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International Dental Journal logoLink to International Dental Journal
. 2020 Nov 6;62(4):213–221. doi: 10.1111/j.1875-595X.2012.00116.x

Total and free available fluoride in toothpastes in Brunei, Cambodia, Laos, the Netherlands and Suriname

Habib Benzian 1,*, Christopher Holmgren 2, Mark Buijs 3, Cor van Loveren 3, Fridus van der Weijden 4, Wim van Palenstein Helderman 5
PMCID: PMC9375049  PMID: 23017004

Abstract

Objectives: This study assessed total and free fluoride concentrations in samples of toothpaste from Brunei, Cambodia, Laos, the Netherlands and Suriname, and investigated the labelling practices of the respective manufacturers. Materials and methods: Convenience samples were bought in the five countries and sent for analysis to the Netherlands. Levels of total and free available fluoride were measured. Details of the information declared on the packaging about type of fluoride and abrasives were recorded, and manufacturing and expiry dates were noted. Results: A total of 119 samples of toothpaste were analysed. With one exception, all samples from the Netherlands complied with ISO (International Organisation for Standardisation) labelling requirements and there were no differences between the fluoride content declared and that found to be present on analysis. In samples purchased in the other countries, sodium monofluorophosphate (SMFP) toothpastes predominantly showed a low percentage of free available fluoride and the majority of toothpastes did not follow standard labelling guidelines. Discussion: This study is not representative of any of the brands analysed, yet it highlights problematic discrepancies in products across countries. These may be related to the lack of a generally accepted methodology for analysing total and free fluoride content, absence of an agreement on the minimum concentration of fluoride required to ensure efficacy, weak regulating institutions that are unable to control labelling and consumer information, as well as a possible influx of counterfeit low-quality toothpaste. Conclusions: Renewed international focus should be directed towards closing gaps in guidelines and standards. Consumers should use only non-expired toothpaste, which should preferably be silica-based fluoride toothpaste that does not include abrasives containing calcium and that is properly labelled.

Key words: Fluoride toothpaste, free available fluoride

INTRODUCTION

The global epidemic of dental decay affects > 90% of the world’s population; 40–90% of 12-year-olds suffer from dental decay and its consequences, such as pain, chronic infection, absenteeism from school, and physical and learning problems, as well as low quality of life. In low-income countries, almost all dental decay remains untreated1., 2..

A group of experts convened in Geneva for the Global Consultation on Oral Health through Fluoride (2006) stated that ‘prevention by using fluoride is the only realistic way of reducing this [caries] burden in populations’3. A subsequent call to action emanating from a joint meeting of the World Health Organisation (WHO), FDI World Dental Federation and International Association for Dental Research (IADR) in Beijing in 2007 stated that:

  • •

    ‘Fluoride toothpaste remains the most widespread and significant form of fluoride used globally and the most rigorously evaluated vehicle for fluoride use’4

  • •

    ‘The effectiveness of fluoride toothpaste has been assessed since the 1940s in over 100 clinical trials and the anti-tooth decay (anti-caries) efficacy of fluoride toothpaste has been confirmed’4

  • •

    ‘Fluoride toothpaste is safe to use irrespective of low, normal or high fluoride exposure from other sources’4.

This call to action strongly recommends the promotion of effective fluoride toothpaste for the mass prevention of tooth decay. In this context, the issue of the effectiveness of fluoride toothpaste is of paramount importance.

Some of the earliest fluoride toothpastes tested in clinical trials in the 1940s and 1950s were not effective against caries5., 6., 7.. These findings, which were not understood at the time, were later explained as resulting from the formation of insoluble calcium fluoride (CaF2) caused by the reaction of free F− with chalk-based abrasives8. For fluoride toothpaste to be effective, it must contain an appropriate concentration of free available fluoride. This implies that added fluoride is not chemically bound to other ingredients in the toothpaste. In toothpastes with NaF, NH4F and SnF2, the fluoride compounds are not compatible with abrasives that contain calcium [e.g. calcium carbonate (CaCO3), dicalciumphosphate (dehydrate) (DCPH), calcium glycerophosphate (CGP), tricalciumphosphate (TCP)]. By contrast, in sodium monofluorophosphate toothpaste [SMFP (Na2PO3F)], the PO3F2− component has greater compatibility with calcium-containing abrasives. This is because in PO3F2− the fluoride is firmly bound to the phosphate and therefore cannot bind to soluble calcium to form insoluble calcium fluoride9.

In the oral cavity, the protective action in SMFP toothpastes results either from the direct effect of the PO3F2− group or from the release of fluoride by hydrolysis in the oral cavity10., 11..

