title: Dimensional changes of demineralized dentin treated with HEMA primers.
abstract: OBJECTIVE
  The purpose of this study was to measure the dimensional changes of demineralized dentin before and after application of HEMA (2-hydroxyethyl methacrylate) by confocal laser scanning microscopy (CLSM).
  
  
  METHODS
  The middle portion of bovine dentin was ground, polished, and covered with a vinyl tape with a 4-mm hole punched through it. A strip of polysiloxane impression material was then placed across the center of the dentin surface to preserve a strip of the original unetched surface. Dentin surfaces were etched with 32% phosphoric acid for 60 s and rinsed with water. The impression material was then removed and the following sequential steps were performed: the dentin surface was mildly air-dried, then strongly air-dried, then treated with either 35 wt.% HEMA/water or 100 wt.% HEMA and mildly air-dried, and then strongly dried again. The shrinkage of the demineralized dentin surface from the original unetched level was measured by CLSM in each step and results analyzed by one-way ANOVA.
  
  
  RESULTS
  The dimensional changes of demineralized dentin after mild air drying were approximately -1 micron and, following strong air drying, resulted in -5 microns shrinkage. Following the application of 35 wt.% HEMA/water, the height of the demineralized dentin changed to a level of -3.3 microns, but then shrank to -4.8 microns after strong drying. ANOVA indicated that re-expansion of the shrunken etched dentin was significant (p < 0.05); however, the treated surface collapsed when it was strongly dried again (p < 0.05). 100% HEMA did not re-expand the shrunken demineralized dentin under any of the application on protocols (p > 0.05).
  
  
  CONCLUSIONS
  Thirty-five wt.% HEMA in water re-expanded the collapsed demineralized dentin matrix, however not to the original level. One hundred wt.% HEMA did not cause any re-expansion.
authors.affiliation: Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 5-45 Yushima 1-chome, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakaoki
authors.forename: T
authors.initials: T
authors.lastname: Nikaido
authors.forename: P N
authors.initials: PN
authors.lastname: Pereira
authors.forename: S
authors.initials: S
authors.lastname: Inokoshi
authors.forename: J
authors.initials: J
authors.lastname: Tagami
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D002417:Cattle; D003094:Collagen / Q000737:chemistry / Q000187:drug effects; D003804:Dentin / Q000737:chemistry / Q000187:drug effects*; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000494:pharmacology*; D003890:Desiccation; D008689:Methacrylates / Q000494:pharmacology*; D018613:Microscopy, Confocal; D019279:Resin Cements / Q000494:pharmacology*; D014867:Water
chemical_list: D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; D014867:Water; C005044:hydroxyethyl methacrylate; D003094:Collagen