# Hydration Characterization of Two Generations of MTA-Based Root Canal Sealers
## 3 Results
### Setting Reaction by FTIR  
FTIR analysis showed nearly similar compositions of the raw pastes of both MTA-based sealers at varying intensities (Figure 1A,B). Their spectra detected bands of calcium hydroxide (Ca(OH)2 \(\approx\) 3642 cm\({}^{-1}\)[18; 19; 20; 21; 22], OH \(\approx\) 3300 cm\({}^{-1}\)[22], methyl (C-H) at 2980-2870 cm\({}^{-1}\), carbonyl group (C=O) at 1700-1500 cm\({}^{-1}\) and 1320-1300 cm\({}^{-1}\), and aromatic C-O bond (\(\approx\)1210 cm\({}^{-1}\)) of salicate [21; 23; 24; 25] with low intensity in MTA-Fillapex. Bands of carbonate (C-O) at 1460-1420, 1240-1200, and \(\approx\)700 cm\({}^{-1}\)[18; 20; 22; 23; 24; 26], sulphate band \(\approx\) 1155 cm\({}^{-1}\)[22] (in Bioseal), titanium oxide at 1092 cm\({}^{-1}\)[27] (in Bioseal), v\({}_{3}\)SiO4 of tricalcium silicate (C\({}_{3}\)S, alite) at 1086 cm\({}^{-1}\)[21], dicalcium silicate (C\({}_{2}\)S, belite) at 868 cm\({}^{-1}\)[20], SiO4 at 859 cm\({}^{-1}\), v\({}_{4}\)SiO4 at 800-700 cm\({}^{-1}\)[22], v\({}_{2}\)SiO4 of C\({}_{3}\)S \(\approx\) 522 cm\({}^{-1}\)[20], v\({}_{1}\)SiO4 of C\({}_{2}\)S \(\approx\) 452 cm\({}^{-1}\)[21], phosphate bands \(\approx\) 1040-1030 cm\({}^{-1}\)[18; 23; 28; 29], aluminum oxide (Al-O-Si) \(\approx\) 750 cm\({}^{-1}\)[25; 30; 31], and Ca-O of tricalcium aluminate \(\approx\) 420 cm\({}^{-1}\) (in Fillapex) [32] were also detected. The spectra of the mixed MTA-sealer showed a dip of calcium hydroxide, amide C=O, C-H, and C\({}_{3}\)S (\(\approx\)860 cm\({}^{-1}\)) bands synchronized with a hump of carbonate and silicate bands. The dip/hump of band intensity was a gradual progression with time. In the spectra of MTA-Bioseal, v\({}_{3}\)v\({}_{3}\)SiO4 bands (at 940 and 573-515 cm\({}^{-1}\)) gradually shifted to higher wave numbers (\(\approx\)950 and 592-577 cm\({}^{-1}\), respectively). Furthermore, the O-Si-O bands at 795 and 440 cm\({}^{-1}\) assigned to calcium silicate hydrate (CSH) [22] became more intense. In MTA-Bioseal spectra, the sulphate band \(\approx\) 1155 cm\({}^{-1}\)[22] gradually dipped over time. No further changes were detected after 24 h. In the spectra of MTA-Fillapex, the bands related to CSH \(\approx\) 950, 795, and 440 cm\({}^{-1}\) failed to be detected up to three months (Figure 1B). The spectra of raw pastes of Adseal detected the bands of OH stretching at 3342 cm\({}^{-1}\), C-H at 2980-2800 and \(\approx\)1340 cm\({}^{-1}\)[21; 33; 34], carbonyl group (C=O) at 1670 and 1602 cm\({}^{-1}\)[23], C=C of the benzene ring at 1518 cm\({}^{-1}\)[35], CH\({}_{3}\) group \(\approx\) 1450 cm\({}^{-1}\), phosphate of v\({}_{3}\)PO\({}_{4}\) at 1100-1000 cm\({}^{-1}\), v\({}_{4}\)PO\({}_{4}\) at 600 and 560 cm\({}^{-1}\) and v\({}_{2}\)PO\({}_{4}\)\(\approx\) 490 cm\({}^{-1}\)[33], CH\({}_{3}\) of epoxoid ring at 740-700 cm\({}^{-1}\)[36; 37], and Si-O at 790 cm\({}^{-1}\)[38]. The spectra of the immediate mix showed humping of the C=O bands at 1672 and 1508 cm\({}^{-1}\), C-C at 1298 cm\({}^{-1}\), CH\({}_{2}\) at 1248 and 790 cm\({}^{-1}\), and CH at 740-700 cm\({}^{-1}\)[37] of the epoxoid ring [34; 36; 37]. The bands of aromatic rings at 829 and 755 cm\({}^{-1}\) humped and shifted to higher wave numbers [34]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & **MTA-Bioseal** & **MTA-Fillapex** & **Adseal** & \(p\) **Value** \\ \hline \multirow{2}{*}{Setting time (hours)} & Initial & 1.3 \(\pm\) 0.13 & 29 \(\pm\) 0.74 \({}^{*}\) & 1.3 \(\pm\) 0.12 & \multirow{2}{*}{\(<\)0.001} \\ \cline{2-5}  & Final & 11.4 \(\pm\) 1.34 & NA \({}^{*}\) & 4.7 \(\pm\) 0.46 & \\ \hline \end{tabular}
\end{table} 
Table 1: Mean \(\pm\) standard deviation values of initial and final setting times of all investigated root canal sealers.