Alkali-soluble fluoride deposition on enamel after professional application of topical fluoride in vitro

Anticaries potential of a fluoride foam

Foam has been used worldwide as a vehicle for the professional application of fluoride and hypothetically should have the same anticaries potential as conventional fluoride gel (F-gel) in terms of the formation of reaction products with enamel. Thus, the ability of Flúor Care® foam (FGM, Joinville, SC, Brazil, 12,300 ppm F, acidulated) to react with enamel was evaluated in comparison with Flúor gel® (DFL, Rio de Janeiro, RJ, Brazil, 12,300 ppm F, acidulated). Slabs (n=10/group) of sound enamel and with caries lesion were used, in which the concentrations of total fluoride (TF), and loosely (CaF2-like) and firmly (FAp) bound types were determined. The importance of agitation during application was previously tested. The determinations were made with fluoride ion-specific electrode and the results were expressed in μg F/cm² of the treated enamel area. ANOVA and Tukey tests were used to analyze the difference among treatments, independently for sound and carious enamel. The agitation of the products during application significantly increased the reactivity of the foam (p<0.05), but not that of the gel (p>0.05). The foam did not differ from F-gel (p>0.05) concerning the formation of TF and CaF2-like in sound or carious enamel. Regarding FAp, the foam did not differ from F-gel (p>0.05) in the carious enamel, but the concentration in the sound was lower (p<0.05). The results show that this commercial fluoride foam tested needs to be agitated during application to improve its reactivity with enamel, which raises a question about other brands.

Fluoride formed on enamel by fluoride varnish or gel application: A randomized controlled clinical trial

Although fluoride varnish (FV) and acidulated phosphate fluoride gel (APF-gel) are considered clinically effective to reduce caries, in vitro studies have shown that FV reacts slowly with enamel because most NaF present in the formulation is not solubilized in the FV. Therefore, we conducted a clinical study to evaluate if the time that FV remains on dental surfaces could overcome its slower chemical reactivity when compared with APF-gel. Sixty-eight volunteers were randomly allocated into four groups: Negative control (Control, no treatment), APF -gel application (1.23% F applied for 4 min), and FV application (Duraphat®, 2.26 % F) for 4 h (FV-4h) or 24 h (FV-24h). To evaluate fluoride formed and retained on enamel, acid biopsies were made on the buccal surfaces of the maxillary central incisors before, at the end of the application of fluoride products (immediately after gel application, or after 4 or 24 h of varnish application) and after 7 and 28 days. Fluoride concentration in dental biofilm was also analyzed before and up to 28 days after initial application. The data were analyzed by 2-way ANOVA, considering treatment and time as factors. The APF-gel and FV-24h groups formed greater fluoride concentration on enamel than the FV-4h and the control group at the end of application (p=0.0001), with no difference from each other (p=0.99). The groups did not differ regarding fluoride in biofilm, fluid (p=0.73) and solids (0.40). In conclusion, fluoride varnish needs to remain in contact with the teeth for prolonged times (>4 h) to reach the same reactivity obtained by a 4-min application of APF-gel.

Calcium pretreatment enhances fluoride reactivity with enamel and dentine

OBJECTIVE

High fluoride concentration treatments are known to react with enamel and dentine forming calcium fluoride (CaF₂)-like deposits, but strategies to improve this reactivity beyond increasing fluoride concentration/reducing pH in fluoride treatments have not been explored. Here we investigated the ability of a calcium pre-treatment to improve fluoride reactivity.

DESIGN

In a blind and randomized in vitro study, sound and carious enamel and dentine slabs (n = 11/group) were randomly allocated into one of the following treatments: Deionized water (negative control); 0.05% sodium fluoride (F, positive control); 150 mM calcium lactate solution followed by 0.05% sodium fluoride solution (Ca→F); 150 mM calcium lactate solution premixed with 0.05% sodium fluoride solution (CaF₂, active control). Alkali-soluble fluoride (representing CaF₂-like deposits formed on the substrates) was extracted from the slabs using 1 M KOH for 24 h and measured by an ion-specific electrode. Carious slabs were further observed under scanning electron microscopy (SEM). Data were analyzed by two-way ANOVA followed by Tukey test.

RESULTS

The Ca→F treatment enhanced fluoride reactivity with all tested substrates when compared with F alone. Carious substrates had a greater reactivity with F and Ca→F than their respective sound substrates, confirming that increased porosity enhances the reactivity with fluoride. Alkali-soluble fluoride concentration after the CaF₂ treatment did not differ among the different substrates, suggesting this treatment causes only contamination with preformed CaF₂, which was noted under SEM.

CONCLUSION

A calcium pretreatment enhances the reactivity of fluoride with enamel and dentine.

Atomic force microscopic comparison of remineralization with casein-phosphopeptide amorphous calcium phosphate paste, acidulated phosphate fluoride gel and iron supplement in primary and permanent teeth: An in-vitro study

Context:

Demineralization of tooth by erosion is caused by frequent contact between the tooth surface and acids present in soft drinks.

Aim:

The present study objective was to evaluate the remineralization potential of casein-phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste, 1.23% acidulated phosphate fluoride (APF) gel and iron supplement on dental erosion by soft drinks in human primary and permanent enamel using atomic force microscopy (AFM).

Materials and Methods:

Specimens were made from extracted 15 primary and 15 permanent teeth which were randomly divided into three treatment groups: CPP-ACP paste, APF gel and iron supplement. AFM was used for baseline readings followed by demineralization and remineralization cycle.

Results and Statistics:

Almost all group of samples showed remineralization that is a reduction in surface roughness which was higher with CPP-ACP paste. Statistical analysis was performed using by one-way ANOVA and Mann-Whitney U-test with P < 0.05.

Conclusions:

It can be concluded that the application of CPP-ACP paste is effective on preventing dental erosion from soft drinks.