Protective benefits of a stabilised stannous-containing fluoride dentifrice against erosive acid damage

Nanoencapsulated fluoride as a remineralization option for dental erosion: an in vitro study

OBJECTIVE

To compare the in vitro performance of different dentifrices indicated for dental erosion and a new dentifrice with controlled fluoride release system (NanoF) in terms of surface microhardness remineralization in enamel erosion lesions.

MATERIALS AND METHODS

72 human enamel specimens were divided into 6 groups (n = 12): PC (100% NaF - positive control); NC (Placebo - negative control); 50%nF (50% NanoF + 50% free NaF), 100%nF (100% NanoF); PN (Sensodyne^® ProNamel™) and AG (Colgate^® Sensitive Pro-Relief™). A surface microhardness analysis was performed before (SH₀) and after (SH₁) the erosion lesion formation. The blocks were submitted to a 5-day de-remineralization cycling model, consisting of 90 s immersion on 0.1% citric acid (4x/day) and 1 min treatment with dentifrice slurries along with 1 mL/block of human saliva (2x/day). Lastly, the final surface microhardness analysis (SH₂) was measured and the percentage of surface microhardness remineralization (%SMH_R) was calculated. Data were analysed with 2-way ANOVA and Tukey's test (p < .05).

RESULTS

Statistically significant differences were observed for SH₂ and %SMH_R between NC and AG with the other groups (p < .05). The best %SMH_R from the experimental groups was found in 100%nF and PN.

CONCLUSION

Dentifrices with NanoF exhibited a surface microhardness remineralization similar to sodium fluoride (PC). Therefore, NanoF dentifrice can be an alternative to prevent and treat patients with dental erosion.

Protective effect of calcium silicate toothpaste on enamel erosion and abrasion in vitro

Objectives

To compare in vitro the effect of a toothpaste containing fluoride (F), calcium silicate (CaSi) and sodium phosphate salts to conventional toothpaste (NaF) on human enamel specimens submitted to erosive and abrasive challenges.

Methods

48 sound and 48 enamel samples pre-treated with 1% citric acid were divided into 4 groups (n = 12): Group 1- Non-fluoride toothpaste; Group 2- NaF toothpaste (1450 ppmF); Group 3- CaSi toothpaste (1450 ppmF; MFP); Group 4- Erosion only. The samples were subjected to pH cycling (3 cycles/day; 90s; 1% citric acid, pH 3.6) and to abrasion for 7 days. After the 1^st and the last cycle, they were submitted to abrasion (15s, 1.5N load), using a brushing machine, soft toothbrush and toothpaste slurry (1:3; 15ml/sample) and then immersed in the slurry for 45s. Samples were immersed in artificial saliva between the challenges. Enamel loss was evaluated using profilometry on days 3 and 7. Data were analysed by ANOVA and Tukey's test (p < 0.05).

Results

For sound enamel at baseline, mean (±SD) enamel loss (μm) for groups 1-4 on day 3 was 2.15 ± 0.35^a, 1.20 ± 0.22^b, 0.95 ± 0.19^b and 1.98 ± 0.32^a; on day 7 was 3.05 ± 0.40^a, 2.07 ± 0.32^b, 1.36 ± 0.33^c and 3.69 ± 0.27^d respectively. For acid-softened enamel at baseline, enamel loss on day 3 was 3.16 ± 0.19^a, 2.17 ± 0.14^b, 1.70 ± 0.11^c and 3.04 ± 0.19^a; on day 7 was 3.92 ± 0.25^a, 3.07 ± 0.13^b, 2.09 ± 0.15^c and 3.87 ± 0.25^a respectively.

Conclusions

Both F toothpastes led to significantly higher enamel protection from short-term erosion and abrasion in comparison to the non-F toothpaste and erosion only. In the longer term, CaSi toothpaste conferred significantly higher protection than NaF toothpaste.

