Translucency, hardness and strength parameters of PMMA resin containing graphene-like material for CAD/CAM restorations

CAD/CAM restorations can be produced from several ceramic and hybrid materials. The moderate mechanical properties of PMMA based resin have hindered its use for permanent restorations. Recently, a graphene reinforced PMMA namely G-CAM has been introduced for permanent CAD/CAM restorations. Although graphene family materials have been successfully used as a reinforcement phase in a variety of polymers, the properties and mechanical behavior of PMMA resin containing graphene-like materials remain unknown. Herein, we have evaluated the translucency, hardness and strength parameters (flexural strength, Weibull modulus and characteristic strength) of G-CAM Al (GA1) and G-CAM B2 (GB2) and benchmarked it against a unmodified PMMA resin (PM), two polymer/ceramic hybrid materials [Vita Enamic WE) and Lava Ultimate (LU)] and one ceramic (e.max, EX) for CAD/CAM restorations. The trends for the translucency parameter were similar for all materials at all thickness tested. The hardness for GA1, GB2 and PM were significantly lower than VE, LU and EX. The biaxial flexural strengths of GA1, GB2, PM and VE were approximately 150 MPa but significantly lower than LU and EX (201 and 313 MPa). All materials presented Weibull modulus higher than 10, except EX (m = 8) The stresses required to fracture 5% and 63.2% of specimens (sigma(5)% and sigma(0)) were similar for GA1, GB2, PM and VE but significantly lower than LU and EX. Overall, the PMMA modified by graphene-like materials presented properties comparable with unmodified PM and VE.