Caries Experience and the Mineral Content of Plaque in a Primitive Population in New Guinea R. G. SCHAMSCHULA,* B. L. ADKINS,t D. E. BARMES,t G. CHARLTON,§ and B. G. DAVEY§
Institute of Dental Research,* 2 Chalmers Street, Sydney, N.S.W. Australia 2010, University of Queensland,t Australia, World Health Organization,t Geneva, Switzerland, and University of Sydney,§ Australia
Caries prevalence was assessed on a single occasion, for permanent teeth only, using criteria described in the W.H.O. manual, Oral Health Surveys: Basic Methods.5 In addition, the type of primary surface involvement and, where appropriate, arrested progress were recorded for each lesion. Plaque was defined as all soft deposits, other than obvious food debris, adhering to coronal surfaces of teeth. Prior to plaque collection extraneous material was carefully removed. Plaque was collected separately from each individual not sooner than two hours after the last meal, using stainless steel chisels. One plaque sample was obtained from defined areas of 2.25 square mm centered on the labial surfaces of the upper lateral Guinea. incisor teeth, adjacent to the gingival margin. In the context of the work described Materials and Methods here, this sample was used only as an indiThe human sample consisted of 301 sub- cator of smooth surface plaque quantity, jects (154 males and 147 females) aged from expressed as mg wet wt.6 12 to 24 years. All subjects were lifelong For plaque mineral determinations, all residents of one of 16 villages located along accessible tooth surfaces were sampled, a confluent watershed, extending from the avoiding the gingival crevice and areas mineral-rich foothills of the New Guinea where supragingival calculus was present. Highlands to the Sepik River plain (Fig 1). Samples for an individual were pooled, heatEvery village in the area was sampled. All sealed in polyethylene tubing, and homogeneligible persons consented to participate ized at a later date. A portion of approxiand, except in Village 13 where the number mately 1 mg dry wt was separated for fluoof prospective subjects exceeded the require- ride determinations carried out using Birkements, were included in the study. The bulk of the Age and residence qualifications were land's method.7 was wet-ashed andsample (2 analyzed to 3 wt) dry mg determined from village or mission records.
Two recent epidemiological studies demonstrated inverse associations between individual caries experience and the total calcium, phosphorus,' and fluoride2 content of dental plaque in industrialized communities. Similar associations are apparent for a range of minerals determined in plaque samples collected from schoolchildren in New South Wales, Australia.3 4 These observations suggest that high mineral content in plaque may confer a degree of protection against caries in Western populations. The present paper reports a study of plaque minerals performed as part of a wider investigation of over 100 intraoral variables in relation to individual caries experience in a rural community in New
Occasional conflicts between recorded and estimated age were resolved according to the eruption status of the dentition or through questioning elders. Dental examinations were carried out by one examiner (R.G.S.) following standardization with another investigator (D.E.B.). C62
SCHAMSCHULA ET AL
for the total contents of: calcium,
potassium,
and magnesium by flame atomic absorption spectroscopy (AAS); strontium, copper, lead, and zinc by flameless AAS; lithium by flame emission spectroscopy and phosphorus by colorimetry.8 All methods required extensive modifications to permit analyses on a J Dent Res Special Issue C
Downloaded from jdr.sagepub.com at Bobst Library, New York University on May 24, 2015 For personal use only. No other uses without permission.
