Fluoride release of polyacid-modified composite resins with and without bonding agents

Objectives: The aim of this study was to investigate the influence of the proprietary bonding agents Hytac OSB (OSB) (Espe), Prime&Bond 2.1 (PB) (Dentsply DeTrey) and Syntac Single Component (SSC) (Vivadent) on the fluoride release of the corresponding polyacid-modified composite resins Hytac (HTC), Dyract AP (DAP) and Compoglass F (CGF), respectively. Methods: Ten cylindrical specimens (6 mm diameter and 3 mm thick) of each polyacid-modified composite were prepared according to the manufacturersʹ instructions: five with bonding agent applied and five without bonding agent as a control. The specimens were immersed individually in 10 ml ultra-pure water at 37°C immediately after light-curing of the polyacid-modified composite resins. Over 140 days, the water was regularly renewed and the fluoride concentration eluted during each period was determined with a combined fluoride ion selective electrode. Results: The fluoride release decreases according to the sequence: CGF>DAP>HTC. The bonding agent significantly reduces the fluoride released by DAP and CGF, respectively, by a factor 2–3 and ±1.4. For HTC, the bonding agent reduces the fluoride released initially by a factor of ±2, but the difference between the fluoride release with and without bonding agent becomes insignificant after approximately 3 weeks. Significance: It can be concluded that the use of bonding agent can significantly reduce fluoride release of polyacid-modified composite resins in the long-term, and especially in the short-term. The decrease in fluoride release might reduce the materialʹs potential to prevent recurrent caries.