Electrodos

Journal of Dentistry (2004) 32, 117–122

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Determination of fluoride ions released from resin-based dental materials using ion-selective electrode and ion chromatograph
Toshiyuki Itotaa,b,*, Thomas E. Carricka, Sandra Rusbya, Omar Taha Al-Naimia, Masahiro Yoshiyamab, John F. McCabea
a

Dental Materials Science Unit, School of Dental Sciences, University ofNewcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4BW, UK b Department of Operative Dentistry, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8525, Japan
Received 11 March 2003; accepted 19 September 2003

KEYWORDS
Chromatography; Fluoride release; Glass ionomer cement; Ionselective electrode; Resin

Summary Objectives. The aim of thisstudy was to investigate the quantities of total and free fluoride ions released from four resin-based composites containing fluoride (Heliomolar (HE), UniFil S (UF), Beautifil (BE) and Reactmer paste (RP)) and one glass ionomer cement (Ketac-Fil Plus Aplicap (KF)). Methods. Five disk specimens of each material were prepared and the fluoride release was measured at 1, 2, 4, 7, 14, 21 and 28 days. Theamounts of total and free fluoride ions released from materials were measured by using an ion-selective electrode (ISE) and ion chromatography (IC). Data were statistically analyzed using a ttest at a significant level of 0.05. Results. For HE, fluoride release is undetectable using the ISE but was detected by the IC method. There were no significant differences in the free and total fluoride ionsreleased from UF and BE ðp . 0:05Þ: For RP, the free fluoride ions were significantly lower than the total fluoride ions after 4 days ðp , 0:05Þ: KF showed significant difference between total and free fluoride ions at 7 and 28 days ðp , 0:05Þ: Conclusions. The nature of the fluoride incorporated into dental materials affected the amounts of free and total fluoride ions released from materials. q 2003Elsevier Ltd. All rights reserved.

Introduction
It has been reported that fluoride ions released from glass ionomer cements are effective for prevention of secondary caries in vitro.1 – 3
*Corresponding author. Tel.: þ81-86-235-6672; fax: þ81-86235-6674. E-mail address: itota@md.okayama-u.ac.jp

Therefore, numerous dental restorative materials containing fluoride, such as compomers andfluoride-releasing resin composites, have been developed and are available on the market and it has been reported that these materials can inhibit secondary caries around restorations in vitro.4,5 Resin-based materials often contain a variety of fluoride-releasing sources such as inorganic

0300-5712/$ - see front matter q 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.jdent.2003.09.002

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T.Itota et al. fluoride ions.13 Thus, IC is useful for the measurement of not only free fluoride ions but also low concentration of fluoride ions that may not be detected by the ISE method. The aim of this study was to investigate the effect of the nature of the fluoride incorporated into the resin-based materials on the amounts of total and free fluoride ions released from materials using both the ISE andIC methods.

fluorides or fluoro-silicate glasses. Different fluoride sources may affect the nature of the fluoride release from materials.6 – 8 For the analysis of fluoride released from materials into aqueous solutions, an ion-selective electrode (ISE) attached to an ion meter is most commonly used. A total ionic strength adjustment buffer (TISAB) solution is normally added to the solution in orderto control pH and prevent to formation of fluoride complexes. Although this method is simple and convenient for the measurement of fluoride release, both free fluoride ions and fluoride complexes released from materials are detected and it is difficult to distinguish between the two species.9,10 However, only free fluoride ions are effective for the enhancement of the resistance of tooth substance...