Vol. 56 1977
CARIES & PLAQUE MINERALS: NEW GUINEA
micro-scale, against the varied background matrix of plaque.9 Pooled plaque quantity was determined by drying both portions of plaque to constant weight. The concentrations of elements were expressed as the proportion of dry weight of plaque. Activated whole saliva was obtained following plaque collection, using soft vinyl tubing as masticatory stimulant. The range of elements determined and the analytical methods employed were substantially the same as for plaque. The geochemical and socio-economic background, diet, oral hygiene practices, and the betel-chewing habit are relevant to both caries experience and the mineral content of plaque. Corresponding attributes of the community were observed, but quantitative data are restricted to selected aspects,
C63
and, with the exception of betel chewing, relate to aggregates of subjects. The frequency of betel chewing was estimated from verbal information and by grading resultant deposits on teeth. Samples of lime used with betel chewing were collected in every village and analyzed for the same elements as plaque, under subcontract (Robertson Research International, Llandudno, Wales, U.K.) using mass spectroscopy. Water samples were obtained from all known sources in the study area. The fluoride content of water was determined using a specific ion electrode. Full details of the field and laboratory methods used have been documented.6 9 Following close personal scrutiny, the data were assessed using biomedical proPAPUA NEW GUINEA
.N
v
FIG 1.-Distribution of number of subjects (n) and mean
caries experience [DMFT] between
villages.
Downloaded from jdr.sagepub.com at Bobst Library, New York University on May 24, 2015 For personal use only. No other uses without permission.
J Dent Res Special Issue C
SCHAMSCHULA ET AL
C64
TABLE 1 MEAN DMFT AND PLAQUE QUANTITY FOR COMBINED VILLAGE GROUPS (VG) VG I + 2 n= 150
VG 3 + 4 n= 151
t
DMFT
5.6 (4.1)$
1.0 (1.3)
13.1O,
Smooth surface plaque (mg wet wt)
0.44 (0.29)
0.21 (0.18)
8.28t
Pooled plaque (mg dry wt)
4.01 (1.73)
3.38 (1.86)
3.04*
P < 0.01 P < 0.001
t (S.D.)
available at the Computer Section of the World Health Organization, Geneva. All individual mineral values were transformed according to the probability integral and interrelationships between variables were examined using discriminant analyses, correlation matrices, and bivariate and multiple linear stepwise regression analyses.
grams
Results
BACKGROUND.-The village communities examined comprise 30 to 300 persons of Melanesian origin, with a high level of inbreeding within distinct village aggregates. The pattern of life is primitive and no medical or dental care is available locally. The staple food is sago, which contains up to 90% starch but no detectable amounts of monosaccharides or disaccharides.10 Supplementary foods are grown in village gardens or obtained locally by gathering, hunting or fishing. In the absence of cash economy, the few processed foods and refined sugar, occasionally available at trade stores, could not have had a material effect on the caries distribution pattern; the mean caries prevalence is very low or zero in Villages 11, 13, and 16, which have the best access to trade stores (Fig 1). About 90% of subjects are addicted to the intoxicating betel-chewing habit, which entails the periodic mastication of Areca nuts and betel leaves or aromatic treebarks with slaked lime, in the form of a bolus. Betel chewing frequency ranged from 0 to 25 nuts used per day. Although traditional forms of oral hygiene practices exist, very few clean teeth were seen, mostly in females. The fluoride content of water did not
exceed 0.052 ppm anywhere in the area. The primary sources of household water were rivers. The fluoride content of rivers decreased gradually with increasing distance from the source and ranged from 0.011 ppm in the Blackwater at Village 14, to 0.042 ppm in the Sepik River at Village 16. DENTAL CARIES. - Individual caries experience ranged from 0 to 22 DMFT. In the almost complete absence of dental care the filled component was negligible. Over the whole sample, 57.1, 28.6, and 7.1% of lesions were classified as of pit and fissure, proximal surface, and smooth surface origin. The primary surface involvement could not be determined for 7.2 % of lesions. The small proportion of teeth lost through caries, 0.9%, suggests relatively slow progress of decay. However, only 1.5% of lesions were classified as arrested. The individual DMFT and DlVMFS scores were strongly correlated (r - 0.98, P < 0.0001, n = 301). Corresponding sample means were 3.3 and 4.2 units. The difference indicates that less than 270%O carious teeth had more than one distinct lesion. The mean caries experience of females was 22% lower than that of males, by both indices. The distribution pattern of mean caries experience between villages (Fig 1) was similar to that observed previously in New Guineall 12 in that, generally, the prevalence of the disease increased with the proximity of mountains and the height of river banks. Exceptions were Villages 1 to 3 where caries prevalence was lower than expected. The villages can be stratified into four distinct groups according to the mean DMFT scores: Group 1 (V 1 to 3) 3.4; Group 2
Downloaded from jdr.sagepub.com at Bobst Library, New York University on May 24, 2015 For personal use only. No other uses without permission.
