Mechanism of fluoride dentifrice effect on enamel demineralization

Should We Wait to Brush Our Teeth? A Scoping Review Regarding Dental Caries and Erosive Tooth Wear

BACKGROUND

Tooth brushing is a universal recommendation. However, the recommendations related to the time of its execution are conflicting, especially when dealing with patients at risk of erosive tooth wear (ETW) or dental caries.

SUMMARY

Our objective was to summarize the evidence on the timing of brushing with fluoridated toothpaste in relation to ETW and cariogenic dietary challenges. We conducted a scoping review following the PRISMA-ScR checklist, using three databases searching for in vivo, in situ, or in vitro studies involving human teeth exposed to either a cariogenic or an erosive challenge. Only models including human saliva and fluoride were assessed. Data selection, extraction, and risk of bias analysis were done in duplicate and independently. From 1,545 identified studies, 17 (16 related to ETW and 1 to dental caries) were included. Most evidence (n = 10) supported that brushing with a fluoride-containing product does not increase ETW, independent of the moment of brushing. Delaying tooth brushing up to 1 h (n = 4) or individualized recommendations based on the patient's problem (n = 2) were less frequent. Only one study reported that brushing pre- or post-meal does not affect Streptococcus mutans counts. Most data were in situ (n = 13), and the overall study quality was judged as sufficient/low risk of bias.

KEY MESSAGES

Although the available evidence lacked robust clinical studies, tooth brushing using fluoridated products immediately after an erosive challenge does not increase the risk of ETW and can be recommended, which is in line with recommendations for dental caries prevention. Furthermore, we suggest updating the international guidelines to promote individualized recommendations based on risk factors to prevent either ETW or dental caries.

Evaluation of the antibacterial activity of Enamelast® and Fluor defender® fluoride varnishes against Streptococcus mutans biofilm: an in vitro study in primary teeth

PURPOSE

The aim of the current work was to compare the antibacterial activity of Enamelast® and Fluor defender® fluoride varnish on biofilm generation by Streptococcus mutans on extracted primary teeth.

METHODS

Thirty-six primary molars were collected and sliced into seventy-two test model disks. All specimens were examined, and the cracked or broken ones were discarded. A total number of specimens (n = 54) were divided into two experimental analyses viz; biofilm formation (n = 27) and microscopic examination (n = 27). Specimens of each analysis were tested under different experimental conditions: a negative control group (n = 9), Fluor defender group (n = 9), and Enamelast group (n = 9). Following treatment, biofilms were generated by adherent Streptococcus mutans on the test model disks on three time intervals: 24 h (n = 3), 48 h (n = 3), and 72 h (n = 3) for each analysis. Then, for biofilm formation analysis, the biofilm was detected spectrophotometrically at 620 nm after being stained by crystal violet. For microscopical analysis, the surfaces of the test model disks were visualized by scanning electron microscopy (SEM), and each image was processed and analyzed using ImageJ software.

RESULTS

At 48 and 72 h, Enamelast® and Fluor defender®-treated group showed significantly (p < 0.001) slight adhered bacterial cells when compared with the negative control group as revealed by the absorbance and SEM. Compared with the Fluor defender®-treated group, the absorbance of the Enamelast®-treated group showed a significant (p < 0.001) increase by approximately 7- and 16.5-fold at 48 and 72 h, respectively. Similarly, SEM showed that the number of bacterial cells adhered to enamel surfaces in the Fluor defender®-treated group was significantly (p < 0.001) fewer than the Enamelast®-treated group by approximately 36.55% and 20.62% at 48 and 72 h after exposure, respectively.

CONCLUSION

We conclude that the anti-biofilm activity of Fluor defender® against Streptococcus mutans was significantly (p < 0.001) greater than Enamelast® fluoride varnish. The use of Fluor defender® is encouraged as a preventive measure in children with the high risk of developing dental caries.

Salivary fluoride bioavailability after use of high-fluoride dentifrices with different compositions: A short-term randomized clinical trial

OBJECTIVE

The objective of the study was to evaluate the kinetics of salivary F bioavailability after the use of high-fluoride dentifrices with different compositions and their amount of total soluble fluoride (TSF).

