title: Water distribution in dentin matrices: bound vs. unbound water.
abstract: OBJECTIVE
  This work measured the amount of bound versus unbound water in completely-demineralized dentin.
  
  
  METHODS
  Dentin beams prepared from extracted human teeth were completely demineralized, rinsed and dried to constant mass. They were rehydrated in 41% relative humidity (RH), while gravimetrically measuring their mass increase until the first plateau was reached at 0.064 (vacuum) or 0.116 gH2O/g dry mass (Drierite). The specimens were then exposed to 60% RH until attaining the second plateau at 0.220 (vacuum) or 0.191 gH2O/g dry mass (Drierite), and subsequently exposed to 99% RH until attaining the third plateau at 0.493 (vacuum) or 0.401 gH2O/g dry mass (Drierite).
  
  
  RESULTS
  Exposure of the first layer of bound water to 0% RH for 5 min produced a -0.3% loss of bound water; in the second layer of bound water it caused a -3.3% loss of bound water; in the third layer it caused a -6% loss of bound water. Immersion in 100% ethanol or acetone for 5 min produced a 2.8 and 1.9% loss of bound water from the first layer, respectively; it caused a -4 and -7% loss of bound water in the second layer, respectively; and a -17 and -23% loss of bound water in the third layer. Bound water represented 21-25% of total dentin water. Chemical dehydration of water-saturated dentin with ethanol/acetone for 1 min only removed between 25 and 35% of unbound water, respectively.
  
  
  CONCLUSIONS
  Attempts to remove bound water by evaporation were not very successful. Chemical dehydration with 100% acetone was more successful than 100% ethanol especially the third layer of bound water. Since unbound water represents between 75 and 79% of total matrix water, the more such water can be removed, the more resin can be infiltrated.
authors.affiliation: Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA 30912-1129, USA.
authors.forename: Kelli A
authors.initials: KA
authors.lastname: Agee
authors.affiliation: Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Prakki
authors.affiliation: Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Tariq
authors.initials: T
authors.lastname: Abu-Haimed
authors.affiliation: Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Ghada H
authors.initials: GH
authors.lastname: Naguib
authors.affiliation: Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Manar Abu
authors.initials: MA
authors.lastname: Nawareg
authors.affiliation: Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Turku, Finland.
authors.forename: Arzu
authors.initials: A
authors.lastname: Tezvergil-Mutluay
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, Araraquara School of Dentistry, UNESP-UnivEstadualPaulista, Araraquara, SP, Brazil.
authors.forename: Debora L S
authors.initials: DL
authors.lastname: Scheffel
authors.affiliation: Department of Endodontology and Oral Mucosa, Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Affiliated Hospital of Stomatology, Nanjing, Jiangsu, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
authors.forename: Seung Soon
authors.initials: SS
authors.lastname: Jang
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
authors.forename: Hyea
authors.initials: H
authors.lastname: Hwang
authors.affiliation: Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA 30912-1129, USA.
authors.forename: Martha
authors.initials: M
authors.lastname: Brackett
authors.affiliation: Department of Biomaterials, Faculty of Odontology, University of Toulouse III, Toulouse, France.
authors.forename: Geneviéve
authors.initials: G
authors.lastname: Grégoire
authors.affiliation: Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA 30912-1129, USA.
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.affiliation: Department of Biomedical and Neuromotor Sciences, DIBINEM, University of Bologna and IGM-CNR, Unit of Bologna, Bologna, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
authors.affiliation: Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA 30912-1129, USA. Electronic address: dpashley@gru.edu.
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D000096:Acetone / Q000737:chemistry; D000134:Acid Etching, Dental; D000327:Adsorption; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D003890:Desiccation / Q000379:methods; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008964:Molar, Third; D019279:Resin Cements / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D017001:Tooth Demineralization; D014867:Water / Q000737:chemistry*
chemical_list: D017220:Dentin-Bonding Agents; D019279:Resin Cements; D012997:Solvents; D014867:Water; D000096:Acetone; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate
keywords: Adhesive dentistry; Bound water; Bulk water; Collagen; Dentin; Hydrogen bonding