Comparison of the Fluoride Ion Release from Composite and Compomer Materials under Varying pH Conditions—Preliminary In Vitro Study

Fluoride prevents the demineralization and supports remineralization of enamel. It is important to maintain a constant low level of fluoride in the oral cavity at all times. Dental restorative materials that are used for this purpose contain NaF in their composition, which is a source of fluoride ions that diffuse into body fluids and surrounding tissues. Two such materials, the flowable composite material Wave (W) (SDI, Hamilton Parkway Itasca, Australia) and compomer material Freedom (F) (SDI, Hamilton Parkway Itasca, Australia), were studied in regards to their release of fluoride ions into various solutions imitating the oral environment: artificial saliva solution with the addition of hydrated calcium chloride (CaCl2) × 2H2O in the pH range of 4.5 and 5.5; artificial saliva free of calcium chloride in the pH range of 4.5, 5.5, 6.0, 7.0, and 7.5; deionized water; and saline solution. The results were assessed over a period of 7 days, i.e., 168 h. The Freedom (F) compomer showed the highest cumulative release of fluoride ions into artificial saliva solution at pH 4.5 (31.195 ± 10.461 μg F/mm2) and the lowest into saline solution (3.694 ± 1.115 μg F/mm2). The Wave (W) composite material revealed the highest cumulative release of fluoride ions into deionized water (7.982 ± 2.011 μg F/mm2); its lowest cumulative emission was observed in artificial saliva solution at pH 7.0 (1.391 ± 0.489 μg F/mm2). The amounts of released fluoride from the Freedom (F) compomer were considerably higher compared to the Wave (W) composite material. The ability to release the largest amounts of fluoride ions in an acidic environment results from the erosion of the surface layer. Different calcium content in available experimental and commercial artificial saliva preparations may influence the obtained results. Both the flowable Wave composite and Freedom compomer released more fluoride in an acidic environment with a pH of 4.5–5.5, but with different dynamics—Wave material had its maximum on the third day while Freedom on the first day of the experiment.