Basic Sc ie n c e s Caries Res 1992;26:367-370
Faculté de Chirurgie Dentaire, Université Louis Pasteur, Strasbourg, France
Key Words Children Diet Fluorides Urine
Urinary Fluoride Excretion in Children Using Potassium Fluoride Containing Salt or Sodium Fluoride Supplements
Abstract With the introduction of fluoridated domestic salt in France in 1986, questions have arisen with respect to its efficacy in caries prevention. It has been of in terest to compare the urinary excretion of fluoride in children who consume fluoridated salt to that in children who take fluoride tablets. Ninety-three schoolchildren, 10-14 years of age, participated in the study and were divided into four groups: group I consumed fluoridated salt with every meal; group II ate at a school restaurant once a day and consequently consumed fluoridated salt at only their evening meal, as fluoridated salt is not authorized for use in collective restaurants; group III consisted of children taking fluoride tablets (1.0 mg F/day) exclusively, and group IV did not receive any systemic adminis tration of fluoride for prevention and constituted a low-fluoride control group. Total 24-hour urine samples were collected from all subjects. The average daily urinary flow rates varied from 0.51 to 0.68 ml/min, but showed no statistically significant differences among the groups. The average urinary fluoride con centrations were 0.60, 0.30, 0.99, and 0.28 mg/1, respectively, for groups I-IV. The mean 24-hour urinary fluoride concentrations and excretion rates for chil dren who consumed fluoridated salt at all meals (group I) were not statistically different from those using tablets (group III). There were also no statistically significant differences between groups II and IV. The differences between uri nary fluoride concentrations and excretion rates of groups I and III, as com pared with group IV, were statistically significant.
On November 28,1985, fluoridated salt (FS) at a con centration of 250 mg F/kg in the form of KF was autho rized for dietary use in France. FS became available to the public 1year later. However, FS was not authorized for use by the food industry nor for collective restaurants and, therefore, has been used only in the preparation of food in domestic kitchens and at the table. The consumer in
Received: November 13. 1991 Accepted after revision: April 2.1992
France can choose freely between fluoridated and nonfluoridated salt, but public information concerning FS has not been widely distributed. With this advent of a new fluoride source, it was deemed important to derive data relating to its safety and its efficacy in caries prevention. Urinary fluoride concen trations in the 1.0-mg/l range are regarded as indicating an
Anne-Marie Obry-Musset Centre de Recherches Odontologiques Faculté de Chirurgie Dentaire Université Louis-Pasteur, 4. Rue Kirschlegcr F-67000 Strasbourg (France)
©1992S.KargcrAG,Bascl 0008-6568/92/0265-0367 $ 2.75/0
Downloaded by: Vanderbilt University Library 129.59.95.115 - 10/26/2017 10:45:15 PM
A.M. Obry-Musset D. Bettembourg RM. Cahen J.C. Voegel R M . Frank
Materials and Methods Ninety-three children, ranging in age from 10 to 14 years and liv ing in Strasbourg - mean water fluoride content 0.1 ppm [Gamier ct al., 1972] -, were assigned to one of four groups. Group I consisted of 26 children who consumed FS (250 mg F/kg) at all meals for at least 3 years. Group II consisted of 26 children who ate lunch at collective school restaurants where the use of FS is forbidden but who con sumed FS at one meal daily (the evening meal) for at least 3 years. Group III consisted of 22 children who received 1.0 mg/day of F by way of one NaF tablet given cither in the morning or in the evening, according to family routine, for at least 3 years. Group IV (controls) consisted of 20 children who did not receive any systemic fluoride ad ministration other than that in the diet and any that might have been swallowed in conjunction with the use of topical fluoride products such as dentifrices. The amount of fluoride swallowed incidentally was not assessed. All children used fluoridated dentifrices and brushed their teeth in the morning after breakfast and in the evening after dinner. Only a few of them brushed after lunch. The dental fluorosis index of Dean [1934] was determined for the children in all four groups. Two examiners were trained and cali brated over a 2-day period using schoolchildren of Strasbourg as sub jects. D ean’s original classification was used. Total 24-hour urine specimens were carefully collected in three parts and stored in separate large polyethylene bottles at -29 °C until the fluoride analyses were carried out. One large polyethylene bottle was used for urine collected from 19.00 to 07.00 h, a second bottle for urine collected from 07.00 to 13.00 h, and a third bottle was used for urine collected from 13.00 to 19.00 h. Hence, separate urinary fluoride measurements related approximately to three ingestion and excre tion times were made possible. In accordance with French dietary habits, FS was mainly consumed at lunch and dinner. It was profit able, therefore, to collect separate afternoon and night-time urine specimens. When collection of urine was incomplete, the entire sam ple was excluded from the study. The total urine volume excreted over the 24-hour period was first determined, and, as described be low, separate fluoride determinations and excretion rate calculations were made for each collection interval as well as for the total 24-hour period.
