title: Ultrastructure and light microscope analysis of intact skin after a varying number of low level laser irradiations in mice.
abstract: Low level laser therapy (LLLT) has been used to relieve pain, inflammation, and wound healing processes. Thus, the skin is overexposed to laser and this effect is not completely understood. This study analyzed the effects of the number of laser applications (three, six, and 10) on the intact skin of the masseteric region in mice of strain HRS/J. The animals (n = 30) were equally divided into control (0 J/cm(2)) and irradiated (20 J/cm(2)), and each of these groups was further equally divided according to the number of laser applications (three, six, and 10) and underwent LLLT on alternate days. Samples were analyzed by light microscopy and transmission electron microscope (TEM). The animals receiving applications exhibited open channels more dilated between the keratinocytes and photobiomodulation effect on endothelial cells and fibroblasts by TEM. Under the light microscope after 10 laser applications, the type I collagen decreased (P < 0.05) compared to the three and six applications. Under these experimental conditions, all numbers of applications provided photobiomodulatory effect on the epidermis and dermis, without damage. More studies are needed to standardize the energy density and number of applications recommended for laser therapy to have a better cost-benefit ratio associated with treatment.
authors.affiliation: Department of Morphology, Physiology and Basic Pathology, Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, Avenida Café, s/n, Monte Alegre, 14040-904 Ribeirão Preto, SP, Brazil.
authors.forename: Mamie Mizusaki
authors.initials: MM
authors.lastname: Iyomasa
authors.affiliation: Department of Morphology, Physiology and Basic Pathology, Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, Avenida Café, s/n, Monte Alegre, 14040-904 Ribeirão Preto, SP, Brazil.
authors.forename: Juliane Caroline
authors.initials: JC
authors.lastname: Leão
authors.affiliation: Department of Morphology, Physiology and Basic Pathology, Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, Avenida Café, s/n, Monte Alegre, 14040-904 Ribeirão Preto, SP, Brazil.
authors.forename: Élen Camargo
authors.initials: ÉC
authors.lastname: Rizzi
authors.affiliation: Department of Morphology, Physiology and Basic Pathology, Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, Avenida Café, s/n, Monte Alegre, 14040-904 Ribeirão Preto, SP, Brazil.
authors.forename: João Paulo Mardegan
authors.initials: JP
authors.lastname: Issa
authors.affiliation: Department of Anatomy, Institute of Biomedical Science, University of Sao Paulo, São Paulo, Avenida Prof. Lineu Prestes, 2415, 05508-000 Butantã, SP, Brazil.
authors.forename: Fernando José
authors.initials: FJ
authors.lastname: Dias
authors.affiliation: Department of Anatomy, Institute of Biomedical Science, University of Sao Paulo, São Paulo, Avenida Prof. Lineu Prestes, 2415, 05508-000 Butantã, SP, Brazil.
authors.forename: Ii-sei
authors.initials: IS
authors.lastname: Watanabe
authors.affiliation: Department of Morphology, Physiology and Basic Pathology, Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, Avenida Café, s/n, Monte Alegre, 14040-904 Ribeirão Preto, SP, Brazil.
authors.forename: Daniela Mizusaki
authors.identifier: 0000-0002-2013-9240
authors.initials: DM
authors.lastname: Iyomasa
mesh_terms: D000818:Animals; D024042:Collagen Type I / Q000378:metabolism; D028022:Low-Level Light Therapy; D051379:Mice; D012867:Skin / Q000166:cytology* / Q000528:radiation effects / Q000648:ultrastructure*; D013194:Staining and Labeling
chemical_list: D024042:Collagen Type I