Ion release from a novel orthodontic resin bonding agent for the reduction and/or prevention of white spot lesions An in vitro study

Objective: To measure ion release from four sol-gel bioactive glass-containing orthodontic resin bonding agents (BAG-Bonds) following immersion into simulated body fluid (SBF) at pH values of 4 and 7. Materials and Methods: Four BAG-Bonds, two containing fluoride, were developed. Prepared in our laboratory, the BAG-Bonds were composed of a mixture of resin monomers and bioactive glasses (BAGs). Workability of the final BAG-Bonds determined the amount of filler added to each, and this varied according to BAG composition. Commercially available Transbond-XT was used as the control. Three disks (10 mm × 2 mm) of each material were individually suspended in 3.5 mL of SBF at pH 4 and pH 7. SBF was analyzed to measure pH and ions released at 1 hour, 10 hours, and 100 hours. Calcium was measured by atomic absorption analysis, phosphate by ultraviolet visible spectrometry, and fluoride by an ion-specific electrode. The data were compared using a three-way analysis of variance, with P ≤ .05. Results: Significant differences in calcium and phosphate ion release were found between the four BAG-Bonds and the control at multiple time points. Significant changes in pH were also found. There was no measureable release of fluoride from any of the materials. Conclusions: The BAG-Bonds showed the capacity for buffering acidic oral environments and significant release of calcium ions into their surrounding environment, and they hold the potential to be biomimetic bonding agents that may reduce white spot lesion formation.