title: Er:YAG laser effects on enamel occlusal fissures: an in vitro study.
abstract: This study evaluated by scanning electron microscopy (SEM) the morphological changes in occlusal fissure enamel, of permanent models, irradiated by Er:YAG laser using contact and noncontact fiberoptics in vitro. Previous studies have demonstrated the efficacy of Er:YAG laser for dental hard tissue removal and cavity preparation. The treatment of occlusal fissures in noncarious permanent human molars (n = 9) was carried out with Er:YAG laser (KEY Laser II) using handpiece no. 2051, noncontact, focused (12 mm), water spray-cooled, pulse energy 200 mJ, and frequency 2 Hz (group 1), and handpiece no. 2055 with a quartz fiberoptic 50/10, in contact, air cooled, pulse energy setting of 350 mJ and frequency 2 Hz (group 2) and 400 mJ/2 Hz (group 3). The specimens were sectioned, dehydrated in a graded series of aqueous ethanol, dried, and sputtering with gold. Morphological change analysis on occlusal fissures was performed by SEM. Group 1 showed removal of fissure debris and predominantly enamel etching-like patterns, and groups 2 and 3 showed irregular edges, melting, and recrystallization of fissure enamel, with a lava-like structure and bubble-like voids. The results of this in vitro study suggest that the irradiation of fissures by Er:YAG laser using a fiberoptics (contact and air cooled) produced melting and recrystallization of fissures enamel. Further studies are required with different energy parameters and water cooling to evaluate the thermal effects on teeth.
authors.affiliation: Department of Restorative Dentistry and Department of Oral Pathology, School of Dentistry, University of São Paulo, Brazil.
authors.forename: Juliana R
authors.initials: JR
authors.lastname: Matson
authors.forename: Edmir
authors.initials: E
authors.lastname: Matson
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Navarro
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Bocangel
authors.forename: Ruy G
authors.initials: RG
authors.lastname: Jaeger
authors.forename: Carlos P
authors.initials: CP
authors.lastname: Eduardo
mesh_terms: D003743:Dental Enamel / Q000528:radiation effects* / Q000648:ultrastructure*; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure*; D005336:Fiber Optic Technology; D006801:Humans; D007834:Lasers; D008855:Microscopy, Electron, Scanning; D009354:Neodymium; D012680:Sensitivity and Specificity; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D009354:Neodymium