title: Wear of visible light-cured restorative materials and removable partial denture direct retainers.
abstract: OBJECTIVE
  This study measured the in vitro wear of visible light-cured restorative materials and removable partial denture direct retainers.
  
  
  METHODS
  An aluminum test die was produced by replicating the facial contours of an extracted human molar (model). The replica's cervical contour was modified by placement of a restorable Class V cavity preparation. The test die became a fixed component of a testing apparatus. The restorative materials tested were Z100 (fine particle filled resin composite), Silux Plus (microfilled resin composite), and Photac-Fil (hybrid glass ionomer). Cast round, half round, I bar, and wrought-wire retainers were designed to engage a 0.254-mm undercut. Caliper measurements of the wear of restorative materials were made at intervals during testing, and after 7,500 retainer placements and removals. The measurements of material- and retainer-wear were subjected to ANOVA and Tukey tests.
  
  
  RESULTS
  Generally, retainers with round profiles caused less wear of the restorative materials than those featuring flat contact surfaces. Wear of the materials ranged from 14 +/- 5.5 microns (Silux Plus by cast round) to 70 +/- 10.0 microns (Photac-Fil by cast half round). Mean wear of retainers, however, ranged only from 2 +/- 4.5 microns for six of 12 possible retainer-material pairings up to 12 +/- 4.5 microns (cast half round by Z100).
  
  
  CONCLUSIONS
  Regardless of their design features, the direct retainers of this study exhibited little wear when paired with any of the restorative materials. Overall, material wear appeared to be greater than retainer wear by a factor of five. When paired with practically any retainer type, the hybrid glass ionomer (Photac-Fil) exhibited more wear than either of the two resin composites (Z100 or Silux Plus). Although not established clearly, retainers with round profiles (wrought-wire and cast round) appeared to produce less wear of restorative materials than their I bar and cast half round counterparts.
authors.affiliation: Department of Prosthodontics, University of Tennessee, College of Dentistry, Memphis 38163, USA.
authors.forename: G H
authors.initials: GH
authors.lastname: Latta
authors.forename: R A
authors.initials: RA
authors.lastname: Wicks
authors.forename: E F
authors.initials: EF
authors.lastname: Huget
authors.forename: G A
authors.initials: GA
authors.lastname: Murray
mesh_terms: D000704:Analysis of Variance; D003764:Dental Materials / Q000528:radiation effects*; D017268:Dental Prosthesis Retention / Q000295:instrumentation* / Q000706:statistics & numerical data; D019554:Dental Restoration Wear / Q000706:statistics & numerical data; D003832:Denture, Partial, Removable / Q000706:statistics & numerical data; D006801:Humans; D066298:In Vitro Techniques; D008027:Light; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data
chemical_list: D003764:Dental Materials