Ion migration from fluoride-releasing dental restorative materials into dental hard tissues Elizabeta Gjorgievska • John W. Nicholson • Aleksandar T. Grcev Received: 9 January 2012 / Accepted: 14 April 2012 / Published online: 25 April 2012 Ó Springer Science+Business Media, LLC 2012 Abstract This study was carried out in order to determine the extent to which ions released from fluoride-containing dental restoratives migrated through the enamel and den- tine of extracted teeth. A total of 40 permanent human 3rd molars were used. They were extracted for orthodontic reasons, and employed within 1 month of extraction. A cervical (Class V) cavity was prepared in each tooth, then filled with one of: a conventional glass-ionomer, a resin- modified glass-ionomer, a polyacid-modified composite resin (‘‘compomer’’) or a fluoride-releasing resin compos- ite. Ten samples were prepared per material. After 1 month, five specimens per material were prepared and examined under SEM/EDX. Concentrations of sodium, aluminium, strontium, fluorine, magnesium, silicon, phos- phorus and calcium were determined within the tooth. After 18 months, the remaining five specimens for each material were prepared and studied in the same way. The greatest extent of ion migration into the tooth was found with the conventional glass-ionomer and least migration was found for the fluoride-releasing composite, which showed no evidence of fluoride migration at all. Levels of migrating ions were generally higher in the 18 month specimens than in the 1 month specimens, and also higher in the dentine than in the enamel. Ions released by restor- ative dental materials have been shown conclusively for the first time to be capable of migrating into the enamel and dentine surrounding the restoration. The conventional glass-ionomer showed the highest level of ion migration whereas the fluoridated composite resin showed little if any ion migration. This suggests that the conventional glass- ionomer has the greatest caries inhibiting effects of all the materials tested, and the fluoridated composite the least. 1 Introduction Fluoride-releasing dental restorative materials are fre- quently used in the clinical practice [1] with the aim of reducing the incidence of dental caries [2]. These materials include the conventional glass-ionomer cements, and also the resin-modified glass-ionomer cements (RMGICs), the compomers, also known as polyacid-modified composite resins, and fluoride-containing conventional composite res- ins [2, 3]. Glass-ionomer cements have been studied most extensively, and shown to be capable of releasing fluoride for several years in vitro [4]. They have also been shown to inhibit caries formation in teeth when tested in the laboratory [5] and to reduce the incidence of interproximal caries [3]. However, in clinical use, the evidence for their effectiveness is more equivocal, and their ability to inhibit caries in vivo has not been demonstrated conclusively [6]. This is probably connected with the fact that the critical amount of fluoride required for inhibition of caries in vivo has not been estab- lished [7], since there is no doubt that fluoride itself is effective against caries [8]. E. Gjorgievska Department of Paediatric and Preventive Dentistry, Faculty of Dental Medicine, University ‘‘Ss. Cyril and Methodius’’ Skopje, Skopje, Republic of Macedonia J. W. Nicholson (&) Department of Pharmaceutical, Chemical and Environmental Sciences, School of Science, University of Greenwich at Medway, Medway, Kent ME4 4TB, UK e-mail: J.W.Nicholson@gre.ac.uk A. T. Grcev Department of Oral and Maxillofacial Surgery, Faculty of Dental Medicine, University ‘‘Ss. Cyril and Methodius’’ Skopje, Skopje, Republic of Macedonia 123 J Mater Sci: Mater Med (2012) 23:1811–1821 DOI 10.1007/s10856-012-4653-z