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Fatigue resistance of composite restorations: effect of filler content
A Htang1, M Ohsawa, H Matsumoto
1Department of Endodontics and Operative Dentistry, Nagasaki University, School of Dentistry, Japan.
Objectives:
The purpose of this study was to evaluate the effects of filler level on the fatigue impact resistance of resin composite.
Methods:
A series of experimental composite materials was prepared by incorporating a silanized quartz filler (3-5 microns in size) into a light-cured resin matrix of Bis-GMA/TEGDMA. The filler contents in the experimental composites varied from 40 to 85 wt%. The composites were placed in standardized Class I cavities prepared in bovine teeth. The specimens were stressed with a repetitive impact load (1.6 x 10(2) joule) with loading cycles ranging from 50,000 to 150,000 times. The cracks induced by cyclic loading were observed on the sectioned surfaces of the tested specimens.
Results:
The composites with considerably low or high filler content (< 60% or > 80% by weight) were significantly low in fatigue resistance. The results revealed that an inverse linear relationship tended to exist between filler level and fatigue resistance of the composite materials beyond a certain level of filler content.
Significance:
Increased filler level does not necessarily improve the fatigue resistance of a resin composite as determined by applying a repetitive impact load.