Current status of fluoride concentration and information labeling of oral hygiene products on the Korean market

Introduction

The market growth rate of quasi-drug products in the market has been the highest in the last 3 years. In 2019, the output of quasi-drug products increased by 14.5%, compared with that in 2018; furthermore, the number of production companies and items increased by 14% and 8.8%, respectively [1]. Among all the product groups, toothpaste was listed top in output, and seven oral hygiene products were included in the top 10 items [1]. Since 2016, the sales rate of oral hygiene products has steadily increased. The most frequently used oral hygiene products are mouthwash, dental floss, and toothpaste.

As mentioned above, oral hygiene products are a top product in the output group, indicating that maintaining good oral health is closely associated with a good quality of life. Growing concerns regarding overall health care have led to this phenomenon;, thus, providing accurate information to consumers is essential.

According to the World Dental Federation/International Organization for Standardization (FDI/ISO), toothpaste is defined as a substance used with a toothbrush to cleanse the tooth surface. Ingredients in toothpaste function as abrasive agents and preservatives and have medicinal properties [2].

Fluoride is the most commonly used active ingredient in toothpaste because of its caries-preventive effect. Its effects have been studied since 1940, and an attempt has been made to include fluoride compounds in toothpaste. A research team from Indiana University found that fluoride compounds in acidic environments reduced enamel solubility. Early clinical experimental results showed that fluoride compounds markedly reduced the incidence of dental caries [3].

Toothpaste was first introduced in South Korea in 1889 by the Lion Corporation of Japan. The first toothpaste, “Lucky” was released by LakHee Chemistry in 1954 [4]. However, the forms, functions, effects, and quality of toothpaste have changed since then. In 1970, the first fluoride toothpaste, containing sodium monofluorophosphate (SMFP), for children was released. The first adult toothpaste containing fluoride compounds was released in 1975. In 1985, a toothpaste containing both SMFP and sodium fluoride (NaF) was released. In 1990, the use of fluoride compounds was popularized in South Korea [5].

Among all the functions of toothpaste, preventive measures are very important. Fluoride compounds serve as the main components of anti-cavity function. The incidence of dental caries has started to decrease significantly in developing countries, and many preventive dentistry specialists state that the daily use of fluoride toothpaste is the main contributor to this [6]. Domestic toothpaste products usually contain fluoride compounds in the form of NaF or SMFP. NaF-containing toothpaste releases free fluoride ions (F-), which are responsible for the anti-cavity effect. Similarly, F- and fluorophosphate ions (PO3F2) are released from the SMFP-containing toothpaste. NaF is known to be more effective than SMFP [7]. According to domestic manufacturing standards, toothpaste can contain up to 1,500 ppm of fluoride; however, the limit usually used was 1,000 ppm, and it was adjusted to 1,450 ppm in 2014 [8]. According to Tanya et al.[9], compared with non-fluoride toothpaste, those with a fluoride concentration of 1,000 ppm suppressed the increase in DMFS in all age groups. Thus, it is necessary to classify toothpaste using a fluoride concentration of 1,000 ppm as the cutoff.

Fluoride compounds are also included in other oral hygiene products, such as mouthwash, dental floss, and toothbrushes. Mouthwash is used for a variety of purposes, such as to treat periodontitis, stomatitis, and bad breath; for disinfection after a procedure such as tooth extraction and implantation; and for dental caries prevention, aside from everyday disinfection of the mouth and throat and for cold prevention [10]. NaF, a fluorine compound in mouthwash for the prevention of dental caries, has been used worldwide since its efficacy in dental caries prevention was demonstrated by the American Dental Association (ADA) in 1960 [11]. Dental floss is an oral hygiene product that is effective in removing plaque between the teeth [12]. Flatt et al.[13] reported that fluoridated dental floss increased salivary fluoride levels for 30 min, thus effectively promoting the remineralization process. Fluoridated toothbrushes are products that contain fluoride. A fluoridated toothbrush releases fluoride from the bristles and is a product for individuals not using toothpaste due to allergy to a toothpaste component or not using fluoride-containing toothpaste due to concern over fluorosis. Zimmer et al. [14] showed that F- are released immediately after brushing by incorporating fluoride compounds into a toothbrush. F- can be incorporated into diverse products and can help protect individuals who are at a high risk of developing dental caries.