A previous study of toothpastes purchased in low-income countries found that in 25% of the toothpastes, < 55% of the declared fluoride was in free available form12. A study in Brazil reported that 13 out of 14 SMFP toothpastes with calcium-containing abrasives used by children contained 15–50% less free available fluoride than the total fluoride content. By contrast, in all the NaF toothpastes with silica abrasive, almost all the fluoride was available in free (ionised) form13. These findings raise questions about the compatibility of a PO3F2− component with calcium-containing abrasives.

Another important issue relevant to the quality of fluoride toothpaste concerns the provision of consumer information through correct labelling. Standards in this context are defined by the International Organisation for Standardisation (ISO) in its standard ISO 11609 (2010). However, huge variations in compliance with ISO labelling requirements are seen in different brands of fluoride toothpaste12.

The present study aimed to assess labelling practices, as well as the amount of total and free available fluoride in samples of fluoride toothpastes purchased in Brunei, Cambodia, Laos, the Netherlands and Suriname. Results are discussed and recommendations for improving toothpaste quality are made.

MATERIALS AND METHODS

Fluoride toothpaste samples

Samples of fluoride toothpastes were purchased in countries in which the present authors had reliable contacts who were able to collaborate and forward samples for analysis. Samples collected in the Netherlands included toothpastes intended for use by young children (< 5 years of age) (n = 27) and adults (n = 19); all were registered by the Keuringsdienst van Waren (Dutch Food and Drug Administration).

Fluoride toothpastes from Suriname (n = 18) were purchased in shops in the capital Paramaribo. Fluoride toothpastes from Brunei (n = 20) were purchased from a supermarket in the capital city Bandar Seri Begawan. In Cambodia and Laos fluoride toothpaste samples (n = 14 and n = 21, respectively) were purchased in the central market of the capital Phnom Penh, and in small shops in Vientiane, respectively.

Information provided on packaging

All toothpaste samples were checked for information provided on the packaging (either the outer carton or the tube itself). The country of production was recorded if available. The information on the package was checked for descriptive names of the fluoride component and its concentration in parts per million (ppm). If only the percentage w/w of NaF, SnF2 or Na2PO3F was declared, the parts per million F (ppm F) were calculated. Descriptive names of abrasives on the packaging were recorded. In toothpastes in which both silica and calcium-containing abrasives were declared, the calcium-containing abrasive was recorded. In two cases in which the date of production was declared on the package, the expiry date was recorded as three years later. If the expiry date was indicated, it was recorded. All tests for fluoride content were performed in the Netherlands within six months after purchase.

Total fluoride measurements

Closed toothpaste tubes were carefully squeezed in order to mix the contents. The tubes were then opened and the first few grams of toothpaste to emerge from the tube were discarded. Two separate portions of 50 mg each were then squeezed from the tube for duplicate fluoride content measurements. Each of these two portions was diluted in 2 mL 1 m HCl and mixed thoroughly until no toothpaste visibly adhered to the vessel. The samples were mounted in an overhead rotator for one hour at 4 °C, after which 2 mL of toluene reagent was added. After overnight overhead rotation at 4 °C, samples of the toluene reagent phase were injected into a gas chromatograph (Gas Chromatograph CP9001; Chrompack International BV, Middelburg, the Netherlands) with a wide-bore injection system and two bore columns of 10 m and 25 m (WCOT fused silica with a coating of CP-SIL-5 CB). The toluene reagent was freshly made by mixing 90 mL toluene (Sigma-Aldrich GmbH, Steinheim, Germany) with 1 mL trimethylchlorosilane (Chrompack International BV) and 10 mL isopentane (Merck BV, Schiphol-Rijk, the Netherlands) stock solution of 0.1% isopentane in toluene12.

Measurements of free available fluoride

Approximately 4 g of the duplicate toothpaste samples were suspended in water at a 1:3 dilution and shaken with a stainless steel ball by hand for two minutes. Then the slurries were centrifuged (Eppendorf AG, Hamburg, Germany) for two minutes at 16,110 g and the supernatants collected. The supernatants were diluted at 1:20 with Milli Q water and treated with four units of acidic phosphatase (Sigma Chemical Co., St Louis, MO, USA) for each 12.5 mg of toothpaste. Acidic phosphatase was dissolved in a fresh mixture with final concentrations of 89 mm NaAc (Merck BV) and 116 mm glacial acetic acid (Merck BV) adjusted to pH 4.8 with potassium hydroxide (KOH). After digestion at room temperature for 24 hours, fluoride was measured with the fluoride electrode. Samples of the phosphatase supernatant mixtures were diluted with Tisab buffer [0.3 m potassium hydrogen phthalate (C8H5KO4), 0.21 m KOH, 1 m KNO3 (all chemicals from Merck BV)]. The fluoride ion was measured with a fluoride electrode (F1052F; Radiometer AS, Copenhagen, Denmark) connected to a digital pH meter (PHM 63; Radiometer AS). This method was used to measure all soluble fluoride; resulting fluoride measurements are referred to as measurements of free available fluoride.

