Zirconia-based ceramics are characterized by excellent mechanical properties that set them apart from other dental ceramics. Typically having yttrium oxide (Y2O3) as the stabilizing agent of the zirconium dioxide (ZrO2), these ceramics are widely used in dentistry because of their excellent biocompatibility and mechanical properties [1], [2]. The first generation of these ceramics consisted of 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), offering optimal mechanical properties but with relative opacity, thus requiring ceramic veneering to enhance the esthetics of the restorations [3], [4]. To address such esthetic challenge, zirconias with reduced alumina and increased yttria content were developed, increasing the cubic phase and enhancing translucency [5], [6], [7], [8]. These innovations led to monolithic zirconia-based restorations with improved esthetics [9], [10], allowing for minimum tooth preparation, lesser antagonist tooth wear, and faster restoration manufacturing, while maintaining biocompatibility and adequate mechanical properties [2], [11].

Adhesion relies heavily on appropriate surface treatment to facilitate bonding with different substrates. Surface treatment methods such as airborne-particle abrasion using alumina particles (AP) and silica coating (Si) have been investigated. AP promotes topographical changes increasing the surface area and micromechanical retention, strengthening bonding at the interface between the ceramic and the bonding system [1], [12], [13], [14]. The bonding achieved through silica coating occurs due to chemical interaction between the resin-based adhesive system and the silica-coated ceramic surface, in addition to the adherent topography changes that facilitate micromechanical bonding to the adhesive system. These techniques, AP and Si, have improved bond strength and longevity for most ceramic restorations[1]. In addition, self-adhesive resin cements containing methacryloyloxy-decyl dihydrogen phosphate (MDP) enhance chemical interaction with zirconia surfaces, contributing to improved and durable bond strength [15], [16], [17].

Achieving satisfactory functional and esthetic outcomes is one of the major challenges in restorative dentistry, requiring comprehensive knowledge of materials properties and techniques to make the best clinical decisions [1]. Several laboratory tests are available to assess the mechanical behavior of materials and structures, and the fatigue tests are often used to simulate oral environment and service [18]. These tests aim to predict possible failures, such as wear and fractures, caused by fatigue [19], [20]. The cyclic method, albeit more time-consuming, is the most clinically relevant as it allows for better understanding of how the material behaves under simulated conditions [21].

Accordingly, the clinical use of translucent zirconia [22] can represent a huge breakthrough in restorative dentistry because it provides satisfactory esthetic outcomes and adequate mechanical properties. Nevertheless, it is important to understand its mechanical and adhesive behaviors under fatigue to predict proper clinical performance and longevity of the restorations. Therefore, the aim of the present study was to assess the fatigue survival rates of zirconia-based ceramics (3Y-TZP and 5Y-PSZ) bonded to resin-based cement after different surface treatments (None- as milled using a CAD/CAM system; Si- silica coating; and AP- airborne-particle abrasion using alumina particles), testing the hypotheses that (1) the surface treatments do not affect the fatigue survival of the resin-bonded zirconia-based ceramics evaluated and (2) the 3Y-TZP has a higher fatigue survival rate than the 5Y-PSZ when bonded to a resin-based cement.