## 2 Materials and Methods  
Thirty-six intact molars, extracted for periodontal reasons, were selected. The occlusal surfaces were flattened using a low-speed diamond saw (Micromet, Remet s.a.s, Casalecchio di Reno, Italy) to expose sound coronal dentin. A standardized smear layer was created using a 600-gri paper (Hermes Schleifmittel GmbH, Hamburg, Germany). Samples were then divided into three groups (\(n=12\) each) according to the dual-curing adhesive cement employed: Group 1, Panavia V5 (V5, Kuraray); Group 2, Bifix QM (QM, VOCO GmbH); Group 3, Estecem (ES, Tokuyama). A detailed composition of the employed materials is showed in Table 1, while a schematic representation of sample preparation is shown in Figure 1.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
_Appl. Sci._**2021**, _11_, 3971 Cerasmart CAD-CAM blocks were serially sectioned into 4 mm slabs using a low-speed diamond saw (Micromet, Remet s.a.s, Casalecchio di Reno, Italy). Each slab was then sandblasted with 50 \(\mu\)m Al\({}_{2}\)O\({}_{3}\) powder at 1.5 bar pressure (Rondoflex, KaVo Italia, Sesto San Giovanni, Italy). Each specimen was then rinsed with white pure alcohol using a microbrush (Microbrush International, Grafton, MA, USA). According to manufacturer instructions and dual-curing cement employed, CAD-CAM slabs were divided into different groups and treated as follows:  
Groux-learfil Ceramic Primer (Kuraray) applied for 20 s with a microbrush and gently air dried. Groux-Bifix Ceramic Bond (VOCO GmbH) applied for 20 s with a microbrush, and gently air dried. Groux-Primer A + Primer B mixed before application in equal proportions (1:1) (Tokuyama),  
1 applied for 20 s with a microbrush and gently air dried after 10 s.  
G3):Tooth specimens were also randomly divided in different groups (\(n=12\) each) and the exposed dentin area was treated according to manufacturer instructions:  
1. V5: V5 tooth primer application on the dental surface for 20 s, followed by gentle air dry. Application of Clearfil Universal Bond Quick dualized with a 1:1 ratio of Clearfil DC Activator (Kuraray) for 20 s and then gently air dried. 2. QM: Application of Futurabond U (VOCO GmbH) for 20 s, then gently air dried. 3. ES: Estelink Bond A + Estelink Bond B mixed before application in equal proportions (1:1) (Tokuyama) application for 20 s, then gently air dried. Adhesively treated specimens were then luted to the pretreated CAD-CAM slabs according to the group assigned: G1: Panavia V5 cement (Kuraray); G2: Bifix QM (VOCO GmbH); G3: Estecem (Tokuyama). After the application of the adhesive cement a constant pressure was applied for 60 s on the composite block to simulate clinical conditions. The specimens were then light cured using a multi-LED lamp (Valo, Ultradent) for 60 s.  
After 7 days of storage at 37 \({}^{\circ}\)C in distilled water, specimens were serially sectioned, using a low speed diamond saw ([PERSON], Remet s.a.s, Casalecchio di Reno, Italy), in order to obtain 1 \(\times\) 1 mm beams according to the \(\mu\)TBS technique [16]. From each group half of the beams were tested to failure immediately (T0), the other half were stored in artificial saliva prepared according to [PERSON] et al. 2004 [17], at a 37 \({}^{\circ}\)C temperature in an incubator, in order to be tested after 12 months of storage (T12). The beams were stuck on a Ciucchi's jig [18] that doesn't permit bending forces and facilitates the exclusive stressing of adhesion surfaces [19]. A fast-setting cyanoacrylate glue with its activator (Akfix 705, Akkim, Pesar, Italy) was employed for fixating beams. Testing was performed using a microtensile tester (BISCO Dental Products, Schaumburg, IL, USA) at a rate of approximately 1 mm/min. The obtained values, measured in newton (N), were then converted in MPa after measuring the adhesion surface of each stick with a digital caliper. Figure 1: Schematic representation of the sample preparation protocol.