title: Effect of depth and tubule direction on ultimate tensile strength of human coronal dentin.
abstract: The purpose of this study was to evaluate the effect of dentin depth and tubule direction on the ultimate tensile strength (UTS) of human dentin. Dentin slabs of 0.5-mm thickness were trimmed either from the mesial and distal (for specimens with the tubules parallel to the tensile force; parallel group) or from the occlusal and pulpal surfaces (perpendicular group) to reduce the cross-sectional area of the superficial, middle, and deep regions to 0.25 mm2, and subjected to microtensile testing. From SEM photomicrographs of the fractured specimens of the parallel group, the tubule density was investigated. For both parallel and perpendicular groups, superficial dentin showed a significantly higher UTS than deep dentin. The tubule density of superficial dentin was significantly lower than that of middle and deep dentin. When performing the microtensile bond test to deep dentin, it is possible that cohesive failure of dentin can occur at relatively low tensile stresses.
authors.affiliation: Section for General Dentistry, Hokkaido University Dental Hospital, North 13 West 6, Kita-ku, Sapporo 060-8586, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Inoue
authors.forename: Patricia N R
authors.initials: PN
authors.lastname: Pereira
authors.forename: Chiharu
authors.initials: C
authors.lastname: Kawamoto
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nakajima
authors.forename: Kenichi
authors.initials: K
authors.lastname: Koshiro
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Carvalho
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Sano
mesh_terms: D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003804:Dentin / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008964:Molar, Third; D013718:Tensile Strength / Q000502:physiology; D019228:Tooth Crown / Q000033:anatomy & histology / Q000502:physiology*