Fluoride containing bioactive glass composite for orthodontic adhesives - ion release properties

Dental materials that release calcium, phosphate and fluoride ions could prevent demineralisation and/or enhance remineralisation of enamel. The objective was to develop a novel bioactive glass (BAG) resin and investigate pH changes and ion release in 3 immersion media.

Quench melt derived BAG (35.25% SiO₂, 6% Na₂O, 43% CaO, 5.75% P₂O₅, and 10% CaF₂) was incorporated into a resin (42.25% BisEMA, 55% TEGDMA, 0.25% DMAEM, 0.5% camphorquinone and 2% 4-Meta), with a filler load of 80% by weight. Ninety composite disks for each BAG loading of 80%, 60%, 50%, 40%, 20%, and 0% were made and each disk was immersed in 10ml of either tris buffer (TB), or artificial saliva at pH=7 (AS7) or pH=4 (AS4), n=30 for each solution. Three disks of each loading were taken from each of the solutions, at ten time points (6h-6months), for measurement of pH, fluoride, calcium and phosphate.

The BAG adhesive raised the pH in all the solutions, release Ca, PO₄ and F ions especially in AS4. The rise in pH and the release of Ca and F are directly related to the BAG loading and the time of immersion. The pH and the ion releases were maintained and continued over 6months.

Unlike glass ionomer resins, favourable ions F, Ca and PO₄ releases were maintained over a long time period especially in acidic condition for this novel BAG-resin composite. This indicates the resin has the potential to prevent formation and progression of early caries lesions.