Influência de dois sistemas adesivos e de duas técnicas de fotopolimerização na microinfiltração marginal de restaurações Classe V após preparo com alta rotação e condicionamento com laser de Er:YAG

by de Oliveira, Gardenia Mascarenhas

The purpose of this study In vitro was to evaluate the influence of two abrasivesystems and two photoactivation techniques on marginal microleakage in Class Vrestorations prepared with high speed rotation and Er:YAG laser conditioning.Besides, this study intended to observe, through scanning electron microscopy, theinterfaces resin/dentin and resin/enamel of all sample groups. A hundred twelvethird human molars were selected and divided into sixteen groups, so that eightyteeth were destined to the study of marginal microleakage (groups I, II, III, IV, IV,VI, VII and VIII) and thirty-two to the analysis under scanning electron microscopy(groups A, B, C, D, E, F, G and H). In all the groups, Class V cavities wereprepared with high speed rotation. In groups, V, E, VI, F, VII G, VIII and H, aftercavity preparation, the enamel and the dentin were conditioned with Er:YAG laser(Kavo Key Laser, 250mj, 3Hz, 300 pulses). Groups I, A, V and E were restoredwith the Prime & Bond NT/Esthet X system and photoactivated with current visiblelight; groups II, B, VI and F were restored with the Prime & Bond NT/Esthet Xsystem and photoactivated with Argon laser (l = 488nm); groups III, C, VI and Gwere restored with the Single Bond/Z250 system and photoactivated with currentvisible light; and groups IV, D, VIII and H were restored with the Single Bond/Z250system and photoactivated with Argon (l = 488nm). Mann Whintey test wasapplied in order to study the marginal microleakage and the results showedsignificant differences (p<0,05) for the dentin in the groups that were conditionedwith Er:YAG laser, when the restorative system was altered, showing lower levelsof dye infiltration when the Single Bond/Z250 system was applied, regardless ofthe source of light used (comparison between groups V and VI and groups VI andVIII). These differences were verified under scanning electron microscopy, whichshowed the absence of cracks and higher smoothness on the surface in groups Gand H, suggestive of better micromechanical imbrication. When the Single Bondsystem was applied, the use of Argon laser presented lower levels of marginalmicroleakage than the current visible light (comparison between groups VII andVIII). In all the groups restored with the Prime & Bond NT/Esthet X system, thepresence of cracks of 10µm or more on the resin/dentin and resin/enamelinterfaces was detected. In the experimental conditions of this study it is possible toconclude that the use of the SingleBond/Z250 system photoactivated with Argonlaser provided lower levels of marginal microleakage and a adequatemicromechanical imbrication on dentin, under scanning electron microscopy, and itseems to be more appropriated to restore cavities after Er:YAG laser conditioning