title: Wear evaluation of porcelain opposing gold, composite resin, and enamel.
abstract: BACKGROUND
  When porcelain surfaces oppose gold and composite resin restorations as well as enamel, wear resistance and abrasiveness of the porcelain are clinical concerns to maintain the occlusal relationship. However, there is limited information on comparison of mutual wear rates when these materials oppose in 2-body and 3-body conditions.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate mutual wear rates of dental porcelain and opposing materials, including a gold alloy, a composite resin, and human enamel, using an in vitro wear test.
  
  
  METHODS
  Mutual wear between high-fusing dental porcelain (Ceramco II) disks (9 x 5-mm thick) with a rough or smooth surface and opposing styli made of gold alloy, composite resin, or human enamel was evaluated in 2-body and 3-body conditions using a wear simulator (n=8). Wear depths (microm) of porcelain disks were determined using a profilometer. Wear depths (microm) of the opposing materials were obtained by converting the worn surface areas into wear depths using image-analysis software. All data were statistically analyzed by 3-way analysis of variance and Bonferroni-Dunn test (alpha=.05). The worn surfaces were observed by scanning electron microscope (SEM).
  
  
  RESULTS
  The wear values for porcelain opposing composite resin or enamel in the 2-body condition were significantly greater than those in the 3-body condition, regardless of the surface condition of the porcelain (P<.001). For stylus specimens, all values in the 2-body condition were significantly greater than those in the 3-body condition, regardless of the surface condition of the opposing porcelain (P<.001). These results are supported by SEM observations of worn surfaces.
  
  
  CONCLUSIONS
  The results of this study suggest that mutual wear rates, when porcelain opposes gold, composite resin, and enamel, are influenced by 2-body and 3-body wear conditions.
authors.affiliation: Fixed Prosthetic Dentistry, Kagoshima University Graduate School of Medical and Dental Sciences, Japan. prosth@dentb.hal.kagoshima-u.ac.jp
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kadokawa
authors.forename: Shiro
authors.initials: S
authors.lastname: Suzuki
authors.forename: Takuo
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D003743:Dental Enamel / Q000473:pathology; D003776:Dental Porcelain / Q000009:adverse effects; D019554:Dental Restoration Wear; D006047:Gold Alloys; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008855:Microscopy, Electron, Scanning; D018709:Statistics, Nonparametric; D013499:Surface Properties; D014072:Tooth Abrasion / Q000209:etiology*
chemical_list: D003188:Composite Resins; D006047:Gold Alloys; D003776:Dental Porcelain