SURFACE MORPHOLOGICAL STUDY OF ROOT CANALS IRRADIATED WITH Er,Cr:YSGG LASER

Objectives: The aim of this study was to evaluate, in vitro, the aspect of roots canals irradiated with Er,Cr:YSGG laser after root canal walls preparation. Methods: To proceed the experiment, nine extracted single-rooted human teeth were chosen. Their crowns were sectioned at the enamel-cementum limit and the roots were instrumented with type-K files up to #80, associated with Endo-PTC and 1% sodium hypochlorite. After preparation, samples were irrigated with the demineralizing solution EDTA-T during 5 minutes and were divided into four groups. Samples of group I were not irradiated, while samples of groups II, III and IV had an association of irrigating solution and Er,Cr:YSGG laser irradiation, according the following fluences: GII (12.5 mJ/pulse; 2.8 J/cm2), GIII (25 mJ/pulse; 8.5 J/cm2) and GIV (75 mJ/pulse; 16.98 J/cm2). Laser irradiation was performed at 20 Hz repetition rate without air-water spray, with four helicoidal movements during approximately 5 seconds. The surfaces of the root canal after lasing were observed by a scanning electron microscope (SEM). Results: The results showed that lased areas presented a slight degree of ablation, which increases proportionally to the laser fluence. No significant difference was found at the coronal third between lased and unlased samples for inorganic debris, smear layer and surface profile. In middle thirds, all lased samples showed opened tubules and less smear layer when compared with unlased samples. In apical third, lased samples exhibited partial opening of the dentinal tubules and a thin layer of dentinal magma. Conclusion: It was possible to conclude that, Er,Cr:YSGG laser irradiation of root canal removes smear layer and propitiates opened dentinal tubules, which can improve dentin permeability of roots canals and, on its turn, the action of therapeutical protocols.