## 4 Discussion  
One of the primary factors influencing the clinical success of root canal treatment is the irrigation technique, as no perfect irrigation protocol can meet all the treatment criteria [54]. A previous study demonstrated that certain irrigants may remove the smear layer with bacteria and penetrate at a distance of up to 130 \(\upmu\)m from the canal wall [55]. However, another study revealed that bacteria and their byproducts could persist at depths of more than 100 \(\upmu\)m [56]. Therefore, the present study focused on evaluating dentin hardness at 50 \(\upmu\)m and 100 \(\upmu\)m from the canal [50]. This study used different irrigants, including IONPs, EDTA, and normal saline. To enhance the microhardness of the root structure while conserving the tooth structure, roots were prepared using various protocols involving ultrasonic activation [57] and an external magnetic field [19], either alone or with ultrasonic oscillation. No clinical data have been investigated to determine the effect of a magnetic field and IONPs on root dentin hardness or tooth structure, nor has the Ca/P ratio in root canals been examined. All prior studies of root canal cleaning, shaping, and irrigation techniques have focused on the microhardness efficiency of each system as the primary goal, but have overlooked the conservative structure of the root canal system. Previous research used the Vickers indenter technique to assess the change in dentin hardness after treatment with different chemical agents [7; 50; 58]. Microhardness measurement can serve as a direct indicator of mineral loss or acquisition in dental hard tissue [59]. A reduction in dentin hardness leads to a decrease in the fracture resistance of the tooth [60]. A study found that five-minute periods of ultrasound irrigation were more effective in eradicating the smear layer than one-minute periods [61]. This aligns with our study of using irrigation for five-minute periods. However, EDTA 17% was used as an irrigant for one minute to remove the smear layers in dentin [62]. New approaches are essential, as obtaining optimal root canal microhardness is associated with a conservative root structure. To achieve this, we investigated the combination of IONPs with magnetic and continuous ultrasound activation as an innovative approach to removing debris without adverse effects on the mechanical and chemical properties of dentin structure, comparing it to chemical methods, such as EDTA, to ensure the success of clinical treatment [21] and improve the effectiveness of the depth of irrigant penetration. The application of ultrasonics in conjunction with an external magnetic field is more effective with deeper irrigant penetration. This idea aligns with [PERSON] et al. 's study, as they suggest that hydrodynamic irrigation progresses to deepen the penetration of irrigant solution into the canal wall dentine [63]. This finding consistently showed that all IONPs irrigant activation methods were more effective than normal saline or EDTA. \begin{table}
\begin{tabular}{c c c c} \hline
**Groups** & **Ca** & **P** & **Ca/P** \\ \hline Control & 26.32 & 9.43 & 2.79 \\ \hline UN & 26 & 8.6 & 3.02 \\ \hline UI & 27.33 & 10.47 & 2.61 \\ \hline MSI & 21.55 & 8.5 & 2.53 \\ \hline MUI & 28.5 & 11.4 & 2.5 \\ \hline EDTA & 22.85 & 10.28 & 2.22 \\ \hline \end{tabular}  
* UN—ultrasound device and normal saline; UI—ultrasound device and IONPs; MSI—magnetic field, endodontic needle and IONPs; MU—magnetic field, ultrasound device, and IONPs; EDTA—ethylenediamineitetraacetic acid; Ca—Calcium; P—phosphorus; Fe—Iron elements.  
\end{table} 
Table 5: Descriptive data of the elements’ weight concentrations and Ca/P ratio in the root structure after using different techniques with different materials. Furthermore, the EDS test revealed that when comparing the Ca/P ratio of the irrigation groups to that of the control group, the IONPs irrigant had a higher ratio than the EDTA 17% irrigant.