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Table of Contents
Year : 2021  |  Volume : 5  |  Issue : 3  |  Page : 133-137

Peppermint flavor oil in fluoride varnishes enhances fluoride release

1 Department of Dental Materials Science, Faculty of Dentistry, Universitas Indonesia, Kampus UI Depok, West Java, Indonesia
2 Department of Chemical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, West Java, Indonesia

Date of Submission16-Mar-2021
Date of Decision25-Jun-2021
Date of Acceptance10-Aug-2021
Date of Web Publication18-Oct-2021

Correspondence Address:
Heri Hermansyah
Department of Chemical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, West Java 16424,
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/SDJ.SDJ_78_21

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Background: Fluoride varnish (FV) is a common dental health treatment for the prevention of early childhood caries. Application of FV with a flavoring agent promotes comfort and acceptance by patients, especially children, and facilitates an effective treatment time. Objective: Flavored FV with a pleasant flavor should allow a faster treatment time, especially with children. The aim of this research was to study basic FV formulations containing different flavors of essential oils (LorAnn) and variations in the concentrations of flavor oils to determine the optimum formulation to enhance the in vitro fluoride release time. Methods: The independent variables were the flavors (apple, melon, and peppermint) and the concentrations (1, 1.5, 2, or 2.5%) of the flavor that gave the best fluoride release (peppermint). The amounts of fluoride ions released in 6 h into deionized water were assessed at 37°C using an ion-selective electrode with the addition of fluoride total ionic strength adjustment buffer solution to strengthen the ion reading. The cumulative ion release was analyzed for normality and equality of variance, and the means were compared using a general linear model test and Statistical Package for Social Sciences version 23.0 software. The significance level was set at α = 0.05. Results: At the same concentration of 2% for the apple, melon, and peppermint flavors, the peppermint formulation gave the best fluoride release, at 173.22 mg/L. A peppermint oil concentration of 2.5% showed the highest fluoride ion release, at 178.95 mg/L. Conclusions: The addition of peppermint flavor oil at a concentration range of 1—2.5% revealed an increasing release of fluoride ions with an increasing peppermint oil concentration. Further investigations are still needed using artificial saliva to replicate actual conditions in the oral cavity.

Keywords: Caries, dental health, flavor oil, fluoride release, fluoride varnish

How to cite this article:
Eriwati YK, Putriani D, Geraldine K, Hermansyah H. Peppermint flavor oil in fluoride varnishes enhances fluoride release. Sci Dent J 2021;5:133-7

How to cite this URL:
Eriwati YK, Putriani D, Geraldine K, Hermansyah H. Peppermint flavor oil in fluoride varnishes enhances fluoride release. Sci Dent J [serial online] 2021 [cited 2021 Nov 27];5:133-7. Available from: https://www.scidentj.com/text.asp?2021/5/3/133/328424

  Background Top

The occurrence of early childhood caries (ECC) has increased in many countries and has become a significant health issue, especially in socially disadvantaged populations. In Indonesia, the Basic Health Research data in 2018 indicated that 93% of children in the age range of 5—6 years experienced caries.[1] A literature review showed the same dental health issue in many less developed countries, where a prevalence of ECC as high as 70% was reported.[2] Dental caries in children can cause nutritional problems, such as stunting because of the disruption of food intake because of perforated teeth, as well other health problems, including local pain, gastrointestinal disorders, and sleeping difficulty.[3],[4],[5]

Dental caries occur due to an imbalance between the demineralization and remineralization processes that occur continuously in the oral cavity. Demineralization is the dissolution of minerals from hydroxyapatite crystals found in hard tissues such as enamel, dentin, cementum, and bone, whereas remineralization is the process of restoring these mineral ions to the hydroxyapatite crystals.[6] Tooth demineralization is promoted when the pH of the oral cavity falls below pH 5.5. The pH of saliva can be lowered by the presence of carbohydrates from food debris on the tooth surface. These materials encourage the growth of microorganisms that are capable of fermenting sugar to acids as byproducts, thereby lowering the pH in the oral cavity.[7] Maintaining the balance between the demineralization and remineralization cycle in the oral cavity is therefore the most crucial concept for preventing dental caries.[8]