368
Fluoride determinations were conducted using a fluoride ion se lective electrode (Orion 9409; Orion Research, Cambridge, Mass., USA) and a glass reference electrode (H90579; Ingold, SteinbachTaunus, FRG). The reference electrode was filled with 3 M KC1 solu tion saturated with AgCl. The fluoride ion activity was evaluated di rectly with the aid of an ion analyzer (Orion 901). Only polyethylene containers were used for sampling and storage. The solutions were handled with disposable pipettes. All plastic containers were steril ized before use, and rinsing was conducted exclusively with deion ized water. Standard fluoride solutions were prepared with deionized water at serial dilutions of a fluoride solution (1 g/1; Titrisol, Merck, Darm stadt, FRG). The water used was deionized using the Milli-Q Water Purification System (Millipore, Bedford. Mass., USA). The water was purified to a total organic carbon content < 10 ppb, a content of Na 0.05) and ranged from 0.51 to 0.68 ml/min. The ingestion of domestic FS at all meals (group 1) re sulted in urinary fluoride concentrations and excretion rates which approached those of the children taking NaF tablets daily (group III). The differences between these two groups were not statistically significant. However, the children who ate at midday in the school restaurants and consumed FS at only one meal a day (group II) had signif icantly lower urinary fluoride concentrations and excre tion rates as compared with those in groups I and III. The
Obry-Mussct/Bettcmbourg/Cahen/Voegel/ Frank
Urinary Fluoride Excretion
Downloaded by: Vanderbilt University Library 129.59.95.115 - 10/26/2017 10:45:15 PM
optimal supply of fluoride by means of salt [Toth and Sugar, 1976; Hefti et al., 1981; Marthaler et al., 1978,1982; Wespi and Biirgi, 1982; Mordasini et al., 1984], Ekstrand et al. [1988] noted that nearly 30% of the ingested fluoride was excreted within 6 h, whereas 60% was excreted within 24 h, emphasizing the importance of analyzing 24-hour urinary samples. The use of sodium fluoride tablets (1.0 mg/day in these age groups) is considered to be an effective regimen for caries prevention. The aim of the present study was to compare the fluoride output of children in Strasbourg us ing FS with that of children taking fluoride tablets, thus deriving a comparative measure of fluoride availability and, indirectly, of efficacy and safety for caries prevention.
Discussion The urinary flow rates observed in the present study were consistent with normal values previously reported for healthy children. Perelman and Gamier [1982] re ported a mean value of 850 ml/24 h (0.59 ml/min) for chil dren 11 years of age, and Menghini et al. [1989] reported similar values for children of approximatively the same age. The excretion of fluoride by the control group can be considered a baseline corresponding to minimal fluoride ingestion by children who do not receive specific fluoride supplementation. Children who consumed FS with every meal (group I) had slightly lower urinary fluoride excretion rates than children who had taken fluoride tablets. It is concluded that the consumption of fluoride with FS at the level of 250 mg F/kg of salt was not excessive. On the other hand, it can be noted that Marthaler and Steiner [1981] who studied children consuming FS at a concentration of 250 mg F/kg in the Canton of Glarus (Switzerland) observed a magni tude of caries reduction with the use of FS similar to that obtained in Basel after 5 years of water fluoridation. In Hungary, Toth [1990], reporting on more than 17 years of trials with FS, demonstrated effectiveness of FS (250 mg F/kg of salt) in preventing dental caries. The mean urinary fluoride excretion rates of our vari ous groups were generally lower than those observed by Menghini et al. [1989] in Switzerland. This could be related
Table 1. Average urinary flow rates, urinary fluoride concentra tions, and urinary fluoride excretion rates during the 24-hour period Group n
I II III IV
26 25 22 20
Urinary Urinary fluoride flow rate concentration ml/min mg/1 (mean ±S D )a mean ± S D s
Urinary fluoride excretion rate mean ±S D
s
0.59 ±0.22 0.51 ±0.21 0.51 ±0.17 0.68 ±0.22
21.12± 10.25 8.69 ±3.61 26.34 ±8.73 11.52 ±5.11
| ** l +++ 1*** l +++
0.60 ±0.20 0.30 ±0.11 0.99 ±0.39 0.28±0.13
(*** l +++ |*** l +++
pg/h
a
No significant differences (p > 0.05). s = Values significantly different. Asterisks - compared to values of group IV; plus marks - compared to values of group II: ** p
Faculté de Chirurgie Dentaire, Université Louis Pasteur, Strasbourg, France
Key Words Children Diet Fluorides Urine
Urinary Fluoride Excretion in Children Using Potassium Fluoride Containing Salt or Sodium Fluoride Supplements
