Biomaterials 24 (2003) 1301–1308 The effects of adding fluoride compounds to a fluoride-free glass ionomer cement on subsequent fluoride and sodium release J.A. Williams a , E. Briggs a , R.W. Billington b , G.J. Pearson b, * a Department of Biomaterials Research, Eastman Dental Institute, 256 Gray’s Inn Road, London WC1X 8LD, UK b Department of Biomaterials in Relation to Dentistry, Queen Mary University of London, Mile End Road, London, E1 4NS, UK Received 5 March 2002; accepted 30 September 2002 Abstract Studies have shown that ions in a glass ionomer matrix are 1–10% of the amounts present in the original glass. To measure more precisely the release from a cement matrix, known amounts of ions were added to LG30 glass which was fluoride and sodium-free. Cement without additions acted as the control. 1.4–1.6% of each of sodium, calcium and aluminum fluorides were added to three portions of control blend. The sodium and fluoride release into deionised water from five discs of each cements blend was measured for 8 months. This represented complete release for sodium but not for fluoride. Traces of fluoride and sodium in the glass produced low but measurable amounts indicating about a third of the fluoride and substantially all sodium present in LG30 was released. The addition of calcium fluoride had no significant effect on sodium or fluoride release and aluminium fluoride minimal effects. Adding sodium fluoride significantly enhanced release of both ions although fluoride release was less than from a glass containing 5% fluoride. Only small proportions of the additions, 2–5% of the fluoride and 13% of sodium, were released. Sodium and fluoride appeared to be released independently. For LG30 cements additives were poor at supplying extra ions. r 2002 Elsevier Science Ltd. All rights reserved. Keywords: Glass ionomer cement; Sodium fluoride; Calcium fluoride; Aluminium fluoride; Additives; Ion release 1. Introduction Fluoride ion is efficacious in reducing the suscept- ibility of hard tooth tissue to caries [1]. Fluoride can be applied to the tooth by dentifrices, mouthwashes, gels or via dental cements. The latter may be either restorative materials (filling materials) or those used to attach prostheses (luting cements); both can provide long term fluoride release. It has been found that all water-based dental cements (silicate, silicophosphate, glass-ionomer, zinc phosphate and zinc polycarboxylate) can release fluoride ion over a period of at least one year [2–6]. In the zinc based cements, this fluoride is added to the powder component as a soluble fluoride compound (most often as SnF2) whereas in the glass-based cements the fluoride is derived from the glass. In each material a portion of the fluoride is present in the cement matrix. For glass ionomer cements fluoride may have been dissolved from the solid component by the cement forming process [7] or was present as a water-soluble species on the surface of the glass particles [8]. A large proportion of glass remains as structural filler and possibly provides a source of continuing fluoride release. In glass-ionomer cements the three cationic species normally associated with fluoride are sodium (Na + ), calcium (Ca 2+ ) and aluminium (Al 3+ ). It is possible that the cation could affect fluoride release [9]. Since the reaction between the polymeric acid and glass compo- nents results in the formation of a continuous phase through which the fluoride ion can diffuse it seemed appropriate that fluoride compounds could be intro- duced as finely divided powders. These would be dispersed throughout the matrix once the cement was produced. The aim of the study was to add fluoride as NaF, CaF 2 and AlF 3 to a sodium and fluoride free glass ionomer and to measure the subsequent fluoride and sodium release. *Corresponding author. Tel./fax: +44-207-882-7977. E-mail address: gjpearson3@aol.com (G.J. Pearson). 0142-9612/02/$-see front matter r 2002 Elsevier Science Ltd. All rights reserved. PII:S0142-9612(02)00467-2