There are many factors to consider when choosing oral hygiene products, especially regarding fluoride concentration. There are numerous options, ranging from non-fluoride to high-fluoride products.

This study was conducted to survey the currently available fluoride-containing oral hygiene products in Korea to provide consumers with information regarding the concentration and form of fluoride in each product and to determine whether the information was easy to understand. As a result, by confirming the fluoride concentration in oral hygiene products, we would like to identify improvements to prevent dental caries and propose information on fluoride concentrations to help consumers choose oral hygiene products.

Methods

1. Materials

According to the Korea Ministry of Food and Drug Safety (MFDS), there are approximately 3,000 types of oral hygiene products on sale, including 12 types of oral hygiene tissue, 257 types of mouthwash, and 2,796 types of toothpaste products [15]. In this study, fluoride-containing oral hygiene products available to the general public were searched on the internet, and those sold in supermarkets and pharmacies in Gwangju Metropolitan City were purchased. As a result, 64-types of fluoride-containing oral hygiene products were selected, which were purchased from an offline market: one type of dental floss, two types of toothbrushes, four types of fluoride applicant, five types of mouthwashes, and 52 types of toothpaste. Of the study materials, fluoride applicant is an over-the-counter medical device that individuals apply to coat their teeth with fluoride ions using a tray for dental remineralization. The selected oral hygiene products were tested for the presence of fluoride compounds and their concentrations.

2. Methods

1) Analysis of fluoride concentration in toothpaste

The fluoride concentration, type, and labeled information status of 52 types of toothpaste were analyzed. Data for fluoride types and concentrations were collected by observing the product box and the online website of the MFDS. Each purchased toothpaste sample was checked for the location of the labels.

2) Analysis of fluoride concentration in mouthwash products

Five types of mouthwash products were analyzed for their fluoride concentrations and forms. The fluoride concentration in the mouthwash was determined using a fluoride electrode (Orion ionplus Fluoride Electrode 9609, Orion Research, Beverly, USA) and an ion analyzer (Expandable ionAnalyzer 940, Thermo Orion, Beverly, USA). One milliliter of 0.5, 1, 5, 10, 50, and 100 ppm diluted fluoride standard solution (Fluoride Standard, Thermo Electron Co., Beverly, USA) and 1 ml of TISAB II (Total Ionic Strength Adjustment Buffer II with CDTA, Thermo Fisher Scientific, Chelmsford, USA) solution were mixed in a 1:1 ratio, and their values were measured. A standard curve was constructed to determine the significance of the values.

3) Analysis of other oral hygiene products

One type of dental floss, two types of toothbrushes, and four types of fluoride applicant were checked for information label status. Data were collected by observing the box and the online websites of the MFDS.

Results

1. Fluoride concentration in toothpaste

In the 52 kinds of toothpaste examined in this study, the fluoride concentrations varied widely. Seven toothpastes for kids contained 290-1,000 ppm fluoride as either NaF or SMFP <Table 1>, and 45 toothpastes for adults contained 132-1,450 ppm fluoride as either NaF or SMFP <Table 2>.

Label locations of fluoride concentrations varied among the toothpastes. Some products had labels on the outside portion of the box, whereas others had labels on the toothpaste tube. Some products had labels both inside and outside the box, but others included information only in one location <Table 1, 2>.

Toothpaste products are classified into three groups based on fluoride concentration: below 1,000 ppm, 1,000 ppm, and above 1,000 ppm. Toothpaste containing 1,000 ppm of fluoride compounds accounted for the largest portion (61.5%). Toothpaste containing below 1,000 ppm fluoride accounted for 34.6% of all toothpastes surveyed, while 3.9% of the toothpastes surveyed had fluoride concentration above 1,000 ppm <Table 3>.