METHODS

A short-term clinical randomized trial was performed in which 15 adult participants were randomly allocated into three groups: 5000 ppm F-dentifrice, 5000 ppm F-dentifrice + TCP (tri-calcium phosphate) and 1450 ppm F-dentifrice. Unstimulated saliva was collected at different times: baseline (before toothbrushing), immediately after brushing/water rinsing and at 5, 15 and 30 min and 1, 2, 4, 8 and 12 h after brushing. The TSF in dentifrices and saliva samples was analysed using an ion-specific electrode. For statistical analysis, the paired t-test and Kruskal-Wallis were used with Dunn's post-test with a 95% confidence interval.

RESULTS

There was no significant difference between the declared TSF and that found in 5000 ppm F-dentifrice and 1450 ppm F-dentifrice (p ≥ 0.13); however, in the 5000 ppm F-dentifrice + TCP, approximately 500 ppm less TSF was observed (p = 0.0024). The area under the curve (AUC, μg F/ml min-1 ) of both high-fluoride dentifrices (321.7 ± 84.0 and 223.6 ± 55.1 for the one without and with TCP, respectively) was higher than the conventional one (89.97 ± 15.6) attesting a higher F-bioavailability (p = 0.04). Furthermore, they were able to provide F-salivary levels higher than the baseline for up to 2 h, while this time was 1 h for the 1450 ppm F-dentifrice (p ≤ 0.003).

CONCLUSION

Both high-fluoride dentifrices similarly increased the salivary-F bioavailability in comparison with 1450 ppm F-dentifrice, despite the lower TSF presented by the dentifrice containing TCP.

3D printing of a controlled fluoride delivery device for the prevention and treatment of tooth decay

Dental decay is a highly prevalent chronic disease affecting people from all ages. Clinically, fluoride supplementation is the primary strategy in the prevention of dental decay. However, the current existing self-application formulations such as gels or mouthwashes are rapidly cleared after administration, resulting in modest efficacy even after repeated applications. Therefore, a user-friendly formulation that can provide sustained fluoride release in the oral cavity is of great interest for dental decay prevention. Herein, we report the utilization of fused deposition modelling to fabricate personalised mouthguards, which allow local and prolonged fluoride elution. Composite filaments comprising sodium fluoride and polymers with tuneable hydrophobicity were produced using blends of poly(ε-caprolactone) (PCL) and poly(vinyl alcohol) or poly(ethylene glycol) (PEG). The materials exhibited suitable mechanical properties for dental devices as well as different release kinetics depending on their composition. Ex vivo studies were performed on decayed human teeth using the 3D printed tooth caps that precisely fit the complex geometries of each specimen. A significant elevation of fluoride content in the lesion mineral in contact with the PCL/PEG tooth caps was achieved compared to the ones in contact with solutions mimicking dental care products. In conclusion, this study suggested that a sustained localized drug release of fluoride from personalised 3D printed mouthguards at the device-enamel interface can improve the incorporation of fluoride in the tooth matrix and prevent lesion progression.

Nocturnal Salivary Fluoride Bioavailability After Brushing with a High-fluoride Dentifrice

The use of fluoridated dentifrices is recognized as the main reason for the decline of dental caries and its effect is associated with the bioavailability of fluoride (F) in the oral cavity. High-fluoride dentifrice has been indicated for patients at high risk of caries and management of root lesions. This study aimed to evaluate the bioavailability of F in saliva after the use of high-fluoride dentifrice during the nocturnal period. Fifteen healthy adults participated in this is in vivo and crossover study in which the concentration of F in their saliva was determined after brushing with the tested dentifrices: a conventional (1450 ppm F) or with high-fluoride concentration (5000 ppm F). Before brushing, the participants collected the non-stimulated saliva (baseline), immediately after brushing (time zero) and after 5min, 2h, 4h, and 8h, during the nocturnal period (between 10:00 pm and 06:00 am). The salivary F concentration was determined using a specific F ion electrode. Regarding statistical analysis, a paired t-test was used to compare dentifrices with p fixed at 5%. At baseline, there was no significant difference between groups (p>0.001). Immediately after brushing, both dentifrices increased the F salivary concentration, with the highest concentration reached in time zero; however, the use of 5000 ppm F dentifrice maintained the higher F salivary concentration at all times evaluated (p<0.001), remaining higher until 8 h after brushing. Furthermore, this treatment showed higher F bioavailability in relation to time, evaluated by the area under the curve (p<0.001). Thus, it can be concluded that the high-fluoride dentifrice increased the bioavailability of salivary F during the nocturnal period in comparison with conventional dentifrice.

