## 3 Results
### Temperature Mantainance along the Root Canal  
Concerning the extraoral heating method, temperatures lower than 70 \({}^{\circ}\)C did not produce a significant temperature increase. On the other hand, in the case of heating at 70 \({}^{\circ}\)C, the T5 mm and T10 mm thermocouples recorded a temperature level slightly higher than 40 \({}^{\circ}\)C for 5.1 s and 5.8 s, respectively (Table 1). Intracanal heating by the F-06 plugger at 100 \({}^{\circ}\)C, showed temperature levels higher than 40 \({}^{\circ}\)C for a significant prolonged time (\(p<0.05\)) at the T5 mm (33.9 s) and T10 mm (48.6 s) thermocouples than that recorded for the extraoral heating method at 70 \({}^{\circ}\)C (Table 1).  
According to the results of the present study, the extraoral heating method was ineffective to produce a significant temperature increase at the apex of the root, as suggested  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & **Ta** & & **TSmm** & & **T10 mm** & \\ \hline \multirow{3}{*}{**Method**} & **Temperature** & \multirow{3}{*}{\(\Delta\)**t [s] for**} & \multirow{3}{*}{\(\Delta\)**t [s] for**} & \multirow{3}{*}{\(\Delta\)**t [s] for T**} & \multirow{3}{*}{\(\Delta\)**t [s] for T**} & \multirow{3}{*}{\(\Delta\)**t [s] for**} & \multirow{3}{*}{\(\Delta\)**t [s] for T**} & \multirow{3}{*}{\(\Delta\)**t [s] for T**} & \multirow{3}{*}{\(\Delta\)**t [s] for T**} \\  & **Setting** & & & & & & \\  & **T \(\times\) 40 \({}^{\circ}\)C** & & & & & & \\ \hline \multirow{3}{*}{Extraoral heating} & 50 & - & - & - & - & - & - & - \\  & 60 & - & - & - & - & - & - & - \\  & 70 & - & 5.1 (2.8) & - & - & 5.8 (3.1) & - & - \\ \hline \multirow{3}{*}{SystemB} & 100 & - & 33.9 (5.0) & - & - & 48.6 (7.4) & 10.2 (4.8) & - \\  & 150 & 1.2 (0.7) & 57.0 (7.4) & 5.5 (2.9) & - & 82.8 (8.1) & 14.9 (5.2) & 8.8 (3.7) \\ \cline{1-1}  & 180 & 48.0 (7.2) & 83.5 (8.2) & 9.0 (3.6) & - & 89.8 (7.9) & 19.7 (5.8) & 10.5 (4.1) \\ \hline \multirow{3}{*}{SystemB} & 100 & - & 27.3 (5.6) & 2.8 (1.4) & - & 25.7 (5.1) & - & - \\  & 150 & 0.9 (0.5) & 74.1 (9.1) & 8.2 (3.1) & - & 61.1 (5.8) & 5.5 (2.8) & - \\ \cline{1-1}  & 180 & 57.6 (6.3) & 108.4 (9.8) & 18.2 (5.8) & 3.3 (1.2) & 101.6 (13.8) & 14.4 (4.9) & - \\ \hline \multirow{3}{*}{SystemB ML-12} & 100 & - & - & - & - & 29.1 (4.8) & - & - \\ \cline{1-1}  & 150 & - & - & - & - & 29.8 (4.9) & - & - \\ \cline{1-1}  & 180 & - & - & - & - & 36.2 (5.4) & 4.0 (2.1) & - \\ \hline \hline \end{tabular}
\end{table}
Table 1: Time interval (seconds) in which temperature at the apical and middle third regions of the root canal persisted higher than 40 \({}^{\circ}\)C, 50 \({}^{\circ}\)C, or 60 \({}^{\circ}\)C. Numbers in brackets represent the standard deviation.  
Figure 6: Temperature profiles in different regions of the tooth by heating sodium-hypochlorite through the ML-12 plugger using temperature set at 100 \({}^{\circ}\)C (**a**), 150 \({}^{\circ}\)C (**b**), and 180 \({}^{\circ}\)C (**c**).  
by the Ta thermocouple. Similar results were obtained using the intracranial heating method through the ML-12 plugger. Only by using a setting level of 180 \({}^{\circ}\)C was it possible to observe a remarkable time interval through which the apical region was at a temperature higher than 40 \({}^{\circ}\)C (Table 1).