## 4 Discussion
Albeit with different plasma applications, both studies included two recently developed calcium-silicate-based sealers: BioRoot RCS [25] and Endosequence [23], reported to have adhesive characteristics and bioactivity. A recent review of current sealers points out that tricalcium silicate sealers are associated with the lowest relative microleakage compared to the standard AH Plus [4]. The higher POBS values obtained can derive from the chemical nature of bioceramic sealers, affecting properties such as fluidity, their easy spread over the dentin walls due to their low contact angle, or an increase in dentin wettability after NTP [15; 23; 31]. It was reported that the dentin surface modification after NTP, such as enhanced wettability and chemical interaction, could favor dental tubule penetration and the bioceramic sealer's bond strength [23]. Although the authors did not explain the minor influence of NTP on the POBS evaluation of AH Plus [23], other factors, such as the chemical and structural alterations that different irrigating solutions can produce in dentin surfaces, might have affected the results [32]. There are other endodontic procedures aimed to open plasma treatments that can be created under low pressure or atmospheric pressure and increase wettability, such as the standard chelating agent EDTA [33]. However, the additional NTP generally increased these properties, acting as an adjuvant procedure, as shown by the higher POBS values or wettability observed after EDTA exposure [13; 25]. Conversely, in the study of [PERSON], et al. [23], the final flush was performed with NaOCl. NaOCl may have caused a deproteinization, causing a hydrophilic surface that did not favor the resinous sealer's hydrophilicity [32]. With a similar irrigating solution sequence (EDTA followed by NaOCl), [PERSON], et al. [24] found similar bonding values to the control for the NTP groups with either AH Plus or MTA Fillapex. The type of sealer might also have influenced the results. NTP has been reported to reach deep into the dental tubules, similar to or further than bacteria, creating reactive oxygen species and damaging the remaining microorganisms, in addition to cleaning/etching [19]. Thus, it seems to ensure higher mechanical retention and adhesion. This rationale was corroborated by [PERSON], et al. [24], [PERSON], et al. [13], and [PERSON], et al. [25], who reported improved adhesion of NTP surfaces. Plasma treatments can be carried out at low pressure or atmospheric pressure. The main difference lies in the pressure at which they operate, which affects the plasma density, confinement, and particle behavior [34]. Low-pressure plasmas are generated and sustained in a vacuum or low-pressure environment using vacuum chambers. The benefit of low-pressure plasmas is that the mean free path of the particles (i.e., atoms, ions, and electrons) is relatively long, meaning that they can travel greater distances between collisions. The conditions are much more controllable and reproducible compared to atmospheric-pressure conditions (typically close to 1 atmosphere, where the particles' mean free path is much shorter than in low-pressure plasmas due to the higher gas density), which could compensate (at least partially) for the practical drawbacks of using low-pressure plasma--especially the need for expensive vacuum equipment [35; 36]. On the other hand, atmospheric-pressure plasmas have become very attractive because they are generated in an open environment and can be easily implemented [37]. Nevertheless, if particular precautions are not taken, they tend to become thermal, i.e., hot plasmas that can damage heat-sensitive materials or burn living tissues [38]. In the included studies, [PERSON], et al. [13] and [PERSON], et al. [25] applied NTP treatments under vacuum conditions using a glass reactor, while [PERSON], et al. [23] and [PERSON], et al. [24] used an atmospheric-pressure plasma jet.