Vol. 56 1977
CARIES & PLAQUE MINERALS: NEW' GUINEA
C65
TABLE 2
TOTAL CONCENTRATIONS OF SELECTED ELEMENTS IN PLAQUE (DRY WT) ALL SUBJECTS, N = 280-300. %
PPM Zn Pb
Cu
F
0.31
120
3.3
9.8
37
0.46
86
2.4
7.6
30
Ca
P
K
Mg
Sr
Li
Mean
2.44
1.69
1.76
0.16
20
SD
1.51
0.70
0.58
0.07
17
(V 4 to 10) 6.4; Group 3 (V 11, 12, 15, 16) 1.5; and Group 4 (V 13, 14) 0.0. INDEPENDENT VARIABLES.-Mean plaque quantity was greater in Groups 1 and 2 than in Groups 3 and 4 (Table 1). For individuals, smooth surface plaque quantity was directly associated with DMFT in the "high caries" Village Group 2 (r = 0.21, P < 0.02) and over the whole sample (r = 0.33, P < 0.0005). In discriminant analyses both expressions of plaque quantity made substantial contributions to the separation of subjects with different levels of caries experience.
"Overall" sample means and standard deviations of the total concentrations of elements determined in plaque are given in Table 2. Generally, Village Group means for an element were similar, despite high coefficients of variation. However, as shown in Table 3, the unexpectedly low caries prevalence in Village Group 1 was associated with high mean fluoride and lithium levels in plaque and the combined medium and high caries Groups 1 + 2 had significantly higher lead but lower zinc mean values than the low and zero caries Groups 3 + 4. The calcium, phosphorus, and strontium means were significantly higher and the copper means lower in Group 4 than the combined means of Groups 1 + 2 + 3 (Table 3). The lowest means for fluoride (28 ppm), lithium (0.25 ppm), and calcium (2.1 %) and the second lowest mean for strontium (18 ppm) were found in Group 2. Table 4 shows the bivariate correlation coefficients between individual caries experience and the total concentrations of minerals in plaque for which significant associations were found. The inverse associations for calcium, fluoride, strontium, and calcium/phosphorus ratio, "overall"' and in Village Group 3, were accompanied by consistent negative trends in Groups 1 and 2;
in addition, lead was directly associated with DMFT in Group 2 (r = 0.26, P < 0.01) . The lithium content of plaque was inversely associated with pooled plaque quantity "overall" (r = -0.55, P < 0.001) and in each Group; further inverse associations were observed for calcium and strontium, but a corresponding trend for fluoride was not significant. Positive trends were noted between pooled plaque quantity and the potassium and magnesium concentrations. Correlation coefficients between selected pairs of elements in plaque, extracted from the complete matrix13 to illustrate salient points, are shown in Table 5. Elements are interdependent to various extents. The strength of correlations between calcium and phosphorus and calcium and strontium indicate that the concentration ratios of these TABLE 3 MEAN CONCENTRATIONS OF SELECTED ELEMENTS IN PLAQUE (DRY WT) By VILLAGE GROUPS (VG) VG I n=38
Fppm
63
Li ppm
Pb ppm Zn ppm
VG 2+3+4 n =263
33
0.41
0.29
VG1+2 n= 150
VG3+4
VG 1+2+3 n = 251
Ca % P% Sr ppm Cu ppm
2.29 1.64 19 10.2
3.86t NS
n= 151
t
2.9
2.81*
3.7
107
t
134 VG 4 50
n
2.77* t
3.24
3.85t
1.94 27
2.91#
7.0
* P < 0.01 P
Institute of Dental Research,* 2 Chalmers Street, Sydney, N.S.W. Australia 2010, University of Queensland,t Australia, World Health Organization,t Geneva, Switzerland, and University of Sydney,§ Australia
Caries prevalence was assessed on a single occasion, for permanent teeth only, using criteria described in the W.H.O. manual, Oral Health Surveys: Basic Methods.5 In addition, the type of primary surface involvement and, where appropriate, arrested progress were recorded for each lesion. Plaque was defined as all soft deposits, other than obvious food debris, adhering to coronal surfaces of teeth. Prior to plaque collection extraneous material was carefully removed. Plaque was collected separately from each individual not sooner than two hours after the last meal, using stainless steel chisels. One plaque sample was obtained from defined areas of 2.25 square mm centered on the labial surfaces of the upper lateral Guinea. incisor teeth, adjacent to the gingival margin. In the context of the work described Materials and Methods here, this sample