pH-cycling Regimen Research Articles

Anticaries potential of a fluoride mouthrinse evaluated in vitro by validated protocols

This blind and randomized study tested in vitro, using validated protocols, the anticaries potential of an experimental fluoride mouthrinse. One-hundred enamel slabs, half sound and half with caries-like lesions (carious), all with known surface microhardness (SMH), were submitted to 3 treatment groups: A) a placebo mouthrinse (negative control); B) a positive control mouthrinse containing 0.05% NaF; and C) an experimental formulation containing 0.05% NaF and cetylpyridinium chloride as an antibacterial substance. To evaluate the formation of F products on enamel, sound (n=10) and carious (n=10) slabs were treated with the formulations during 10 min and loosely and firmly-bound F formed in enamel were determined after extraction with alkali and acid, respectively. To evaluate the inhibition of enamel demineralization, sound enamel slabs (n=10) were treated with the mouthrinse formulations 2x/day during 1 min and subjected to a pH-cycling regimen simulating a cariogenic challenge (demineralization). To evaluate enamel remineralization, the carious slabs (n=10) were submitted to the treatments 3x/day and subjected to a pH-cycling model simulating a remineralizing condition. After 8 days, enamel SMH was determined again and the percentage of SMH loss or SMH recovery was calculated for the sound and carious slabs, respectively. The experimental formulation was superior to the negative control (p<0.05) and equivalent to the positive control (p>0.05) in the formation of F products in enamel, and in the inhibition of enamel demineralization and enhancement of remineralization. These data suggest that the tested experimental fluoride mouthrinse has anticaries potential.

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.