## 2 Materials and Methods  
A total of 33 human maxillary and mandibular molars with no cracks, restorations, or other defects were collected. The project has been evaluated and approved by the Ethical Committee for Non-invasive Research of the Faculty of Medicine of Cukurova University with the number 50243401/2021-10. The extracted teeth were disinfected in 0.5% chloramine for 24 h and stored in a distilled water at room temperature. The teeth were then embedded in an acrylic resin material (Technovit; Kulzer, Wehrheim, Germany). The occlusal half of each tooth was removed with a diamond saw to expose the mid-coronal dentin, and then polished flat with a 600-grit silicon carbide abrasive paper (Hermes; ExaktApparatbau, Norderstad, Germany) under wet conditions (Exakt 400 CS, ExaktApparatbau, Norderstad, Germany). The surfaces were inspected with a stereomicroscope (Mantis FX, Vision Engineering, Surrey, UK) under a magnification of \(\times 20\) to disclose enamel remnants. A stainless-steel mould with a diameter of 5 mm and a 3 mm depth was manufactured. Autopolymerizing acrylic resin disc patterns (Pattern Resin LS, GC America In, Alsip, IL, USA) were prepared using the steel mould. After inspection for surface irregularities, the disc patterns were spread (Wax wire, BEGO, Bremen, Germany), invested with a phosphate-bonded investment (IPS PressVEST Speed, IvoclarVivadent, Schaan, Liechtenstein), and pressed from lithium disilicate pressable ingots (IPS e.max Press; IvoclarVivadent, Schaan, Liechtenstein) according to the manufacturer's instructions. Sprues were cut using a diamond saw and ceramic discs were inspected for surface porosities. A total of 30 lithium disilicate discs with a diameter of 5 mm and a depth of 3 mm were prepared. Before the cementation procedure, the numbers were drawn to randomize the specimens and determine the corresponding test group. In total, 30 of the specimens were divided into 3 groups (n = 10 per group). An additional 3 prepared specimens from each group were reserved for scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) examinations without surface conditioning with DBA to evaluate the try-in paste contamination of the dentin surfaces. The flow chart of the study is presented in Figure 1.  
The adherent surfaces of the ceramic discs were sandblasted with 50 micron Al\({}_{2}\)O\({}_{3}\) (Korox, Bego, Bremen, Germany), ultrasonically cleaned (Biosonic JR, Whaledent Int, Melville, NY, USA) with distilled water, and dried, and silane was applied (MonobondPlus; IvoclarVivadent, Schaan, Liechtenstein). Resin-based discs from provisional restoration material (Protemp Garant; 3M ESPE, Seefeld, Germany) were fabricated using the same steel mould and then used for preparing acrylic patterns. Group A: The routine clinical application procedures of lithium disilicate (IPS e.max Press; IvoclarVivadent, Schaan, Liechtenstein) restorative material from preparation to cementation were simulated. Group B: The adhesive was immediately applied to dentin. Group C: The dentin surfaces were conditioned only in the final cementation for DDS. For the Group A samples, the immediate dentin coating procedure and try-in paste contamination were not applied. Before coating, 600-grit silicon carbide paper was applied to the dentin surface to remove any possible roughness on the surface. The exposed dentin was polished with SiC sandpapers (#600) for 30 s to standardize the smear layer [17]. The tooth surface was covered with eugenol-free interim cement material (Kerr, Tempbond NE, KaVo Kerr, Brea, CA, USA). The samples were kept in distilled water for a week. At the end of the waiting period, the interim cement material was cleaned with pumice powder and water [18]. The inner surfaces of the porcelain discs were roughened with hydrofluoric acid for 20 s (BICSO, Inc. 1100 W. Irving Park Rd. Schaumburg, IL, USA), washed with compressed air and water for 60 s, and dried.