RESULTS

The duplicate analysis of separately prepared samples and subsequent fluoride measurement revealed a duplicate measurement error [√∑(x1 – x2)2/2n] for the total fluoride measurement of 29 ppm F and for the free available fluoride measurement of 61 ppm F.

Most of the toothpastes for children aged < 5 years and adults in the Netherlands were NaF toothpastes, but seven toothpastes contained Na2PO3F and two contained Na2PO3F in combination with NaF. Four toothpastes contained NH4F. One toothpaste for children aged < 5 years declared a fluoride content of 260 ppm F but showed 239 ppm F in the test. Two toothpastes for young children that declared fluoride content of 400 ppm F were found to contain 356–374 ppm F in the test. All toothpastes for young children that declared fluoride content of 500 ppm F were found to show fluoride contents of 442–554 ppm F in the tests. All fluoride toothpastes for young children in the Netherlands (n = 27) contained > 70% free available fluoride except one brand (Table 1). The manufacturer of this brand adjusted the composition of the toothpaste after being informed that the free available fluoride was low. One adult toothpaste did not declare its fluoride content, which was shown on testing to be 760 ppm F. The five toothpastes declaring content of 1000 ppm F were found to contain 936–1082 ppm F, and the 11 toothpastes declaring content of 1100 ppm F were found to contain 1005–1078 ppm F. One toothpaste claiming 1350 ppm F contained 1303 ppm F, and one toothpaste stating 1400 ppm F contained 1306 ppm F. All adult fluoride toothpastes (n = 19) contained > 90% free available fluoride (Table 2). The mean concentration of free available fluoride in all toothpastes obtained in the Netherlands was 94%.

Table 1.

Results of analyses of fluoride toothpastes for children aged < 5 years purchased in the Netherlands in January 2006 and analysed in February 2006

Lab no. Label F compound on label ppm F calculated Total ppm F in analysis % free F of total in analysis
1 Edah Duck Toddler NaF 260 239 77
2 Colgate My First 0–6 NaF 400 356 100
3 Colgate My First 0–6 NaF 400 374 100
4* Kruidvat Toddler NaF 500 442 41
5 Trekpleister Kids 44240742 NaF, Na2PO3F 500 489 90
6 Trekpleister Kids 44396343 NaF, Na2PO3F 500 454 100
7 Trekpleister Toddler 44398788 NaF 500 458 100
8 TheraMed Junior NaF 500 449 89
9 DA Toddler toothpaste NaF 500 492 97
10 DA Toddler 44240416 NaF 500 493 94
11 DA Toddler 44398494 NaF 500 472 99
12 Zendium Toddler NaF 500 482 79
13 Zendium Toddler Mice NaF 500 468 73
14 Elmex Toddler NH4F 500 456 96
15 Prodent Toddler Tinky Winky NaF 500 489 80
16 Sensodyne Sesamstr Junior 0–5 Na2PO3F 500 537 100
17 EtosToddler 44221845 NaF 500 459 86
18 Etos Toddler 44397986 NaF 500 457 95
19 Edah Mildfris for Kids NaF 500 452 94
20 Schlecker AS-dent NH4F 500 480 76
21 Schlecker AS-dent Framboos NaF 500 554 71
22 AS-dent Softmint NH4F 500 537 72
23 AS-dent Framboos NaF 500 474 84
24 HEMA Jip & Janneke NaF 500 454 100
25 HEMA Everclean Child 0–4 NaF 500 480 81
26 Oral B Stages NaF 500 462 100
27 Periodent Zahngel fur Kinder Na2PO3F 500 506 100
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*

Later adjusted by the producer and not included in the calculation of the mean.

Table 2.

