Publicidade

I. Souza

L. Primo

L. Silva

P. Cordeiro

R. Vianna

The possibility of having a commercial product which associates two effective agents in controlling and preventing caries seems to be promising. The aim of this research was to determine the uptake of fluoride on tooth enamel in situ after the utilization of a dental floss with fluoride. One hundred blocks of bovine enamel were artificially demineralized and randomly separated into two groups: Control (C) and Test (T). The dental blocks in group T were mounted two-by-two simulating proximal contacts and were fixed into intra-oral lower devices. Eight volunteers with a similar salivary flow and buffer capacity wore the devices for eight days. During this period of time they applyed between the blocks, 3 times a day for 2 minutes after each meal, a 25 cm long of mint waxed floss with fluoride (Oral BR, 0.15 mgF/m). At the same time, brushing was carried out with a free fluoride tooth paste. The alkali-soluble fluoride (CaF2) formed in the enamel was extracted through the Caslavska et al. method (1975) and measured with the Orion 96-09 electrode-specific and the EA 720 ion analyzer. The results showed that the group that had the most CaF2 on the enamel (median, minimum and maximum in µF/cm2) was T (3.00, 2.11 and 4.00), which differed significantly (Wilcoxon Test, p<0.01) from group C (0.26, 0.10 and 0.69). It was concluded that fluoride uptake on enamel was 8.7 times higher after use of dental floss with fluoride.

Abstract

The possibility of having a commercial product which associates two effective agents in controlling and preventing caries seems to be promising. The aim of this research was to determine the uptake of fluoride on tooth enamel in situ after the utilization of a dental floss with fluoride. One hundred blocks of bovine enamel were artificially demineralized and randomly separated into two groups: Control (C) and Test (T). The dental blocks in group T were mounted two-by-two simulating proximal contacts and were fixed into intra-oral lower devices. Eight volunteers with a similar salivary flow and buffer capacity wore the devices for eight days. During this period of time they applyed between the blocks, 3 times a day for 2 minutes after each meal, a 25 cm long of mint waxed floss with fluoride (Oral BR, 0.15 mgF/m). At the same time, brushing was carried out with a free fluoride tooth paste. The alkali-soluble fluoride (CaF₂) formed in the enamel was extracted through the Caslavska et al. method (1975) and measured with the Orion 96-09 electrode-specific and the EA 720 ion analyzer. The results showed that the group that had the most CaF₂ on the enamel (median, minimum and maximum in µF/cm²) was T (3.00, 2.11 and 4.00), which differed significantly (Wilcoxon Test, p<0.01) from group C (0.26, 0.10 and 0.69). It was concluded that fluoride uptake on enamel was 8.7 times higher after use of dental floss with fluoride.

Introduction

Flossing is the most widely recommended and efficient method for interproximal bacterial plaque removal.^{1 2,3} The method has also proved efficient in reducing S. mutans on proximal surfaces when impregnated with SnF₂.⁴

Although several studies corroborate the efficacy of mechanical methods (flossing and brushing) in plaque removal and in reducing gingivitis in adults and children, the efficacy of such methods in caries reduction have been harder to establish.³

Frequent applications of fluoride in low concentrations seem to be the most effective means in caries prevention,⁵ particularly on high risk surfaces, such as interproximal surfaces. Several fluoride application methods have been tested in vitro, with promising results: toothpicks with fluoride,⁶ fluoride-impregnated dental floss^7,8 or industrially prepared dental floss with fluoride.⁹  Satisfactory results have also been obtained in vivo after use of a fluoride-impregnated toothpick.¹⁰

The combination of a mechanical agent and a chemical one in the same commercial product brings together two elements that have proved successful by itselves. The aim of this research was to determine fluoride uptake by dental enamel in situ after use of a dental floss with fluoride. 

Materials and Methods

Preparation of Samples

One hundred bovine teeth were evaluated under a 16X stereoscopic microscope (Zeiss 475200-9901), to verify whether they were free from flaws and fissures, and were then stored in formaldehyde at 2%, pH 7, at 4º C until the experiment was carried out. The teeth were sectioned at the middle third with a double face diamond wheel mounted on a low speed motor, with an adequate humidity level, to obtain one hundred 9mm² blocks. The blocks were then subjected to a prophilaxis with pumice and water, by means of rubber cups (one for each five teeth) at low speed. The blocks were then rinsed with de-ionized water and dried with air. Artificial subsurface caries lesions were then created on exposed areas by immersing the blocks in a demineralizing solution¹¹ containing 3mM Ca, 3mM P and 50 mM acetic acid, pH 4.5, for 5 days. The blocks were then randomly separated into two groups: control (C) and test (T) group. Intra-oral lower arch devices, similar to those described by Creanor et al.¹², were constructed for each subject. Six dental blocks in group T were mounted two-by-two simulating proximal contacts and were attached on the lingual aspect of the intra-oral devices. (Figure 1). 