Clinical significance

The results showed that for the longer term the CaSi toothpaste provided significantly higher protection than the NaF toothpaste, which indicates a good potential of the former to help prevent erosive tooth wear.

Effectiveness of a Novel Dentifrice Containing Stabilized Chlorine Dioxide, Sarkosyl, and Sodium Fluoride

This in vitro study evaluated the effectiveness of a novel dentifrice containing stabilized chlorine dioxide, sodium lauroyl sarcosinate (sarkosyl), and sodium fluoride in enhancing enamel fluoride uptake, remineralization, pellicle cleaning and inhibiting biofilm regrowth. Remineralization was measured by fluoride uptake and surface microhardness assessment tests. Artificial stains were removed and scored based on pellicle cleaning ratio. Biofilm regrowth was measured by counting colonies on the agar plates. All studies were conducted using bovine teeth specimens. The efficacy of Toothpaste C (CloSYS anticavity toothpaste) was compared with United States Pharmacopoeia Reference Dentifrice, Toothpaste B (discontinued CloSYS anticavity toothpaste formulation) and leading commercial toothpastes. The enamel fluoride uptake and remineralization by Toothpaste C was 96.1% to 303.3% and 38.0% to 102.4% higher than the tested toothpastes, respectively. The mean pellicle cleaning ratio of Toothpaste C was similar to American Dental Association Reference Material. Toothpaste C had a significant reduction in regrowth of the oral polymicrobial biofilm compared to the control. All tested toothpastes contained 0.24% sodium fluoride. Toothpaste C exhibited significantly superior performance towards fluoride uptake and remineralization compared to the tested toothpastes. Therefore, toothpaste ingredients other than sodium fluoride accounted for the enhanced fluoride uptake and remineralization.

Evaluation of free and total fluoride concentration in mouthwashes via measurement with ion-selective electrode

BACKGROUND

The aim of this study was to compare free fluoride concentration and total fluoride concentration in mouthwashes.

METHODS

Fluorine-containing mouthwashes from various companies and manufacturers (Colgate Total Plax Classic Mint®, Colgate-Palmolive, New York, USA; Colgate Total Plax Gentle Mint®, Colgate-Palmolive, New York, USA; Colgate Total Plax Fresh Mint®, Colgate-Palmolive, New York, USA; Oral B Advantage®, Procter&Gamble, Cincinnati, USA; Reach Fresh Mint®, Johnson&Johnson, New Brunswick, USA; Foramen®, Laboratorios Foramen, Guarnizo, Spain; Lacalut Sensitive®, Dr. THEISS, Homburg, Germany; Sensodyne®, GlaxoSmithKline, London, UK; Vesna F®, Vita, Saint Petersburg, Russia; Lacalut Fresh®, Dr. THEISS, Homburg, Germany) were selected as study objects. Fluoride measurements were carried out using the fluoride selective electrode.

RESULTS

Free fluoride:total fluoride ratio was more than 80% for six samples (Colgate Total Plax Gentle Mint® - 88%, Colgate Total Plax Fresh Mint® - 99%, Oral B Advantage® - 92%, Reach Fresh Mint® - 92 and 89% for the mouthwash of another batch, Lacalut Sensitive® - 94%) and less than 63% for three samples (Colgate Total Plax Classic Mint® - 56%, Foramen® - 62%, Vesna F® - 61%). Two samples had more than 70% and less than 80% of unbound fluoride, respectively (Sensodyne® - 77%, another batch of Oral B Advantage® mouthwash - 74%). Rinse containing sodium monofluorophosphate (Na₂PO₃F) (Vesna F®) had more than 50% of free fluoride, while the rinse containing amine fluoride (AmF) (Lacalut Sensitive®) had 94%. The difference in the free fluoride:total fluoride ratio can be explained by binding of fluoride ions by components contained in mouthwashes, such as coloring agents and polymeric compounds. The lowest concentration of free fluoride ions (0.000093 mol/L) was observed for aluminum fluoride (AlF₃) rinse (Lacalut Fresh®), while the total fluoride amount was not determined due to possible generation of strong fluoride complexes. This implies that fluoride ions will not be uptaken by tooth tissue and may even be washed away from it, compromising the efficacy of mouthwashes.

