title: Dynamic shear properties of the porcine molar periodontal ligament.
abstract: The role of the periodontal ligament (PDL) is to support the tooth during function and resist external forces applied to it. The dominant vertical component of these forces is associated with shear in the PDL. Little information, however, is available on the dynamic behavior of the PDL in shear. Therefore, the present study was designed to determine the dynamic shear properties of the PDL in the porcine molar (n=10). From dissected mandibles transverse sections of the mesial root of the first molar were obtained at the apical and coronal levels and used for dynamic shear tests. Shear strain (0.5%, 1.0%, and 1.5%) was applied in superoinferior direction parallel to the root axis with a wide range of frequencies (0.01-100 Hz). The dynamic complex and storage moduli increased significantly with the loading frequency, the dynamic loss modulus showed only a small increase. The dynamic elasticity was significantly larger in the coronal region than in the apical region although the dynamic viscosity was similar in both regions. The present results suggest that non-linearities, compression/shear coupling, and intrinsic viscoelasticity affect the shear material behavior of the PDL, which might have important implications for load transmission from tooth to bone and vice versa.
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan. etanaka@hiroshima-u.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Inubushi
authors.forename: Koji
authors.initials: K
authors.lastname: Takahashi
authors.forename: Maya
authors.initials: M
authors.lastname: Shirakura
authors.forename: Ryota
authors.initials: R
authors.lastname: Sano
authors.forename: Diego A
authors.initials: DA
authors.lastname: Dalla-Bona
authors.forename: Akira
authors.initials: A
authors.lastname: Nakajima
authors.forename: Theo M G J
authors.initials: TM
authors.lastname: van Eijden
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanne
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D004548:Elasticity; D008963:Molar; D010513:Periodontal Ligament / Q000502:physiology*; D033081:Shear Strength; D013552:Swine