title: Evaluation of two quantitative analysis methods of optical coherence tomography for detection of enamel demineralization and comparison with microhardness.
abstract: OBJECTIVE
  We aimed to evaluate in the same study two quantitative methods for quantification of incipient caries in human dental enamel by using optical coherence tomography (OCT): the optical attenuation coefficient and the area under the A-scan signal, and to compare their results with those obtained from microhardness analysis.
  
  
  METHODS
  One hundred and sixty samples were obtained from 40 sound human third molars, which had their crowns sectioned. Simulated caries were created by a pH cycling method. OCT measurements were performed on the samples, before and after the induced demineralization. We determined the total optical attenuation coefficient from the OCT signal in each site and evaluated the sensitivity and specificity of this approach to the detection of the demineralization. Also, the areas under the OCT curves (AUC-OCT) and those from sectional microhardness tests (AUC-MH) were compared.
  
  
  RESULTS
  Both the analysis of the optical attenuation coefficient and the AUC-OCT were adequate to efficiently distinguish sound and demineralized samples with sensitivity of 0.93 and specificity of 0.96. The AUC-MH and the AUC-OCT data presented linear relationship and correlation of 0.99.
  
  
  CONCLUSIONS
  Both methods for signal analysis from OCT allowed detection of demineralization with good performance. The AUC-OCT approach enables obtaining a linear relation with the microhardness results, for a quantitative assessment of mineral loss in human teeth.
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares, São Paulo, CEP 05508-000, SP, Brazil.
authors.forename: Ana C B
authors.initials: AC
authors.lastname: Cara
authors.forename: Denise M
authors.initials: DM
authors.lastname: Zezell
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Ana
authors.forename: Edison P
authors.initials: EP
authors.lastname: Maldonado
authors.forename: Anderson Z
authors.initials: AZ
authors.lastname: Freitas
mesh_terms: D019540:Area Under Curve; D003731:Dental Caries / Q000175:diagnosis* / Q000209:etiology; D003743:Dental Enamel / Q000473:pathology; D006245:Hardness Tests; D006801:Humans; D008964:Molar, Third; D012680:Sensitivity and Specificity; D046509:Tissue Culture Techniques; D041623:Tomography, Optical Coherence
keywords: caries research; dental tissue demineralization; optical attenuation in enamel