Degree of conversion of resin cements polymerizated throught a translucent-post

Objective: This study aimed to evaluate the light transmittance of a translucent post in the root canal by analyzing the degree of conversion of light-, dual- and chemical-cure resin cements. Methods: Nine human teeth had their root canals prepared with a low speed calibrated drill of a Light Post (Bisco) system at a working length of 12 mm. Afterwards, the outer surface of each tooth was covered with black nail varnish to allow passage of light only through the most coronal portion. All teeth were treated with All Bond 2 (Bisco) bonding agent divided into groups according to the resin cement: G1) non light-cured Duo-link dual-cure cement (Bisco), G2) light-cured Duo-link dual-cure cement, G3) Illusion light-cure resin cement (Bisco). Following that, the teeth were sectioned perpendicular to their long axis with a diamond saw under water irrigation. Segments, measuring nearly 2mm, were achieved, with one from each study region: cervical (C), middle (M) and apical (A) regions, allowing the determination of the degree of conversion at different levels of the root. This analysis was made with µ-Raman spectroscopy, at 2 different points of each segment. Results: The ANOVA test showed significant differences between the groups. The tukey's test showed that the cervical regions of all groups 1C (61.5, 6.64) 2C (63.5, 8.43) e 3C (59.8, 8.71) were similar. The groups 1M (52.8, 8.97), 1A (46.93, 5.44), and 2M (45.01, 8.43) were statistically similar and the groups 2A (21.05, 10.48), 3M (36.87,6.4) and 3A (29, 8.11) were similar. Conclusion: The dual cement without polymerization showed higher conversion degree values than the other groups. For every groups the apical region showed lowest values.