The effect of repeated fluoride recharge and storage media on bond durability of fluoride rechargeable Giomer bonding agent

Background:  For a restorative material or adhesive to exhibit caries inhibitive potential through fluoride release, it must be capable of fluoride recharge. The aim of this study was to evaluate the effect of repeated fluoride recharge and different storage media on dentine bond strength durability. Methods:  Two self‐etch adhesive systems (two‐step) were evaluated: fluoride‐rechargeable Giomer FL‐Bond II and non‐fluoride‐containing UniFil Bond. For each adhesive 32 human dentine specimens were prepared for shear bond strength testing. The specimens were randomly allocated to one of four storage groups: Group 1 – 24‐hour water ageing; Group 2 – four‐month water ageing; Group 3 – four‐month water ageing with weekly fluoride recharge (5000 ppm for 10 minutes); and Group 4 – four‐month acid ageing with weekly fluoride recharge. Results:  Weekly fluoride recharge over four months ageing did not significantly (p > 0.05) reduce the dentine shear bond strength of FL‐Bond II or UniFil Bond. Storage media did not significantly (p > 0.05) affect bond durability. Conclusions:  The adhesion between fluoride rechargeable FL‐Bond II and dentine maintained durability despite regular fluoride recharge over the four months ageing. Clinicians prescribing the fluoride recharge regime used in the present study to reduce recurrent caries incidence associated with Giomer FL‐Bond II restorations can do so without compromising dentine bond strengths.