Chemical Durability of Dicor and Fluorocanasite-based Glass-ceramics

Abstract

Fluorocanasite (Al₂O₃-CaO-F-K₂O-Na₂O-SiO₂) glass-ceramics exhibit fracture toughness values of up to 5.0 MPa·m^1/2. However, their chemical durability is not adequate for dental applications. The objective of this study was to test the hypothesis that an increased concentration of Al₂O₃ can increase the chemical durability of fluorocanasite-based glass-ceramics. Glass frits containing 2 wt% (CAN2), 5 wt% (CAN5), and 10 wt% Al₂O₃ (CAN10) were melted individually, poured into a graphite mold, and cut into 16-mm-diam. x 2-mm-thick disks. Each disk was crystallized at 850°C for 6 hrs. The disks were immersed in a solution of de-ionized-distilled water, 4% acetic acid, or a pH 1 buffer solution, and sealed in 90-mL Teflon containers. Corrosion testing was performed by means of vibrational motion at 60 cycles per min in a shaker-bath at 80°C for 15 days. Solution analyses were performed by means of a pH meter, an atomic absorption spectrophotometer, and an inductively coupled plasma spectrometer. Samples exposed to 4% acetic acid solution exhibited a mean weight loss rate (WLR) for the control group (Dicor) of 0.04 ± 0.01 mg/cm²·day, which was significantly lower (p ≤ 0.0001) than the mean WLR of the CAN2 (1.08 ± 0.02 mg/cm2.day), CAN5 (1.31 ± 0.02 mg/cm²·day), and CAN10 (1.51 ± 0.05 mg/cm²·day) groups. The reduced durability of fluorocanasite-based glass-ceramics with increasing Al₂O₃ concentration is most likely associated with a more uniform distribution of smaller crystals during heat treatment of the glass.

Keywords

fluorocanasite Dicor glass-ceramic chemical durability.

Get full access to this article

View all access options for this article.

References

Anusavice KJ , Zhang N. -Z (1996). Effect of nucleation temperature on toughness and flexure strength of fluorocanasite glass-ceramics (abstract). J Dent Res 75:67.

Anusavice KJ , Zhang N. -Z (1997). Chemical durability of Dicor and lithia-based glass-ceramics. Dent Mater 13:13-19.

Cotton FA , Wilkinson G. (1976). First principles. In: Basic inorganic chemistry. New York: John Wiley & Sons, Inc., pp. 1-30.

David RL (1994). CRC handbook of chemistry and physics. 74th ed. Cleveland, OH: The Chemical Rubber Co., pp. 8-45.

De Rijk WG , Jennings KA , Menis DL (1985). A comparison of chemical durability test solutions for dental porcelains. In: Biomedical engineering-recent developments. Proceedings of the Southern Biomedical Engineering Conference . Sauer BW, editor. New York: Pergamon, pp. 152-155.

Fujishima A. , Miyazaki T. , Takatama M. , Suzuki E. , Miyaji T. (1989). Chemical durability of composite resins. Shika Zairyo Kikai (Dental Mater Dev) 8:242-253.

Fukui H. , Abe Y. , Ai S. (1977). Studies of calcium phosphate glass-ceramics-development of dental materials. (Part 2) Acid resistance. Shika Rikogaku Zasshi (J Dent Eng) 18(42):146-151.

Grossman DG , Walters HV (1984). The chemical durability of dental ceramics (abstract) . J Dent Res 63:234.

Leng-Ward G. , Lewis MH (1989). Oxynitride glasses and their glass-ceramic derivatives . In: Glass and glass-ceramics. Lewis MN , editor. New York: Chapman and Hall, pp. 107-155.