was used only as an indiThe human sample consisted of 301 sub- cator of smooth surface plaque quantity, jects (154 males and 147 females) aged from expressed as mg wet wt.6 12 to 24 years. All subjects were lifelong For plaque mineral determinations, all residents of one of 16 villages located along accessible tooth surfaces were sampled, a confluent watershed, extending from the avoiding the gingival crevice and areas mineral-rich foothills of the New Guinea where supragingival calculus was present. Highlands to the Sepik River plain (Fig 1). Samples for an individual were pooled, heatEvery village in the area was sampled. All sealed in polyethylene tubing, and homogeneligible persons consented to participate ized at a later date. A portion of approxiand, except in Village 13 where the number mately 1 mg dry wt was separated for fluoof prospective subjects exceeded the require- ride determinations carried out using Birkements, were included in the study. The bulk of the Age and residence qualifications were land's method.7 was wet-ashed andsample (2 analyzed to 3 wt) dry mg determined from village or mission records.
Two recent epidemiological studies demonstrated inverse associations between individual caries experience and the total calcium, phosphorus,' and fluoride2 content of dental plaque in industrialized communities. Similar associations are apparent for a range of minerals determined in plaque samples collected from schoolchildren in New South Wales, Australia.3 4 These observations suggest that high mineral content in plaque may confer a degree of protection against caries in Western populations. The present paper reports a study of plaque minerals performed as part of a wider investigation of over 100 intraoral variables in relation to individual caries experience in a rural community in New
Occasional conflicts between recorded and estimated age were resolved according to the eruption status of the dentition or through questioning elders. Dental examinations were carried out by one examiner (R.G.S.) following standardization with another investigator (D.E.B.). C62
SCHAMSCHULA ET AL
for the total contents of: calcium,
potassium,
and magnesium by flame atomic absorption spectroscopy (AAS); strontium, copper, lead, and zinc by flameless AAS; lithium by flame emission spectroscopy and phosphorus by colorimetry.8 All methods required extensive modifications to permit analyses on a J Dent Res Special Issue C
Downloaded from jdr.sagepub.com at Bobst Library, New York University on May 24, 2015 For personal use only. No other uses without permission.
Vol. 56 1977
CARIES & PLAQUE MINERALS: NEW GUINEA
micro-scale, against the varied background matrix of plaque.9 Pooled plaque quantity was determined by drying both portions of plaque to constant weight. The concentrations of elements were expressed as the proportion of dry weight of plaque. Activated whole saliva was obtained following plaque collection, using soft vinyl tubing as masticatory stimulant. The range of elements determined and the analytical methods employed were substantially the same as for plaque. The geochemical and socio-economic background, diet, oral hygiene practices, and the betel-chewing habit are relevant to both caries experience and the mineral content of plaque. Corresponding attributes of the community were observed, but quantitative data are restricted to selected aspects,
C63
and, with the exception of betel chewing, relate to aggregates of subjects. The frequency of betel chewing was estimated from verbal information and by grading resultant deposits on teeth. Samples of lime used with betel chewing were collected in every village and analyzed for the same elements as plaque, under subcontract (Robertson Research International, Llandudno, Wales, U.K.) using mass spectroscopy. Water samples were obtained from all known sources in the study area. The fluoride content of water was determined using a specific ion electrode. Full details of the field and laboratory methods used have been documented.6 9 Following close personal scrutiny, the data were assessed using biomedical proPAPUA NEW GUINEA
.N
v
FIG 1.-Distribution of number of subjects (n) and mean
caries experience [DMFT] between
villages.
