title: Relationship between analysis of laser speckle image and Knoop hardness on softening enamel.
abstract: BACKGROUND
  In this study is presented the correlation between laser speckle images and enamel hardness loss.
  
  
  METHODS
  In order to shift the enamel hardness, a dental demineralization model was applied to 32 samples of vestibular bovine teeth. After they were cleaned, cut and polished, the samples were divided into 4 groups and immersed in 30ml of a cola-based soft drink for 10, 20, 30 and 40min twice a day for 7 consecutive days with half the surface protected by two layers of nail polish. Each sample was analyzed by Knoop hardness and laser speckle imaging.
  
  
  RESULTS
  Pearson's correlation analysis demonstrated that the laser speckle image technique presents a strong correlation with the hardness loss of the enamel (r=0.7085, p<0.0001). This finding is corroborated by Blend & Altman analysis, in which the data presented a constant behavior throughout the whole interval. For both analyses, more than 95% of the data is within the confidence interval, as expected.
  
  
  CONCLUSIONS
  This work demonstrates, for the first time to our knowledge, an empirical model for correlating laser speckle images with the loss of tooth enamel hardness.
authors.affiliation: Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Engineering, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
authors.forename: Nelson H
authors.initials: NH
authors.lastname: Koshoji
authors.affiliation: Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Dentistry, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil. Electronic address: pratesra@uninove.br.
authors.forename: Renato A
authors.initials: RA
authors.lastname: Prates
authors.affiliation: Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Dentistry, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Bussadori
authors.affiliation: Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Dentistry, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
authors.forename: Carolina C
authors.initials: CC
authors.lastname: Bortoletto
authors.affiliation: School of Dentistry, Universidade de São Paulo (USP), São Paulo, Brazil.
authors.forename: Walter G
authors.initials: WG
authors.lastname: de Miranda Junior
authors.affiliation: School of Information Technology, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; Dep. of Informatics and Knowledge Management, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
authors.forename: André F H
authors.initials: AF
authors.lastname: Librantz
authors.affiliation: Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Dentistry, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
authors.forename: Cintia Raquel Lima
authors.initials: CR
authors.lastname: Leal
authors.affiliation: School of Dentistry, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
authors.forename: Marcelo T
authors.initials: MT
authors.lastname: Oliveira
authors.affiliation: Dep. of Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; School of Information Technology, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil; Dep. of Informatics and Knowledge Management, Universidade Nove de Julho (UNINOVE), São Paulo, Brazil.
authors.forename: Alessandro M
authors.initials: AM
authors.lastname: Deana
mesh_terms: D000818:Animals; D002417:Cattle; D003198:Computer Simulation; D003733:Dental Caries Susceptibility; D003743:Dental Enamel / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003747:Dental Enamel Solubility; D006244:Hardness; D006245:Hardness Tests / Q000379:methods*; D066298:In Vitro Techniques; D018613:Microscopy, Confocal / Q000379:methods*; D008954:Models, Biological; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017001:Tooth Demineralization / Q000175:diagnosis* / Q000503:physiopathology*
keywords: Caries diagnosis; Dental lesion; Optical diagnosis; Oral diseases