## 4 Discussion
According to this investigation, when exposed to NaOCl, Angelus MTA displayed the most pronounced discoloration. In a previous study, discoloration resulting from exposure of wMTA to a NaOCl solution was attributed to the reaction between bismuth oxide in MTA and NaOCl. The mechanism of the discoloration was the reduction of NaOCl resulting from the contact between bismuth oxide and sodium chloride [18]. In this study, Angelus MTA containing bismuth oxide as a radiopacifier agent showed similar results. It is thought that Biodentine and BIGfactor MTA do not include bismuth oxide and therefore may have low interaction with NaOCl. It was determined that CHX had the greatest impact on the color of Biodentine. Previously, it has been reported that there was a significant color change when Biodentine and wMTA came into contact with the commonly used irrigation agents NaOCl and CHX [46]. The mechanism of CHX-caused material discoloration is still not clear. However, some research suggests that the micro-surface porosities of calcium silicate-based materials may be responsible for this discoloration [19; 47]. It has been determined that the color change values of the materials in distilled water are very similar and that there is not a statistically significant difference. The outcomes of our investigation agree with those of earlier research that examined the color stability of calcium silicate-based materials when they came into contact with various irrigation solutions [48; 49]. In conjunction with our findings, all calcium silicate-based compounds showed discoloration in these investigations, and NaOCl showed greater discoloration in bismuth oxide-containing materials. In a recent study that investigated the color stability of calcium silicate-based materials in endodontic irrigation solutions, BIOfactor MTA showed more color change than Biodentine [23]. Another major finding from that study was the lack of statistically significant color changes caused by various irrigation agents [50]. This finding supports the current body of research in which we confirmed that various irrigation solutions did not make noteworthy color changes on both BIOfactor MTA and Biodentine. We selected a 24 h contact time based on previous research [48; 51]. Although the materials may be exposed to different solutions and varying durations, we chose a 24 h duration during which the set specimens were submerged in irrigation solutions. This duration does not fully reflect clinical conditions; however, this decision was made to replicate prolonged contact between the solutions and calcium silicate-based materials [48]. Additionally, we applied the same duration for every material to standardize the method. Another limitation regarding the contact duration is that the residual effect of the irrigation solution, which may influence the long-term color stability of the material, was ignored in this study. Further research with larger sample sizes would enhance the statistical power and generalizability of our findings. Including a broader range of irrigation solutions and longer evaluation periods would provide a more thorough assessment of the materials' color stability over extended exposure times. The findings of the second part show that the tested materials stained the tooth structure to varying degrees, as seen by the variation in \(\Delta\)E values. Biodentine did not cause any color change on the teeth at the 1-week and 1-month point. The \(\Delta\)E value then increased both at the 3-month and 6-month points, with the 6-month point showing the highest color change value. BIOfactor MTA, on the other hand, showed no color change on teeth except at the 6-month period. An unexpected finding was that both Biodentine and BIOfactor MTA groups had more color changes than Angelus MTA. This outcome is also consistent with the results of the earlier color research which showed less discoloration in bismuth oxide containing ProRoot MTA than Endosequence and Biodentine [52].