title: Influence of Er:YAG laser frequency on dentin caries removal capacity.
abstract: The purposes of this study were to evaluate in vitro the influence of different frequencies of Er:YAG laser on the human dentin caries removal capacity. Thirty fragments obtained from third molars were randomly assigned into three groups (n = 10) according to the laser frequency used: 4, 6, and 10 Hz. The caries lesion (±1 mm deep) was induced before the irradiation by S.mutans cultures for 6 weeks. The specimens of all groups were irradiated with 200 mJ of energy in noncontact and focused mode under constant refrigeration (water flow: 2.5 mL/min). Quantitative analysis of the caries removal was performed by DIAGNOdent™ and the Axion Vision™ software. Qualitative analysis was performed by Scanning electron microscope (SEM) and light microscope (LM). Data were analyzed by ANOVA and Fishers' tests. The DIAGNOdent™ revealed that the caries removal was similar with 4 and 6 Hz and was superior with 10 Hz (P < 0.05). The analysis with Axion Vision™ software revealed that the caries removal was similar with 6 and 10 Hz and the 4 Hz group promoted the lowest caries removal. Through SEM morphologic analysis, some specimens irradiated with 4 Hz presented, under the demineralized dentin, a disorganized collagenous matrix. The LM images revealed that all frequencies used promoted irregular caries removal, being observed over preparations with 6 and 10 Hz. It can be concluded that the increase of Er:YAG laser frequency provided a higher dentin caries removal without selectivity to the disorganized dentin.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil. rgpalma@forp.usp.br, rauccineto@yahoo.com.br.
authors.forename: Walter
authors.initials: W
authors.lastname: Raucci-Neto
authors.forename: Michelle Alexandra
authors.initials: MA
authors.lastname: Chinelatti
authors.forename: Izabel Yoko
authors.initials: IY
authors.lastname: Ito
authors.forename: Jesus Djalma
authors.initials: JD
authors.lastname: Pécora
authors.forename: Regina Guenka
authors.initials: RG
authors.lastname: Palma-Dibb
mesh_terms: D003731:Dental Caries / Q000628:therapy*; D003804:Dentin / Q000528:radiation effects*; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008027:Light; D008964:Molar, Third / Q000528:radiation effects