One active ingredient acknowledged to prevent caries is fluoride.[9] Fluoride varnish (FV) was developed in 1960 and has been used widely in the Americas and Europe since 1970. Fluoride works by inhibiting the formation of bacterial colonization on the tooth surface and by increasing the tooth enamel resistance to acids or demineralization through the formation of fluorapatite (CA10(PO4)6F2).[10] Fluoride has been developed as a topical treatment in various forms, including pastes, solutions, gels, and varnishes. The topical therapeutic use of FV is the most effective method for preventing early caries and has a 37—43% success rate and it can only be administered in the dental office by a dental professional.[11] Varnish formulations also provide the best comfort to the patient compared with the other topical forms. Commercial FVes typically contains 5% sodium fluoride (22,600 ppm of F ion) and are usually applied twice a year as a dental health treatment.[12]

Most commercial FV products on the market have a long fluoride ion release time (≥4 h), as indicated by the recommended length of the application time given in the product instructions.[13] Following an FV treatment, the patient is forbidden to do a number of activities involving the oral cavity, including eating, drinking, or brushing the teeth for the time indicated in the product recommendations. The varnish must remain in contact with the teeth for a sufficient time to allow optimum fluoride release into the oral cavity. However, the duration can actually be more than 4 h, and this is a long time to refrain from activity, especially for children.

Research has shown that fluoride ion release differs for two commercial products with different types of flavor, ClearVarnish Watermelon and ClearVarnish Strawberry.[14] Flavored fluoride varnish (FFV) is very well liked by children for caries prevention treatments; therefore, the aim of this research was to evaluate the effect of adding a flavor oil to an FV formula on the subsequent release of fluoride ions.[15]

  Materials and Methods Top

The release of fluoride ions was conducted in three samples formulation of FFV with different flavor types and one sample of base FV with no added flavor oil as the positive control. The goal was to determine the effect of adding various flavor oils on fluoride ion release to identify which flavor oil type causes the greatest fluoride ion release. That oil would then be used in the next stage of the study. The flavor oils were LorAnn’s oil, produced in Lansing, Michigan, with flavor varieties of apple, melon, and peppermint.

Fluoride varnish formulation

Foral AX-E fully hydrogenated rosin (Eastman, USA) and 99.9% ethanol (Merck KGaA, Germany) was mixed in a glass beaker using a magnetic stirrer at 240 rpm at room temperature until an even mixture was obtained (3 h). Sodium fluoride powder (Merck KGaA, Germany) was then added to the mixture and stirred for a further 1 h. A flavor oil (apple, melon, or peppermint) (LorAnn Oils, Lansing, Michigan) was then added to the mixture and stirred for another 1 h. The total weight of each varnish formulation was about 100 g. The detailed compositions of the FVs are shown in [Table 1].
Table 1: Percent composition of the fluoride varnish ingredients

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Fluoride ion release test

A 0.05 g sample of each varnish formulation was applied to the bottom of the 50-mL transparent plastic polypropylene cup and 25 mL of deionized water was added. The cup with the sample was incubated for 30 min at 37°C. The test solution was then transferred to another container, the sample cup was filled with fresh deionized water, and the cup was incubated again for 30 min. The test solution was measured for its fluoride ion content using an ion-selective fluoride electrode (LaquaAct pH 130, Horiba, Japan) following the addition of 25 mL of a fluoride total ionic strength adjustment buffer solution (Horiba, Japan) to strengthen the ion reading. The ion readings were performed three times. This procedure was repeated every 30 min to measure the release of fluoride ions for a total of 6 h.

Data analysis

The cumulative fluoride ion release data were analyzed for normality and equality of variance, and the means were compared using a general linear model test and Statistical Package for Social Sciences version 23.0 software (IBM, Armonk, NY, USA). The significance level was set at α = 0.05 for all statistical tests.

