title: SEM and TEM analysis of water degradation of human dentinal collagen.
abstract: Recently several long-term studies have reported evidence of the hydrolytic degradation of collagen fibrils based on fractured surface observations after bond testing. Those studies suggested that one cause of the decline in the bond strength was the degradation of the collagen fibrils within the bonds. However, one concern has been raised that the dentinal collagen fibrils may be stable in water that does not contain oral bacteria or enzymes. Therefore, the present study aimed to clarify the micromorphological change in naked collagen fibrils after 500 days of water storage. To prepare exposed collagen fibrils, sectioned and polished human dentin surfaces were acid conditioned for 15 s with the use of two commercially available acid conditioners: All-Etch (10% phosphoric acid) and Uni-Etch (32% phosphoric acid) (Bisco, Inc.). Those specimens were stored in distilled water at 37 degrees C for 1 day (control) for 500 days. After the storage periods, the samples were examined with the use of SEM and TEM. Under SEM and TEM examination, micromorphological alterations (disarrangement of collagen web, widening the interfibrillar space, and the thinning diameter of collagen fibrils) were found in the specimens after 500 days in water.
authors.affiliation: Division of Pediatric Dentistry, Hokkaido University, Graduate School of Dental Medicine, Sapporo, Hokkaido, Japan. masanori-h@mue.biglobe.ne.jp
authors.forename: Masanori
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ohno
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Sano
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kaga
authors.forename: Cincia
authors.initials: C
authors.lastname: Yiu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kumagai
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kudou
authors.forename: Minoru
authors.initials: M
authors.lastname: Kubota
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Oguchi
mesh_terms: D000134:Acid Etching, Dental; D001672:Biocompatible Materials / Q000737:chemistry; D001673:Biodegradation, Environmental; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D003804:Dentin / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D006868:Hydrolysis; D066298:In Vitro Techniques; D008422:Materials Testing; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D014867:Water
chemical_list: D001672:Biocompatible Materials; D014867:Water; D003094:Collagen