Abstract With the introduction of fluoridated domestic salt in France in 1986, questions have arisen with respect to its efficacy in caries prevention. It has been of in terest to compare the urinary excretion of fluoride in children who consume fluoridated salt to that in children who take fluoride tablets. Ninety-three schoolchildren, 10-14 years of age, participated in the study and were divided into four groups: group I consumed fluoridated salt with every meal; group II ate at a school restaurant once a day and consequently consumed fluoridated salt at only their evening meal, as fluoridated salt is not authorized for use in collective restaurants; group III consisted of children taking fluoride tablets (1.0 mg F/day) exclusively, and group IV did not receive any systemic adminis tration of fluoride for prevention and constituted a low-fluoride control group. Total 24-hour urine samples were collected from all subjects. The average daily urinary flow rates varied from 0.51 to 0.68 ml/min, but showed no statistically significant differences among the groups. The average urinary fluoride con centrations were 0.60, 0.30, 0.99, and 0.28 mg/1, respectively, for groups I-IV. The mean 24-hour urinary fluoride concentrations and excretion rates for chil dren who consumed fluoridated salt at all meals (group I) were not statistically different from those using tablets (group III). There were also no statistically significant differences between groups II and IV. The differences between uri nary fluoride concentrations and excretion rates of groups I and III, as com pared with group IV, were statistically significant.
On November 28,1985, fluoridated salt (FS) at a con centration of 250 mg F/kg in the form of KF was autho rized for dietary use in France. FS became available to the public 1year later. However, FS was not authorized for use by the food industry nor for collective restaurants and, therefore, has been used only in the preparation of food in domestic kitchens and at the table. The consumer in
Received: November 13. 1991 Accepted after revision: April 2.1992
France can choose freely between fluoridated and nonfluoridated salt, but public information concerning FS has not been widely distributed. With this advent of a new fluoride source, it was deemed important to derive data relating to its safety and its efficacy in caries prevention. Urinary fluoride concen trations in the 1.0-mg/l range are regarded as indicating an
Anne-Marie Obry-Musset Centre de Recherches Odontologiques Faculté de Chirurgie Dentaire Université Louis-Pasteur, 4. Rue Kirschlegcr F-67000 Strasbourg (France)
©1992S.KargcrAG,Bascl 0008-6568/92/0265-0367 $ 2.75/0
Downloaded by: Vanderbilt University Library 129.59.95.115 - 10/26/2017 10:45:15 PM
A.M. Obry-Musset D. Bettembourg RM. Cahen J.C. Voegel R M . Frank
Materials and Methods Ninety-three children, ranging in age from 10 to 14 years and liv ing in Strasbourg - mean water fluoride content 0.1 ppm [Gamier ct al., 1972] -, were assigned to one of four groups. Group I consisted of 26 children who consumed FS (250 mg F/kg) at all meals for at least 3 years. Group II consisted of 26 children who ate lunch at collective school restaurants where the use of FS is forbidden but who con sumed FS at one meal daily (the evening meal) for at least 3 years. Group III consisted of 22 children who received 1.0 mg/day of F by way of one NaF tablet given cither in the morning or in the evening, according to family routine, for at least 3 years. Group IV (controls) consisted of 20 children who did not receive any systemic fluoride ad ministration other than that in the diet and any that might have been swallowed in conjunction with the use of topical fluoride products such as dentifrices. The amount of fluoride swallowed incidentally was not assessed. All children used fluoridated dentifrices and brushed their teeth in the morning after breakfast and in the evening after dinner. Only a few of them brushed after lunch. The dental fluorosis index of Dean [1934] was determined for the children in all four groups. Two examiners were trained and cali brated over a 2-day period using schoolchildren of Strasbourg as sub jects. D ean’s original classification was used. Total 24-hour urine specimens were carefully collected in three parts and stored in separate large polyethylene bottles at -29 °C until the fluoride analyses were carried out. One large polyethylene bottle was used for urine collected from 19.00 to 07.00 h, a second bottle for urine collected from 07.00 to 13.00 h, and a third bottle was used for urine collected from 13.00 to 19.00 h. Hence, separate urinary fluoride measurements related approximately to three ingestion and excre tion times were made possible. In accordance with French dietary habits, FS was mainly consumed at lunch and dinner. It was profit able, therefore, to collect separate afternoon and night-time urine specimens. When collection of urine was incomplete, the entire sam ple was excluded from the study. The total urine volume excreted over the 24-hour period was first determined, and, as described be low, separate fluoride determinations and excretion rate calculations were made for each collection interval as well as for the total 24-hour period.
