title: Comprehensive analyses of how tubule occlusion and advanced glycation end-products diminish strength of aged dentin.
abstract: In clinical dentistry, since fracture is a major cause of tooth loss, better understanding of mechanical properties of teeth structures is important. Dentin, the major hard tissue of teeth, has similar composition to bone. In this study, we investigated the mechanical properties of human dentin not only in terms of mineral density but also using structural and quality parameters as recently accepted in evaluating bone strength. Aged crown and root dentin (age ≥ 40) exhibited significantly lower flexural strength and toughness than young dentin (age < 40). Aged dentin, in which the dentinal tubules were occluded with calcified material, recorded the highest mineral density; but showed significantly lower flexural strength than young dentin. Dentin with strong alignment of the c-axis in hydroxyapatite exhibited high fracture strength, possibly because the aligned apatite along the collagen fibrils may reinforce the intertubular dentin. Aged dentin, showing a high advanced glycation end-products (AGEs) level in its collagen, recorded low flexural strength. We first comprehensively identified significant factors, which affected the inferior mechanical properties of aged dentin. The low mechanical strength of aged dentin is caused by the high mineral density resulting from occlusion of dentinal tubules and accumulation of AGEs in dentin collagen.
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shinno
authors.affiliation: Division of Materials and Manufacturing Science, Osaka University Graduate School of Engineering, 1-2 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Ishimoto
authors.affiliation: Department of Orthopaedic Surgery, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minatoku, Tokyo 105-0003, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Saito
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Reo
authors.initials: R
authors.lastname: Uemura
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Arino
authors.affiliation: Department of Orthopaedic Surgery, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minatoku, Tokyo 105-0003, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Marumo
authors.affiliation: Division of Materials and Manufacturing Science, Osaka University Graduate School of Engineering, 1-2 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nakano
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Mikako
authors.initials: M
authors.lastname: Hayashi
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001031:Apatites / Q000737:chemistry; D003804:Dentin / Q000502:physiology*; D055119:Elastic Modulus; D017127:Glycation End Products, Advanced / Q000494:pharmacology*; D006244:Hardness; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D008903:Minerals / Q000378:metabolism; D013718:Tensile Strength; D019228:Tooth Crown / Q000187:drug effects / Q000502:physiology*; D014092:Tooth Root / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
chemical_list: D001031:Apatites; D017127:Glycation End Products, Advanced; D008903:Minerals