## 3 Results
### ESHF and AHPS  
After 10 days, the tissue response to ESHF and AHPS was scored as Severe. A granulomatous tissue composed of lymphocytes, polymorphonuclear leucocytes, macrophages, blood vessels and some areas of necrosis were observed in contact with either material (Figure 1A-D).  
After 30 days, the reaction to both materials had diminished. ESHF scored a tissue reaction of Mild. A juvenile NHBF covered by a thin fibrous capsule had progressed with a tendency to cover the open end of the tubes. Below the capsule, a few inflammatory cells were still present. This picture was common for all specimens of the ESHF group (Figure 2A,B). Tissue reaction to AHPS was scored as Mild (one specimen) and Moderate (seven specimens). Under a discrete initial fibrous tissue formation, a fibro-granulomatous tissue containing clusters of lymphocytes, macrophages, plasmocytes, blood vessels and islets of necrosis were observed (Figure 2C,D).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{
\begin{tabular}{c} **Inflammatory** \\ **Response** \\ \end{tabular} } & \multicolumn{2}{c}{**10 Days**} & \multicolumn{2}{c}{**30 Days**} & \multicolumn{2}{c}{**90 Days**} \\ \cline{2-7}  & **ESHF** & **AHPS** & **ESHF** & **AHPS** & **ESHF** & **AHPS** \\ \cline{2-7}  & \(n\) **(\%)** & \(n\) **(\%)** & \(n\) **(\%)** & \(n\) **(\%)** & \(n\) **(\%)** & \(n\) **(\%)** \\ \hline None & 0 (0) & 0 (0) & 0 (0) & 0 (0) & 8 (100) & 0 (0) \\ \hline Mild & 0 (0) & 0 (0) & 8 (100) & 1 (12.50) & 0 (0) & 8 (100) \\ \hline Moderate & 0 (0) & 0 (0) & 0 (0) & 7 (87.50) & 0 (0) & 0 (0) \\ \hline Severe & 8 (100) & 8 (100) & 0 (0) & 0 (0) & 0 (0) & 0 (0) \\ \hline \end{tabular}
\end{table}
Table 1: Number (%) of samples in each group categorized according to the inflammatory score and the observation period.  
At the end of the experiment (90 days), all samples with ESHF received scores of None. Complete bone deposition of healthy new bone trabeculae lined by active osteoblast-like cells was observed (Figure 3A,B). The NHBF was covered by a thin fibrous capsule free of inflammatory cells. In contact with AHPS (Figure 3C,D), the tissue reaction was scored as Mild. There was a dense fibrous connective tissue formation containing a few persistent lymphocytes, but no NHBF was observed.  
Figure 1: At 10 days. **(A)** Photomicrograph of a representative specimen of ESHF showing a dense inflammatory reaction (white arrow) in contact with the sealer (empty space). Black arrow: bone marrow; BC: cortical bone (Hematoxylin and Eosin; original magnification \(\times\)100). **(B)** Higher magnification from the square area in **(A)** showing a granulomatous tissue in which polymorphonuclear leucocytes (PN), lymphocytes (L) and plasmocytes (PL) were observed. White arrow indicates the presence of an islet of necrotic area (Hematoxylin and Eosin; original magnification \(\times\)400). **(C)** Photomicrograph of a representative specimen of AHPS showing an inflammatory reaction and a necrotic area (white arrow) in contact with the sealer (empty space). Below, black arrows indicate the presence of reduced marrow space (Hematoxylin and Eosin; original magnification \(\times\)100). **(D)** Higher magnification from the square area in **(C)**. This shows a granulomatous tissue containing polymorphonuclear leucocytes, lymphocytes, macrophages, and blood vessels (BV). Note the presence of a free bone particle (white arrow) and a reduced bone marrow area (black arrow) (Hematoxylin and Eosin; original magnification \(\times\)400).