CONCLUSIONS

The differences in free fluoride: total fluoride ratio between analyzed mouthwashes reveal a need to develop a method for evaluation of free fluorides in mouthwashes for proper updating of national and international guidelines.

Is the dentifrice containing calcium silicate, sodium phosphate, and fluoride able to protect enamel against chemical mechanical wear? An in situ/ex vivo study

OBJECTIVES

The aim of this study was to investigate the effect of a dentifrice that contains calcium silicate, sodium phosphate, and fluoride on erosive-abrasive enamel wear.

MATERIAL AND METHODS

This randomized, single-blind in situ/ex vivo study was conducted with four crossover phases of 5 days (one group tested per phase). Bovine enamel blocks (n = 256) were allocated to 16 volunteers and 8 groups. The groups under study were test dentifrice, with calcium silicate, sodium phosphate, and 1450 ppm sodium monofluorophosphate; tin dentifrice, with 3500 ppm stannous chloride, 700 ppm amine fluoride, and 700 ppm sodium fluoride; conventional dentifrice, with 1450 ppm sodium monofluorophosphate; and control (deionized water). Half of the enamel blocks were subjected to erosion and the other half to erosion plus abrasion. The daily extraoral protocol consisted in four citric acid exposures (2 min) and two applications of dentifrice slurry on all blocks for 30 s; after, half of the blocks were brushed for 15 s. The response variable was enamel loss. Data were analyzed by two-way ANOVA and Fisher's test (p < 0.05).

RESULTS

For erosion, the test dentifrice promoted less enamel loss than water (4.7 ± 3.1 and 5.8 ± 2.5 μm, respectively, p < 0.05), and did not differ from tin (4.8 ± 2.5 μm) and conventional (4.8 ± 1.4 μm) dentifrices (p > 0.05). However, the test dentifrice (7.7 ± 3.8 μm) promoted higher wear after erosive plus abrasive procedures than tin (5.4 ± 1.5 μm) and conventional (6.2 ± 1.7 μm, p < 0.05) dentifrices, and did not differ from water (6.9 ± 2.0 μm).

CONCLUSIONS

The investigated dentifrice reduced enamel loss against acid challenge but had no effect against acid and brushing challenge.

CLINICAL RELEVANCE

Little is known regarding the preventive effect of dentifrices indicated for dental erosion. The tested anti-erosive dentifrice was unable to protect enamel when erosion was associated to toothbrushing abrasion.

Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges

This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15): GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3) for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (p<0.05). The result showed no statistically significant difference between groups (GS = 14.60±2.86 and GE = .14.69±2.21 μm). The presence of initial erosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

Erosion protection benefits of stabilized SnF2 dentifrice versus an arginine-sodium monofluorophosphate dentifrice: results from in vitro and in situ clinical studies

Objectives

The aim of these investigations was to assess the ability of two fluoride dentifrices to protect against the initiation and progression of dental erosion using a predictive in vitro erosion cycling model and a human in situ erosion prevention clinical trial for verification of effectiveness.

Materials and methods

A stabilized stannous fluoride (SnF₂) dentifrice (0.454 % SnF₂ + 0.077 % sodium fluoride [NaF]; total F = 1450 ppm F) [dentifrice A] and a sodium monofluorophosphate [SMFP]/arginine dentifrice (1.1 % SMFP + 1.5 % arginine; total F = 1450 ppm F) [dentifrice B] were tested in a 5-day in vitro erosion cycling model and a 10-day randomized, controlled, double-blind, two-treatment, four-period crossover in situ clinical trial. In each study, human enamel specimens were exposed to repetitive product treatments using a standardized dilution of test products followed by erosive acid challenges in a systematic fashion.

