## 1 Introduction  
The smear layer is a 1-2 \(\upmu\)m-thick thin film arranged on the root canal wall system that acts as a barrier blocking the opening of dentinal tubules [1]. This layer must be removed because it limits the diffusion purpose of the disinfecting agent and compromises the sealing ability of the root canal system [2]. Consequently, eradicating this layer during endodontic treatment is necessary for successful treatment and to prevent the recolonization of microorganisms within the prepared canal. Unfortunately, chemomechanical treatments, utilizing a chemical irrigant with excessive mechanical root canal preparation, cannot approach all anatomical depths of the canal to eradicate the microorganisms from the dentinal tubules and debridement debris from the root canal system [3]. Lateral canals, isthmi, fins, accessory canals, apical ramifications, and recesses are present in the root canal system, representing a harbor for bacterial biofilm and preventing the objective of preparation for treatment by impeding cleaning, disinfection, and the shaping of the root canal system [4; 5]. In addition to the above, chemical chelating factors have been proposed for removing the smear layer [6]. These may also lead to the demineralization of the inorganic structure and the loss of the root canal's structural integrity [7]. A sodium hypochlorite agent (NaOCI) can dissolve tissue and has antimicrobial properties. However, it can negatively reduce the physical characteristics of the dentine matrix and harm the periapical area due to accidental extrusion beyond the foramen [8]. Ethylenediaminetetraacetic acid (EDTA) is most commonly applied as a chelating factor. It can remove calcium ions from the root structure, resulting in changes to dentin microhardness [7] and eroding the root canal wall [9]. The chemical result of the irrigant used in endodontic treatment adversely affects the composition of the dentin structure, depending on the concentration and time of exposure [10]. Consequently, there is an increase in the susceptibility to root fractures [11]. Nanotechnology enhances the fabrication of new materials, creating novel materials, structures, and devices with special properties and functions [12]. It has been applied to various scientific disciplines, including medicine and dentistry. Magnetic nanoparticles (MNPs) are one type of material utilized in various technologies, such as in biomedicine for drug delivery [13]. For endodontic treatment, they are used as a root canal irrigant due to their association with peroxidase, which aids in improving antibacterial activity on the root canal wall [14] to mitigate the formation of dental plaque biofilms [15]. MNPs also enhance adhesion to dentin [16] and, under the control of a magnetic field, deeply penetrate root canal sealers to improve periapical healing [17]. Under a magnetic field, the nanoparticles are directed to a target area; this is the major application of IONPs in nanomedicine, which are coated with organic or inorganic materials for drug delivery [18; 19]. Magnetic, with its chemical formula of Fe\({}_{3}\)O\({}_{4}\), forms a spinel structure and is prevalent [20]. Hence, it is clear that successful cleaning and shaping in endodontic treatment require the use of irrigant solutions that neither affect the root canal surface nor cause alterations in the mechanical and chemical characteristics of the tooth structure [21]. Iron oxide nanoparticles (IONPs) have special properties, including excellent physicochemical properties, stability in aqueous solutions, minimal cytotoxicity, biocompatibility, and persistent magnetic characteristics.