## 4 Discussion
The researchers could not find provisional remnants on the dentin surface with EDS analysis except for the groups cleaned with hand instruments and water rinse only. Another study investigated the influence of different cleaning methods on IDS and DDS. The highest bond strength values were found when fluoride-free pumice paste was chosen for the cleaning method [12]. In another study, it was pointed out that all cleaning methods decreased the thickness of the DBA, especially when they had a non-filler content. However, none of the cleaning procedures removed the entire thickness of the DBA [3]. The researchers also pointed out the importance of the application of an air barrier to prevent an oxygen-inhibited layer from removing the entire DBA and exposing the dentin [3]. The fluoride-free pumice cleaning method was employed in the current study with a low-speed hand instrument using a brush. The application of an air barrier before polymerization was performed for every specimen. Metal oxides are commonly used as colourants in the dental industry. They are mixed in a composition of impression pastes, dental ceramics, and dental composites, among others. Try-in pastes are composed of glycerol and metal oxides like Al, Si, Ti, Fe, and Zn, which are used for creating different colours to match the colour of the resin cement [9]. Earlier a study on uncontaminated dentin with X-ray photoelectron spectroscopy and EDS presents the peaks of the major elements like Ca, P, C, N, and O [13]. In the current study, EDS from intra- and intertubular dentin disclosed metal oxide besides the natural composition of dentin, which is evidence of try-in paste remnants. Intertubular and intrattubular EDS analysis results were obtained. In the analysis taken from the intratubular region, Ca and P found in dentin tissue were detected in high amounts. Also, C, O, Si, Al, Pt, Zn, and Mg were found in trace amounts. The weight percentages of the elements were 0.47% Mg, 4.58% Al, 5.74% Si, 26.8% P, 57.67% Ca, and 4.74% Zn. In the analysis taken from the intertubular region, Ca, P, C, O, Si, Pt, Zn, and Mg were detected in different amounts. The weight percentages were determined as 1.64% Mg, 1.94% Al, 2.16% Si, 33.17% P, 55.89% Ca, and 5.21% Zn. The presence of these metal oxides, which are used as colour pigments, was in accordance with the mechanical test results and pointed out the try-in paste contamination for group C causing lower bond strengths. A strong bond can be achieved by creating a solid interphase or hybrid layer with the penetration of monomers into hard tissues. The importance of this penetration was pointed out because once this infiltrated monomer polymerized, a structural bond, as in the dentin-enamel junction, can be created [1]. SEM images from Groups A and B revealed peritubular pullout, which was evidence of strong adhesion. Usually, a strong correlation is found between the mean bond strength and the type of failure. The higher the bond strength, the higher the rate of cohesive failure [11]. Failure types are given in Table 2. When the failure types in this study were examined, adhesive-type failure was seen mostly in Group B, the IDS-applied group, and mixed-type failure was seen in Group C. In [PERSON] et al. 's study, the failure type mostly seen in IDS-applied groups was mixed-type [20]. In [PERSON] et al. 's study, adhesive failure was seen mostly in the group without IDS [23]. However, it is stated that the failure type depends on the difference in the surface structure of the dentin, head speed, and the fact that the force is not distributed equally to every point for any reason [24]. It was also reported that the observed interface failure is related to the test method used. Figure 5 shows an SEM image of a sample from the IDS-applied group. Breaks at the dentin tubule mouths indicate cohesive breakage within the dentin tissue. Considering the bond strength data of this group, cohesive rupture in dentin is an indicator of good bonding to dentin.