title: Water content in experimental dentine primers to minimize the contraction gap width of a light-cured resin composite.
abstract: OBJECTIVE
  The effect of water content in experimental dentine primers consisting of an aqueous solution of either glyceryl methacrylate (GM) or hydroxyethyl methacrylate (HEMA), and in experimental self-etching dentine primers composed of methacryloxyethyl hydrogen phenyl phosphate (Phenyl-P), was evaluated by measuring the wall-to-wall polymerization contraction gap width of a commercial light-activated resin composite filled in a cylindrical dentine cavity prepared in an extracted human molar.
  
  
  METHODS
  A commercial light-cured dentine bonding agent was applied to the cavity after cleaning with EDTA and priming with either GM or HEMA, or after self-etching priming by Phenyl-P diluted in either GM or HEMA solution.
  
  
  RESULTS
  In the GM and HEMA solutions, the gap width was minimized when the water content was 65 wt% even though gap formation could not be prevented by HEMA solution. With the self-etching dentine primers, gaps could not be observed under the light microscope with 16 wt% Phenyl-P diluted in 35 wt% GM or HEMA or with 20 wt% Phenyl-P diluted in 20 wt% GM or HEMA.
  
  
  CONCLUSIONS
  The water content in both the experimental dentine primers and the self-etching dentine primers which yielded the minimum contraction gap width for the resin composite in the dentine cavity was approximately 60 wt%.
authors.affiliation: Department of Operative Dentistry, Showa University School of Dentistry, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yokoi
authors.forename: H
authors.initials: H
authors.lastname: Miyaji
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: H
authors.initials: H
authors.lastname: Hisamitsu
authors.forename: S
authors.initials: S
authors.lastname: Wakumoto
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D018772:Dental Marginal Adaptation; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005989:Glycerides / Q000737:chemistry; D016018:Least-Squares Analysis; D008689:Methacrylates / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000737:chemistry; D019279:Resin Cements; D014867:Water
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005989:Glycerides; D008689:Methacrylates; D009943:Organophosphorus Compounds; C074232:Phenyl-P adhesion promoting monomer; D019279:Resin Cements; D014867:Water; C074669:Clearfil Photo Bond; C074741:Silux Plus; C069750:glyceryl methacrylate; C005044:hydroxyethyl methacrylate