## 3 Results
### ESEM-EDX Analysis  
In the SC group, the coronal third examination revealed few electron-dense granules on the dental surface (Figure 5). The dental tubules were partially occluded by the smear layer. The EDX microanalysis showed the presence of tracer elements that can be attributed to the sealer (W) and gutta-percha cone (Zn). The dentine surface at the middle third was characterized by a thick layer of remnants. The images at 100\(\times\) showed an irregular layer, with some areas filled by electron-dense remnants and a few areas with limited remnants. The images at 3000\(\times\) showed dentinal tubules completely filled by electron-dense granules. The EDX revealed high peaks of elements that can be attributed to the AH Plus (Wolframium, W) and gutta-percha cone (Zinc, Zn, and Silicon, Si). Nitrogen (N), an index of the organic components of dentine  
Figure 5: Root canal obturated with SC technique, sectioned and examined with ESEM/EDX. Coronal third examination at 100\(\times\) (**A**) revealed a few electron-dense granules on the dental surface. Dentinal tubules at 3000\(\times\) were partially occluded by smear layer (**B**). EDX microanalysis showed the presence of tracer elements that can be attributed to the sealer (W) and gutta-percha cone (Zn) (**C**). Dentine surface at the middle third at 100\(\times\) (**D**) was characterized by a thick layer of remnants. Image at 3000\(\times\) (**E**) shows an irregular layer with some areas filled by electron dense remnants, and few areas with limited remnants. EDX (**F**) revealed high peaks of elements attributable to AH plus (W) and gutta-percha cone (Zn, and Si). N, index of collagen was not detected in this area. Dentine surface at the apical third (**G**) was partially free from remnants. At 100\(\times\) displayed few thin layers of remnants close to the anatomical apex. At 3000\(\times\) revealed dentine surface with a few remnants (**H**). In this area, the tubules were mostly open and well visible. EDX microanalysis revealed low presence of sealer tracer elements (W) and no gutta-percha tracing elements (**I**). (collagen), was not detected in this area. The dentine surface at the apical third was partially free from remnants. At 100\(\times\), the analysis displayed a few thin layers of remnants close to the anatomical apex. At 3000\(\times\), it revealed the dentine surface with a few remnants. In this area, the tubules were mostly open and well visible. The EDX microanalysis revealed a low presence of sealer tracer elements (W) and no gutta-percha tracing elements. In the GF group, the ESEM images at the coronal and at the middle third displayed a high presence of electron-dense remnants (Figure 6). The dentine surface was characterized by open dentinal tubules and partially covered by electron-dense remnants. These remnants were not detected in the periapical X-ray and CBCT examinations. At the middle third, the ESEM images (100\(\times\)) revealed a large remnant layer. At a high magnification (3000\(\times\)), the remnants completely covered the dentinal structures, with no signs of tubules. The EDX examination of the remnants revealed a high presence of elements from Guttafusion, namely Zn, Barium (Ba), and Titanium (Ti). Some remnants that were not observable in radiographical examinations were detected in the  
Figure 6: Root canal obturated with GF technique, sectioned, and examined with ESEM/EDX. Coronal third examination at 100\(\times\) (**A**) revealed a few electron-dense granules on the dentinal surface. Dentine surface at 3000\(\times\) (**B**) was characterized by open dentinal tubules and partially covered by the electron-dense remnants. EDX microanalysis (**C**) showed the presence of tracer elements attributable gutta-percha (Zn). Middle third at 100\(\times\) (**D**) displayed a high presence of electron-dense remnants. At high magnification (3000\(\times\)), (**E**) the remnants completely covered the dentinal structure, with no signs of tubules.