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.

Analysis of Fluoride Concentration in Toothpastes in the United Arab Emirates: Closing the Gap between Local Regulation and Practice

Background: While there is much scientific evidence supporting the benefits of fluoride for oral health, the concentration of fluoride in over-the-counter fluoride toothpaste should meet United Arab Emirates (UAE) regulations of a fluoride concentration not exceeding 0.15%. Objectives: The current study examines the fluoridated toothpaste products available on the UAE market and aims to quantify their total fluoride content. Methods: A total of 50 toothpaste products were collected and analyzed in this study. Ion Chromatography (IC) conductivity analysis was performed to determine the total fluoride content. Results: Among the 50 products tested, 10 exceeded the recommended concentration of total fluoride of less than 0.15%, while 12 had a total fluoride concentration that was less than was declared on their labels. Moreover, this study has revealed that 22 of the sampled products had a total fluoride concentration below 1000 ppm fluoride. An increased risk of higher total fluoride content was observed in the toothpaste products with monofluorophosphate active ingredients than in products with potassium nitrate/sodium fluoride and sodium fluoride (p = 0.011). Conclusions: There is a need to reassess the effectiveness of current regulations in the UAE to ensure that all fluoridated toothpastes available on the market are safe and effective for the consumer. Specifically, appropriate guidelines should be established on the basis of the risks and benefits inherent in fluoride exposure. Moreover, fluoridated toothpastes need to be subject to stricter monitoring and control regarding their safety and quality through good manufacturing practices (GMPs), education, research, and adverse event reporting.

Cyclodextrin and TiF4 Nanocomplex on Enamel Demineralization

The aim of this study was to assess the effect of a newly developed nanocomplex formed of hydroxypropyl-b-cyclodextrin and 1% titanium tetrafluoride (TiF4) after distinct complexation periods (12/72 h) on demineralization of bovine enamel in vitro. Enamel blocks (n=60) were allocated in different groups: Mili-Q water, hydroxypropyl-b-cyclodextrin, 1% TiF4, hydroxypropyl-b-cyclodextrin + 1% TiF4 after 12 h of complexation and hydroxypropyl-b-cyclodextrin + 1% TiF4 after 72 h of complexation. The samples were evaluated by surface microhardness, cross-sectional microhardness and micro-CT. Scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDX) were also obtained. Hydroxypropyl-b-cyclodextrin + 1% TiF4 after 12 h complexation resulted in lower percentage of surface microhardness loss compared to Mili-Q water, hydroxypropyl-b-cyclodextrin, 1% TiF4 and hydroxypropyl-b-cyclodextrin + 1% TiF4 after 72 h of complexation group, with a large effect size (from 1.307 to 2.943) and high power (84.9 to 99%). All groups resulted in similar integrated mineral loss (ΔZ) obtained by both internal microhardness and micro-CT techniques. Enamel treated with TiF4 and TiF4 + hydroxypropyl-b-cyclodextrin groups showed a TiO2 glaze-layer, while EDX evaluation identified Ti. The solution containing the inclusion complex of hydroxypropyl-b-cyclodextrin + TiF4 with 12 h of complexation period demonstrated a significant ability to reduce surface demineralization of sound enamel under an artificial cariogenic challenge.

