|Year : 2014 | Volume
| Issue : 4 | Page : 320-322
Assessment of total and soluble fluoride content in commercial dentifrices in Davangere: A cross sectional survey
DJ Veeresh, Umesh Wadgave
Department of Public Health Dentistry, Bapuji Dental College and Hospital, Davangere, Karnataka, India
|Date of Web Publication||24-Dec-2014|
Room No. 8, Department of Public Health Dentistry, Bapuji dental college and hospital, MCC 'B' block. Davangere 577 004, Karnataka
Source of Support: None, Conflict of Interest: None
Introduction: The major reason for decline in dental caries across globe is because of widespread use of fluoride dentifrices. For a fluoride dentifrice to be effective in the control of dental caries, an adequate concentration of the fluoride must be soluble. Objective: To assess soluble fluoride and total fluoride content in selected commercial dentifrices in Davangere. Materials and Methods: The soluble fluoride and total fluoride content in six selected commercial dentifrices in Davangere were assessed and expressed as ppm of fluoride (F) (mgF/g). Total fluoride and soluble fluoride was determined using an ion-specific electrode. Descriptive statistics applied to assess the mean total fluoride and soluble fluoride. Results: The total fluoride and soluble fluoride concentrations were approximately near to 1,000 ppm. Among the six dentifrices evaluated, four contained sodium fluoride (NaF) and two contained sodium monofluorophosphate (Na MFP) as fluoride compound. Conclusions: All the fluoridated dentifrices evaluated in this study contain adequate amount of soluble and total fluoride.
Keywords: Dental caries, dentifrice, soluble fluoride, total fluoride
|How to cite this article:|
Veeresh D J, Wadgave U. Assessment of total and soluble fluoride content in commercial dentifrices in Davangere: A cross sectional survey
. J Indian Assoc Public Health Dent 2014;12:320-2
|How to cite this URL:|
Veeresh D J, Wadgave U. Assessment of total and soluble fluoride content in commercial dentifrices in Davangere: A cross sectional survey
. J Indian Assoc Public Health Dent [serial online] 2014 [cited 2019 Oct 21];12:320-2. Available from: http://www.jiaphd.org/text.asp?2014/12/4/320/147679
| Introduction|| |
Dental diseases are among the most widespread diseases around the globe.  According to the World Health Organization (WHO) report 2004, dental caries remains a major public health problem in most Asian and Latin American countries.  The principal reasons for this increase are growing sugar consumption and inadequate exposure to fluorides.  In India, dental caries is a major public health problem.  National Health Survey conducted in 2004 throughout India has shown dental caries in 51.9% in 5-year-old children, 53.8% in 12-year-old children, 63.1% in 15-year-old teenagers, and about 70% of elderly population of 60 plus years (which comprises 7.8% of population) suffer from root caries. 
Daily use of fluoride toothpaste forms the foundation of caries prophylaxis with fluorides, as it is readily available and, when used regularly, continually provides fluoride ions for caries protective processes on the tooth's surface. This caries prophylactic effect is evident in all age-groups  and increases with increasing fluoride concentration.  Cochrane systematic review approves the benefits of using fluoride toothpaste in preventing caries in children and adolescents when compared to placebo, but only significantly for fluoride concentrations of 1,000 ppm and above.  Furthermore, toothpaste is the delivery vehicle of fluoride most accessible for the majority of the population, regardless of their socioeconomic status. 
For a fluoridated dentifrice to be effective in controlling dental caries, an adequate concentration of fluoride must be soluble,  assuring fluoride bioavailability in the oral cavity during toothbrushing.  Labels of commercial dentifrices declare only information regarding the total fluoride and not the active soluble fluoride concentration. Since only total soluble fluoride (TSF) should be considered potentially active against caries, knowing the content of this fraction when consumers choose a dentifrice is important. Deficiencies were found regarding the total as well as the free ionizable fluoride concentration of toothpastes bought in several countries. ,,,, Unclear labeling concerning the type and concentration of fluoride was often encountered. ,,, A need for quality control of fluoride toothpastes is recommended.  Hence, this study is aimed at assessing soluble fluoride and total fluoride content in selected commercial dentifrices in Davangere City, Karnataka.
| Materials and Methods|| |
The present study is a descriptive survey which assessed the soluble fluoride and total fluoride content in six selected commercial dentifrices in Davangere. Prior to the study, ethical clearance was obtained from Institutional Review Board.
In the present study, two fluoride containing dentifrices belonging to six different brands were purchased from three different conveniently selected commercial shops in Davangere. Six different toothpaste brands were conveniently selected based on the popularity. Each dentifrice was coded with a letter to allow blind analysis (single blinding). All the samples were purchased and analyzed before their expiry date and the analyses was performed in duplicate. Two investigators were involved in the study; one selected the dentifrices from the commercial shop and another investigator did the analysis of selected samples.
To determine fluoride concentration, three different fluoride fractions were assessed:
- Total soluble fluoride (TSF or free fluoride), which represents ionic fluoride (IF + F as MFP ion),
- Total fluoride (TF), TF corresponds to TSF + insoluble fluoride (InF). InF is fluoride bound to the abrasive.