2. Fluoride concentration in mouthwash products

Five mouthwash products were examined, and they contained 99-240 ppm fluoride (in the form of NaF) <Table 4>. The highest concentration was found in Listerine natural green tea mild (240 ppm), and the lowest was in All care gargle (99 ppm). Only two of these mouthwashes displayed the fluoride concentration on the label <Table 4>.

3. Other oral hygiene products

The seven oral hygiene products contained fluoride in either NaF or HF forms. Information regarding the fluoride concentration was shown on the labels in only three products <Table 5>.

Discussion

This study examined the concentration and form of fluoride in fluoride-containing oral hygiene products sold in Korea. First, the fluorine compounds contained in the 52 kinds of toothpaste were either NaF or SMFP. The concentrations ranged from 132 to 1,450 ppm. Among them, toothpaste containing 1,000 ppm of fluoride compounds accounted for the largest portion (61.5%). Toothpaste products containing below and above 1,000 ppm fluoride accounted for 34.6% and 3.9%, respectively. Thus, the results revealed that toothpastes with fluoride concentrations above 1,000 ppm are rare in the market.

The European Commission on Consumer Product Safety stated that the anti-cavity effects of toothpaste vary according to fluoride concentration. A higher fluoride concentration has a greater anti-cavity effect than a lower fluoride concentration [16]. Furthermore, Walsh et al. performed a qualitative meta-analysis to evaluate the anti-cavity effect of fluorides. Compared to the control group, it was reported that the DMFT prevention rate of 1,000/1,055/1,100/1,250 ppm fluoride was 23%, and 2,400/2,500/2,800 ppm fluoride was 36%. In contrast, 440/500/550 ppm fluoride had no effect on the prevention of dental caries [17]. Although the limit was adjusted, its regulation differed between quasi-drug production standards and approval regulations. Despite the clinically proven effects of high fluoride concentrations, it can not be sold because of the difference in limitations [18]. In case of people with a high risk of dental caries, whose purpose is to prevent caries, high-fluoride-containing products are beneficial. It seems important to popularize high-fluoride-toothpaste so that a broader selection of toothpaste can be offered to consumers who are in need.

Label locations of fluoride concentrations varied between different toothpastes. Some products included labels on the outside portion of the box, whereas others were included on the toothpaste tube. Not only the location of the labels but also the number of labels were different for each product. Some products included labels both inside and outside the box, whereas others included information only in one location. Variations were observed within the same company. As can be seen from Table 2, GlaxoSmithKline consumer healthcare products and Sensodyne fresh gel toothpaste included labels only outside the box. On the other hand, Sensodyne Multicare or Parodontax daily fluoride toothpaste from the same company included the labels both on the tube and outside portion of the box. To maximize accessibility to information, manufacturers should include labels at both locations. Moreover, label sizes differed between products. one type of toothpaste label was large enough for consumers to recognize at a glance. However, the labels of other toothpaste were small; thus, it was difficult to obtain the requisite information by just looking. The label size should be larger to improve the readability.

Surprisingly, there was no place to find information about the fluoride concentration in oral hygiene products online. Although the MFDS provides information such as product name, manufacturer, and active ingredients, there was no exact value provided for fluoride concentration. Therefore, consumers must go offline and rely only on labels located on the product box. Official websites should provide online information so that consumers can access data on fluoride concent ration prior to purchasing products.

Five mouthwash products containing 99-240 ppm fluoride in the form of NaF were examined. According to the Centers for Disease Control and Prevention (CDC), the fluoride concentration of mouthwash products for daily rinsing and caries prevention is 0.05% NaF solution (230 ppm) [19]. ChikaChika mouthwash (230 ppm fluoride) and Listerine natural green tea mild (240 ppm fluoride) met the CDC standards. The other three types of mouthwash products (All care gargle (99 ppm fluoride), Garglin original (115 ppm fluoride), Perioe total 7 strong mint flavor (140 ppm fluoride)) contained less than 230 ppm fluoride. To promote anti-cavity effects, increasing the fluoride content in mouthwash products is suggested. In three out of five mouthwashes no information on fluoride concentration was found on the label. To help consumers make choices, such information should be provided on product labels.

