# Characterization and Crystallinity of Two Bioactive Sealers: Qualitative and Quantitative Analysis
## 3 Results
### FTIR Spectroscopy  
The FTIR spectra of both bioceramic sealers revealed an increase in the intensity of Amide I bands (1720-1550 cm\({}^{-1}\)) in water with a decrease in PBS (Figure 3(Ca,Ea)). In Cerafil, there were no obvious changes in \(v_{1}v_{3}\) phosphate band intensity (1200-900 cm\({}^{-1}\)) in water and a decrease in PBS (Figure 3(Cb)); however, it was increased by water immersion, with a further increase in PBS in Endosequence (Figure 3(Eb)). The carbonate band (900-800 cm\({}^{-1}\)) increased during water immersion and decreased in PBS in both bioceramic sealers (Figure 3(Cb,Eb)). In AH-26, the intensity of amide I bands increased in both solutions, while there was a decrease in the mineral bands (phosphate bands) and an increase in the carbonate band (Figure 3(Aa,Ab), respectively).  
Accordingly, the PO4\({}^{3-}\)/amide I ratio was significantly greater in raw Endosequence (24.06 \(\pm\) 1.3) followed by raw Cerafil (20.66 \(\pm\) 3.7), while raw AH-26 had the lowest significant value (5.86 \(\pm\) 0.26) at \(p\) < 0.001. This ratio was significantly increased with water immersion and furtherly increased by PBS in both Endosequence and Cerafil. There was no change in AH-26 in either solution (Figure 4A).  
Figure 2: Scanning electron microscopy photographs for Cerafil (**C**), Endosequence (**E**), and AH-26. (**A**) sealers before (**R**) and after immersion in water (**W**) and PBS; (**P**) shows the particle size of each sealer.  
Figure 3: FTIR spectra of investigated sealers, Cerafil (**C**), Endosequence (**E**), and AH-26 (**A**), in different environments, showing the different areas of amide I at 1720–1580 cm\({}^{-1}\) (**a**), mineral and carbonate at 1200–900 and 900–890 cm\({}^{-1}\), respectively (**b**), and degree of crystallization based on \(\upsilon\)4 PO4\({}^{3-}\) peaks at \(\approx\)603 and 580 cm\({}^{-1}\) (**c**). Spectra of the three sealers related to crystallinity degree after immersion in PBS (**D**).  
Figure 4: Mean \(\pm\) standard deviation of FTIR PO43–/Amide I ratio (**A**), CO32–/PO43– ratio (**B**), and crystallinity index (**C**). The symbol (*) refers to the greatest significant mean at \(p\) < 0.001, the symbol (\(\dagger\)) refers to the lowest significant mean at \(p\) < 0.001, and the symbol (\(\
eq\)) indicates no significant difference between the sealers of the same symbol at \(p\) > 0.05.  
The represented hydroxyapatite split doublet/\(v_{4}\) phosphate bands at \(\approx\)600 and 560 cm\({}^{-1}\) were obvious when the bioceramic was immersed in the solution, particularly in PBS (Figure 3(Cc,Ec)). This was not applicable for AH-26 due to a lack of band height at 590 cm\({}^{-1}\) (Figure 3(Ac)). Figure 3D confirms the hydroxyapatite bands for both bioceramic sealers. Accordingly, the crystallinity index (CT\({}_{\rm FTIR}\)) represents the crystallinity degree of hydroxyapatite. Although Cerafil had the greater values both in water (5.35 \(\pm\) 0.51) and PBS (6.93 \(\pm\) 0.86), there was no significant difference compared with Endosequence (4.15 \(\pm\) 0.47 and 4.7 \(\pm\) 0.51, respectively) at \(p>\) 0.05 (Figure 4C).