title: Organic material and the optical properties of the dark zone in caries lesions of enamel.
abstract: Sections of uncavitated natural caries lesions of human enamel were extracted with various solvents and examined by polarizing microscopy. After lipid extraction, the dark zone enlarged by 19-162% and its birefringence increased, while after protein extraction it shrank by 37-92% and became less birefringent. It is concluded that occlusion of submicroscopic pores by organic material largely accounts for the optical properties of the dark zone. The results are not consistent with occlusion of pores by reprecipitation of mineral. On the basis of previous work, organic material in this location could influence demineralization and remineralization.
authors.affiliation: Division of Restorative Dentistry, Department of Oral and Dental Science, University of Bristol, Bristol, UK. r.p.shellis@bris.ac.uk
authors.forename: R P
authors.initials: RP
authors.lastname: Shellis
authors.forename: A S
authors.initials: AS
authors.lastname: Hallsworth
authors.forename: J
authors.initials: J
authors.lastname: Kirkham
authors.forename: C
authors.initials: C
authors.lastname: Robinson
mesh_terms: D002118:Calcium / Q000032:analysis / Q000737:chemistry; D002254:Carbonates / Q000032:analysis / Q000737:chemistry; D011232:Chemical Precipitation; D003731:Dental Caries / Q000378:metabolism / Q000473:pathology*; D003743:Dental Enamel / Q000737:chemistry / Q000648:ultrastructure*; D006801:Humans; D008055:Lipids / Q000032:analysis / Q000737:chemistry; D008274:Magnesium / Q000032:analysis / Q000737:chemistry; D008859:Microscopy, Polarization; D008903:Minerals / Q000032:analysis / Q000737:chemistry; D055095:Optics and Photonics; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry; D011506:Proteins / Q000032:analysis / Q000737:chemistry; D012997:Solvents; D017001:Tooth Demineralization / Q000378:metabolism / Q000473:pathology; D014089:Tooth Remineralization
chemical_list: D002254:Carbonates; D008055:Lipids; D008903:Minerals; D011506:Proteins; D012997:Solvents; D010758:Phosphorus; D008274:Magnesium; D002118:Calcium