Downloaded from jdr.sagepub.com at Bobst Library, New York University on May 24, 2015 For personal use only. No other uses without permission.
J Dent Res Special Issue C
SCHAMSCHULA ET AL
C64
TABLE 1 MEAN DMFT AND PLAQUE QUANTITY FOR COMBINED VILLAGE GROUPS (VG) VG I + 2 n= 150
VG 3 + 4 n= 151
t
DMFT
5.6 (4.1)$
1.0 (1.3)
13.1O,
Smooth surface plaque (mg wet wt)
0.44 (0.29)
0.21 (0.18)
8.28t
Pooled plaque (mg dry wt)
4.01 (1.73)
3.38 (1.86)
3.04*
P < 0.01 P < 0.001
t (S.D.)
available at the Computer Section of the World Health Organization, Geneva. All individual mineral values were transformed according to the probability integral and interrelationships between variables were examined using discriminant analyses, correlation matrices, and bivariate and multiple linear stepwise regression analyses.
grams
Results
BACKGROUND.-The village communities examined comprise 30 to 300 persons of Melanesian origin, with a high level of inbreeding within distinct village aggregates. The pattern of life is primitive and no medical or dental care is available locally. The staple food is sago, which contains up to 90% starch but no detectable amounts of monosaccharides or disaccharides.10 Supplementary foods are grown in village gardens or obtained locally by gathering, hunting or fishing. In the absence of cash economy, the few processed foods and refined sugar, occasionally available at trade stores, could not have had a material effect on the caries distribution pattern; the mean caries prevalence is very low or zero in Villages 11, 13, and 16, which have the best access to trade stores (Fig 1). About 90% of subjects are addicted to the intoxicating betel-chewing habit, which entails the periodic mastication of Areca nuts and betel leaves or aromatic treebarks with slaked lime, in the form of a bolus. Betel chewing frequency ranged from 0 to 25 nuts used per day. Although traditional forms of oral hygiene practices exist, very few clean teeth were seen, mostly in females. The fluoride content of water did not
exceed 0.052 ppm anywhere in the area. The primary sources of household water were rivers. The fluoride content of rivers decreased gradually with increasing distance from the source and ranged from 0.011 ppm in the Blackwater at Village 14, to 0.042 ppm in the Sepik River at Village 16. DENTAL CARIES. - Individual caries experience ranged from 0 to 22 DMFT. In the almost complete absence of dental care the filled component was negligible. Over the whole sample, 57.1, 28.6, and 7.1% of lesions were classified as of pit and fissure, proximal surface, and smooth surface origin. The primary surface involvement could not be determined for 7.2 % of lesions. The small proportion of teeth lost through caries, 0.9%, suggests relatively slow progress of decay. However, only 1.5% of lesions were classified as arrested. The individual DMFT and DlVMFS scores were strongly correlated (r - 0.98, P < 0.0001, n = 301). Corresponding sample means were 3.3 and 4.2 units. The difference indicates that less than 270%O carious teeth had more than one distinct lesion. The mean caries experience of females was 22% lower than that of males, by both indices. The distribution pattern of mean caries experience between villages (Fig 1) was similar to that observed previously in New Guineall 12 in that, generally, the prevalence of the disease increased with the proximity of mountains and the height of river banks. Exceptions were Villages 1 to 3 where caries prevalence was lower than expected. The villages can be stratified into four distinct groups according to the mean DMFT scores: Group 1 (V 1 to 3) 3.4; Group 2
Downloaded from jdr.sagepub.com at Bobst Library, New York University on May 24, 2015 For personal use only. No other uses without permission.
