Theobaldo JD, et al. – This research scrutinized the impact of composite preheating and polymerization mode on the degree of conversion (DC), microhardness (KHN), plasticization (P), and depth of polymerization (DP) of a bulk fill composite. The findings suggested that composite preheating increased the polymerization degree of 4–mm–increment bulk fill, however, it led to a higher plasticization compared to the conventional flowable composite evaluated.