## 1 Introduction  
Machinable materials are nowadays widely used in restorative dentistry and computer-aided design/computer-aided manufacturing (CAD-CAM) approach has become the only way to produce restorations of certain materials, such as cubic zirconia. As stated in the classification by [PERSON] [1], all restorative ceramic materials can be classified into three big families: glass matrix ceramics, polycrystalline ceramics and resin matrix ceramics. Resin nanoceramics (e.g., Lava Ultimate), glass ceramic in a resin interpretntating matrix (e.g., Banamic) and Zirconia-silica ceramic in a resin interpretntating matrix (e.g., Shofu Block HC) belong to the last group. Cerasmart (GC Europe, Leuven, Belgium) can be classified as a family near resin nanoceramics, since it consists of evenly dispersed ceramic nanoparticles in a high density composite (71% of silica and barium glass filler by weight) [2]. These materials, with a prevalent resin composition, have several functional advantages: their mechanical properties and their \"cushion effect\" can lead to a reduction of occlusal forces and, therefore, restoration fracture or antagonist abrasion [3]. Besides these advantages, their composition leads to lower light transmission, causing a diminished curing reaction. A proposed way to avoid polymerization problems is the initial reconstruction of the tooth with an adhesive build up in order to decrease the reconstruction's thickness, associated with the use of a dual curing adhesive/cement [3]. According to the type of curing, adhesive cements can be classified as: chemical cured (CC), light-cured (LC) and dual cured (DC). CC cements are indicated for thick restorations, radicular posts and crowns made of light-blocking materials [4], but their reduced working time and their low esthetical properties limit their use [5]. On the other hand LC cements are the best choice for situations where light can be almost totally transmitted through the restoration, such as translucent veneers and shallow inlays [6]. In situations where light is highly attenuated, such as indirect posterior restorations, DC cements are the best choice, granting controlled working time and short setting time [7]. A proper light activation, after 1 min of exclusive chemical cure, is however crucial in giving the DC cement a proper polymerization [8]. Independently from the curing kinetics, cements can require or not the use of adhesive systems. On one hand, self-adhesive cements simplify the adhesive luting procedure thanks to a chemical reaction like self-etching adhesives. The acidity of these cements is gradually neutralized when reacting with apatite, causing a shift from a hydrophilic compound to a more hydrophobic one [9]. Although they find clinical application with fiber posts, giving the best retention, their mechanical properties and wear resistance are poorer than conventional resin cements [10]. On the other hand, conventional resin cements still rely on the fundamental principles of adhesion with two main approaches: etch-and-rinse (ER) or self-etch (SE). These systems base their effectiveness on different interactions with the dental substrate. The ER approach is based on the complete removal of the smear layer created during cavity preparation, in order to micromechanically interlock with enamel and dentin, while SE employs a smear layer as a substrate for chemical and mechanical adhesion [11; 12]. In both cases the interdiffusion zone between collagen and resin, called the hybrid layer, is present, granting the possibility of copolymerization with composite resins, creating a durable bond. A new class of adhesive systems, called \"universal\" or \"multimode\" was introduced with the possibility of being used both in SE and ER mode [13]. However, different works in literature showed that, despite good results on dentin, the etching procedure provides better uTBS results on enamel [14]. Some of these new universal adhesives hold in their formulation a silane coupling agent that helps create siloxane bonds between different materials.