldent NanoFill composites. The objectives were to measure each mechanical property using standardized laboratory testing methods, compare the performances of the four materials, and identify the composite exhibiting the most favorable overall mechanical characteristics for clinical restorative applications.