  Results Top

Effect of flavor type on fluoride ion release

[Figure 1] shows that, compared to the other flavors, the 2% peppermint FFV gave the highest fluoride ion release of 173.22 mg/L after 6 h. The 2% melon FFV gave a fluoride release of 155.08 mg/L, and the base FV without flavor released 153.99 mg/L. The 2% apple FFV had the lowest fluoride ion release of 143.93 mg/L. Statistical analysis using a generalized linear model test revealed that the cumulative release of fluoride ions at each test time was significantly different for the different FFVs with P value <0.05. Peppermint oil gave the best fluoride release and was used in subsequent experiments.
Figure 1: Correlation between flavor type variation on number of fluoride ions released in the period of time

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Effect of peppermint flavor oil concentration on fluoride ion release

The previous results showed that peppermint flavor provided the best release of fluoride ions; therefore, the effect of four concentrations (1, 1.5, 2, and 2.5%) of peppermint oil on fluoride release was examined. The selection of this concentration range was based on Patent US 20180116914A1, which states that a concentration of flavor between 0.5% and 2.5% is the recommended concentration range for an FV product.[16]

[Figure 2] shows that 2.5% peppermint FFV gave the highest ion fluoride release of 178.95 mg/L after 6 h, followed by 2% peppermint FFV gave the ion fluoride release of 173.22 mg/L, and 1.5% gave the ion release of 168.60 mg/L, with 1% giving the lowest fluoride ion release of 166.99 mg/L. Statistical analysis of the cumulative fluoride release values showed that the variations in flavor concentration have a significantly different effect on the release of ions with P value = 0.047 < 0.050.
Figure 2: Correlation between variation of peppermint flavor oil concentration on number of fluoride ions released in the period of time

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  Discussion Top

The specification data for LorAnn flavor oils provided in [Table 2] show that the addition of a flavor oil with the lowest density (peppermint) to an FFV results in the release of the highest number of fluoride ions in 6 h. However, the addition of a flavor oil with the highest density (apple) to the FFV results in the lowest release of fluoride ions in the same time frame. The release of fluoride ions relies heavily on the matrix of the FV; therefore, a high-viscosity matrix will inhibit fluoride release by inhibiting the dissolution of fluoride into the test solution, in this case, deionized water.[17],[18]
Table 2: Ingredients and density specification data of apple, melon, and peppermint LorAnn flavor oil

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The addition of flavor oils with different densities can affect the final viscosity of the FV; therefore, at the same concentration of flavor oil, the FFV made with apple flavor had a higher density than the FFV made with peppermint flavor oil. The lower density of the peppermint FFV led to a lower viscosity and a greater fluoride ion release from the FV. The flavor oil density was lower than that of deionized water, so the fluoride ions in the FV were able to diffuse out.[19] Future investigations are needed to test fluoride release from peppermint FFV into artificial saliva to better simulate the actual conditions in the oral cavity. FFV made with flavor oils with densities lower than that of saliva are likely to give the best results for fluoride ion release into the oral cavity.

Peppermint flavor oil gave the best fluoride release when supplied at a concentration of 2.5%. This result can be explained by a decrease in the density and viscosity of the FFV with increasing concentrations of peppermint oil and a resulting increase in the diffusion of fluoride ions into the deionized water. The addition of peppermint flavor oil at 1—2.5% resulted in a concentration-dependent release of fluoride ions. Analysis of the data from the different peppermint oil concentrations revealed a similar cumulative release of fluoride ions at each test time. Therefore, the addition of peppermint flavor oil at a concentration range of 1—2.5% would be expected to promote fluoride release into the oral cavity from FVes applied to teeth. Besides the addition of flavor oil in a certain range concentration, other studies used calcium phosphate as an agent in promoting fluoride release from FV.[20],[21]

  Conclusion Top

The addition of different flavor oils to FVs had an effect in increasing fluoride ion release over time into deionized water. Peppermint flavor gave the highest fluoride ion release compared with the other flavor because of its lowest flavor oil density that affected the final matrix of FV. Increasing the concentration of peppermint flavor oil from 1% to 2.5% resulted in a concentration-dependent increase in fluoride ion release from the varnish. This research needs further investigations conducted in artificial saliva, as this will provide data that more closely reflect the actual conditions in the oral cavity.

  Acknowledgments Top

This research was funded by the Ministry of Research and Technology Republic of Indonesia and Universitas Indonesia through PDUPT Grant with Grant Number NKB-2785/UN2.RST/HKP.05.00/2020.

Financial support and sponsorship


Conflicts of interest

The authors declare no conflicts of interest.

  References Top

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Forssten SD, Björklund M, Ouwehand AC. Streptococcus mutans, caries and simulation models. Nutrients 2010;2:290-8.  Back to cited text no. 8
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  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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