is similar to the natural enamel [9; 10], their marginal precision [9; 11] and the reduced abrasiveness towards the antagonistic dentition [12]. Unfortunately, in recent decades, the intrinsically unpleasing aesthetic of gold alloys has drastically limited their use, even for the posterior teeth occlusal surfaces. Nevertheless, the selection of alternative materials with a wear resistance that is analogous to natural enamel is still essential, especially when dealing with extensive full-mouth rehabilitations. Nowadays, resin composites are amongst the most employed restorative materials. Composite resins are made of an organic matrix, inorganic fillers, bonding agents, pigments, catalysts and inhibitors [13]. In terms of organic matrix composition, urethane dimethacrylate (UDMA) showed higher mechanical properties compared to triethylene glycol dimethacrylate (TEGDMA), ethoxylated bisphenol A-dimethacrylate (Bis-EMA) and bisphenol A-glycidyl methacrylate (Bis-GMA) [14]. For small- and medium-sized cavities, composites can be applied with a direct technique by the clinician, while for large-sized cavities, indirect restorations are suggested [15]. During the curing step, resin composite properties are affected by the double carbon bonds conversion degree to single ones [16]. Light-curing of direct restorations does not guarantee a complete monomer conversion [17], due to approximately up to 45% of unreacted monomers and double bonds [18]. Indirect restorations can receive further extra oral polymerization steps, subjecting them to additional heat-curing cycles [19], finally enhancing their mechanical properties [20; 21; 22; 23]. Concerning indirect dental materials, the recent implementation of industrially polymerized resin-based composites, made available as CAD/CAM resin-based blocks or discs, has further enhanced their indications for a widespread and increasing number of different clinical applications. In comparison to light-cured composites, CAD/CAM materials show superior mechanical and surface properties [24; 25; 26], color stability [27; 28; 29], reduced bacterial adhesion [30; 31] and a decreased release of monomers [32]. Furthermore, the CAD/CAM workflow seems to promote patient satisfaction [33], reducing the clinical chairside time and laboratory costs [34]. At the same time, the CAD/CAM restorations' intaglio surface fit [35; 36; 37; 38] appears at least similar to what is achievable using more traditional analogical laboratory workflows. Among the different CAD/CAM manufacturing methods, the subtractive systems use milling machines to cut prefabricated and industrially polymerized discs or blocks into the desired shape [39]. The pre-polymerized resins are manufactured under elevated temperature (>100 \({}^{\circ}\)C) and pressure conditions (>150 MPa) to obtain highly dense material [40; 41]. This allows us to significantly increase the cross-linking degree (up to 90-95%) and achieve a more uniform polymerization, as high temperature increases the chains' mobility and the monomer conversion, while high pressure balances the shrinkage and reduces the number of defects and their size [41; 42]. The isotropic mixture compaction increases its density, promoting the reduction of defects in number and size [41], which may further improve the material mechanical properties [43; 44]. Polymerization with high temperature and high pressure limits the shrinkage because of monomers getting closer together [41]. High pressure can promote a more homogeneous in-mass polymerization than light-curing, as this reaction requires a light-source and some distance from the composite [41]. All of the above-mentioned potential benefits have led to a strong and increasing interest towards CAD/CAM resin-based composites lately, raising the need for carefully investigating the laboratory performances of any new material that is made available on the market, in order to independently confirm the presence of adequate mechanical properties.