Study Design

Eight subjects (three men and five women), aged 24 to 34 years, mean age 26.6 years, were screened for this clinical study. All subjects gave informed signed consent prior to starting the study. To be included in the study they had to be in a similar state of good general health, to have a similar salivary flow and buffer capacity, and live in areas with a similar fluoride concentration in the water supply. The fluoride concentration in the water supply at each subject’s place of residence was determined potentiometrically using a specific electrode (Orion 96 - 09) and an ion analyzer (Procyon SA 720) calibrated with 0.1 and 1.0mgF/ml standards. To measure the subjects’ salivary flow and buffer capacity, the stimulated saliva was collected. Each subject was instructed to chew a piece of sugarless gum for 3 minutes and to spit his/her saliva into a plastic cup. The salivary flow rate was measured with a 10 ml graded pipette and the result was given in ml/min. The buffer capacity was determined by means of the Ericson method modified by Brathall & Hager¹³ , in which 1 ml of saliva was added to 3 ml of HCl 0.005M, the colorimetric reading being taken after 20 minutes with strips. The subjects wore the intra-oral devices for eight consecutive days, removing them to treat the dental blocks with 25cm of mint flavored waxed floss with fluoride (Oral B Laboratories, Redwood City, Ca ,US; 0.15 mg F/m) dabbed with the subject’s saliva. The fragments were flossed for 2 minutes three times a day after meals. Throughout the experiment brushing was carried out with a non-fluoride tooth paste and the subjects were instructed not to use mouth washes with fluoride, to avoid food and beverages with a high fluoride content, and to remove the devices only at meal times and for the cleaning procedure described above.

The calcium fluoride (CaF₂) - an alkali soluble fluoride - present in the enamel was extracted by means of the Caslavska et al. method¹⁴ and measured with the Orion 96-09 specific electrode and the Procyon SA 720 ion analyzer calibrated with fluoride concentration standards varying from 0.1 to 1.0 mgF/ml. 

Data Analysis

The Wilcoxon non-parametric test was used for the statistical analysis of the results. ¹⁵ 

Results

The amounts of CaF₂ of groups C and T are given in Table 1. Group T had the most CaF₂ (mg F/cm²), differing significantly from group C (p<0.01).

Table I

Enamel Fluoride Uptake (mg F/cm²) After Use of Dental Floss with Fluoride

 Discussion

The results suggest that there was an increase of F in the enamel after flossing with a fluoridated dental floss. This result seems encouraging, particularly when it is taken into account that proximal surfaces are high caries risk areas where a toothbrush and dentifrice with fluoride cannot always reach. The possibility of making fluoride available directly to such areas meets the recommendations of researchers as Manji and Fejerskov¹⁶ regarding the use of fluoride administration methods which minimize systemic exposure.

The dental floss used in this study contains NaF (0.15 mgF/m) incorporated to the wax, which hydrolyzes as it comes into contact with the saliva, and releases fluoride which becomes available to react with tooth enamel. This reaction can be seen in Table 1 which shows an 8.7 fluoride content increase in tooth enamel on the interproximal surfaces after an 8-day treatment with a fluoridated dental floss, as compared with untreated surfaces (p<0.01). The in vitro study by Vianna et al.⁹ showed fluoride concentrations 3.1 and 5.7 higher after using a dental floss and a dental tape, respectively. Similar results with a different research design was obtained by Chaet and Wei⁸, who demonstrated that interproximal surfaces treated in vitro with dental floss impregnated with fluoride acquired 3 times more fluoride than those treated with a plain dental floss.

The findings of this study seem to have great clinical significance, particularly considering the great frequency with which the product is used by the general population, considering the product’s low fluoride concentration, and considering its easy use and safety.  Not only does dental floss remove bacterial deposits, by its effect is potentialized by the action of rubbing the therapeutic agent onto an area at the same time. This may be an advantage when compared with dentifrice as a fluoride carrier, which necessitates the aid of a toothbrush to achieve surface contact. This comment does not aim to establish a comparison between dental floss and dentifrice, but to emphasize the need to use both as part of oral hygiene.

Fluoride concentrations in saliva also increases significantly after treatment with a toothpick impregnated with 4% NaF¹⁰ and with a fluoridated dental floss or dental tape.¹⁷  This is positive in terms of product efficacy, according to Ekstrand, ¹⁸ who claims that there is a clear relationship between fluoride concentration in oral fluids and the action of fluoride on enamel and on its environment.

For caries reduction to occur, all surfaces must undergo topic fluoride application.  Consequently, dental floss is an agent which is potentially capable of preventing or arresting caries lesions on proximal surfaces, mainly because its multiple use can increase and maintain fluoride content on proximal surfaces in vivo.⁷

Considering that previous studies^19,20 have shown that frequent use of a dental floss without fluoride causes a significant reduction of interproximal caries in deciduous teeth, it may be inferred that this result can be achieved more efficiently with a dental floss with fluoride.

The methods used in this study allowed fluoride acquisition after an 8-day, 3 times daily treatment to be determined. Further studies are therefore suggested that consider longer periods and different number of daily applications of a dental floss in vivo in order to confirm the beneficial effects observed in this experiment.

Conclusion

Based on the conditions of this study, it was possible to conclude that there was a significant fluoride uptake in situ on the dental enamel after the use of a dental floss with fluoride. 

Acknowledgments

The authors thank the volunteers Alexandre Vieira, Claúdia Marinho, Henrique Ruschell, Laura Primo, Lucianne Maia, Mônica Gomes, Paula Cordeiro and Roberto Silveira for their participation in this study.

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RR Oral B ^R (Oral B Laboratories, Belmont CA)