Fluoride release and secondary caries inhibition by adhesive systems on root dentine

This study tested the fluoride-release rate and the root caries inhibitory effect of dental adhesives. In phase 1, the fluoride released from samples (n = 5) of the adhesives A (Optibond Solo), B (One-up Bond F), C (Prime & Bond NT), D (Tenure Quick), and also of the controls [+] (glass-ionomer cement) and [-] (non-fluoride releasing adhesive), was quantified on a daily basis during a pH-cycling, caries-simulating phenomenon. In phase 2, restorations were made in bovine root dentine slabs (n = 16) with the same adhesives associated with a non-fluoridated composite. Control [+] restorations were made entirely with glass-ionomer cement. Specimens were thermocycled and submitted to the pH-cycling regimen. Demineralization areas and the presence of the wall lesion (WL) and the inhibition zone (IZ) were determined by polarizing light microscopy in dentine adjacent to the restoration. The highest concentration of fluoride was released by the control [+]; adhesives A, B and C, also released fluoride. No detectable amount of fluoride was released by D or [-]. Smaller areas of demineralization were found with control [+], whereas the demineralization areas of adhesives A-D and [-] did not differ from each other. No WL was detected, and higher percentages of IZ were recorded to [+] and to adhesive A. Although some dental adhesives were able to release fluoride, they could not inhibit secondary caries development as well as the glass-ionomer cement.