Campus et al.[20] reported that the fluoride concentration in saliva increased after the use of toothpaste and mouthwash containing fluoride. This finding demonstrates the effect of fluoride in toothpaste and mouthwashes, not only that after topical application to tooth surfaces but also that following the elevation of salivary fluoride concentration. In a study by Flatt et al.[13], salivary fluoride concentration was elevated for 30 min after the use of fluoride-containing dental floss, suggesting the release of fluoride from the floss. Therefore, increased salivary fluoride concentration after the use of a fluoride-containing toothbrush or dental floss may be effective in preventing dental caries and causing tooth remineralization.

The seven other oral hygiene products contained fluoride in either NaF or HF form. In only three products, information regarding the fluoride concentration was shown on the label. Fluoride concentration should be specified on the product labels of all dental hygiene products, including mouthwashes, to provide consumers with correct information. Toothpaste and mouthwash products are classified as quasi-drug products, whereas dental floss, tongue cleaners, and toothbrushes are classified as industrial products [21]. According to the Ministry of Health and Welfare (MOHW), there are an average of 51 complain reports to the Korea Consumer Agency (KCA) annually. Of all complaint reports, 62.5% were product-related problems, including hazardous contaminants or lacerations related to product use [22]. The 14-year-old and older age group reported 50% of the total complaints, indicating that it is not just a matter of children’s safety issues. The safety management of industrial products seems inadequate, and stricter regulations are suggested. Additionally, for consumer convenience, standardized information regarding fluoride concentration should be provided on the product label as well as online for all dental hygiene products, as this practice will help prevent consumer complaints.

There are approximately 3,000 types of commercial domestic products. In this study, the number of oral hygiene products studied was significantly small so as to represent all commercial products; however, this investigation is meaningful. There have been many studies on the effects of fluoride and its contents; however, there have been no studies on the information status for the practical use of oral hygiene products. In the future, studies with larger sample size and more detailed methodology will result in more reliable data.

Conclusions

This study was conducted to survey the currently available fluoride-containing oral hygiene products in Korea to provide consumers with information regarding the concentration and form of fluoride in each product and to determine whether the information was easy to understand. Thus, confirming fluoride concentration in oral hygiene products and providing this information on the product labels can aid customers in selecting the appropriate oral hygiene products, thus helping to prevent dental caries.

Studying the 64 types of domestic commercial oral hygiene products purchased from an offline market and evaluated, we found the following:

1. Domestic commercial toothpaste products contain fluoride in the form of NaF and SMFP. In this study, toothpaste containing 1,000 ppm of fluoride compounds accounted for the largest proportion (61.5%); toothpastes with fluoride concentration below 1,000 ppm accounted for 34.6% and those with concentrations above 1,000 ppm, for 3.9%. Therefore toothpastes with fluoride concentrations above 1,000 ppm have not been popularized domestically.

2. Mouthwash products contained less than 300 ppm fluoride concentration. For daily-use purposes, mouthwash products should contain 0.05% NaF (230 ppm). In this study, ChikaChika mouthwash and Listerine natural green tea mild mouthwashes met the standards. Of the five types of mouthwash products, only two included labels indicating fluoride concentration.

3. Location of the labels indicating fluoride concentration differed between manufacturers and even within the same manufacturer.

4. There was no information regarding fluoride concentration available online.

According to the results above, it seems important to popularize high-fluoride toothpaste so that a broader selection of toothpaste can be offered to consumers who are in need. Furthermore, it is considered that improvements should be made to the information-labeling system. Standardized information should be provided for consumer convenience to aid in choosing appropriate oral hygiene products.