Comparison of the Fluoride Ion Release from nanofluoroapatite-modified orthodontic cement under different pH Conditions - an in vitro Study

Purpose Construction of the orthodontic bracket promotes food accumulation, which is the cause of plaque formation. Modern trends in the design of adhesive orthodontic cements focus on the ability to release cariostatic fluoride ions. One of the methods is to incorporate the material with fluorapatite nanoparticles. The aim of the study was to determine the fluoride release capacity of orthodontic cement doped with nanosized fluorapatite in selected media and solution pH over a 12-week period. Methods A commercial light-curing two-component orthodontic cement GC Fuji Ortho®LC was modified by the addition of nanofluorapatite at 2% or 5% by weight. Each of the three groups (5 samples in 9 different media of varying ionic composition and pH). Fluoride determination was performed at 18 time intervals. Results The largest amount of fluoride is released in the first hour of incubation of all samples. Incorporating cement with 5% w/w nFAp significantly increases the amount of ions released. Low pH and artificial saliva rich in calcium cations promote significantly lower fluoride detection, which is associated with the formation of CaF2 conglomerates. The erosion of the surface layer was confirmed by the SEM image to be responsible for the ability to release the largest amounts of fluoride ions in an acidic environment. Conclusions The selection of experimental media for studying the fluoride release capacity of biomaterials is important in terms of the results achieved. The nanofluorapatite content correlates with the amount of fluorine released. Some limitations of the current research require further studies.