ORIGINAL ARTICLE Correlation between light transmission and permeability of human dentin Ana Paula Silveira Turrioni & Camila Fávero de Oliveira & Fernanda Gonçalves Basso & Lilian Tan Moriyama & Cristina Kurachi & Josimeri Hebling & Vanderlei S. Bagnato & Carlos Alberto de Souza Costa Received: 25 November 2010 / Accepted: 18 April 2011 / Published online: 10 May 2011 # Springer-Verlag London Ltd 2011 Abstract The influence of dentin permeability on trans- dentinal LED light propagation should be evaluated since this kind of phototherapy may further be clinically used to stimulate the metabolism of pulp cells, improving the healing of damaged pulps. This study evaluated the influence of the dentin permeability on the transdentinal LED light (630 nm) transmission. Forty-five 0.5-mm-thick dentin disks were prepared from the coronal dentin of extracted sound human molars. An initial measurement of transdentinal LED light transmission was carried out by illuminating the discs in the occlusal-to-pulpal direction onto a light power sensor to determine light attenuation. The discs were treated with EDTA for smear layer removal, subjected to analysis of hydraulic conductance, and a new measurement of transdentinal LED light transmission was taken. Spearman’ s correlation coefficient was used for analysis of data and showed a weak correlation between dentin permeability and light attenuation (coefficient= 0.19). This result indicates that higher or lower dentin permeability does not reflect the transdentinal propagation of LED light. Significantly greater transdentinal propaga- tion of light was observed after treatment of dentin surface with EDTA (Wilcoxon test, p <0.05). According to the experimental conditions of this in vitro study, it may be concluded that dentin permeability does not interfere in the transdentinal LED light transmission, and that smear layer removal facilitates this propagation. Keywords Dentin permeability . LED . Transillumination . Light propagation Introduction Phototherapy using light emitting diodes (LEDs) has been used in several health fields, including the treatment of dermatitis, Alzheimer’ s disease, and muscle analgesia [1–3]. Light has also been applied combined with a photosensitizing agent in the photodynamic therapy for the treatment of neoplasias [4]. In dentistry, several studies have been directed to investigate the effects of LED light irradiation on oral mucositis [5, 6], dentin hypersensitivity [7], candidiasis [8], and decontamination of carious cavities [9]. A LED therapy protocol established by Sacono et al. [6] was effective in reducing the severity of mucositis induced by a chemo- therapeutic agent associated with superficial scratching of the cheek pouch of hamsters. Lizarelli et al. [7] evaluated the clinical effect of LED and low-level laser therapy (LLLT) on A. P. S. Turrioni : C. F. de Oliveira : J. Hebling Department of Pediatric Dentistry and Orthodontics, UNESP - Univ. Estadual Paulista, Araraquara, SP 14801903, Brazil F. G. Basso Department of Oral Diagnosis, UNICAMP - Universidade de Campinas, Piracicaba, SP 13414-903, Brazil L. T. Moriyama : C. Kurachi : V. S. Bagnato USP - Universidade de São Paulo, Institute of Physics, São Carlos, SP 13560-970, Brazil C. A. de Souza Costa Department of Physiology and Pathology, UNESP - Univ. Estadual Paulista, Araraquara, SP 14801903, Brazil C. A. de Souza Costa (*) Departamento de Fisiologia and Patologia. Faculdade de Odontologia de Araraquara, Universidade Estadual Paulista, Rua Humaitá, 1680. Centro, Caixa Postal: 331 Cep: 14801903, Araraquara, SP, Brazil e-mail: casouzac@foar.unesp.br Lasers Med Sci (2012) 27:191–196 DOI 10.1007/s10103-011-0931-0