This article was originally published in and reproduced here with the permission of, Dental Digest, which is provided as a service to health professionals through an educational grant from the Sugar Bureau.
Slow-release Fluoride Devices
K J Toumba
The consensus of current scientific opinion is that a constant supply of low levels of intra-oral fluoride, particularly at the plaque/saliva/enamel interface, are of most benefit in preventing dental caries (1). Thus frequent applications of topical fluoride are advised to maximise the effects of preventive regimes. It is the activity of the fluoride ion in the oral fluid that is of most importance in reducing the net demineralisation of the enamel, rather than a high content of fluoride in enamel itself. The latest research is investigating the use of slow-release fluoride devices (SRFD) for the long-term provision of intra-oral fluoride. Consistently elevated levels of fluoride in the mouth have been related to remineralisation of early carious lesions. Approaches to enhancing the provision of fluoride have been many but most suffer from the common problems that they are not consistent and rely on patient compliance. The objective of a slow- release device, fitted intra-ora1ly is to release low levels of fluoride constantly into the mouth, so that salivary fluoride concentrations are enhanced to a level that facilitates remineralisation. Therefore, the development of suitable intra-oral devices that release fluoride at a constant rate for periods of one to two years would be beneficial.
The intra-oral devices currently in use are of two types – copolymer membrane and glass devices (2). The copolymer membrane device was developed in the USA and is a membrane-controlled reservoir. The duration of release has been reported as between 30 – 180 days. The fluoride glass device was developed in Leeds (UK) for dental use. This can be attached to the buccal aspect of upper permanent molar teeth using an acid- etch composite. It dissolves slowly, when moist with saliva, so releasing fluoride into the oral environment.
In a human study (3) fluoride glass devices were found to be completely safe from the possibility of fluoride toxicity following accidental ingestion when compared with the plasma levels achieved from swallowing one 2.2mg sodium fluoride supplement tablet. The results showed that the baseline plasma fluoride levels were 0.01-0.02mg/L, and when the fluoride glass slow-release devices were ingested the plasma fluoride levels did not change from baseline levels at all. The findings of this study suggest that when swallowed the devices either pass through the stomach and small intestine very quickly or remain insoluble.
The only human caries study using fluoride glass devices to be reported is also by Toumba and Curzon (4). This was a double-blind clinical trial over a period of two years, involving 174 children aged 8 years, living in an inner-city area of Leeds, using fluoride (test group) and non-fluoride (control group) slow-releasing glass devices. The results showed 67% fewer new carious teeth. There are numerous potential applications of fluoride slow- release devices and these are 1. Caries prevention (especially high caries-risk groups). 2. Root caries prevention in adults. 3. Alleviation of dentine hypersensitivity. 4. Prevention of demineralisation in orthodontics. 5. Enhanced fluoride release of dental minerals.
1. Featherstone JD: Prevention and reversal of dental caries: the role of low-level fluoride. Community Dent Oral Epidemiol (1999) 27:31-40. 2. Toumba KJ, Curzon MEJ: Slow-release fluoride. Caries Res (1993) 27(Suppll):43-46. 3. Curzon MEJ and Toumba KJ. In vitro and in vivo assessment of a glass slow fluoride releasing device: a pilot study. Brit Dent J (2004) 196:543-546. 4. Toumba KJ and Curzon MEJ. A Clinical trial of a slow- releasing fluoride device in children. Caries Res (2005) 39:195-200.
Professor Jack Toumba, Division of Child Dental Health, Leeds Dental Institute, University of Leeds
33 Weymouth Street, London, W1G 7BY