## 4 Discussion
These findings are in line with other studies, such as those by [PERSON] et al. (2023) and [PERSON] et al. (2021) that also concluded that the use of charcoal whitening toothpaste did not increase enamel surface roughness [18; 37]. However, there are differences between the methodology of the studies, with the main one being the usage of bovine teeth in the studies carried out by [PERSON] et al. (2021) [37]. Despite this result, the CBW group displayed a tendency to higher average roughness values in comparison to the control group. The observed decrease in values within the control group across both protocols can be attributed to the absence of whitening agents in this toothpaste variant (control group). This validates the study's findings. In the long-term protocol, none of the three whitening toothpastes resulted in differences in the enamel surface roughness. However, it is noteworthy that the surface roughness value recorded for the OB3D group in protocol L differs from the value reported in the current literature [10], which may have resulted from the inherent limitations of an in vitro study. Regarding the color evaluation for protocol S and considering the NBS scale, no differences were observed within the groups. However, the CBW and SWN groups exhibited a \"extremely marked change\", while the CTO and OB3D groups demonstrated a \"change to another color\". Nevertheless, it would be expected that the control group, which is absent of whitening agents, would exhibit lower scores than any of the other groups. This can be attributed to the fact that this toothpaste, although considered \"conventional\" and containing no additional whitening agent, also contains abrasive particles that remove extrinsic pigmentation from tooth surfaces. Additionally, the literature suggests that the efficacy of extrinsic pigment removal is also directly related to the level of oral hygiene practices, motivation, and the mechanical action of the toothbrush, which may influence the results regardless of the toothpaste used [30; 38]. The outcome was as expected for the three whitening toothpastes, all of which demonstrated a whitening effect on the enamel surface, probably due to the chemical and mechanical combination of the whitening and abrasive agents, respectively. In the long-term protocol and considering the NBS score, all groups registered a score between 6 and 12, which is considered a \"extremely marked change\". The control group had the lowest score, followed by the OB3D, SWN, and CBW groups, contrary to what was expected based on the assumption that the effects registered in the S protocol would only intensify in the L protocol [10]. Protocol S was designed to mimic normal daily brushing of three cycles per day for 15 days. Protocol L aimed to simulate, in just three days, the same number of cycles that would be obtained if the samples were brushed three times a day for six months, to try and simulate the long-term effects of different toothpastes. Regarding the results of protocol L, one would anticipate the values to align or potentially exacerbate those recorded in protocol S, given that the aim of protocol L was to simulate extensive use. However, it is important to note that this discrepancy was not the primary focus of the study, nor was it subjected to statistical analysis. We can assume that for protocol L, within each of the 30 brushing cycles, the amount of toothpaste used replicated only the amount used in a single brushing, which may have caused a loss in properties over time within the same cycle, due to the long duration. The Optishade Style Italiano is a contemporary and underutilized colorimeter, with only one scientific study existing in the field of endodontics [39]. Equipped with red, green, and blue filters to approximate the human eye's spectrum, this colorimeter operates by capturing colors through processing the light reflection via said filters [40]. In every in vitro study, inherent limitations are present during its execution.