Effect of mechanical properties of fillers on the grindability of composite resin adhesives

• Published in: American journal of orthodontics and dentofacial orthopedics 2010-10, Vol.138 (4), p.420-426
• Main Authors: Iijima, Masahiro, Muguruma, Takeshi, Brantley, William A, Yuasa, Toshihiro, Uechi, Jun, Mizoguchi, Itaru
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Dental Debonding - instrumentation; Dental Debonding - methods; Dentistry; Elastic Modulus; Hardness; Materials Testing; Medical sciences; Microscopy, Electron, Scanning; Orthodontic Appliances; Otorhinolaryngology. Stomatology; Particle Size; Physical Phenomena; Resin Cements - chemistry
• ISSN: 0889-5406; 1097-6752
• DOI: 10.1016/j.ajodo.2008.08.039

Introduction 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.