Effect of mechanical properties of fillers on the grindability of composite resin adhesives.
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.
Iijima
Masahiro
M
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.
Muguruma
Takeshi
T
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.
Brantley
William A
WA
Professor, Division of Restorative and Prosthetic Dentistry, College of Dentistry, Ohio State University, Columbus, Ohio.
Yuasa
Toshihiro
T
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.
Uechi
Jun
J
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.
Mizoguchi
Itaru
I
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.
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*
D019279:Resin Cements