Effect of modulated photoactivation of bulkfill composite on microleakage in fluorosed and nonfluorosed teeth: A confocal laser scanning microscopy study

AIM: The aim of this study is to compare the microleakage of bulkfill composite activated by modulated photoactivation between fluorosed and nonfluorosed teeth using the confocal laser scanning microscope. METHODOLOGY: One hundred and twenty intact human premolar teeth with Thylstrup and Fejerskov index fluorosis index 0–4 were stored in 0.5% thymol at the room temperature until further use. Standardized Class V preparations of 2 mm depth, 3 mm width, and 2 mm height were prepared on the buccal surface. The cavities were etched with 37% phosphoric acid, rinsed and primed with Tetric N bond, cured for 20 s with Quartz Tungsten Halogen (QTH) variable intensity light-curing unit spectrum-800 operating at 450 mW/cm(2). Later, bulk fill composite was placed in the cavity and cured. Depending on the curing mode used, all the fluorosed and nonfluorosed teeth were divided into three subgroups each (n = 20) – Conventional light curing, stepped curing, and pulse delayed curing. All samples were stored in distilled water at the room temperature for 24 h and subjected to 500 thermocycles. The prepared teeth were placed in 0.6% rhodamine solution for 48 h; sectioned longitudinally using a hard-tissue microtome and scanned under a confocal laser scanning electron microscope. Data were analyzed using the one-way ANNOVA, Wilcoxson signed-rank test, and Kruskal–Wallis test. RESULTS: Significant differences were observed between fluorosed and nonfluorosed groups. Intragroup comparisons showed significant differences between fluorosed step and conventional subgroups. CONCLUSION: Fluorosed teeth had higher microleakage values than nonfluorosed teeth. Pulse-delayed subgroup had the least microleakage to that of conventional and stepped curing subgroups, in both fluorosed and nonfluorosed groups.