Influence of Light-curing on the Resin Cement Diametral Tesile Strength

Objectives: the aim of this work was to evaluate the bond strength between a glass fiber post and a resin cement after photoactivation with different sources. Methods: thirty composite resin cylinders were confectioned and glass fiber posts (ReforPost – Angellus) were cemented with dual-cure resin cement (RELY-X – 3M). The photoactivation of the cement was done through a variation of light curing units: Optlight Plus – GNATUS (O), RADII – SDI (R), and Elipar Freelight2 - 3M (E). Each cylinder were cut into three parts: cervical (c), middle (m) and apical thirds(a), resulting 90 discs which were divided in 09 groups (n=10). All the groups were submitted to diametrical tensile strength (DTS) in a testing machine EMIC 2000 until failure. Results: the means / standard deviation (MPa) were: G1-Oc: 25.08/4.20; G2-Om: 23.44/4.64; G3-Oa: 20.88/3.62; G4-Rc: 22.86/5.93; G5-Rm: 22.12/6.72; G6-Ra: 22.04/5.61; G7-Ec: 26.01/3.33; G8-Em: 19.81/6.09; G9-Ea: 17.74/4.14. The group G9-Ea showed the lowest resistance, revealing statistically significant difference to the groups G7-Ec and G1-Oc and there was not any difference between the light cure units. Conclusions: based on these results we can affirm that QTH and LED lights presented similar results, and the LED (R) device showed constant values in all the analyzed thirds.