Truly Universal Dental Cements vs. Conventional Ones—Comparison of Mechanical Properties

This article evaluates the mechanical performance of truly universal resin cements, which promise broad substrate compatibility, simplified self-adhesive dual-cure mechanisms, and functional monomers. It addresses the inconsistent classification of market materials labelled as ‘universal’ and the lack of clear guidelines. Flexural strength (FS), diametral tensile strength (DTS), and Vickers hardness (HV) of ten resin cements were evaluated: five classified as truly universal (RelyX Universal, Calibra Universal+, Nexus Universal, Panavia SA, SoloCem) and five conventional (Panavia V5, RelyX U200, Cem SE DC, G-Cem One, Maxcem Elite). Significant variations occurred across the tested materials. RelyX Universal exhibited the highest HV (68), while Panavia V5 the lowest (20). FS ranged from 73.0 MPa (Panavia SA) to 114.4 MPa (G-Cem One). Elastic modulus values were lowest for RelyX Universal (3638 MPa) and Panavia SA Cement Universal (3812 MPa), and highest for Cem SE DC (8092 MPa). DTS values were comparable across the groups (35.4–50.2 MPa). No clear differences were observed between cements classified as truly universal and conventional materials in terms of FS, DTS, or HV. However, significant variations were found among individual materials (p < 0.05), indicating that mechanical performance is material-dependent rather than classification-based. Greater transparency in product characterisation is essential to enable accurate material classification.