Chemically Soluble Fluoride in Na2FPO3/CaCO3-Based Toothpaste as an Indicator of Fluoride Bioavailability in Saliva during and after Toothbrushing

The relationship between the concentration of chemically soluble fluoride found in toothpaste and that present in saliva, during and after brushing, was evaluated as an indicator of potentially bioavailable fluoride in toothpaste. Ten adult participants brushed their teeth with the assigned toothpastes: group I: fresh sample of a fluoride toothpaste: Na2FPO3/CaCO3, 1,378 µg F/g of total soluble fluoride (TSF); groups II-IV: aged samples of toothpaste presenting TSF concentrations of 1,160, 900, and 597 µg F/g, respectively; group V: non-F placebo toothpaste. The volunteers brushed their teeth for 1 min with 0.7 g of the toothpaste, all toothbrushing residues (TR) produced were collected, the mouth was rinsed with water, and saliva samples were collected up to 120 min. Total fluoride (TF) and TSF concentrations were determined in TR and in saliva samples using a fluoride ion-selective electrode. TSF concentration (µg F/mL) in TR was determined as an indicator of fluoride bioavailability during toothbrushing and the areas under curves of saliva fluoride concentration versus time (area under the curve, AUC = µg F/mL × min) were calculated as an indicator of fluoride bioavailability after toothbrushing. A significant correlation was found between the TSF concentrations in the toothpastes and the variables TR (r = 0.850; p = 0.0001) and AUC (r = 0.445; p = 0.004). For TF no significant correlation was found for TR (r = -0.099; p = 0.542) and AUC (r = -0.018; p = 0.912). The findings suggest that TSF concentration chemically found in Na2FPO3/CaCO3-based toothpaste could estimate how much fluoride would be bioavailable in saliva when the teeth are brushed.

Influence of Ultrapulsed CO2 Laser, before Application of Different Types of Fluoride, on the Increase of Microhardness of Enamel In Vitro

Objective

To evaluate the influence of ultrapulsed CO₂ laser in combination with commercial fluoride products in order to verify the increase of microhardness of artificial enamel caries lesions.

Materials and Methods

Bovine enamel specimens were prepared, and artificial enamel caries lesions were created. Teeth were randomly divided into 5 groups (n=10): treated with laser (L), laser + neutral fluoride gel 2% (LNF), laser + acidulated phosphate fluoride gel 1.23% (LAFG), laser + acidulated fluoride mousse 1.23% (LAFM), and laser + fluoride varnish 5% (LFV). Microhardness was evaluated at baseline, after caries induction, after CO₂ laser irradiation + fluoride treatment in the 1st week, and after fluoride treatment at 3rd and 5th week.

Results

There was a decrease in microhardness in all groups after artificial enamel caries lesion formation; no increase in microhardness was found in the first and third weeks in all groups (p > 0.05). In the fifth week, an increase in microhardness occurred in all groups (p < 0.05).

Conclusion

Although CO2 laser irradiation in combination with different commercial fluoride products was capable of increasing microhardness on enamel caries lesions in bovine tooth enamel it is necessary to confirm these results by testing the isolated effect of fluoride on enamel surface microhardness. Also, although microhardness was higher in the fluoride varnish group than in the other groups in the fifth week it is not possible to discard the best effect of fluoride varnish treatment on absence of artifacts that may occur with the other fluoride treatments.

Clinical Relevance

In order to prove that CO2 laser may contribute to an increase in microhardness when applied to enamel lesions in combination with different commercial fluoride products it is necessary to conduct additional studies. Also, higher microhardness of fluoride varnish group should be carefully considered.

Microhardness of bovine enamel after different fluoride application protocols

The aim of the present study was to evaluate microhardness, mineral recovery and the enamel surface after the application of topical fluoride to artificial dental caries. Twenty-five bovine enamel blocks were prepared for artificial caries-like lesions and randomly divided into five groups (n=5): untreated (C control), 1.23% acidulated phosphate fluoride gel (APG), 2% neutral fluoride gel (NFG), 1.23% acidulated fluoride mousse (AFM) and fluoride varnish (5% Duraphat, DFV). Knoop microhardness (KHN) was evaluated after 7 and 14 days of treatment as well as 1 week after 28 days of treatment. Electron and confocal microscopy and energy dispersive spectroscopy were performed. KHN data were treated with two-way ANOVA (material×time) and Tukey's test at a 5% significance level. Differences were found among groups over time (p<0.001). Microhardness varied after 7 and 14 days of treatment and remained stable 1 week after 28 days of treatment. Mineral recovery and enamel topography varied among groups, with the fluoride varnish achieving the most uniform topography.

