Archs oral BIO/. Vol
22. pp. 409 to 414. Pergamon
Press 1977. Printed in Great Britmn.
THE RELATIONSHIP BETWEEN DIETARY SUGAR EXPERIENCE AND THE QUANTITY AND BIOCHEMICAL COMPOSITION OF DENTAL PLAQUE IN MAN F. P. ASHLEYand R. F. WILSON Department of Periodontology and Preventive ,Dentistry, Guy’s Hospital Dental School, London SE1 9RT, England Summary-The calcium and inorganic phosphorus concentrations of 2-day plaque in adults were inversely related to the previous dietary sugar experience; the dry weight and concentrations of water-soluble and alkali-insoluble carbohydrate were directly related to the dietary sugar experience. However, the relationship with the diet appeared to be limited to carbohydrate concentrations in mature plaque from children. INTRODUCI’ION
intervals for three years, without standard&&ion plaque age or exposure to sugar.
It is generally accepted that both dietary sugar and dental plaque have an important role in the aetiology of dental caries. A single intake of dietary sugar may be accompanied by an increase in carbohydrate levels (Critchley et al., 1967) and a reduction in pH (Stephan, 1940) of dental plaque which may be associated with changes in the concentrations of calcium and inorganic phosphorus (Coolidge, 1947; Dawes and Jenkins, 1962; Luoma, 1964; Ferguson and Thomas, 1973; Tatevossian, Edgar and Jenkins, 1975). However, the effect on calcium and phosphorus levels has not been a consistent finding, and Ashley (1975a) suggested that this may be due to variation in the dietary sugar experience prior to the single intake under investigation. Although previous comparisons of the plaque in human subjects consuming diets either high or low in sugar have shown differences in quantity and concentration of carbohydrate (Carlsson and Egelberg, 1965; Von der Fehr, LiK and Theilade, 1970; Gawronski et al., 1975), no differences in calcium and phosphorus have been reported. Our aim was to investigate the relationship between previous dietary sugar experience and the dry weight and biochemical composition of dental plaque under both standard&d and non-standard&d conditions.
MATERIALS
Experimental design
(a) Preliminary experiments: comparison of sugarrich and sugar-free diets. (1) Ten adult subjects with
AND METHODS
Preliminary studies were carried out in adults to establish whether there was a difference in the effect of relatively sugar-rich and sugar-free diets on the quantity and composition of plaque formed under controlled conditions. Further investigations were then undertaken in which normal variation of dietary sugar intake was recorded for each subject during 2&y plaque formation to assess the degree of correlation with plaque weight and composition. In one study, the last intake of sugar was standardised at 15 min before plaque collection; in the other, plaque was collected following overnight starvation. Finally, in order to investigate the effect of previous dietary sugar experience on mature plaque under normal conditions, dental plaque and dietary information was collected from a group of schoolchildren at yearly 0.B. 2217-A
of
409
a mean age of 26.1 yr (range 194) devoted 2 days to an experimental diet during successive weeks. Following a thorough prophylaxis on each occasion, the subjects abstained from oral hygiene and consumed a self-selected diet from which all obvious sources of dietary sugar were eliminated. During the sugar-rich period, the beverages consumed were supplemented with sucrose-between 10 and 15 intakes depending upon the normal consumption of each subject. During the sugar-free period, a virtually identical diet was consumed with the beverages remaining unsupplemented. Plaque was collected from each subject one hour following the final supplemented or unsup plemented beverage. (2) A second experiment, involving eight adult subjects with a mean age of 25.9 yr (range 19-36), was carried out in an identical manner. (b) 2-day plaque: 15 min following exposure to sugar. Following a thorough prophylaxis, 99 student subjects abstained from oral hygiene for 2 days, during which time they kept a complete written record of their diet. Each subject then sucked a boiled sweet for 5 min; plaque collection followed 15 min after removal of the sweet from the mouth. (c) Z-day plaque: following overnight starvation. One or two weeks following experiment (b), 43 of the subjects performed their own thorough baseline plaque removal and again abstained from oral hygiene for 2 days, keeping a complete dietary record. Plaque collection was carried out following overnight starvation, a minimum of 8 h having elapsed since taking food or drink. (d) Mature plaque: variable time since exposure to sugar. Dental plaque was collected from 51 schoolboys, initially aged 11-12 yr, at yearly intervals over a 3-yr period. No oral hygiene restrictions were imposed. A retrospective dietary history for the previous 24 h was obtained by close enquiry at the time of plaque collection. Assessment of the relationship