Results

Both studies demonstrated statistically significant differences between the two products, with dentifrice A providing significantly better enamel protection in each study. In vitro, dentifrice A provided a 75.8 % benefit over dentifrice B (p < 0.05, ANOVA), while after 10 days in the in situ model, dentifrice A provided 93.9 % greater protection versus dentifrice B (p < 0.0001, general linear mixed model).

Conclusion

These results support the superiority of stabilized SnF₂ dentifrices for protecting human teeth against the initiation and progression of dental erosion.

Clinical relevance

Stabilized SnF₂ dentifrices may provide more significant benefits to consumers than conventional fluoride dentifrices.

Re- and Demineralization Characteristics of Enamel Depending on Baseline Mineral Loss and Lesion Depth in situ

Objectives: The aim of this double-blinded, randomized, cross-over in situ study was to evaluate the re- and demineralization characteristics of sound enamel as well as lowly and highly demineralized caries-like enamel lesions after the application of different fluoride compounds. Methods: In each of three experimental legs of 4 weeks, 21 participants wore intraoral mandibular appliances containing 4 bovine enamel specimens (2 lowly and 2 highly demineralized). Each specimen included one sound enamel and either one lowly demineralized (7 days, pH 4.95) or one highly demineralized (21 days, pH 4.95) lesion, and was positioned 1 mm below the acrylic under a plastic mesh. The three randomly allocated treatments (application only) included the following dentifrices: (1) 1,100 ppm F as NaF, (2) 1,100 ppm F as SnF2 and (3) 0 ppm F (fluoride-free) as negative control. Differences in integrated mineral loss (ΔΔZ) and lesion depth (ΔLD) were calculated between values before and after the in situ period using transversal microradiography. Results: Of the 21 participants, 6 did not complete the study and 2 were excluded due to protocol violation. Irrespectively of the treatment, higher baseline mineral loss and lesion depth led to a less pronounced change in mineral loss and lesion depth. Except for ΔΔZ of the dentifrice with 0 ppm F, sound surfaces showed significantly higher ΔΔZ and ΔLD values compared with lowly and highly demineralized lesions (p < 0.05, t test). Conclusion: Re- and demineralization characteristics of enamel depended directly on baseline mineral loss and lesion depth. Treatment groups should therefore be well balanced with respect to baseline mineral loss and lesion depth.

Effects of dentifrices differing in fluoride compounds on artificial enamel caries lesions in vitro

The aim of this study was to compare the caries-preventive effect of a stabilized stannous fluoride/sodium fluoride dentifrice containing sodium hexametaphosphate with those of a regular, solely sodium fluoride-containing and amine fluoride-containing dentifrice on pre-demineralized bovine enamel specimens using a pH-cycling model. Bovine enamel specimens with two artificial lesions each were prepared. Baseline mineral loss of both lesions was analyzed using transversal microradiography (TMR). Eighty-five specimens with a mean (SD) baseline mineral loss of 3393 (683) vol% × µm were selected and randomly allocated to five groups (n = 13/15). Treatments during pH-cycling (28 days and 2 × 20 min demineralization/day) were: brushing twice daily with slurries of AmF (1400 ppm F^-), NaF (1450 ppm F^-), SnF₂/NaF (1100 ppm F^-/350 ppm F^-), and fluoride-free (FF) dentifrices or they were immersed in distilled water and remained unbrushed (NB). Subsequently, from each specimen one lesion was covered with acid-resistant varnish, while the remaining lesion was demineralized for another 14 days. Differences in integrated mineral loss (∆∆Z) were calculated between values before and after pH-cycling (∆∆Z _E1) as well as before pH-cycling and after second demineralization (∆∆Z _E2) using TMR. Treatments AmF and NaF induced a significantly higher mineral gain (∆∆Z _E1/∆∆Z _E2) compared to treatments FF and NB (p < 0.05; ANOVA test). Except for treatments AmF and NaF no significant differences in mineral loss between before and after pH-cycling could be observed (p < 0.05; t test) [∆∆Z _E1: AmF:1563 (767); NaF:1222 (1246); SnF₂/NaF:258 (1259); FF:-52 (1223); NB:-151 (834)]. Both dentifrices with either AmF or NaF promoted remineralization, whereas SnF₂/NaF dentifrice did not promote remineralization in a biofilm-free pH-cycling model.

