hchs
orul viol. Vol. 21, pi
691 to 695. Pergamon
Press 1976. Printed
in Great Bntain.
THE RELATIONSHIP BETWEEN STRONTIUM IN WATER SUPPLIES AND HUMAN TOOTH ENAMEL G. S. NIXON and C. A. HELSBY Department of Conservative Dentistry, University of Manchester, Dental Hospital, Bridgeford Street, Manchester Ml5 6FH, England Summary--Tooth enamel from life-long residents of 12 towns in England was analysed for strontium: the range of concentrations in deciduous enamel was 67 to 161 parts/lo6 and in permanent enamel 80 to 181 parts. The water supplies to the towns were analysed for strontium, calcium and fluoride; the concentration ranges were 0.0241 to 1.716 parts/106, 7.9 to 137.6 parts/lo6 and 0.019 to 1.52 parts/lo6 respectively. A relationship was observed between the strontium content of the enamel and the strontium concentration of the water supply. The ratio of the strontium content of permanent enamel to that of deciduous enamel was constant irrespective of the water supply. When the water supply contained a high fluoride concentration. the strontium concentration was high also.
INTRODUCTION Strontium is closely related to calcium in its biological behaviour and the two elements follow the same food chain from soils to plants, animals and man. Strontium readily enters the body through the alimentary tract and lungs, and is mainly deposited in the calcified tissul:s where it is incorporated in the apatite. The presence 0.‘ strontium in enamel and dentine was qualitatively established by Drea in 1936. The development of more sensitive analytical techniques made possible quantitative analysis of the dental tissues. (Table 1). Rygh (1949a,b) showed in animal experiments that dental caries increased when the diet was lacking in strontium and vanadium but experiments by Shaw and Griffiths (1961) gave inconsistent results. The first evidence that strontium may reduce caries in man Table 1. Distribution
Authors Sijrmark and Samsahl (1961) Lundberg et al. (j-965) Calonius and Visaplti (1965) Little and Steadman (1966) Hardwick and Martin (1967) Retief rt al. (1971a,b) Losee et al. (1974.) Derise and Ritch:y (1974) Siiremark and Samsahl (1962a) Retief et al. (1971a,b) Derise and Ritch:y (1974) Siiremark and Samsahl (1962b) Swift (1967) Wolf et a/. (1973) Kubota et al. (1974)
was shown in Bonn, W. Germany (Lerdrup, 1953) where the drinking water contains high levels of calcium, strontium and vanadium. Further evidence derived from North West Ohio (Losee and Adkins, 1969) where the water supply contains unusually high levels of strontium and boron and has been shown to have a cariostatic effect by rat-feeding experiments (Losee and Adkins, 1968). Curzon et al. (1970) found a low caries prevalence in the two towns in North West Ohio where the water supplies contained high levels of strontium and boron. Handelman and Losee (1971) investigated the in tlitro solubility of enamel and hydroxyapatite in nutrient medium made up with water from a low-caries area in Ohio and inoculated with acidogenic streptococci. Dissolution of enamel and hydroxyapatite was inhibited and changes occurred in the glycolytic enzyme system of the cariogenie organisms suggesting possible mechanisms for
of strontium
Sample
in dental tissues
Method
Enamel Enamel Enamel and dentine Enamel Enamel and dentine Enamel Enamel Enamel Dentine Dentine Dentine Calculus Plaque Whole tooth Whole tooth
691
of analysis
Activation analysis Activation analysis X-ray emission Spectrometry Mass spectrometry Activation analysis Mass spectrometry Atomic absorption Activation analysis Activation analysis Atomic absorption Atomic absorption Mass spectrometry Atomic absorption Atomic absorption X-ray emission
Strontium concentration (parts/106) 93.5 + 21.9 83 & 32 l&l000 6@110 loo-loo0 lll.l;+ 9.86 81 7 11 33-283 69.9 f 18.0 94.33 * 11.47 139-219 34.3 + 3.2 2.0 73-l 19 66-564 15-540
692
G. S. Nixon and C. A. Helsby
the anticariogenic effect. On the other hand, Anderson (1966) found no reduction in caries prevalence in an area in Britain with large underground strontium deposits. Little and Barrett (1974) found that enamel from a low-caries area contained higher levels of strontium and fluoride than that from a high caries area, although both areas had similar low levels of tluoride in the water supply. The aim of our investigation was to evaluate the concentration range of strontium encountered in permanent and deciduous enamel from various areas of England, and to relate this to the levels of strontium, calcium and fluoride in the water supplies. Twelve towns with water supplies ranging from “soft” to “very hard” and an area with large underground strontium deposits (Yate in South West England) were selected. These covered the complete range of “hardness” found in public water supplies in England.