Results of analyses of adult fluoride toothpastes purchased in the Netherlands in January 2006 and analysed in February 2006

Lab no. Label F compound on label ppm F calculated Total ppm F in analysis % free F of total in analysis
28 Snoopy Na2PO3F ? 760 100
29 DA Junior 44240432 Na2PO3F 1000 993 100
30 DA Junior 44398516 Na2PO3F 1000 978 100
31 Oral B Stages NaF 1000 1082 100
32 Kauboy Happy Minze NaF 1000 972 100
33 Kauboy Happy Frucht NaF 1000 936 100
34 Colgate Bugs Bunny 44240297 NaF 1100 1036 100
35 Colgate Bugs Bunny 44399458 NaF 1100 1022 100
36 Colgate Tweety NaF 1100 1039 100
37 HEMA Jip & Janneke 5–12 NaF 1100 1022 97
38 HEMA Space Boyz 5–12 NaF 1100 1007 100
39 HEMA Shiny Girlz 5–12 NaF 1100 1015 100
40 Kruidvat Ultradent Junior NaF 1100 1005 100
41 Oral B Stages Fruit power rangers NaF 1100 1078 94
42 Prodent Rocket Power 44396025 NaF 1100 1027 98
43 Prodent Rocket Power 44399687 NaF 1100 1015 100
44 Prodent Rocket Power 44399695 NaF 1100 1032 100
45 Aquafresh Junior mild & minty NaF 1350 1303 92
46 Elmex Junior 5–12 NH4F 1400 1306 100
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Information on and test results for toothpastes from Brunei, Cambodia, Laos and Suriname are presented in Table 3, Table 4, Table 5, Table 6. In total, 73 toothpastes were tested, including five toothpastes for young children from Laos with a declared fluoride content of 500 ppm F (a calculated 498–501 ppm F). In two cases the country of manufacture could not be retrieved from the information on the package. The expiry or production date could only be retrieved from 21 of the 73 toothpastes. Six of these toothpastes had an expiry date that was < 1 year from the date of purchase. The packaging of 13 of the 73 toothpastes contained no information on the abrasive. Seventeen toothpastes did not declare the fluoride concentration. Three of the toothpastes declared to be fluoride toothpastes did not contain any fluoride and another three contained < 300 ppm F. The remaining 67 toothpastes, except the five toothpastes for children aged < 5 years from Laos, contained 899–1659 ppm F according to the tests. Of the remaining 67 toothpastes including the five toothpastes for young children, 37 contained Na2PO3F and 30 contained only NaF. Of the 37 toothpastes containing Na2PO3F, 17 had < 50% free available fluoride (Table 7). With one exception these 17 Na2PO3F toothpastes contained calcium-based abrasives according to the information on the package. The mean concentration of free available fluoride in Na2PO3F toothpastes with a calcium-containing abrasive was 53.2%, which was statistically significantly lower than the mean free available fluoride concentration of 90.4% in NaF toothpastes with silica (Student’s t-test, P < 0.001) (Table 7). The mean concentration of free available fluoride in NaF toothpastes that did not declare an abrasive was 95.7%. All 30 NaF toothpastes contained > 70% free available fluoride and only eight contained 70–80% free available fluoride.

Table 3.

Results of analyses of fluoride toothpastes purchased in Brunei in November 2007 and analysed in March 2008

Lab no. Label Country of manufacture Expiry date Abrasives F compound on label ppm F calculated Total ppm F in analysis % free F of total in analysis
301 Ciptadent Lion Corp Indonesia ? CaCO3 Na2PO3F 0.8%, NaF 0.01% 1101 1049 61
302* Follow me Earth Chemical Japan Malaysia ? CaCO3 Na2PO3F%? ? 167 55
303 Jaifun Malaysia ? DCPD Na2PO3F%? ? 922 51
304 Systema Lion Corp Japan ? Silica NaF%? ? 978 71
305 Sensodyne freshmint GSK Australia 0309 Silica NaF 0.32% 1448 1364 86
306 Colgate Kayu Sugi China 0810 CaCO3 Na2PO3F 1.1% 1451 1450 71
307 Colgate Fresh Thailand 0810 Silica NaF 0.221% 1000 962 74
308 Pepsodent Whitening Unilever Indonesia ? CaCO3 Na2PO3F 0.8% 1056 1114 46
309 Sensitive Church & Dwight Canada ? ? NaF 0.243% 1099 1095 84
310 Siwaki F Indonesia ? CaCO3 Na2PO3F 0.7% 924 1109 37
312 Colgate Total 12 Thailand 0710 Silica NaF 0.22% 995 1023 72
313 Smile Up Lion Corp Indonesia ? Silica Na2PO3F 0.8%, NaF 0.01% 1101 1035 81
314 Pepsodent Herbal Unilever Indonesia ? CaCO3 Na2PO3F 0.8% 1056 1109 35
317 Colgate PCP regular flavour Thailand 1109 DCPD Na2PO3F 0.76%, NaF 0.1% 1455 1441 43
318 Colgate PCP Cool mint Thailand 0610 DCPD Na2PO3F 0.76%, NaF 0.1% 1455 1509 38
319 Pepsodent Gum Care Unilever Indonesia ? Silica NaF 0.32% 1448 1312 75
320 Pepsodent Pencegah Unilever Indonesia ? CaCO3 Na2PO3F 1.18% 1557 1659 60
321 Darlie Hawley & Hazel China 0910 Silica NaF%? ? 977 79
322 Sensodyne Gum Care GSK Thailand 0209 Silica NaF 0.221% 1000 1065 84
323* Safi Malaysia 0210 CaCO3 Na2PO3F%? ? 266 31
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*

