title: Effect of super short pulse Er:YAG laser on human dentin--Scanning electron microscopy analysis.
abstract: This study evaluated the effect of different pulse widths in the morphological characteristics of human dentin irradiated with Er:YAG in cavity preparation protocols and dentin pretreatment. Dentin discs with 2 mm thickness were obtained from 18 human molars. The experimental groups were composed from two variables: (1) clinical protocol-cavity preparation (E = 200 mJ/20 Hz)-and pretreatment (E = 80 mJ/2 Hz); and (2) pulse duration-50, 300, and 600 μs. This formed six experimental groups (n = 3): G1 (E = 200 mJ/20 Hz/50 μs); G2 (E = 200 mJ/20 Hz/300 μs); G3 (E = 200 mJ/20 Hz/600 μs); G4 (E = 80 mJ/2 Hz/50 μs); G5 (E = 80 mJ/2 Hz/300 μs); G6 (E = 80 mJ/2 Hz/600 μs). The samples were irradiated with the Er:YAG laser by noncontact mode at a focal distance of 7 mm from the target point under continuous water spray (60% water and 40% air). After the irradiation, they were processed for scanning electron microscopy (SEM). Morphological analysis showed an irregular dentin surface, absence of smear layer with opening of the exposure of dentinal tubules and protruding peritubular dentin-without indications of changes for all protocols used. Regardless of the analyzed experimental group, the dentin surface showed a microretentive morphology characteristic of ablation. The G1 and G4 showed a rougher surface when compared to other groups. Finally, we concluded that the pulse width can influence the morphological characteristics of the irradiated dentin tested in different clinical indications. The larger surface irregularity caused by regulation with less pulse width (50 µs) seems more appropriate to get a microretentive pattern necessary for successful adhesives restoration procedures.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Lívia Tosi
authors.initials: LT
authors.lastname: Trevelin
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Márcia Martins
authors.initials: MM
authors.lastname: Marques
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Ana Cecília Correa
authors.initials: AC
authors.lastname: Aranha
authors.affiliation: Department of Biomaterials and Oral Biology, University of São Paulo, São Paulo, Brazil.
authors.forename: Victor Elias
authors.initials: VE
authors.lastname: Arana-Chavez
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Adriana Bona
authors.initials: AB
authors.lastname: Matos
mesh_terms: D003731:Dental Caries / Q000532:radiotherapy*; D003737:Dental Cavity Preparation / Q000379:methods*; D003738:Dental Cements / Q000737:chemistry; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000473:pathology / Q000528:radiation effects / Q000648:ultrastructure; D016369:Smear Layer / Q000648:ultrastructure; D013499:Surface Properties
chemical_list: D003738:Dental Cements
keywords: SEM; dentin; erbium lasers; pulse width