In vitro evaluation of the morphologic changes on the root dentine irradiated by CO2 laser associated or not to calcium hydroxide application

This in vitro study has evaluated the structural changes on the root dentine irradiated by a CO2 laser associated or not to calcium hydroxide application, from the irradiated surface analysis by means of Scanning Electronic Microscopy (SEM). The purpose of this evaluation has been the study of an alternative method for the treatment of dentine hypersensitivity. Fourteen human teeth were utilized, third molars, divided into 7 groups. Group I (control group) to which no treatment was applied; Groups II, III and IV were given an application of Ca (OH)2 paste followed by C02 laser irradiation, lasting 5 seconds each with intervals of 10 seconds between each application, with continuous emission, power of 0.5 W (Group II), 1.0 W (Group III), and 1.5 W (Group IV); Groups V, VI, and VII were given laser irradiations without the Ca (OH)2 paste following the same parameters applied to groups II, III, and IV respectively. Morphologic changes suggesting to fusion and re-solidification have been observed, as well as the presence of material obstructing the whole analyzed surface on groups II, III, and IV (laser + Ca (OH)2). As for groups V, VI, and VII, it has been observed fusion, re-solidification, and cracks, and these results being statistically significant when compared the '(Ca (OH)2)' groups to the laser groups. No statistically significant differences were observed regarding the different powers applied in the groups that used the same treatment. Despite this result, it can be stated that powers above 1.0 W (DP = 125,38 W/cm2) are unfavorable due to the undesirable morphologic alterations and aesthetic compromising. (author)