title: Effect of mechanical properties of fillers on the grindability of composite resin adhesives.
abstract: BACKGROUND
  The purpose of this study was to investigate the effect of filler properties on the grindability of composite resin adhesives.
  
  
  METHODS
  Six composite resin products were selected: Transbond XT (3M Unitek, Monrovia, Calif), Transbond Plus (3M Unitek), Enlight (Ormco, Glendora, Calif), Kurasper F (Kuraray Medical, Tokyo, Japan), Beauty Ortho Bond (Shofu, Kyoto, Japan), and Beauty Ortho Bond Salivatect (Shofu). Compositions and weight fractions of fillers were determined by x-ray fluorescence analysis and ash test, respectively. The polished surface of each resin specimen was examined with a scanning electron microscope. Vickers hardness of plate specimens (15 × 10 × 3 mm) was measured, and nano-indentation was performed on large filler particles (>10 μm). Grindability for a low-speed tungsten-carbide bur was estimated. Data were compared with anlaysis of variance (ANOVA) and the Tukey multiple range test. Relationships among grindability, filler content, filler nano-indentation hardness (nano-hardness), filler elastic modulus, and Vickers hardness of the composite resins were investigated with the Pearson correlation coefficient test.
  
  
  RESULTS
  Morphology and filler size of these adhesives showed great variations. The products could be divided into 2 groups, based on composition, which affected grindability. Vickers hardness of the adhesives did not correlate (r = 0.140) with filler nano-hardness, which showed a significant negative correlation (r = -0.664) with grindability.
  
  
  CONCLUSIONS
  Filler nano-hardness greatly influences the grindability of composite resin adhesives.
authors.affiliation: Associate professor, Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan. Electronic address: iijima@hoku-iryo-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iijima
authors.affiliation: Instructor, Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Muguruma
authors.affiliation: Professor, Division of Restorative and Prosthetic Dentistry, College of Dentistry, Ohio State University, Columbus, Ohio.
authors.forename: William A
authors.initials: WA
authors.lastname: Brantley
authors.affiliation: Instructor, Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yuasa
authors.affiliation: Instructor, Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Uechi
authors.affiliation: Professor, Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Itaru
authors.initials: I
authors.lastname: Mizoguchi
mesh_terms: D017005:Dental Debonding / Q000295:instrumentation / Q000379:methods; D055119:Elastic Modulus; D006244:Hardness; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009967:Orthodontic Appliances; D010316:Particle Size; D055585:Physical Phenomena; D019279:Resin Cements / Q000737:chemistry*
chemical_list: D019279:Resin Cements