Relationship between refractive index and mineral content of enamel and dentin using SS-OCT and TMR

Ilnaz Hariri, Alireza Sadr, Yasushi Shimada, Syozi Nakashima, Yasunori Sumi, Junji Tagami

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


The aim of this work was to investigate relationship between refractive index (n) and mineral content (MC) (vol %) of enamel and dentin using swept-source optical coherence tomography (SS-OCT) and transverse microradiography (TMR). Enamel and dentin blocks were partitioned into three regions. The middle partition of each sample was covered with a nail polish to protect the sound area during exposure to the treatment solutions. Samples were demineralized in a demineralizing solution, which was refreshed once a week, for 2 months. One window was covered with acid-resistant varnish, leaving the other window exposed; the samples were placed in a solution for remineralization. Samples then were sliced into disks with thickness of 300 μm to 400 μm and placed on metal plate in order to capture cross-sectional images of sound, demineralized and remineralized regions by OCT at 1319 nm center wavelength. The n then was calculated via formula using image analysis software. Following n measurement, these specimens were further polished for the TMR analysis. Correlation between OCT n and TMR MC was examined. A significant and highly positive correlation was found between the measured n and the actual MC at the corresponding locations (Pearson correlation coefficients (r) were 0.94 and 0.97 in enamel and 0.95 and 0.91 in dentin after de-/remineralization process, respectively p < 0.05). OCT showed a potential for quantitative analysis of the mineral loss or gain by measuring of the n in vitro. Supported by the grant from the Japanese Ministry of Education, Global Center of Excellence (GCOE) Program, "International Research Center for Molecular Science in Tooth and Bone Diseases.".

Original languageEnglish
Title of host publicationLasers in Dentistry XVIII
Publication statusPublished - 2012
Externally publishedYes
EventLasers in Dentistry XVIII - San Francisco, CA, United States
Duration: Jan 22 2012Jan 22 2012

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherLasers in Dentistry XVIII
Country/TerritoryUnited States
CitySan Francisco, CA


  • Dentin
  • Enamel
  • Mineral content
  • Refractive Index
  • SS-OCT

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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