410
F. P.
Ashley and R. F. Wilson
between dental plaque and caries in these subjects has been presented previously (Ashley and Wilson. 1977).
The 2&y dietary records in studies (b) and (c) and the 24 h dietary histories in study (d) were analysed as follows, using standard references for sugar content of foodstuffs (McCance and Widdowson, 1960; Church and Church, 1975): (i) Time since sugar-the time elapsed since the last dietary sugar intake before plaque collection. in hours. (ii) Sugar intakes-the number of 30-min periods which included a dietary sugar intake. (iii) Total sugar-estimated amount of sugar consumed in grams. (iv) Total dissolved sugar--estimated amount of sugar consumed in solution in grams. In study (b), (i) excluded the sweet sucked 15 mm before plaque collection, as otherwise this parameter would have been identical for all the subjects. In study (d), insufficient information was obtained on portion size to regard (iii) and (iv) as accurate and they are not presented. Plaque collection and analysis
The detailed methods of plaque collection, estimation of dry weight and analysis of calcium, phosphorus, protein and carbohydrate have been described (Ashley, 1975b; Ashley and Wilson, 1977). Full-mouth plaque samples were collected in study (a). In study (b), plaque was collected by area, and full-mouth results similar to those for study (a) were extrapolated from the figures for the four separate areas. Lateral half-mputh plaque samples were collected in studies (c) and (d); but plaque was not collected from the lingual surfaces of the lower anterior teeth in study (c), or the buccal and lingual sur-
faces of these teeth in study (d). These surfaces were excluded to avoid contamination with calculus. Analysis of plaque was carried out following storage at - 17”C, except in study (b) where plaque was dried to constant weight before analysis. Estimations of dry weight and measurement of the concentrations of Ca and P in plaque were performed in all studies. Analysis of protein and carbohydrate concentrations was carried out in studies (a), (c) and (d). In addition. separation and analysis of water-soluble. alkalisoluble and alkali-insoluble carbohydrate fractions 01 plaque was carried out in studies (a-2). (c) and (d). RESULTS
Preliminary experiments: comparison of plaque on sugar-rich and sugar-free diets (a)
Comparison of the composition of dental plaque formed on sugar-rich and sugar-free diets (Table 1) indicated that the sugar-rich diet was associated with significantly lower concentrations of calcium and inorganic phosphorus and significantly higher concentrations of total carbohydrate than the sugar-free diet. The difference observed between total carbohydrate concentrations of plaque formed on the two diets was mainly due to differences in the water-soluble and alkali-insoluble carbohydrate fractions. No significant differences were observed in either protein or organic phosphorus concentrations. The dry weight of plaque formed on the sugar-rich diet was higher than that formed on the sugar-free diet, the difference being greater in the second study. (h) J-day plaque: 15 min following exposure to sugar Complete results were available for 68 subjects, and Table 2 presents the mean figures for dry weight and calcium and phosphorus concentrations of plaque together with the dietary parameters. Correlation of the plaque composition with the diet (Table 3)
Table I. Study (a): Biochemical constituents (pg/mg dry weight) and dry weight (mg) of 2-day plaque formed on sugar-free and sugar-rich diets in adults
Calcium Phosphorus. inorganic Phosphorus, organic Protein Carbohydrate, total Carbohydrate. water-soluble Carbohydrate, alkali-soluble Carbohydrate, alkali-insoluble Dry weight *p
22. pp. 409 to 414. Pergamon
Press 1977. Printed in Great Britmn.
