Effect of strontium in combination with fluoride on enamel remineralisation in vitro

Previous studies showed that strontium (Sr) as well as fluoride (F) can enhance enamel remineralisation. The aim of this study was to evaluate the effects of Sr in combination with F on enamel remineralisation in vitro. Sixty enamel specimens obtained from caries free human premolars were demineralised to produce caries-like lesions. Half of each lesion was covered with nail varnish as an untreated control. The specimens were then randomly divided into F and Sr + F treatment groups. The F group was exposed to remineralising solutions (1.5 mM CaCl2, 0.9 mM KH2PO4) containing 1 ppm, 0.1 ppm or 0.05 ppm F. The Sr + F treatment group was exposed to the same solutions including 10 ppm Sr. After 2 weeks, lesion depth, mineral loss and percentage enamel remineralisation were determined using transversal microradiography. There was a significant decrease in mineral loss in all groups (p < 0.001). Lesion depth was significantly reduced for all groups (p < 0.05) with the exception of group F. Remineralisation was significantly affected by F concentration (p = 0.000). The participation of Sr resulted in a significant enhancement of remineralisation (p < 0.001) with a synergistic effect of the Sr + F combination (p < 0.01). It was concluded that while the remineralising process was affected by the concentration of F, there was also an interaction between F and Sr when they were used in conjunction.