title: The overwet phenomenon: a scanning electron microscopic study of surface moisture in the acid-conditioned, resin-dentin interface.
abstract: OBJECTIVE
  To study with the scanning electron microscope the interfacial phenomenon that occurred in the presence of excessive surface moisture following the application of an acetone-based adhesive to acid-conditioned dentin.
  
  
  METHODS
  Specimens consisted of flat dentin discs that were divided into three groups based upon the status of remaining surface moisture: (1) 3-second dry group, (2) blot-dry group, with the conditioned dentin surface remaining shiny as opposed to matte, and (3) overwet group: an additional 40 mL of distilled water spread thin on the dentin surface after blot-drying. Polished resin-dentin interfaces were brought into relief using plasma-etching and examined without further embedding.
  
  
  RESULTS
  Although a hybrid layer was observed in all three groups, there was (1) a sequential deterioration of the bonded assembly along the hybrid layer-resin interface, and (2) loss of complete tubular seal as the quantity of surface moisture increased. Intratubular resin globules were observed beneath short resin plugs in the 3-second dry group. Small, isolated blister-like spaces, trapped within the resin layer, were observed along the surface of the hybrid layer in the blot-dry group, while similar, but larger spaces were found in the overwet group. The blister-like spaces, which were often continuous with incompletely sealed tubular orifices, were partially filled with extraneous resin globules dispersed within an amorphous matrix.
authors.affiliation: Department of Children's Dentistry and Orthodontics, Faculty of Dentistry, University of Hong Kong.
authors.forename: F R
authors.initials: FR
authors.lastname: Tay
authors.forename: A J
authors.initials: AJ
authors.lastname: Gwinnett
authors.forename: S H
authors.initials: SH
authors.lastname: Wei
mesh_terms: D000134:Acid Etching, Dental; D001713:Biphenyl Compounds; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D001840:Dental Bonding / Q000379:methods; D003804:Dentin / Q000648:ultrastructure*; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D006874:Hydrostatic Pressure; D008689:Methacrylates; D008855:Microscopy, Electron, Scanning; D016062:Porosity; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D001713:Biphenyl Compounds; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D014867:Water; C039790:N-(4-tolyl)glycine-glycidyl methacrylate