rinsed with deionized water and dried at 104.C for 48 hr in a hot-air oven, sealed in polythene bags and stored over silica gel until required for analysis. The enamel was analysed by the technique described by Helsby (1974). Water samples were collected in polythene bottles and the pH adjusted to less than 2.0 to prevent loss of the trace elements by precipitation. In some towns, the water supply came from more than one source, in which case each source was analysed. A PerkinElmer Atomic Absorption Spectrophotometer Model 303 fitted with “Intensitron” hollow cathode lamps, recorder-readout accessory and Hitachi 165 recorder was used for the analysis of strontium and calcium. Fluoride was analysed using an Orion 94-09A fluoride electrode in conjunction with an Orion 94-09A reference electrode connected to a Radiometer digital selective ion-meter PHM52. Strontium
MATERIALS
AND METHODS
Permanent and deciduous teeth from life-long residents were used for the analysis. The number of teeth from each town varied. Wherever possible, teeth without fillings were used. The enamel was separated mechanically from the dentine. The samples were
Table 2. Strontium
analysis of the water supplies
Atomic adsorption spectrometry was employed for the analysis of strontium in the water samples. The calibration was achieved using the standard addition technique in which sample and standard were matched with regard to interference effects, total solids and viscosity. Recovery studies involving water samples with concentrations of strontium ranging
concentration
parts/lo6
Number of Number of individuals samples
Town
of enamel Range of Sr cont.
Mean Sr cont.
(P)
5 12
5 24
58878 72-96
67 +- 8 80 + 8
Leeds
(d) (P)
5 5
9 5
6&72 7593
68 * 5 86 _t 8
Wrexham
(d) (P)
4 13
5 16
7&74 74111
72 k 2 85 k 11
Stoke on Trent
(d) (P)
9 10
12 12
599100 755104
69 k 13 89 f 10
Carlisle
(d) (P)
10 11
11 17
73-96 855106
83 k 9 92 + 7
Portsmouth
(d) (P)
4 5
5 5
82-85 799110
84 * 1 97f 12
Bournemouth
(d) (P) (d) (P) (d) (P)
3 9
3 21
777114 81-137
93 _t 19 106 _t 21
4 9 11 10
8 14 12 14
8697 977115 755111 91-145
91 104 91 107
York
(d) (P)
7 9
12 14
76122 1033126
96 + 21 113 -+ 9
Norwich
(d) (P)
7 7
14 8
lW114 l&179
102 f 13 160 + 16
Hartlepool
(d) (P)
8 12
13 23
1288192 141-239
161 k 18 181 f 35
Yate
(d) (P)
5 8
5 8
11 l-209 1422176
150 * 39 164 k 12
Manchester
Reading Grimsby
(d) = deciduous (p) = permanent
(4
teeth. teeth.
* k * k
5 6 13 16
693
Water-supply Sr and human enamel Table 3. Results of the analysis of the water supplies
Source of supply
Town
Mean cont. of Sr (parts/106)
Mean cont. of Ca (parts/106)
Sr :Ca Ratio (mg Sr/g Ca)
Mean cont. of F (parts/106)
Manchester
Reservoirs
24.1
7.90
3.0
0.07
Leeds
Reservoirs, rivers, springs, boreholes
48.2 42.8
16.58 14.88
2.9 2.9
0.06
orul viol. Vol. 21, pi
691 to 695. Pergamon
Press 1976. Printed
in Great Bntain.
