Does fluoride mouth rinse affect antibacterial properties of orthodontic cements?

Antibacterial orthodontic cements may be advantageous in prevention of carious lesions in the proximity of the orthodontic devices. The aim of this study was to investigate orthodontic cements ability to regain antibacterial effect after aging for 1month, followed by 2 weeks of fluoride "recharging" through daily fluoride rinse.

Methods: Orthodontic cements were tested: composite resin based materials – Transbond XT, and Transbond Plus, a conventional glass ionomer cement- CX-Plus and dual cured resin-reinforced glass ionomer cement - Fuji ORTHO LC were tested by the direct contact test. After polymerization and 30 day aging process, the samples were daily rinsed with 0.05% NaF solution for 14 days. 24h after the last fluoride rinse, Streptococcus mutans cells (ca. 1 x 10⁶) were placed on the surface of each sample for 1 hour at 37ºC to establish direct contact. Bacterial growth was monitored for 24h by temperature controlled spectrophotometer. Similar experiments were conducted after aging for 48 h and 72 h after the last fluoride rinse. One-way ANOVA, two-way ANOVA and Tukey’s multiple comparison procedures were applied to the data.

Results: 24h after the last fluoride rinse, the resin modified glass- ionomer –and the glass–ionomer, showed potent antibacterial properties, whereas the composite-based material Transbond XT  encouraged bacterial growth. After 72h only Fuji Ortho LC maintained its bacteriostatic properties while all the other tested materials showed no antibacterial activity.

Conclusions: 14 days daily fluoride rinse temporarily revives the antibacterial properties of the resin modified glass-ionomer cement and glass–ionomer based cement.