THE RELATIONSHIP BETWEEN DIETARY SUGAR EXPERIENCE AND THE QUANTITY AND BIOCHEMICAL COMPOSITION OF DENTAL PLAQUE IN MAN F. P. ASHLEYand R. F. WILSON Department of Periodontology and Preventive ,Dentistry, Guy’s Hospital Dental School, London SE1 9RT, England Summary-The calcium and inorganic phosphorus concentrations of 2-day plaque in adults were inversely related to the previous dietary sugar experience; the dry weight and concentrations of water-soluble and alkali-insoluble carbohydrate were directly related to the dietary sugar experience. However, the relationship with the diet appeared to be limited to carbohydrate concentrations in mature plaque from children. INTRODUCI’ION
intervals for three years, without standard&&ion plaque age or exposure to sugar.
It is generally accepted that both dietary sugar and dental plaque have an important role in the aetiology of dental caries. A single intake of dietary sugar may be accompanied by an increase in carbohydrate levels (Critchley et al., 1967) and a reduction in pH (Stephan, 1940) of dental plaque which may be associated with changes in the concentrations of calcium and inorganic phosphorus (Coolidge, 1947; Dawes and Jenkins, 1962; Luoma, 1964; Ferguson and Thomas, 1973; Tatevossian, Edgar and Jenkins, 1975). However, the effect on calcium and phosphorus levels has not been a consistent finding, and Ashley (1975a) suggested that this may be due to variation in the dietary sugar experience prior to the single intake under investigation. Although previous comparisons of the plaque in human subjects consuming diets either high or low in sugar have shown differences in quantity and concentration of carbohydrate (Carlsson and Egelberg, 1965; Von der Fehr, LiK and Theilade, 1970; Gawronski et al., 1975), no differences in calcium and phosphorus have been reported. Our aim was to investigate the relationship between previous dietary sugar experience and the dry weight and biochemical composition of dental plaque under both standard&d and non-standard&d conditions.
MATERIALS
Experimental design
(a) Preliminary experiments: comparison of sugarrich and sugar-free diets. (1) Ten adult subjects with
AND METHODS
Preliminary studies were carried out in adults to establish whether there was a difference in the effect of relatively sugar-rich and sugar-free diets on the quantity and composition of plaque formed under controlled conditions. Further investigations were then undertaken in which normal variation of dietary sugar intake was recorded for each subject during 2&y plaque formation to assess the degree of correlation with plaque weight and composition. In one study, the last intake of sugar was standardised at 15 min before plaque collection; in the other, plaque was collected following overnight starvation. Finally, in order to investigate the effect of previous dietary sugar experience on mature plaque under normal conditions, dental plaque and dietary information was collected from a group of schoolchildren at yearly 0.B. 2217-A
of
409
a mean age of 26.1 yr (range 194) devoted 2 days to an experimental diet during successive weeks. Following a thorough prophylaxis on each occasion, the subjects abstained from oral hygiene and consumed a self-selected diet from which all obvious sources of dietary sugar were eliminated. During the sugar-rich period, the beverages consumed were supplemented with sucrose-between 10 and 15 intakes depending upon the normal consumption of each subject. During the sugar-free period, a virtually identical diet was consumed with the beverages remaining unsupplemented. Plaque was collected from each subject one hour following the final supplemented or unsup plemented beverage. (2) A second experiment, involving eight adult subjects with a mean age of 25.9 yr (range 19-36), was carried out in an identical manner. (b) 2-day plaque: 15 min following exposure to sugar. Following a thorough prophylaxis, 99 student subjects abstained from oral hygiene for 2 days, during which time they kept a complete written record of their diet. Each subject then sucked a boiled sweet for 5 min; plaque collection followed 15 min after removal of the sweet from the mouth. (c) Z-day plaque: following overnight starvation. One or two weeks following experiment (b), 43 of the subjects performed their own thorough baseline plaque removal and again abstained from oral hygiene for 2 days, keeping a complete dietary record. Plaque collection was carried out following overnight starvation, a minimum of 8 h having elapsed since taking food or drink. (d) Mature plaque: variable time since exposure to sugar. Dental plaque was collected from 51 schoolboys, initially aged 11-12 yr, at yearly intervals over a 3-yr period. No oral hygiene restrictions were imposed. A retrospective dietary history for the previous 24 h was obtained by close enquiry at the time of plaque collection. Assessment of the relationship