Fluoride Penetration and Clearance Are Higher in Exopolysaccharide-Containing Bacterial Pellets

Extracellular polysaccharides (EPS) could increase the penetration of fluoride through dental biofilm, reducing its cariogenicity. We measured the concentration of fluoride in EPS-containing (EPS+) or not-containing (EPS-) Streptococcus mutans bacterial pellets resembling test biofilms, before and up to 60 min after a 0.05% NaF rinse in situ. Fluoride penetration and clearance were higher in EPS+ bacterial pellets. The data suggest that EPS enhances fluoride penetration, but also accelerates fluoride clearance from dental biofilms.

Biomimetic Tooth Repair: Amelogenin-Derived Peptide Enables in Vitro Remineralization of Human Enamel

White spot lesions (WSL) and incipient caries on enamel surfaces are the earliest clinical outcomes for demineralization and caries. If left untreated, the caries can progress and may cause complex restorative procedures or even tooth extraction which destroys soft and hard tissue architecture as a consequence of connective tissue and bone loss. Current clinical practices are insufficient in treating dental caries. A long-standing practical challenge associated with demineralization related to dental diseases is incorporating a functional mineral microlayer which is fully integrated into the molecular structure of the tooth in repairing damaged enamel. This study demonstrates that small peptide domains derived from native protein amelogenin can be utilized to construct a mineral layer on damaged human enamel in vitro. Six groups were prepared to carry out remineralization on artificially created lesions on enamel: (1) no treatment, (2) Ca²⁺ and PO₄^3- only, (3) 1100 ppm fluoride (F), (4) 20 000 ppm F, (5) 1100 ppm F and peptide, and (6) peptide alone. While the 1100 ppm F sample (indicative of common F content of toothpaste for homecare) did not deliver F to the thinly deposited mineral layer, high F test sample (indicative of clinical varnish treatment) formed mainly CaF₂ nanoparticles on the surface. Fluoride, however, was deposited in the presence of the peptide, which also formed a thin mineral layer which was partially crystallized as fluorapatite. Among the test groups, only the peptide-alone sample resulted in remineralization of fairly thick (10 μm) dense mineralized layer containing HAp mineral, resembling the structure of the healthy enamel. The newly formed mineralized layer exhibited integration with the underlying enamel as evident by cross-sectional imaging. The peptide-guided remineralization approach sets the foundation for future development of biomimetic products and treatments for dental health care.

Measuring the Remineralization Potential of Different Agents with Quantitative Light-Induced Fluorescence Digital Biluminator

Background

The aim of this study was to investigate the effectiveness of different remineralization agents by quantitative light-induced fluorescence digital Biluminator™ (QLF-D).

Methods

Artificial caries lesions were created, and the teeth were divided according to the tested materials: (i) distilled water, (ii) acidulated phosphate fluoride (APF), (iii) Curodont Repair (CR), (iv) ammonium hexafluorosilicate (SiF) and (v) ammonium hexafluorosilicate plus cetylpyridinium chloride (SiF + CPC). After treatment procedures, each of the samples was placed in artificial saliva. After demineralization and 1 and 4 weeks of remineralization procedures, fluorescence loss and lesion areas were measured with QLF-D. Data were statistically analyzed (α = 0.05).

Results

The fluorescence values of the demineralized enamel specimens treated with the various agents differed significantly compared with pretreatment values for both 1 and 4 weeks (p<0.05). At 4 weeks, the highest fluorescence gain was calculated in the CR, APF and SiF groups compared with the control (p<0.05).

Conclusions

APF, SiF and CR groups yielded greater remineralization ability than SiF + CPC and control groups.

