title: Formation and characterization of hypermineralized zone beneath dentine lesion body induced by topical fluoride in-vitro.
abstract: OBJECTIVE
  This in-vitro study aimed to evaluate and characterize the hypermineralized zone (Hyper-zone) formed beneath the remineralized dentine lesion body by transverse microradiography (TMR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS).
  
  
  METHODS
  Demineralized bovine dentine specimens were treated with fluoride solutions (APF, NaF) and remineralized for 2-4 weeks. Then thin sections were prepared to characterize the Hyper-zone by TMR, EDS. Fractured specimen surfaces were observed by SEM.
  
  
  RESULTS
  TMR analysis revealed a higher mineral density at Hyper-zone than that of sound dentine (48vol%) ranging from 50 up to 61vol% and the thickness ranging from 197 to 344μm for 4-week specimens, while specimens without fluoride treatment did not show Hyper-zone. SEM pictures at Hyper-zone showed no evident crystal-like deposits in dentinal tubules and no notable difference when compared to that in sound dentine. EDS analysis demonstrated higher concentrations of Ca and P at Hyper-zone than those in sound dentine, which corresponded to the TMR profile, while the magnesium (Mg) concentration was low at this zone.
  
  
  CONCLUSIONS
  Demineralized dentine lesions exposed to fluoride and remineralization treatments exhibited Hyper-zone beneath the lesion body, in which the mineral density was higher than that of sound dentine. Possible mechanism for the formation of Hyper-zone was discussed by assuming removal of mineral regulators such as Mg and other organic substances from sound dentine during de-/remineralization processes.
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: dr.sahar_40@hotmail.com.
authors.forename: Sahar J
authors.initials: SJ
authors.lastname: Khunkar
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: sachiko_utaka@yahoo.co.jp.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Utaka
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: ilnazhariri@gmail.com.
authors.forename: Ilnaz
authors.initials: I
authors.lastname: Hariri
authors.affiliation: International Exchange Center, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: arireza@gmail.com.
authors.forename: Alireza
authors.initials: A
authors.lastname: Sadr
authors.affiliation: Department of Oral Health Care Sciences, Clinical Oral Science of Tokyo Medical and Dental University, 5-45 Yushima 1-chome, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: ikeda.csoe@tmd.ac.jp.
authors.forename: Masaomi
authors.initials: M
authors.lastname: Ikeda
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: nakashima_japanjp@yahoo.co.jp.
authors.forename: Syozi
authors.initials: S
authors.lastname: Nakashima
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: nikaido.ope@tmd.ac.jp.
authors.forename: Toru
authors.initials: T
authors.lastname: Nikaido
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: tagami.ope@tmd.ac.jp.
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
mesh_terms: D000287:Administration, Topical; D000818:Animals; D002118:Calcium / Q000737:chemistry; D002417:Cattle; D003804:Dentin / Q000737:chemistry* / Q000187:drug effects*; D066298:In Vitro Techniques; D008274:Magnesium / Q000737:chemistry; D008852:Microradiography; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry; D012969:Sodium Fluoride / Q000008:administration & dosage / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D017001:Tooth Demineralization / Q000188:drug therapy*; D014089:Tooth Remineralization
chemical_list: D010710:Phosphates; D012969:Sodium Fluoride; D008274:Magnesium; D002118:Calcium
keywords: Demineralization; Dentine; Fluoride; Hypermineralization; Remineralization