Chemical assays were carried out in the Department of Environmental sciences. All the analyses were carried out in duplicates. In each sample, 90-110 mg of each toothpastes was weighed (±0.01 mg) and homogenized in 10.0 mL of deionized water to create a suspension from which the different fluoride fractions were obtained and measured by a selective fluoride electrode, as follows:
A 0.25-mL in duplicate of the suspension was transferred to test tubes and 0.25 ml of 2 M HCl was added to break MFP ion into fluoride ion and to five dissolve InF bound to the abrasive. Acidified suspension was maintained 1 hour at 45°C and neutralized afterwards using 0.5 ml 1 M NaOH, followed by 1 ml Total ionic strength adjustment buffer II, total ionic strength adjustment buffer (TISAB) 1 M acetate buffer, pH 5.0, containing 1 M NaCl, and 0.4% 1, 2-cyclohexanediaminetetraacetic acid low sodium (CDTA).
Total soluble fluoride
Dentifrice suspension was centrifuged (10 min at 3000 g) at room temperature to remove InF bound to the abrasive. To 0.25 ml of the supernatant, 0.25 ml of 2 M HCl was added to break MFP into IF and the tube was maintained for 1 hour at 45°C. Acidified solution was then buffered with 0.5 ml 1 M NaOH, followed by 1 ml of TISAB II.
To determine fluoride concentration in each of the three suspensions analyses, fluoride electrode (Orion model 96-09, Orion Research, Cambridge, MA) coupled to anion analyzer (Orion EA-740) was used, which was calibrated with fluoride standards containing 0.06-8.0 ppm fluoride made with the same reagents used to prepare the samples. The concentrations of TF and TSF were expressed in ppm (mg F/g).
Analysis of data
Mean and standard deviation of the total fluoride and TSF was calculated.
| Results|| |
The dentifrices assessed in the present study contain TF concentrations approximately near to 1,000 ppm as stated in the manufacturer's label. TF found in the F-toothpastes ranged from 930-987 ppm fluoride (mean 959 ± 58.8 ppm).
Among the six dentifrices evaluated, four contained NaF and two contained Na MFP as fluoride compound as cited in the manufactures' label. Fluoride concentration in the TSF fraction ranged from 916-943 ppm (mean 937 ± 72.4 ppm). When measured TF was compared with TSF, the active fraction, some of the dentifrices exhibited lower TSF than TF. The missing part of TSF with respect to TF of those toothpastes corresponds to InF bound to the abrasive.
Among all dentifrices evaluated, one contained silica and calcium carbonate, another one contains silica, and remaining four contains hydrated silica as abrasive. Taken together, almost all the selected dentifrices studied contained TSF within the range of 916-943 ppm, regardless of the TF contained.
| Discussion|| |
The contribution of fluoridated dentifrice in reduction of worldwide dental caries is irrefutable.  Few studies in different parts of world assessed the fluoride content of the over-the-counter toothpaste, ,,, but no study has reported fluoride concentration in the toothpastes commercialized in India.
The results of present study revealed that all the six selected dentifrices had met the basic fluoride concentration of 1,000 ppm. This requirement does not specify whether fluoride must be soluble or not. In order to be active, fluoride contained in a dentifrice must be soluble.  Even if TF content of toothpastes is high, important portions of the available fluoride may have reacted with the abrasive, affecting the purpose of preventing caries or enhancing remineralization. Previous studies have shown that when CaCO3 or DCPD is used as an abrasive in toothpastes, a fraction of fluoride precipitates as CaF 2 ,  which decreases the amount of soluble F.
All the dentifrices included in the present study had the optimum TSF content (1,000 ppm) which required proving as effective anti caries dentifrice. And these results are in accordance with study done in Chile,  Japan,  and Brazil.  However, the measurement of total and free fluoride concentrations of dentifrices available in the Gambia (West Africa) showed inhomogeneity. 
In general, toothpastes contain fluoride either as ionic fluoride (IF) derived from NaF or from MFP. To interfere with the caries process, dentifrices must provide soluble fluoride in their formula, ensuring Fluoride bioavailability in the oral cavity during brushing.  Soluble Fluoride is capable to prevent demineralization and enhance remineralization of the hard dental tissues. Fluoride bioavailability in the mouth depends on the chemical compatibility between the fluoridated agent, NaF or MFP, and the abrasive used. Most MFP-based dentifrices analyzed contained dicalcium phosphate dihydrate (DCPD) as an abrasive. Importantly, a fraction of MFP undergoes hydrolysis into the toothpaste tube and releases ionic F, which in turn binds to the abrasive. In the bound form, fluoride becomes insoluble and inactive against caries.  But this might not have influenced the results, since most of the dentifrices analyzed had hydrated silica as an abrasive, NaF was used as a source of soluble F.
It was also found that the soluble fluoride concentration decreases over time during storage of the products.  Hence, additional studies are essential to assess the stability of fluoride concentration over a period of time. Since only limited brands of fluoride toothpastes were selected conveniently, the study results cannot be generalized to all the toothpaste brands, further studies are mandatory with many more brands to confirm this finding.
In conclusion, selected toothpastes match the declared content of TF. Dentifrices contain TSF close to TF, ensuring bioavailability, and meet the internationally acceptable soluble fluoride concentration of 1,000 and 1,500 ppm to attain an anti-caries effect [Table 1].
|Table 1: Measured total soluble fluoride and measured total fluoride of the tested dentifrices |
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