Bonding Performance, Mass Stability and Mechanical Properties of Self-Adhesive Resin Composites and Conventional Dental Composites: A Comparative Laboratory Evaluation

Abstract

Self-adhesive resin composites (SARCs) are gaining popularity due to their simplified clinical steps. The objectives of the study were to evaluate the bonding performance, mass stability and mechanical properties of three SARC materials and to compare them with those of two conventional RC materials using a universal adhesive system (UAS). Materials and Methods: A total of 80 bovine enamel blocks with 5 mm × 5 mm dimensions were prepared and embedded in acrylic molds. The surface of the enamel was polished using 600-grit carbide to create the smear layer. After acid etching, 2 mm × 2 mm cylinder-shaped restorations were made either with one of the three SARCs or with two types of RCs using UASs. Shear bond strength tests were performed after 24 h of water incubation and after 1 year of artificial aging. The mass stability of the hexagonal-shaped SARC and conventional RC was evaluated using water sorption and solubility tests. Then the mechanical properties of the bonded composites were tested, including Vickers hardness, elastic modulus and creep, after 24 h of water incubation and after 1 year of artificial aging. Results: Both the material types and aging showed a significant effect on the bonding performance, mass stability and mechanical properties of SARCs and conventional RCs (p < 0.05). The shear bond strength of SARCs was comparable to that of a conventional RC + UAS. Conventional RCs showed lower water sorption and solubility compared to SARCs. The Vickers hardness, elastic modulus and creep properties of some SARCs were inferior compared to conventional RCs both at 24 h and at 1 year. Conclusions: The bonding performance of SARCs can substitute the conventional RC+ UAS; however, its inferior mass stability and mechanical properties limit its use in routine dental restorative procedures.