Anticaries Potential of Low Fluoride Dentifrices Found in The Brazilian Market

Low-fluoride (F) dentifrices (<600 µg F/g) are widely available worldwide, but evidence to recommend the use of such dentifrices, with either regular or improved formulations, is still lacking. Therefore, the aim of this study was to evaluate the anticaries potential of low-F dentifrices found in the Brazilian market, using a validated and tested pH-cycling model. Enamel blocks were selected by surface hardness (SH) and randomized into four treatment groups (n=12): non-F dentifrice (negative control), low-F dentifrice (500 μg F/g), low-F acidulated dentifrice (550 μg F/g) and 1,100 μg F/g dentifrice (positive control). The blocks were subjected to pH-cycling regimen for 8 days and were treated 2x/day with dentifrice slurries prepared in water (1:3, w/v). The pH of the slurries was checked, and only the acidulated one had low pH. After the pH cycling, SH was again determined and the percentage of surface hardness loss was calculated as indicator of demineralization. Loosely- and firmly-bound F concentrations in enamel were also determined. The 1,100 μg F/g dentifrice was more effective than the low-F ones to reduce enamel demineralization and was the only one that differed from the non-F (p<0.05). All F dentifrices formed higher concentration of loosely-bound F on enamel than the non-F (p<0.05), but the 1,100 μg F/g was the only one that differed from the non-F in the ability to form firmly-bound F. The findings suggest that the low-F dentifrices available in the Brazilian market, irrespective of their formulation, do not have anticaries potential.

Frequency of Fluoride Dentifrice Use and Caries Lesions Inhibition and Repair

The clinical relevance of the frequency of fluoride dentifrice (FD) use on enamel caries is based on evidence. However, the relative effect of FD on reduction of demineralization or enhancement of remineralization is unknown and the effect of frequency on root dentine caries has not been explored. The aim of this double-blind, crossover, in situ study, which was conducted in 4 phases of 14 days each, was to evaluate the relationship between the frequency of FD use and enamel and root dentine de- and remineralization. Eighteen volunteers wore palatal appliances containing enamel and root dentine slabs, either sound or carious. Biofilm accumulation on the slab surface was allowed, and 20% sucrose solution was dripped 3 or 8 times per day on the carious and sound slabs, respectively. Volunteers used FD (1,100 μg F/g) in the frequencies 0 (fluoride-placebo dentifrice), 1, 2 and 3 times per day. The demineralization and remineralization that occurred in sound or carious slabs was estimated by the percentage of surface hardness loss (%SHL) or recovery (%SHR). Loosely (CaF2) and firmly (FAp) bound fluoride concentrations were also determined. The relationship between the variables was analyzed by linear regression. The %SHL, CaF2 and FAp concentrations were a function of the frequency of FD use for enamel and dentine, but the %SHR was a function of the frequency of FD use only for enamel (p < 0.05). The results suggest that demineralization in enamel and root dentine is reduced in proportion to the frequency of FD use, but for remineralization the effect of the frequency of FD use was relevant only to enamel.

An innovative approach to treating dental decay in children. A new anti-caries agent

The aim of this work is to evaluate the antimicrobial and cytotoxic activity of a formulation containing silver nanoparticles and chitosan, provisionally called nano silver fluoride (NSF), against Streptococcus mutans in comparison to chlorhexidine and silver diamine fluoride (SDF). The product was characterised by transmission electron microscopy and UV-Vis absorption spectroscopy. The minimum inhibition concentration (MIC) was evaluated by the spectrophotometric microdilution method and turbidity. The minimum bactericide concentration (MBC) was evaluated in brain heart infusion plates, and cytotoxicity was evaluated by haemolytic activity. The MIC and MBC for NSF were, respectively, 33.54 ± 14.52 and 50.32 µg/mL; for SDF were 33.33 ± 14.43 and 50.0 µg/mL, respectively; and for CHX were 3.3 ± 0.5 and 6 µg/mL, respectively. An ANOVA for MIC gave P = 0.032, and for MBC P = 0.035. The cytotoxic effect of NSF compared to SDF demonstrated a statistically significant difference in the MIC value (t test P < 0.05). The NSF formulation may be effective against S. mutans with much lower doses, may have lower toxicity than SDF, and may not stain teeth.

