# The Impact of Silver Nanoparticles on Detntinal Tubule Penetration of Endodontic Bioceramic Sealer
## 4 Discussion  
The objective of the present investigation was to evaluate the impact of AgNPs on the penetration of BC sealers into dental tubules by employing various obturation techniques. Based on the results, the tested hypothesis was rejected because there were significant differences in the extent of dental tubules penetration both when the BC sealers were used alone and when incorporated with AgNPs, as well as across various root canal filling techniques. Obtaining a full picture of the numerous characteristics of nanoscale substances often necessitates the employment of several techniques, including microscopy-based techniques and other specialized approaches for certain materials, such as the magnetic techniques, which frequently require the integration of more than one method for assessment [25]. The current study examined the size, morphology, particle distribution, as well as the extent of agglomeration of the nanoparticles utilizing SEM and TEM techniques. The images demonstrated spherical nanoparticles 5-20 nm in size with a homogeneous spread, both alone and in combination with the BC sealer, with no visible clusters within the sealer's structure. This study utilized 20 nm particles to promote penetration via dental tubules, which average to 2.5 um in diameter. It has been reported that particle size substantially affects the extent of dentin penetration; particles with smaller dimensions have a higher infiltrative ability [20]. The deep penetration of the sealer into dental tubules is regarded as an essential characteristic in the obturation process of the root canal system. In addition to the mechanical retention of sealer within the tubules, it creates an unpleasant environment that inhibits the microbial repopulation of the remaining viable bacteria within the tubules. Furthermore, it enhances the antibacterial efficacy of the sealer to a greater depth [11]. Evidence indicated that bacteria could penetrate dental tubules up to 1000 um in depth; notably, the penetration of calcium silicate sealers was found to be in a comparable range of 1000-2000 um under confocal microscopy assessment [26; 27]. Researchers have examined various factors to evaluate sealer tubular penetration, including irrigation protocols [28], activation of sealers or irrigants [18], root canal filling techniques [29; 30], the physical and chemical properties of the sealer [31], and root canal morphology [32]. The current investigation observed sealer penetration depths ranging from 1108 to 2096 um, consistent with previous studies [13; 14]. The removal of the smear layer is important for exposing dental tubules and permitting further penetration [33]; in this study, we used a chelating chemical (Ethylenediaminetetraacetic acid) for this purpose. The findings of our study indicated that the experimental TotalFill(r) Hillow BC sealer containing AgNPs exhibited superior tubular penetration values compared to the same sealer without any nanoparticles, especially when used with the single-cone technique. A plausible explanation for this finding is that the silver nanoparticles exhibit hydrophilic behavior, which raises the wettability and surface area of the nanoscale objects against the dental surfaces and facilitates their tubular penetration [34]. The intrinsic wetting of a nanoscale structure loaded to a material can be tuned by changing the roughness on its surface, particularly when loaded onto hydrophilic materials [35]. Additionally, the slowly released silver ions can react with the nucleophilic moieties of proteins, including amino, carboxyl, and imidazole units, as well as phosphate moieties on cell membranes and enzymes, resulting in protein denaturation [36]. This great affinity of the silver ions alters the shape of the plasma protein skeleton within the dental fluid and could enhance the sealer infiltration into dental tubules.