## 4 Discussion
Both BC-sealers exhibit high alkaline pH range between 10.5 and 12, with the maximum value at 21 days for BC-HiFlow, while maintained continuous increased up to 28 days for BC-EndoSquence (Figure 1B). Similar pH values of BC-EndoSquence [18; 33; 43] and BC-HiFlow sealers [39] were previously reported. However, one study reported lower value for BC-HiFlow that did not exceed 8.5 among 28 days [16]. Their alkalinity was increased consequent to increase the solubility and increasing the releasing Ca\({}^{2+}\) among the successive experimental periods. The pH value seems to be associated with the setting time. Although both BC-sealers display high alkaline pH among all the experimental periods, gradual decline of this value by BC-HiFlow after 7 days was noted and may be attributed to its fast setting within this time. However, BC-EndoSquence represents further increase in pH up to 28 days that may be attributed to its prolonged final setting time which extended over 3 months. On the other hand, [PERSON] et al. 2021 reported that high alkaline environment reduced the solubility of the BC-EndoSquence sealer [6]. As a result of the hydration reaction of the calcium silicate-based sealers, calcium hydroxide was formed and dissociated into hydroxyl ions (OH\({}^{-}\)). With high alkaline medium, supersaturation of OH\({}^{-}\) may reduce further ion dissociation and thus reduce sealer solubility [6]. However, Adseal displayed weak alkaline pH (\(\approx\)8.5) among all experimental periods. It was suggested that the low alkalinity was favourable for epoxy resin sealer as it eliminates the corrosion and degradation of sealer particles and in turn reduce its solubility [6]. Assuming the similar composition of both BC-sealers, FTIR analysis revealed similar composition of both sealers with different band intensity indicating the variable concentration of their constituents, which related to their different chemical properties. The high solubility may be attributed to the Ca(OH)\({}_{2}\) content [38] that was detected with high band intensity in FTIR spectra of BC-HiFlow (Figure 2A). Furthermore, the high intensity of CH-of organic filler indicates an increase in the setting accelerating agent while the decrease of OH- (at 3400 and \(\approx\) 1650 cm\({}^{-1}\)) bands indicates the consumption of water during hydration reaction. The high intense v\({}_{4}\)SiO\({}_{4}\approx\) 750 and 450 cm\({}^{-1}\) indicates the formation of polymerized calcium silicate hydrate (CSH) [25; 28; 32]. These findings explained the faster setting of BC-HiFlow compared with spectra of BC-Endosequence (Figure 2B). However, the spectra of BC-Endosequence detected high intensity of v\({}_{4}\)SiO\({}_{4}\) of C\({}_{2}\)S at 874 cm\({}^{-1}\) indicating greater content of unreacted particles [25], which may be related to its prolonged setting time and possibility of higher solubility. On the contrast, Adseal contained insoluble resin matrix that formed during polymerization reaction of amine group of epoxide groups having covalent cross-linked bond that resist the solubility. Furthermore, gain weight was initially obtained by Adseal that may be attributed to initial water sorption of resinous matrix during polymerization expansion [5; 35]. However, Adseal exhibited delay weight loss after 21 days and that may be attributed to degradation of unreacted particles [44]. The solubility is considered as prerequisite for leaching particles. Since calcium silicate is the main constituent in BC-sealer, and calcium phosphate in Adseal, the leachable Si\({}^{4+}\) and PO\({}_{4}\)\({}^{3-}\) are respectively critical for these sealers. It confirmed by the current study where significant greater released of Si\({}^{4+}\) was detected in BC-HiFlow followed by BC-EndoSquence. BC-HiFlow contained greater wt.% of Si than BC-EndoSquence (Figure 3D,E). Meanwhile, Adseal released greater PO\({}_{4}\)\({}^{3-}\) that attributed to its greater P wt.% (Figure 3F).