title: Effects of the freezing and thawing process on biomechanical properties of the human skull.
abstract: The aim of this study was to determine if biomechanical investigations of skull samples are reliable after skulls have been subjected to a freezing and thawing process. The skulls were obtained from 105 Japanese cadavers (66 males, 39 females) of known age that were autopsied in our department between October 2012 and June 2013. We obtained bone specimens from eight sites (four bilaterally symmetrical pairs) of each skull and measured the mass of each specimen. They were then classified into three groups (A, B, C) based on the duration of freezing of the experimental samples. The left-side samples were subjected to frozen storage (experimental group). The corresponding right-side samples were their controls. Bending tests were performed on the controls immediately after they were obtained. The experimental samples were preserved by refrigeration at -20 °C for 1 day (group A), 1 month (group B), or 3 months (group C). Following refrigeration, these samples were placed at 37 °C to thaw for 1 h and then were subjected to bending tests using a three-point-bending apparatus attached to a Handy force gauge. The device recorded the fracture load automatically when the specimen fractured. Statistical analyses revealed that there were no significant differences in sample fracture loads between the frozen preserved/thawed samples and the unfrozen controls for each of the cryopreservation intervals. We eliminated any possible sample mass bias by using controls from the same skull in each case. The results suggest that the freezing/thawing process has little effect on the mechanical properties of human skulls. Thus, frozen storage for up to 3 months is a good method for preserving human skulls.
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: number60188@chiba-u.jp.
authors.forename: Suguru
authors.initials: S
authors.lastname: Torimitsu
authors.affiliation: Designing Everyday Life Function and Social System Team, Digital Human Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Nishida
authors.affiliation: Designing Everyday Life Function and Social System Team, Digital Human Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Tachio
authors.initials: T
authors.lastname: Takano
authors.affiliation: Designing Everyday Life Function and Social System Team, Digital Human Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Koizumi
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Hayakawa
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yajima
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Inokuchi
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Makino
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Motomura
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Fumiko
authors.initials: F
authors.lastname: Chiba
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Hirotaro
authors.initials: H
authors.lastname: Iwase
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D015925:Cryopreservation; D005260:Female; D005554:Forensic Medicine; D006801:Humans; D008297:Male; D008875:Middle Aged; D012886:Skull / Q000502:physiology*; D012887:Skull Fractures / Q000503:physiopathology; D013048:Specimen Handling / Q000379:methods; D013997:Time Factors; D055815:Young Adult
keywords: Cranial bones; Fracture load; Frozen preservation; Stiffness