## 4 Discussion
[9], in terms of translucency, no significant difference was observed between polishing and glazing, as the color difference remained below the perceptibility threshold, with both processes leading to a reduction in L\({}^{\star}\) values. Conversely, [PERSON] et al. [28] observed that color changes in zirconia restorations caused by glazing were greater than those induced by polishing. However, in monolithic restorations, glazing is generally recommended to avoid the need for additional adjustments using rotary instruments [16]. According to the literature, a substrate such as a natural dental core can affect the color of a restoration, especially when a translucent restorative material is used, introducing significant esthetic limitations. The impact of the substrate on color depends on the intensity and amount of light transmission through the ceramic material [29,30]. In this case, and based on the obtained results, the metal substrate showed \(\Delta\)E values that differed from those of the other substrates, which aligns with findings in the literature. As an alternative to metal substrates, zirconia substrates are available [31]. In this study, the zirconia substrate displayed \(\Delta\)E values similar to those of the natural tooth substrate. In the present study, two resin cements were selected, both from Ivoclar (Liechtenstein). According to the company brochure available on the website, the Light cement has a lower translucency of 12%, compared to the Neutral cement that exhibits 17%, and its effect on a restoration or crown is to \"slightly lighten\" the final shade. The manufacturer recommends using non-polymerizable try-in pastes to better assess the final result. In this study, statistical analysis showed that the ZZ crowns' \(\Delta\)E values were higher when the Light cement was used, regardless of the substrate. This suggests that, because this zirconia is more translucent, and the cement try-in is also more translucent (12%) when compared to the Neutral cement (17%), it is more affected by the cement, resulting in a final restoration color that deviated further from the intended A2 shade, leading to increased \(\Delta\)E values. Conversely, for the AG crowns, no direct relationship was observed with any of the cements used. Specifically, for the metal substrate, the highest \(\Delta\)E value was obtained when glycerol was placed between the restoration and the substrate, whereas no significant differences were observed for the natural tooth substrate. Clinically, the use of a more translucent zirconia should be taken with caution since it has a greater potential to be affected by the background substrate and also the cement color, increasing \(\Delta\)E values. In implant cases, using zirconia abutments is advisable when possible instead of using metallic abutments since they lower \(\Delta\)E values. Caution regarding the assumption of these results should be taken, since the literature also shows that the final color of cemented crowns can be slightly different from the observed results when using try-in pastes [32]. Even considering the risk of small differences in results, the use of try-in pastes is meaningful in clinical and research settings as it allows trying different conditions without compromising the tooth integrity. In an in vitro setup, such as the one used for this research, using twenty different teeth with the same shape and color would be nearly impossible. According to the literature, resin cements can influence the final color of feldspathic ceramics and lithium disilicate ceramics due to their high translucency. However, in zirconia ceramics, despite their lower translucency, the effect of the cement on the final color can still occur, as it depends on the type of zirconia used [16; 33]. Not all authors agree on the influence of cement on the color of restorations. In the in vivo study of [PERSON] et al.