Fluoride releasing and enamel demineralization around orthodontic brackets by fluoride-releasing composite containing nanoparticles

INTRODUCTION

Fluoride-containing materials have been suggested to control enamel demineralization around orthodontic brackets during the treatment with fixed appliances. The improvement of their properties has been made through innovations, such as the application of nanotechnology by incorporation of nanofillers.

OBJECTIVE

This in vitro study evaluated the capacity of fluoride releasing and enamel demineralization inhibition of fluoride-releasing nanofilled cement around orthodontic brackets using an artificial caries biofilm model.

MATERIALS AND METHODS

Forty bovine enamel discs were selected by evaluating surface microhardness and randomized into four groups (n = 10): non-fluoride-releasing microfilled composite, fluoride-releasing microfilled composite, resin-modified glass ionomer cement (RMGI), and fluoride-releasing nanofilled composite (FN). After brackets bonding in each disc, the specimens were subjected to a cariogenic challenge through a Streptococcus mutans biofilm model. After the experimental period, the biofilm formed around the brackets was collected for fluoride analysis and the mineral loss around the brackets was determined by integrated demineralization via cross-sectional microhardness measurement at 20 and 70 μm from the bracket margin. Additionally, samples of each group were subjected to energy-dispersive X-ray spectroscopy (EDX) analysis examined under a scanning electron microscopy (SEM). ANOVA followed by Tukey test were applied for fluoride concentration and mineral loss data, respectively.

RESULTS

At both distances, only RMGI statistically differed from the other groups presenting the lowest demineralization, although there was a trend to a lower demineralization of enamel around brackets in FN group. Similar condition was found to fluoride concentration and EDX/SEM analysis.

CONCLUSIONS

Under the cariogenic exposure condition of this study, the fluoride-releasing nanofilled material had similar performance to fluoride-releasing microfilled materials.

CLINICAL RELEVANCE

The presence of nanofillers in the fluoride-releasing materials studied did not promote further benefits against caries lesion development around brackets and presented inferior demineralization inhibition than the resin-modified glass ionomer material.

Fluoride content in toothpastes commercialized for children in Chile and discussion on professional recommendations of use

BACKGROUND

In Chile, no information is available regarding the soluble fluoride (F) content in the toothpastes commercialized for children and the country's guidelines recommend the use of F in toothpastes in an age-dependent concentration. No global consensus has been reached on this subject.

AIM

To determine the soluble F concentration in dentifrices for children sold in Chile and to discuss Chilean guidelines and professional recommendations of use.

DESIGN

Three samples of twelve different dentifrices were purchased from drugstores. Toothpastes were analysed in duplicate using an ion-specific electrode. The concentrations of total F (TF) and total soluble F (TSF) were determined (μg F/g).

RESULTS

Measured TF was consistent with that declared by the manufacturer in eight products. Two dentifrices showed lower TF and two higher F concentrations than declared. A toothpaste, marketed as low-F (450 ppm), showed F concentration threefold higher. Most dentifrices exhibited TSF concentrations similar to the TF content, except one sample that displayed considerably lower TSF than TF. Recommendations on F toothpastes use in children widely vary from country to country.

CONCLUSIONS

Most dentifrices for children match F content in the labelling, but recommendations are not supported by the best evidence available on the benefit/risk of F toothpastes use.

Effect of a third application of toothpastes (1450 and 5000 ppm F), including a 'massage' method on fluoride retention and pH drop in plaque

OBJECTIVE

The aim was to investigate fluoride (F) retention in plaque, saliva and pH drop in plaque using high-F toothpaste (5000 ppm F) or standard toothpaste (1450 ppm F) twice a day or 3-times a day. A method using the toothpaste as a 'lotion' and massaging the buccal surfaces with the fingertip was also evaluated.

MATERIALS AND METHODS

The investigation had a randomized, single-blinded, cross-over design and 16 subjects participated in six brushing regimes: (1) 5000 ppm F; twice a day, (2) 5000 ppm; 3-times/day, (3) 5000 ppm; twice a day, plus the 'massage' method once a day, (4) 1450 ppm F; twice a day, (5) 1450 ppm; 3-times/day and (6) 1450 ppm; twice a day, plus the 'massage' method once a day. The outcome measure was F retention in plaque, saliva and the plaque-pH change after a sucrose rinse.