THE RELATIONSHIP BETWEEN STRONTIUM IN WATER SUPPLIES AND HUMAN TOOTH ENAMEL G. S. NIXON and C. A. HELSBY Department of Conservative Dentistry, University of Manchester, Dental Hospital, Bridgeford Street, Manchester Ml5 6FH, England Summary--Tooth enamel from life-long residents of 12 towns in England was analysed for strontium: the range of concentrations in deciduous enamel was 67 to 161 parts/lo6 and in permanent enamel 80 to 181 parts. The water supplies to the towns were analysed for strontium, calcium and fluoride; the concentration ranges were 0.0241 to 1.716 parts/106, 7.9 to 137.6 parts/lo6 and 0.019 to 1.52 parts/lo6 respectively. A relationship was observed between the strontium content of the enamel and the strontium concentration of the water supply. The ratio of the strontium content of permanent enamel to that of deciduous enamel was constant irrespective of the water supply. When the water supply contained a high fluoride concentration. the strontium concentration was high also.
INTRODUCTION Strontium is closely related to calcium in its biological behaviour and the two elements follow the same food chain from soils to plants, animals and man. Strontium readily enters the body through the alimentary tract and lungs, and is mainly deposited in the calcified tissul:s where it is incorporated in the apatite. The presence 0.‘ strontium in enamel and dentine was qualitatively established by Drea in 1936. The development of more sensitive analytical techniques made possible quantitative analysis of the dental tissues. (Table 1). Rygh (1949a,b) showed in animal experiments that dental caries increased when the diet was lacking in strontium and vanadium but experiments by Shaw and Griffiths (1961) gave inconsistent results. The first evidence that strontium may reduce caries in man Table 1. Distribution
Authors Sijrmark and Samsahl (1961) Lundberg et al. (j-965) Calonius and Visaplti (1965) Little and Steadman (1966) Hardwick and Martin (1967) Retief rt al. (1971a,b) Losee et al. (1974.) Derise and Ritch:y (1974) Siiremark and Samsahl (1962a) Retief et al. (1971a,b) Derise and Ritch:y (1974) Siiremark and Samsahl (1962b) Swift (1967) Wolf et a/. (1973) Kubota et al. (1974)
was shown in Bonn, W. Germany (Lerdrup, 1953) where the drinking water contains high levels of calcium, strontium and vanadium. Further evidence derived from North West Ohio (Losee and Adkins, 1969) where the water supply contains unusually high levels of strontium and boron and has been shown to have a cariostatic effect by rat-feeding experiments (Losee and Adkins, 1968). Curzon et al. (1970) found a low caries prevalence in the two towns in North West Ohio where the water supplies contained high levels of strontium and boron. Handelman and Losee (1971) investigated the in tlitro solubility of enamel and hydroxyapatite in nutrient medium made up with water from a low-caries area in Ohio and inoculated with acidogenic streptococci. Dissolution of enamel and hydroxyapatite was inhibited and changes occurred in the glycolytic enzyme system of the cariogenie organisms suggesting possible mechanisms for
of strontium
Sample
in dental tissues
Method
Enamel Enamel Enamel and dentine Enamel Enamel and dentine Enamel Enamel Enamel Dentine Dentine Dentine Calculus Plaque Whole tooth Whole tooth
691
of analysis
Activation analysis Activation analysis X-ray emission Spectrometry Mass spectrometry Activation analysis Mass spectrometry Atomic absorption Activation analysis Activation analysis Atomic absorption Atomic absorption Mass spectrometry Atomic absorption Atomic absorption X-ray emission
Strontium concentration (parts/106) 93.5 + 21.9 83 & 32 l&l000 6@110 loo-loo0 lll.l;+ 9.86 81 7 11 33-283 69.9 f 18.0 94.33 * 11.47 139-219 34.3 + 3.2 2.0 73-l 19 66-564 15-540
692
G. S. Nixon and C. A. Helsby
the anticariogenic effect. On the other hand, Anderson (1966) found no reduction in caries prevalence in an area in Britain with large underground strontium deposits. Little and Barrett (1974) found that enamel from a low-caries area contained higher levels of strontium and fluoride than that from a high caries area, although both areas had similar low levels of tluoride in the water supply. The aim of our investigation was to evaluate the concentration range of strontium encountered in permanent and deciduous enamel from various areas of England, and to relate this to the levels of strontium, calcium and fluoride in the water supplies. Twelve towns with water supplies ranging from “soft” to “very hard” and an area with large underground strontium deposits (Yate in South West England) were selected. These covered the complete range of “hardness” found in public water supplies in England.