Vol. 56 1977
CARIES & PLAQUE MINERALS: NEW' GUINEA
C65
TABLE 2
TOTAL CONCENTRATIONS OF SELECTED ELEMENTS IN PLAQUE (DRY WT) ALL SUBJECTS, N = 280-300. %
PPM Zn Pb
Cu
F
0.31
120
3.3
9.8
37
0.46
86
2.4
7.6
30
Ca
P
K
Mg
Sr
Li
Mean
2.44
1.69
1.76
0.16
20
SD
1.51
0.70
0.58
0.07
17
(V 4 to 10) 6.4; Group 3 (V 11, 12, 15, 16) 1.5; and Group 4 (V 13, 14) 0.0. INDEPENDENT VARIABLES.-Mean plaque quantity was greater in Groups 1 and 2 than in Groups 3 and 4 (Table 1). For individuals, smooth surface plaque quantity was directly associated with DMFT in the "high caries" Village Group 2 (r = 0.21, P < 0.02) and over the whole sample (r = 0.33, P < 0.0005). In discriminant analyses both expressions of plaque quantity made substantial contributions to the separation of subjects with different levels of caries experience.
"Overall" sample means and standard deviations of the total concentrations of elements determined in plaque are given in Table 2. Generally, Village Group means for an element were similar, despite high coefficients of variation. However, as shown in Table 3, the unexpectedly low caries prevalence in Village Group 1 was associated with high mean fluoride and lithium levels in plaque and the combined medium and high caries Groups 1 + 2 had significantly higher lead but lower zinc mean values than the low and zero caries Groups 3 + 4. The calcium, phosphorus, and strontium means were significantly higher and the copper means lower in Group 4 than the combined means of Groups 1 + 2 + 3 (Table 3). The lowest means for fluoride (28 ppm), lithium (0.25 ppm), and calcium (2.1 %) and the second lowest mean for strontium (18 ppm) were found in Group 2. Table 4 shows the bivariate correlation coefficients between individual caries experience and the total concentrations of minerals in plaque for which significant associations were found. The inverse associations for calcium, fluoride, strontium, and calcium/phosphorus ratio, "overall"' and in Village Group 3, were accompanied by consistent negative trends in Groups 1 and 2;
in addition, lead was directly associated with DMFT in Group 2 (r = 0.26, P < 0.01) . The lithium content of plaque was inversely associated with pooled plaque quantity "overall" (r = -0.55, P < 0.001) and in each Group; further inverse associations were observed for calcium and strontium, but a corresponding trend for fluoride was not significant. Positive trends were noted between pooled plaque quantity and the potassium and magnesium concentrations. Correlation coefficients between selected pairs of elements in plaque, extracted from the complete matrix13 to illustrate salient points, are shown in Table 5. Elements are interdependent to various extents. The strength of correlations between calcium and phosphorus and calcium and strontium indicate that the concentration ratios of these TABLE 3 MEAN CONCENTRATIONS OF SELECTED ELEMENTS IN PLAQUE (DRY WT) By VILLAGE GROUPS (VG) VG I n=38
Fppm
63
Li ppm
Pb ppm Zn ppm
VG 2+3+4 n =263
33
0.41
0.29
VG1+2 n= 150
VG3+4
VG 1+2+3 n = 251
Ca % P% Sr ppm Cu ppm
2.29 1.64 19 10.2
3.86t NS
n= 151
t
2.9
2.81*
3.7
107
t
134 VG 4 50
n
2.77* t
3.24
3.85t
1.94 27
2.91#
7.0
* P < 0.01 P
