title: Nanomechanical properties of hydrated carious human dentin.
abstract: Most restorative materials are bonded to caries-affected dentin that has altered structure. We tested the hypothesis that hydrated dentin of the transparent zone did not have increased hardness or elastic modulus. Nanoindentation by modified AFM was used to determine site-specific elastic modulus and hardness for components of hydrated dentin from 8 carious and non-carious human teeth. Indentations in intertubular dentin were made at intervals from pulp through the affected layers (subtransparent, transparent, and discolored zones). The values of intertubular dentin increased slightly from near the pulp into the transparent zone, then remained constant or decreased slightly through transparent dentin (E, 18.3 GPa; H, 0.8 GPa; confirming the hypothesis), and decreased markedly through the discolored region. Peritubular dentin values were unaltered in transparent dentin, and intratubular mineral had values between those of normal peritubular and intertubular dentin. Superficial areas contained distorted tubules without peritubular dentin or intratubular mineral.
authors.affiliation: Dept. of Preventive and Restorative Dental Sciences, University of California, San Francisco 94143-0758, USA. graymar@itsa.ucsf.edu
authors.forename: G W
authors.initials: GW
authors.lastname: Marshall
authors.forename: S
authors.initials: S
authors.lastname: Habelitz
authors.forename: R
authors.initials: R
authors.lastname: Gallagher
authors.forename: M
authors.initials: M
authors.lastname: Balooch
authors.forename: G
authors.initials: G
authors.lastname: Balooch
authors.forename: S J
authors.initials: SJ
authors.lastname: Marshall
mesh_terms: D000704:Analysis of Variance; D003731:Dental Caries / Q000473:pathology / Q000503:physiopathology*; D003782:Dental Pulp / Q000648:ultrastructure; D003804:Dentin / Q000503:physiopathology* / Q000648:ultrastructure; D004548:Elasticity; D006244:Hardness; D006801:Humans; D018625:Microscopy, Atomic Force; D008903:Minerals / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D014075:Tooth Discoloration / Q000503:physiopathology; D014867:Water
chemical_list: D008903:Minerals; D014867:Water