Not included in the calculation of the mean percentage of free fluoride.

DCPD, dicalciumphosphate dihydrate.

Table 4.

Results of analyses of fluoride toothpastes purchased in Cambodia in August 2007 and analysed in November 2007

Lab no. Label Country of manufacture Expiry date Abrasives F compound on label ppm F calculated Total ppm F in analysis % free F of total in analysis
253 Colgate Max Fresh Cooling Crystals Thailand 0510 Silica NaF 0.22% 995 1001 93
254 Colgate Herbal China ? CaCO3 Na2PO3F 0.76% 1003 1123 44
255 Colgate Herbal salt Thailand ? CaCO3 Na2PO3F 0.76% 1003 979 100
256 Colgate Proven Cavity protection blue Thailand ? DCPD Na2PO3F 0.76% 1003 1008 78
257 Colgate Proven Cavity protection green Thailand ? DCPD Na2PO3F 0.76% 1003 1127 68
258 Colgate Double Cool Stripe Thailand ? ? NaF 0.22% 995 1029 91
259 Close up Unilever Fluo-active Vietnam 0810 Silica NaF 0.22% 995 950 100
260 Close up Unilever Milk Calcium Vietnam 0210 Silica NaF 0.22% 995 933 100
261 Close up Unilever Crystal White Vietnam ? Silica NaF 0.22% 995 933 100
262 Darlie Full Fluoride Protection China ? DCPD Na2PO3F%? ? 1015 46
263 Darlie Fresh’s Brite China 1009 Silica NaF%? ? 1019 100
264 Darlie Double Action Thailand ? DCPD Na2PO3F 0.76% 1003 1124 63
268 Lucky Kids Strawberry Flavor Korea ? CGP Na2PO3F 0.76% 1003 1013 100
269 Pepsodent Unilever ? 0209 CaCO3, CGP Na2PO3F%? ? 1559 31
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DCPD, dicalciumphosphate dihydrate; CGP, calcium glycerophosphate.

Table 5.

Results of analyses of fluoride toothpastes purchased in Laos in August 2007 and analysed in November 2007

Lab no. Label Country of manufacture Expiry date Abrasives F compound on label ppm F calculated Total ppm F in analysis % free F of total in analysis
228 Colgate Total 12 hours whitening gel Thailand ? Silica NaF 0.22% 995 961 98
229 Colgate Total 12 Fresh Stripe Thailand ? Silica NaF 0.22% 995 987 95
230 Colgate Max Fresh with Cooling Crystals Peppermint Ice Thailand ? Silica NaF 0.22% 995 982 100
231 Colgate Max Fresh with Cooling Crystals Minty Blast Thailand ? Silica NaF 0.22% 995 936 100
232 Colgate Herbal salt Thailand ? CaCO3 Na2PO3F 0.76% 1003 899 100
233 Colgate Proven Cavity protection-Great regular flavour blue Thailand ? DCPD Na2PO3F 0.76% 1003 990 52
234 Colgate Proven Cavity protection-Fresh cool mint green Thailand ? DCPD Na2PO3F 0.76% 1003 1120 49
235 Colgate Fresh Confidence A Verifiere Thailand ? ? NaF 0.221% 1000 944 100
236 Colgate Double Cool Stripe Thailand ? ? NaF 0.22% 995 989 100
237 Colgate Herbal white Vietnam ? CaCO3 Na2PO3F 0.76% 1003 991 100
238 Sensodyne Original GSK Thailand 0808 ? NaF 0.22% 995 971 96
239* Sensodyne Cool Gel GSK Thailand 0709 ? SnF2%? ? 0 –
240 Darlie Double action License China Thailand ? TCP Na2PO3F 0.76% 1003 1050 79
241 Darlie Tea care License China Thailand ? ? NaF 0.22% 995 967 98
244 Close up Unilever Milk Calcium Vietnam ? Silica NaF 0.22% 995 979 96
245 Close up Unilever Menthol Chill Vietnam ? Silica NaF 0.22% 995 966 87
246 Kodomo Lion Japan Children Xylitol Plus Toothpaste orange flavour Thailand ? ? NaF 0.11% 498 491 94
247 Kodomo Lion Japan Children Xylitol Plus Toothpaste grape flavour Thailand ? ? NaF 0.11% 498 492 94
248 Kodomo Lion Japan Children Gel Toothpaste bubble fruit flavour Thailand ? ? NaF 0.11% 498 472 100
249 Kodomo Lion Japan Children Gel Toothpaste strawberry flavour red Thailand ? ? Na2PO3F 0.38% 501 498 100
250 Kodomo Lion Japan Children Gel Toothpaste strawberry flavour pink Thailand ? ? NaF 0.11% 498 484 100
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*

