## 4 Discussion
This process involves micromechanical anchoring and chemical bonding, increasing the bond strength and durability between the adhesive and tooth structures while reducing the risk of edgeleakage [21]. In our study, Clearfil Tri-S Bond Universal was applied to the inner surfaces of dentin using the self-etch method, thus minimizing cytotoxic effects. Permanent tooth discoloration that occurs because of some materials used in endodontic treatment may require additional bleaching procedures. For this reason, protocols to prevent material-induced tooth discoloration are considered to have an important place in clinical practice. Studies show that DBAs do not completely prevent discoloration but do significantly alleviate it as compared with the control groups with no treatment [12; 16]. Although studies have shown that DBAs and laser irradiation can reduce tooth discoloration [17; 19], our results suggest that such surface treatments may provide limited additional benefit when PPBCs are used. In addition, Nd-YAG lasers are widely preferred in the treatment of dentin hypersensitivity because of their high efficiency in occluding dentinal tubules and deep penetration capacity, but their presence in our study did not significantly affect the color results. ECPR is a kind of CSC used in dental applications, especially for VPT and root end filling. It is known for its bioactivity, biocompatibility, and antibacterial properties, making it a popular choice in endodontics. By using the premixed syringe product, convenient clinical user customization and reduced treatment time have been achieved [33]. There are limited studies comparing the discoloration of ECP with DBA application. In this study, the effect of DBA application on the color change caused by triple antibiotic paste (TAP) was investigated. The results show that DBA application is effective in preventing the color change caused by CSCs [34]. Since materials that have already been proven to cause discoloration were not used in our study, it can be said that the effects of surface treatments (DBA and Nd-YAG lasers) on dentinal tubules were less pronounced than in the previous study. Although coronal discoloration due to CSCs may continue to increase for up to two years, according to the results of previous trials, the minimal discoloration observed in our 180-day in vitro model is consistent with these long-term clinical data [3; 35]. The present findings suggest that premixed hydraulic CSCs may support restorative success in aesthetic regions by minimizing tooth discoloration [36]. Recent studies have also reported favorable cytocompatibility for materials such as Bio-C Repair and NeoPUTTY, indicating that these cements provide a dual benefit, preserving optical integrity while supporting pulp-dentin healing [37; 38]. However, short periods of laboratory observation cannot accurately mimic intraoral conditions; long-term in vivo studies are still needed. Taken together, the available evidence suggests that premixed cements, such as NeoPUTTY and Bio-C Repair, are promising options for procedures in esthetically critical areas because of their low potential for discoloration. The main limitations of this study stem from its in vitro design and the 180-day observation period. Important clinical variables, such as pulpal pressure, tissue fluids, salivary enzymes, and oral biofilm formation, were not simulated in the study design. Each of these factors can affect the diffusion of staining agents, the curing behavior of CSCs, and the optical properties of dentin over time. For example, pulpal pressure can alter material-dentin interactions by altering dentin fluid flow, while biofilm metabolites may contribute to extrinsic or intrinsic discoloration. In addition, the spectrophotometric measurements were obtained by the same operator. Although intra-observer reliability is high, the lack of validation among observers limits the generalizability of our findings.