368
Fluoride determinations were conducted using a fluoride ion se lective electrode (Orion 9409; Orion Research, Cambridge, Mass., USA) and a glass reference electrode (H90579; Ingold, SteinbachTaunus, FRG). The reference electrode was filled with 3 M KC1 solu tion saturated with AgCl. The fluoride ion activity was evaluated di rectly with the aid of an ion analyzer (Orion 901). Only polyethylene containers were used for sampling and storage. The solutions were handled with disposable pipettes. All plastic containers were steril ized before use, and rinsing was conducted exclusively with deion ized water. Standard fluoride solutions were prepared with deionized water at serial dilutions of a fluoride solution (1 g/1; Titrisol, Merck, Darm stadt, FRG). The water used was deionized using the Milli-Q Water Purification System (Millipore, Bedford. Mass., USA). The water was purified to a total organic carbon content < 10 ppb, a content of Na 0.05) and ranged from 0.51 to 0.68 ml/min. The ingestion of domestic FS at all meals (group 1) re sulted in urinary fluoride concentrations and excretion rates which approached those of the children taking NaF tablets daily (group III). The differences between these two groups were not statistically significant. However, the children who ate at midday in the school restaurants and consumed FS at only one meal a day (group II) had signif icantly lower urinary fluoride concentrations and excre tion rates as compared with those in groups I and III. The
Obry-Mussct/Bettcmbourg/Cahen/Voegel/ Frank
Urinary Fluoride Excretion
Downloaded by: Vanderbilt University Library 129.59.95.115 - 10/26/2017 10:45:15 PM
optimal supply of fluoride by means of salt [Toth and Sugar, 1976; Hefti et al., 1981; Marthaler et al., 1978,1982; Wespi and Biirgi, 1982; Mordasini et al., 1984], Ekstrand et al. [1988] noted that nearly 30% of the ingested fluoride was excreted within 6 h, whereas 60% was excreted within 24 h, emphasizing the importance of analyzing 24-hour urinary samples. The use of sodium fluoride tablets (1.0 mg/day in these age groups) is considered to be an effective regimen for caries prevention. The aim of the present study was to compare the fluoride output of children in Strasbourg us ing FS with that of children taking fluoride tablets, thus deriving a comparative measure of fluoride availability and, indirectly, of efficacy and safety for caries prevention.
Discussion The urinary flow rates observed in the present study were consistent with normal values previously reported for healthy children. Perelman and Gamier [1982] re ported a mean value of 850 ml/24 h (0.59 ml/min) for chil dren 11 years of age, and Menghini et al. [1989] reported similar values for children of approximatively the same age. The excretion of fluoride by the control group can be considered a baseline corresponding to minimal fluoride ingestion by children who do not receive specific fluoride supplementation. Children who consumed FS with every meal (group I) had slightly lower urinary fluoride excretion rates than children who had taken fluoride tablets. It is concluded that the consumption of fluoride with FS at the level of 250 mg F/kg of salt was not excessive. On the other hand, it can be noted that Marthaler and Steiner [1981] who studied children consuming FS at a concentration of 250 mg F/kg in the Canton of Glarus (Switzerland) observed a magni tude of caries reduction with the use of FS similar to that obtained in Basel after 5 years of water fluoridation. In Hungary, Toth [1990], reporting on more than 17 years of trials with FS, demonstrated effectiveness of FS (250 mg F/kg of salt) in preventing dental caries. The mean urinary fluoride excretion rates of our vari ous groups were generally lower than those observed by Menghini et al. [1989] in Switzerland. This could be related
Table 1. Average urinary flow rates, urinary fluoride concentra tions, and urinary fluoride excretion rates during the 24-hour period Group n
I II III IV
26 25 22 20
Urinary Urinary fluoride flow rate concentration ml/min mg/1 (mean ±S D )a mean ± S D s
Urinary fluoride excretion rate mean ±S D
s
0.59 ±0.22 0.51 ±0.21 0.51 ±0.17 0.68 ±0.22
21.12± 10.25 8.69 ±3.61 26.34 ±8.73 11.52 ±5.11
| ** l +++ 1*** l +++
0.60 ±0.20 0.30 ±0.11 0.99 ±0.39 0.28±0.13
(*** l +++ |*** l +++
pg/h
a
No significant differences (p > 0.05). s = Values significantly different. Asterisks - compared to values of group IV; plus marks - compared to values of group II: ** p
