Single-crystalline ceramic whisker-reinforced carboxylic acid-resin composites with fluoride release

Currently available glass-ionomer, resin-modified glass-ionomer, and compom er materials have relatively low strength and toughness and, therefore, are inadequate for use in large stress-bearing posterior restorations. In the present study ceramic single-crystalline whiskers were mixed with fluorosil icate glass particles and used as fillers to reinforce experimental carboxy lic acid-resin composites. The carboxylic acid was a monofunctional methacr yloxyethyl phthalate (MEP). Five mass fractions of whisker/(whisker + fluor osilicate glass), and corresponding resin (resin + MEP), were evaluated. Fo ur control materials were also tested for comparison: a glass ionomer, a re sin-modified glass ionomer, a compomer, and a hybrid composite resin. Flexu ral specimens were fabricated to measure the flexural strength, elastic mod ulus, and work-of-fracture (an indication of toughness). Fluoride release w as measured by using a fluoride ion selective electrode. The properties of whisker composites depended on the whisker/(whisker + fluorosilicate glass) mass fraction. At a mass fraction of 0.8, the whisker composite had a flex ural strength in MPa (mean +/- sd; n = 6) of 150 +/- 16, significantly high er than that of a glass ionomer (15 +/- 7) or a compomer control (89 +/- 18 ) (Tukey's multiple comparison test; family confidence coefficient = 0.95). Depending on the ratio of whisker:fluorosilicate glass, the whisker compos ites had a cumulative fluoride release up to 60% of that of a traditional g lass ionomer. To conclude, combining ceramic whiskers and fluorosilicate gl ass in a carboxylic acid-resin matrix can result in fluoride-releasing comp osites with significantly improved mechanical properties.