Not included in the calculation of the mean percentage of free fluoride.

DCPD, dicalciumphosphate dehydrate; TCP, tricalciumphosphate.

Table 6.

Results of analyses of fluoride toothpastes purchased in Suriname in August 2007 and analysed in November 2007

Lab no. Label Country of manufacture Expiry date Abrasives F compound on label ppm F calculated Total ppm F in analysis % free F of total in analysis
274 Colgate Maximum Cavity Protection Dominica 0508 DCPD Na2PO3F, NaF %? ? 1438 23
275 Colgate Proven Cavity Protection Thailand 0508 DCPD Na2PO3F 0.76%, NaF 0.1% 1455 1460 49
276 Colgate Herbal Brazil ? CaCO3 Na2PO3F 1.1% 1451 1566 52
277 Colgate China ? DCP Na2PO3F, NaF %? ? 1509 52
278 Maxam China ? Silica Na2PO3F %? ? 1242 13
279 Maxam Strawberry Children toothpaste China ? DCP Na2PO3F %? ? 1333 20
280 Maxam Gel Fresh China ? Silica Na2PO3F %? ? 1093 100
281 Maxam Freshmint China ? CGP Na2PO3F 0.8% 1056 1074 100
282* Maxam Whitening China ? Silica Na2PO3F %? ? 0 –
283* Maxam Spearmint Flavor China ? Silica Na2PO3F %? ? 0 –
285* Maxam Triple Action contains China ? ? NaF%? ? 245 33
286 Pepsodent Bi-Calcio-Activ contains Chile ? CaCO3 Na2PO3F 1.14% 1504 1614 15
287 Pepsodent Peppermint Unilever contains Chile ? Silica Na2PO3F 0.8% 1056 1027 100
288 Pepsodent Unilever ? ? CaCO3 Na2PO3F 1000 ppm F 1000 991 28
289 Pepsodent Bi-calcio-Activ Unilever contains Chile ? CaCO3 Na2PO3F 1.14% 1504 1567 13
290 Close-Up Septibucal Max Protection Unilever contains Chile 1107 Silica NaF 0.32% 1448 1475 98
291 Close-Up Septibucal Max Protection Unilever contains Chile 0308 Silica NaF 0.32% 1448 1422 100
292 Contente Plus Menta Brazil 0907 CaCO3 Na2PO3F 1500ppm F 1500 1591 39
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*

Not included in the calculation of the mean percentage of free fluoride.

DCPD, dicalciumphosphate dehydrate; DCP, dicalciumphosphate; CGP, calcium glycerophosphate.

Table 7.

Mean percentage of free fluoride in Na2PO3F and NaF toothpastes with various abrasives from low-income countries and the number of these toothpastes with a free fluoride content of < 50% of total fluoride content

Type of toothpaste n Free F, %, mean ± SE Toothpastes with < 50% free fluoride, n
Na2PO3F with calcium-containing abrasives 32 53.2 ± 4.3 16
Na2PO3F with silica or unknown abrasives 5 78.8 ± 19.1 1
NaF with silica 20 90.4 ± 2.4 0
NaF with unknown abrasives 10 95.7 ± 1.6 0
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SE, standard error.

