Fluoride Recharge of Five Different Restorative Materials

Objectives: To measure the fluoride release from 4 different restorative materials stored in water after recharging with fluoride-containing toothpaste
Methods: A mold was used to make disc-shaped specimens (size 12x12x2mm). The materials tested in this study (n=10) were glass ionomer (GI; Equia Forte), resin-modified glass ionomer (RMGI; Fuji II LC), resin composite (Filtek Supreme), and two “bioactive” materials (Activa Bioactive, Cention N). The materials (aside from GI) were light cured for 20sec using Bluephase 20i curing light (Irradiance=1100 mW/cm2). The specimens were stored in a test tube of deionized water at 37C for 1 months prior to testing to deplete the specimens of fluoride. The initial fluoride concentration (Day 1) was then was measured using an ion specific electrode attached to a MM340 GLP pH/ISE Laboratory Meter (HACH Company). Prior to testing, calibration curves were created with standard ion solutions. All measurements were taken with 5 ml of deionoized water mixed with 1ml TISAB III. The specimens were then immersed for a period of 5 minutes in a stirred sodium fluoride slurry (1000 ppm F). After recharge, specimens were rinsed with deionized water, air dried and placed in to a container with 15ml of fresh water at 37C. Two days after recharging (Day 3) fluoride was remeasured and specimens were placed into new 37C deionized water. The next day (Day 4), specimens were remeasured, immediately recharged, and placed into new 37C PBS. Two days later (Day 6) and three days later (Day 7), the specimens were remeasured. The data were analyzed with a 2-way ANOVA and Tukey post-hoc analysis.
Results: The 2-way ANOVA found statistical differences for factors material and time and their interaction (p<.01). Groups in each column with similar letters are statistically similar.
Conclusions: The Fuji II LC and Cention N recharged significantly more fluoride than other materials.