## 4 Discussion
The same explanation could be offered for Transbond XT in the CG for the 24 h DC measurements where no difference was observed between curing protocols (Figure 4), suggesting the material's ability to compensate for lower initial DC values through a more extensive post-cure DC development. The short-term DC values for Heliosit for the conventional and rapid curing protocols were in the high-end range among all of the tested materials (Figure 2). Heliosit is a more flowable and translucent system than Enlight and Transbond XT as it has a higher monomer ratio (>85 wt%), which could promote higher initial DC values, but as polymerization progresses, fewer monomers are left for post-cure DC development, resulting in lower 24 h DC values [50]. Similar observations were made in a previous study [31] where Heliosit showed the same changes in comparisons between short-term and 24 h DC values. Furthermore, Heliosit exhibited the most pronounced difference in DC values when the curing protocol was changed, which could also be attributed to the previously discussed mechanism of accelerated monomer consumption during the initial phase of the reaction. It has been reported that curing with a higher light intensity can lead to a better crosslinking density of organic matrix, which can in turn impair the mobility of reactive species and, together with the higher rate of bimolecular termination, diminish the final extent of polymerization [3; 43]. Rapid curing resulted in more variable DC values across experimental runs within the same group (coefficients of variability of 0.9-3.6%) compared to the conventional protocol in short-term DC measurements (0.8-1.5%, Figure 6), while the coefficients of variability were similar for both curing protocols within the same group for 24 h DC measurements (0.8-1.7% for the conventional protocol and 0.8-1.8% for the rapid curing protocol, Figure 7). Previous studies [51; 52] reported that the early stage of polymerization tends to be significantly affected by high-intensity curing due to a rapid increase in viscosity of the reaction medium, which could result in uneven and incomplete monomer conversion. The highest variability in the second minute of short-term DC measurements for Heliosit and Transbond XT supported this finding. Additionally, Transbond XT had pronounced variability for rapid curing modes in both groups and time points of measurement compared to Heliosit and Enlight, suggesting that some materials could better compensate for the negative effects of rapid curing in the early stages of polymerization, depending on the material's composition [52]. The analysis of the relative influences of the factors \"Material,\" \"Curing protocol,\" and \"Bracket\" on DC showed that the factor \"Material\" had a notable and similar impact on both short-term and 24 h DC values compared to other factors (Tables 2 and 3). This indicated that the DC variability is strongly dependent on the material's composition [53], which is not fully disclosed by the manufacturers [40] and therefore limits interpretation for relating the quantitative results with a specific compositional feature. Interestingly, the factor \"Bracket\" was the most influential on short-term DC values in contrast to 24 h DC values, where it was of the least significance, indicating that light attenuation and the consequent reduction in total received energy more significantly affected the early stage of polymerization. By contrast, for the 24 h DC values, apart from the factor \"Material,\" which ranked the highest, \"Curing protocol\" ranked as the second most influential factor, indicating its more significant role over time. The interaction between the factors \"Material\" \(\leftrightarrow\) \" Bracket\" was more significant than the interaction between the factors \"Material\" \(\leftrightarrow\) \"Curing protocol,\" indicating that given the same material, the presence of the bracket had a greater effect on both DC values than the curing protocol.