RESULTS

The highest F concentration was found using high-F toothpaste (No 1-3) and differed significantly from those with 1450 ppm (No 4-6). Brushing with high-F toothpaste 3-times a day (No 2) resulted in a 3.6-times higher F saliva value compared with standard toothpaste twice a day (No 4) (p < 0.001). Increasing the frequency of application, from twice to 3-times a day, increased the F retention in plaque significantly when the two methods for application 3-times a day were pooled (p < 0.05). Brushing with 5000 and 1450 ppm toothpastes twice a day plus the 'massage' once a day resulted in the same F concentration in saliva and plaque as brushing 3-times a day with the same paste.

CONCLUSION

A third application of toothpaste is increasing the F retention and toothpaste as a 'lotion' and massaging the buccal surfaces with the fingertip may be a simple and inexpensive way of delivering F a third time during the day.

Fluoride concentration in the top-selling Brazilian toothpastes purchased at different regions

To be relevant in terms of public health, widely-used toothpastes should have at least 1,000 ppm of soluble fluoride (F) concentration. Thus, the concentrations of total fluoride (TF) and total soluble fluoride (TSF) in the top-selling Brazilian toothpastes were evaluated. Samples (n=3) from toothpastes Colgate Anti-cáries(®), Colgate Total 12 Clean Mint(®), Colgate Tripla Ação Menta Original(®), Colgate Tripla Ação Menta Suave(®) and Sorriso Dentes Brancos(®) were obtained from each of the five regions of the country. The concentrations of TF and TSF were analyzed with ion-specific electrode calibrated with F standards and the results were expressed in ppm (µg F/g). All toothpastes showed TF concentration lower than 1,500 ppm F (1,388.2 ± 25.8 to 1,483.2 ± 98.2). The TSF values were higher than 1,000 ppm F and ranged from 1,035.5 ± 61.5 to 1,221.8 ± 35.2 for calcium carbonate/monofluorophosphate-based toothpastes and from 1,455.6 ± 12.5 to 1,543.0 ± 147.3 for silica/sodium fluoride-based toothpaste. Top-selling Brazilian toothpastes presented available fluoride concentration to control caries regardless of the region where they are purchased.

Influence of the curing mode on fluoride ion release of self-adhesive resin luting cements in water or during pH-cycling regimen

This study evaluated the effects of curing modes and storage conditions on fluoride release of resin cements. In phase 1, the cumulative fluoride release rate from samples of the resin cements (Panavia F 2.0, RelyX Unicem, MaxCem, and BisCem) was quantified after 15 days storage in water (n=4). In phase 2, the fluoride release profiles from the same materials were analyzed during pH cycling (n=4). In this second phase, fluoride was measured at specific times (one, two, three, five, eight, and 15 days). Disk-shaped specimens were prepared (10 mm × 0.5 mm), and the materials were either light activated or allowed to autopolymerize. For both phases, the fluoride release was measured using a fluoride ion-specific electrode. The fluoride release in water was not affected by the curing mode of RelyX Unicem and Maxcem resin cements. Panavia F. 2.0 and BisCem resin cements, either light cured or autopolymerized modes, released higher amounts of fluoride in water than the other self-adhesive cements. In phase 2, the concentration of fluoride released decreased from the first day of pH cycling until the 15th day for all resin cements, for both curing modes, regardless of the storage solution used (demineralizing/remineralizing). The fluoride release rate during pH cycling by Panavia F 2.0 and MaxCem was not affected by the curing mode. The effect of the curing mode on fluoride ion release in water or during pH cycling was product dependent.

Fluoride: its role in dentistry

In spite of decades of research on fluoride and the recognition of its role as the cornerstone of dental caries reduction in the last fifty years, questions still arise on its use at community, self-applied and professional application levels. Which method of fluoride delivery should be used? How and when should it be used? How can its benefits be maximized and still reduce the risks associated with its use? These are only some of the challenging questions facing us daily. The aim of this paper is to present scientific background to understand the importance of each method of fluoride use considering the current caries epidemiological scenario, and to discuss how individual or combined methods can be used based on the best evidence available.