rinsed with deionized water and dried at 104.C for 48 hr in a hot-air oven, sealed in polythene bags and stored over silica gel until required for analysis. The enamel was analysed by the technique described by Helsby (1974). Water samples were collected in polythene bottles and the pH adjusted to less than 2.0 to prevent loss of the trace elements by precipitation. In some towns, the water supply came from more than one source, in which case each source was analysed. A PerkinElmer Atomic Absorption Spectrophotometer Model 303 fitted with “Intensitron” hollow cathode lamps, recorder-readout accessory and Hitachi 165 recorder was used for the analysis of strontium and calcium. Fluoride was analysed using an Orion 94-09A fluoride electrode in conjunction with an Orion 94-09A reference electrode connected to a Radiometer digital selective ion-meter PHM52. Strontium
MATERIALS
AND METHODS
Permanent and deciduous teeth from life-long residents were used for the analysis. The number of teeth from each town varied. Wherever possible, teeth without fillings were used. The enamel was separated mechanically from the dentine. The samples were
Table 2. Strontium
analysis of the water supplies
Atomic adsorption spectrometry was employed for the analysis of strontium in the water samples. The calibration was achieved using the standard addition technique in which sample and standard were matched with regard to interference effects, total solids and viscosity. Recovery studies involving water samples with concentrations of strontium ranging
concentration
parts/lo6
Number of Number of individuals samples
Town
of enamel Range of Sr cont.
Mean Sr cont.
(P)
5 12
5 24
58878 72-96
67 +- 8 80 + 8
Leeds
(d) (P)
5 5
9 5
6&72 7593
68 * 5 86 _t 8
Wrexham
(d) (P)
4 13
5 16
7&74 74111
72 k 2 85 k 11
Stoke on Trent
(d) (P)
9 10
12 12
599100 755104
69 k 13 89 f 10
Carlisle
(d) (P)
10 11
11 17
73-96 855106
83 k 9 92 + 7
Portsmouth
(d) (P)
4 5
5 5
82-85 799110
84 * 1 97f 12
Bournemouth
(d) (P) (d) (P) (d) (P)
3 9
3 21
777114 81-137
93 _t 19 106 _t 21
4 9 11 10
8 14 12 14
8697 977115 755111 91-145
91 104 91 107
York
(d) (P)
7 9
12 14
76122 1033126
96 + 21 113 -+ 9
Norwich
(d) (P)
7 7
14 8
lW114 l&179
102 f 13 160 + 16
Hartlepool
(d) (P)
8 12
13 23
1288192 141-239
161 k 18 181 f 35
Yate
(d) (P)
5 8
5 8
11 l-209 1422176
150 * 39 164 k 12
Manchester
Reading Grimsby
(d) = deciduous (p) = permanent
(4
teeth. teeth.
* k * k
5 6 13 16
693
Water-supply Sr and human enamel Table 3. Results of the analysis of the water supplies
Source of supply
Town
Mean cont. of Sr (parts/106)
Mean cont. of Ca (parts/106)
Sr :Ca Ratio (mg Sr/g Ca)
Mean cont. of F (parts/106)
Manchester
Reservoirs
24.1
7.90
3.0
0.07
Leeds
Reservoirs, rivers, springs, boreholes
48.2 42.8
16.58 14.88
2.9 2.9
0.06