410
F. P.
Ashley and R. F. Wilson
between dental plaque and caries in these subjects has been presented previously (Ashley and Wilson. 1977).
The 2&y dietary records in studies (b) and (c) and the 24 h dietary histories in study (d) were analysed as follows, using standard references for sugar content of foodstuffs (McCance and Widdowson, 1960; Church and Church, 1975): (i) Time since sugar-the time elapsed since the last dietary sugar intake before plaque collection. in hours. (ii) Sugar intakes-the number of 30-min periods which included a dietary sugar intake. (iii) Total sugar-estimated amount of sugar consumed in grams. (iv) Total dissolved sugar--estimated amount of sugar consumed in solution in grams. In study (b), (i) excluded the sweet sucked 15 mm before plaque collection, as otherwise this parameter would have been identical for all the subjects. In study (d), insufficient information was obtained on portion size to regard (iii) and (iv) as accurate and they are not presented. Plaque collection and analysis
The detailed methods of plaque collection, estimation of dry weight and analysis of calcium, phosphorus, protein and carbohydrate have been described (Ashley, 1975b; Ashley and Wilson, 1977). Full-mouth plaque samples were collected in study (a). In study (b), plaque was collected by area, and full-mouth results similar to those for study (a) were extrapolated from the figures for the four separate areas. Lateral half-mputh plaque samples were collected in studies (c) and (d); but plaque was not collected from the lingual surfaces of the lower anterior teeth in study (c), or the buccal and lingual sur-
faces of these teeth in study (d). These surfaces were excluded to avoid contamination with calculus. Analysis of plaque was carried out following storage at - 17”C, except in study (b) where plaque was dried to constant weight before analysis. Estimations of dry weight and measurement of the concentrations of Ca and P in plaque were performed in all studies. Analysis of protein and carbohydrate concentrations was carried out in studies (a), (c) and (d). In addition. separation and analysis of water-soluble. alkalisoluble and alkali-insoluble carbohydrate fractions 01 plaque was carried out in studies (a-2). (c) and (d). RESULTS
Preliminary experiments: comparison of plaque on sugar-rich and sugar-free diets (a)
Comparison of the composition of dental plaque formed on sugar-rich and sugar-free diets (Table 1) indicated that the sugar-rich diet was associated with significantly lower concentrations of calcium and inorganic phosphorus and significantly higher concentrations of total carbohydrate than the sugar-free diet. The difference observed between total carbohydrate concentrations of plaque formed on the two diets was mainly due to differences in the water-soluble and alkali-insoluble carbohydrate fractions. No significant differences were observed in either protein or organic phosphorus concentrations. The dry weight of plaque formed on the sugar-rich diet was higher than that formed on the sugar-free diet, the difference being greater in the second study. (h) J-day plaque: 15 min following exposure to sugar Complete results were available for 68 subjects, and Table 2 presents the mean figures for dry weight and calcium and phosphorus concentrations of plaque together with the dietary parameters. Correlation of the plaque composition with the diet (Table 3)
Table I. Study (a): Biochemical constituents (pg/mg dry weight) and dry weight (mg) of 2-day plaque formed on sugar-free and sugar-rich diets in adults
Calcium Phosphorus. inorganic Phosphorus, organic Protein Carbohydrate, total Carbohydrate. water-soluble Carbohydrate, alkali-soluble Carbohydrate, alkali-insoluble Dry weight *p
