Studies on Deterioration Process of Dental Materials

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 10044287
• Research Category: Grant-in-Aid for Scientific Research (B).
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Conservative dentistry
• Research Institution: Osaka University
• Principal Investigator: KAWAI Keiji Faculty of Dentistry, Osaka University Assistant Professor, 歯学部・附属病院, 講師 (40204664)
• Co-Investigator(Kenkyū-buntansha): EBISU Shigeyuki Fauty of Dentistry, Osaka University Professor, 歯学部, 教授 (50116000)
• Project Period (FY): 1998 – 1999
• Keywords: Wear / Resin compsoite / Microfiller / Quartz / Amorphous silica / Barium glass / Strontium glass / Filler content

Research Abstract

The purpose of this study is to investigate the effects of filler type and filler content on the wear resistance of resin composites using a three-body wear testing machine. Experimental light-cured resin composites were fabricated with inorganic fillers, resin monomers (Bis-GMA/TEGDMA), photo-initiator, accelerator and inhibitor. Five kinds of fillers (Quartz, Q; Amorphous silica, Am; Barium glass, Ba; Strontium glass, Sr; Microfine silica, MF) were used as inorganic phase. For every resin composites, the filler size distribution was tried to be the same as much a possible. Mean filler size was around 3.0 i m. In addition, two additional composites were filled with 20wt% and 40wt% microfine silica fillers. The in vitro wear testing was carried out using the Alabama wear simulator. After wear testing, the amount of wear was measured with 3D-laserscanner. As a result, Am, Ba or Sr and Q showed the maximum wear loss when the filler content was 40, 60 and 70 wt %, respectively. Am- and Ba-loaded composites showed a significant difference among the composites with different filler content, while no difference was found with Q- and Sr- loaded ones. Next, when more than 60 wt% of fillers are loaded in matrix resin, Am-loaded composites showed the most wear resistance, then followed by Ba- and Q-loaded ones. Sr-containing composites exhibited the largest amount of ear irrespective of filler content. At a filler load less than 40 wt% the microfilled materials had in both cases a significantly reduced amount of wear. Addition of 20 wt% microfillers to 60 wt% conventional resin composites (hybridization) increased the ear resistance for all filler types. The same level of wear as with microfilled composites is reached by hybridization of the filler system. It could be concluded from these results that size, type and content of fillers influence the wear resistance of resin composites.