In vitro and in vivo assessment of a glass slow fluoride releasing device: a pilot study.

Abstract

The aims were to evaluate a) whether a slow release fluoride-glass pellet (SFG) would be retained in the mouth and release fluoride (F) over a long period of time, b) what concentrations of F in the glass would provide ideal intra-oral saliva F concentrations and c) whether an SFG would affect blood plasma concentrations of F after swallowing compared with ingestion of a commercial NaF tablet. a) A prototype SFG was attached to a maxillary molar of a volunteer. Baseline saliva F concentrations were measured prior to glass placement, daily in week one; one day a week for weeks two to three and then one day a month up to 18 months. Four subjects had the SFG for six months with saliva F concentration assessments at periodic intervals. b) SFGs containing F at 13.3%, 18.3% and 21.9%, and an improved solubility, were tested using three volunteers and saliva F concentrations measured. c) Five volunteers each swallowed either a SFG or a NaF tablet. Blood plasma samples were taken at baseline and F measured at time intervals of 2.5, 5, 10, 20, 30, 45, 60, 90 and 120 mins post-ingestion. a) The prototype SFG were successfully retained and released F into saliva; mean concentrations of 0.035 mg L(-1) were achieved lasting for over 18 months. Overall saliva F concentrations were approximately doubled. Analysis of the pellet at the end of use showed it still contained some F possibly indicating a recharging effect. b) The 13.3% F concentration SFG produced significantly higher saliva F levels than the two other concentrations tested. The two higher concentration F glasses contained aluminium as part of the formulation of the glass structure, which is known to bind F whereas the 13.3% glass contained F alone. c) While blood plasma F levels increased after ingestion of the NaF tablet there was no increase in F when the SFG was swallowed. A slow release F containing glass device showed promise as a means to enhance intra-oral F saliva concentration.