DISCUSSION

Limitations of the study

The study has several limitations and therefore its results should be interpreted with caution. These limitations include:

  • •

    Sampling: the toothpaste samples included in the study were not obtained in a systematic manner. Because of the small sample size and the geographical focus of the five countries selected, the results cannot be considered representative of fluoride content or labelling quality of any particular brand. Labelling in particular can show large variations from country to country. Although we list the respective brand names in the result tables, we do not imply that other samples of these brands, or the brand overall, would show the same results in further analysis

  • •

    Analysis methodology: currently, there is no standardised methodology to measure free available fluoride concentrations in toothpaste. The description of a testing method, originally included in ISO Standard 11609, was taken out of the standard and is subject to further work by an ISO subcommittee. The methodology used in this study may thus differ from methods used by other laboratories or the manufacturers themselves

  • •

    Genuine and fake products: it has become increasingly complicated, if not impossible, to distinguish between a genuine and a counterfeit product. Labelling and packaging are all too often copied so accurately that even experts have difficulty in clearly identifying fake products. It is thus possible that some of the samples included in the study are in fact fake products. Although this would be an important finding with far-reaching consequences for consumers, national regulatory bodies and manufacturers, we can neither exclude nor confirm this assumption.

Despite these relevant limitations, the results strongly highlight critical problem areas related to fluoride toothpaste, particularly in countries in which regulatory and quality control systems for consumer products are weak.

Fluoride content and efficacy

The results showed that all but one of the fluoride toothpastes sampled from the Netherlands (both child and adult toothpastes) contained the declared amount and type of fluoride and these complied with ISO Standard 11609. The picture was quite different for toothpastes from the other four countries, 8% of which contained either only a very low level of fluoride or no fluoride at all.

All samples from the Netherlands contained comparable amounts of total and free available fluoride (again with just one exemption), whereas toothpastes from the other four countries, particularly SMFP toothpastes, showed a low percentage of free available fluoride. Possible reasons for the differences in concentrations of free available fluoride include, but are not limited to:

  • •

    Toothpastes that are produced locally through subcontracted companies of global manufacturers may not be produced correctly or may be inadequately controlled for quality

  • •

    Low-cost toothpaste may use cheaper ingredients (abrasives) to increase profit margins

  • •

    Large batches of toothpaste nearing its expiry date may be sold by unscrupulous distributors in countries with weak controls and regulation

  • •

    Toothpaste may have a slow turnover depending on country, shop location, season etc., resulting in lengthy shelf life and sales near or beyond the expiration date

  • •

    High storage temperatures may have a negative influence on the stability of toothpaste in tropical regions

  • •

    Counterfeit products that imitate recognised brands may be of low quality.

Five of the six non-Dutch fluoride toothpastes that contained either very little or no fluoride were local brand products; the sixth claimed to be a multinational toothpaste brand. Counterfeit products and medicines are a rapidly growing global problem. The WHO defines a counterfeit medicine as: ‘…one which is deliberately and fraudulently mislabelled with respect to identity and/or source. Counterfeiting can apply to both branded and generic products and counterfeit products may include products with the correct ingredients or with the wrong ingredients, without active ingredients, with insufficient active ingredients or with counterfeit packaging’14.

Although counterfeiting affects the toothpaste industry, the real extent of the problem is unknown. For example, counterfeit toothpaste falsely labelled as Colgate appeared on the market in Nigeria and Mozambique in 2007 and was found to contain potentially harmful concentrations of diethylene glycol15., 16.. It is therefore possible that some of the toothpastes from outside the Netherlands included in this study were indeed fake products. In this context it is worth mentioning that one toothpaste (no. 285), purchased in Suriname, was labelled as containing diethylene glycol, whereas five other toothpastes (nos. 286, 287, 289, 290 and 291) contained formaldehyde. In the European Union (EU), these chemicals are considered to be toxic and carcinogenic agents and are not allowed in toothpastes.

Although it is possible to maintain fluoride stability in toothpastes for > 3 years, studies have shown this is not always the case in commercially available toothpastes17., 18.. The belief that SMFP has the advantage of being compatible with chalk-based abrasives is still widespread19. A paper on the effective use of fluorides in the Bulletin of the WHO20 suggested precipitated calcium carbonate as the abrasive agent of choice because of its low cost and availability in developing countries. Reference was made to a clinical trial conducted under the auspices of the WHO in Indonesia. However, the paper21 describing this clinical trial admitted that calcium carbonate was not optimally compatible with the fluoride source in the toothpaste and argued that the formation of CaF2 in the SMFP toothpaste was prevented by the addition of a stabiliser to the toothpaste. Notwithstanding this latter statement the present study challenges the claimed stability of SMFP toothpastes with calcium-containing abrasives because 46% of the SMFP toothpastes from countries outwith the Netherlands contained < 50% free available fluoride. These findings are supported by several other papers. A study in Brazil showed that the percentage of free available fluoride in nine fresh SMFP toothpastes with calcium-containing abrasives was significantly lower than the mean percentage of free available fluoride in seven NaF toothpastes containing silica (mean free available fluoride: 81% in SMFP vs. 98% in NaF toothpastes)22. Toothpastes lose free available fluoride as they age and with increasing temperatures, particularly SMFP toothpastes with calcium-containing abrasives22., 23., 24., 25.. Studies have shown toothpastes to lose an average of 25% of free available fluoride after one year of storage at 22 °C, and a mean of about 35% of free available fluoride after one year of storage at 29 °C23., 25..