Biofilm community diversity after exposure to 0·4% stannous fluoride gels

AIMS

To test the effect of 0·4% stannous fluoride (SnF2 ) glycerine-based gels on specific portions of the bacterial community in both a clinical observational study and in vitro multispecies plaque-derived (MSPD) biofilm model.

METHODS AND RESULTS

Potential changes to specific portions of the bacterial community were determined through the Human Oral Microbial Identification Microarray (HOMIM). Both the observational clinical study and the biofilm model showed that short-term use of 0·4% SnF2 gel has little effect on the bacterial community depicted by hierarchical cluster analysis. The amount of plaque accumulation on a subject's teeth, which was measured by plaque index scores, failed to show statistical significant changes over the two baselines or after treatment (P = 0·9928). The in vitro results were similar when examining the effect of 0·4% SnF2 gels on biofilm adherence through a crystal violet assay (P = 0·1157).

CONCLUSIONS

The bacteria within the dental biofilms showed resilience in maintaining the overall community diversity after exposure to 0·4% SnF2 topical gels.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study supports that the immediate benefits of using 0·4% SnF2 gels in children may be strictly from fluoride ions inhibiting tooth demineralization rather than delivering substantial antimicrobial effects.

A randomised in situ trial, measuring the anti-erosive properties of a stannous-containing sodium fluoride dentifrice compared with a sodium fluoride/potassium nitrate dentifrice

OBJECTIVES

To determine if a stabilised, stannous-containing sodium fluoride dentifrice provides greater enamel protection in situ against intraoral dietary erosive challenges compared with a sodium fluoride/potassium nitrate dentifrice.

METHODS

A single-centre, investigator blind, randomised, supervised, two-treatment, non-brushing, four-period crossover in situ study was undertaken, with each test period being 15 days. Thirty-five healthy adult subjects were recruited to participate in the study, which included four erosive acid challenges per day. Subjects were randomised to product treatment, which included either: (1) a stannous-containing sodium fluoride dentifrice (Oral-B(®) Pro-Expert Sensitive) or (2) a sodium fluoride/potassium nitrate dentifrice (Sensodyne(®) Pronamel(®) ). Each study subject wore an intraoral appliance retaining two sterilised, polished human enamel samples for 6 hours/day. Subjects swished with an allocated dentifrice slurry twice a day and with 250 ml of orange juice for 10 minutes (25 ml/minute over a 10-minute period) four times per day. The primary and secondary outcomes for this study were enamel loss measured using contact profilometry at days 15 and 5, respectively, using parametric analysis methods.

RESULTS

At day 15, a 38% lower enamel loss (P < 0.0001) was observed, with estimated medians of 2.03 μm (SE 0.247) and 3.30 μm (SE 0.379), in favour of the stannous-containing dentifrice. At day 5, specimens treated with the stannous-containing sodium fluoride dentifrice demonstrated 25% less enamel loss than those treated with the sodium fluoride/potassium nitrate dentifrice. Treatment differences at day 5 were also statistically significant (P < 0.05), with estimated medians of 1.37 μm (SE 0.177) and 1.83 μm (SE 0.223), respectively.

CONCLUSIONS

Results of this in situ study suggest the stabilised, stannous-containing sodium fluoride dentifrice could be used to provide significantly greater protection to enamel from erosive acid challenge compared with that provided by conventional fluoride-containing products.