title: Effect of low O2-gas transmission rate barrier films on knoop hardness and toothbrush abrasion of resin cements.
abstract: OBJECTIVE
  To investigate the influence of utilizing films with different oxygen transmission rates (O2-GTR) on Knoop hardness and toothbrush abrasion of resin cements for luting.
  
  
  METHODS
  Four dual-activated, composite-type resin cements, and a chemically activated PMMA-type resin cement, were used. Three different types of barrier films (Techbarrier HI, Harden Film N130, and Lix-2) were used. Resin cement was mixed and inserted into a cylindrical mold (4 mm in diameter, 3 mm in height), then chemically activated. The specimens were stored in the dark at 37 +/- 1 degrees C, 90 +/- 5%RH conditions for 1 hour. Knoop hardness on the top surface of the resin cement was measured with a microhardness tester. The top surface of specimens (8 mm in diameter, 3 mm in height) polymerized under the same conditions were used for toothbrush abrasion testing. One-way ANOVA followed by Tukey HSD test (P< 0.05) were done.
  
  
  RESULTS
  When the cement surface was covered by low O2-GTR film, a significant increase in Knoop hardness and resistance to toothbrush abrasion was observed for the dual activated, composite-type resin cements, but not for the chemically activated PMMA type resin cement. From the results of this study, the use of low O2-GTR matrix barrier films for the dual activated, composite-type resin cements could be effective in eliminating the oxygen inhibited layer on the cement surface.
authors.affiliation: Department of Operative Dentistry, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-Ku, Tokyo 101-8310, Japan.
authors.forename: Youkei
authors.initials: Y
authors.lastname: Asaka
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kurokawa
authors.forename: Toshiki
authors.initials: T
authors.lastname: Takamizawa
authors.forename: B Keith
authors.initials: BK
authors.lastname: Moore
mesh_terms: D006244:Hardness; D008567:Membranes, Artificial; D010100:Oxygen / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013499:Surface Properties; D014072:Tooth Abrasion / Q000517:prevention & control*; D014099:Toothbrushing / Q000009:adverse effects*
chemical_list: D008567:Membranes, Artificial; D019279:Resin Cements; D010100:Oxygen