The literature indicates the existence of a statistically significant positive relationship between the caries protective effect and fluoride content in toothpastes with > 1100 ppm F26. Concentrations of 440 ppm F, 500 ppm F and 550 ppm F and below showed no statistically significant effect on dental caries compared with placebo27., 28.. However, the conclusion that the efficacy of toothpastes containing 440–550 ppm F does not significantly differ from that of placebo is based on the outcomes of only two trials, whereas the claim that toothpastes with 1500 ppm F had a preventive effect superior to that of toothpastes with 1000 ppm F is based on the findings of a considerable number of trials. Nevertheless, the literature does not provide conclusive information on which concentration of free available fluoride in toothpaste exerts the best anti-caries efficacy. Consequently, national and international guidelines for cosmetic products primarily deal with the total fluoride content of toothpastes and these state that this should not exceed 1500 ppm F. The only exception are the guidelines of the US Food and Drug Administration, which state that NaF and SMFP toothpastes containing 850–1150 ppm total fluoride should contain ≥ 650 ppm and ≥ 800 ppm available fluoride, respectively. The rationale for these values remains obscure29. The ISO Standard 11609 currently refers only to the total fluoride content of toothpaste and does not address the need to indicate the content of free available fluoride in toothpaste, although this is an essential requirement for anti-caries efficacy30.

The absence of requirements based on definitions of fluoride toothpaste efficacy in many current national and international guidelines leads to a situation in which even a toothpaste that contains only minimal quantities of free available fluoride would be considered a fluoride dentifrice, despite the lack of any anti-caries benefit.

Content declaration and labelling

Most of the toothpastes from the four non-Dutch countries did not indicate an expiry date on the package, and six of the 21 declared an expiry date of < 1 year from purchase. Information on expiry date is important because manufacturers do not guarantee the quality of toothpaste after expiry. Failure to provide an expiry or manufacturing date represents the withholding of essential information about the efficacy of the product from consumers. In fact, ISO Standard 11609 defines minimum labelling requirements that relate to expiry date, a full declaration of the fluoride type and amount contained and the type of abrasive. However, the large majority of fluoride toothpastes bought for the study in countries other than the Netherlands did not meet such requirements.

CONCLUSIONS

Toothpastes in the Netherlands have full anti-caries efficacy in accordance with declared total fluoride content. Many toothpastes in this sample from countries outwith the Netherlands, including those labelled as major brands, may have questionable anti-caries efficacy as a result of a lack of free available fluoride. Possible causes of this lack are discussed in this paper.

Given that fluoride toothpaste remains the most widespread and significant form of fluoride application and is used worldwide for the reduction and control of dental caries, it is essential that fluoride toothpastes contain sufficient free available fluoride to assure their effectiveness. This study has highlighted problem areas relating to quality control, standard setting and compliance with existing standards for fluoride toothpaste. Weak quality control systems and lack of compliance on the part of manufacturers may put consumers, particularly in low- and middle-income countries, at further disadvantage or even risk. Appropriate quality control of toothpaste requires technical capacity, but also the political will and commitment to establish strong national drug and consumer product regulatory authorities. Such bodies would also be responsible for ensuring that products on the market comply with minimum labelling and packaging requirements, such as ISO Standard 11609. An additional problem regarding the quality of toothpaste concerns the almost total neglect of the importance of free available fluoride. It is recommended and overdue that international standards are defined in order to determine what constitutes effective fluoride toothpaste.

Recommendations for health communication

As long as the quality of toothpastes available in many countries cannot be ensured, it is important for health communication and consumer advocacy to suggest these simple guidelines:

  • •

    Always check the expiry date of toothpaste

  • •

    Do not purchase a toothpaste that has expired or that does not show an expiry date

  • •

    Silica-based fluoride toothpaste without any calcium-containing abrasive is more likely to have full anti-caries efficacy

  • •

    SMFP toothpaste is less likely to be fully effective against dental caries unless it has been recently produced (three years before the expiry date).

Conflicts of interest

None declared.

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Articles from International Dental Journal are provided here courtesy of Elsevier

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