Effects of Single Exposure to Sugar on Calcium and Phosphorus Concentrations of Dental Plaque F. P. ASHLEY Department of Periodontology and Preventive Dentistry, Guy's Hospital Dental School, London SEI 9RWT, England
The results from three studies on the plaque of children and adults indicated that the response of the plaque to a single five-minute exposure to sugar cubes or boiled sweets (candies) depended on the initial condition of the plaque. Thus, significant decreases in the levels of calcium and phosphorus in plaque were observed in previously starved plaques but not in plaque from participants without previous dietary sugar restriction. There have been several conflicting reports on the effects of a single exposure of sugar on the calcium and phosphorus levels of dental plaque.1'5 As the movement of calcium and phosphate ions from the enamel to the plaque and from the plaque to the oral fluids must be considered essential to the process of caries, the effect of sugar on the calcium and phosphorus levels of plaque is of interest and was investigated in the three studies reported in this article. The first and third of the present three studies assessed the effect on the calcium and phosphorus levels of plaque of exposure to sugar in the form of a boiled sweet (candy) under different experimental conditions. In the second study, the experimental conditions were the same as those of the first, but the exposure to sugar was in the form of solid sucrose. This study was undertaken in case there was any variation due to the differences between boiled sweets and sugar cubes.
Materials and Methods STUDY 1.-The participants were 51 boys 12 to 13 years of age who were taking part in a longitudinal study of the relationship between caries incidence and the levels of calReceived for publication August 20, 1974. Accepted for publication March 4, 1975.
cium and phosphorus in plaque. Boys were chosen because previous experience had shown that in this age group boys tend to be less enthusiastic in their oral hygiene than girls and therefore provide more plaque without any restriction on their normal oral hygiene procedures. Thus, the plaque collected was of unknown age and will be referred to as "mature." All the available plaque was carefully removed from the teeth on one side of the mouth with the exception of the lower anterior teeth. The side chosen was randomized and the lower anterior teeth were excluded because of the greater possibility of contamination of the plaque with calculus in this area. The boys then sucked a boiled sweet for five minutes, and 15 minutes later the plaque was collected from the other side of the mouth. Boiled sweets are approximately two-thirds sucrose and one-third glucose syrup. The glucose syrup used is produced by the partial hydrolysis of maize starch and consists of glucose (15%,), maltose (11%), and higher polymers. The procedure was carried out during the school day and therefore the time since the last meal or other food varied between the boys. STUDY 2.-This study used the same group of boys as study 1 and took place approximately one year later. The experimental procedure was identical to study 1 with the exception that the boiled sweet was replaced by solid sucrose in the form of two cubes of sugar-one being sucked at the commencement of the five-minute period and another halfway through the period. STUDY 3.-The participants were 22 preclinical dental students 19 to 21 years old whose teeth were all thoroughly scaled and polished in the fortnight before the present 1015
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1016
study. They were given disclosing tablets, a toothbrush, and a nonfluoride dentifrice and were asked to perform their own baseline plaque removal before going to bed on a specified day; they then ceased toothbrushing for two days before plaque collection on the third morning at 8 AM. The students abstained from food and drink that morning. The collection of plaque before and after exposure to a boiled sweet was carried out as in study 1, but only the lingual aspects of the lower anterior teeth were excluded in this study since in such a short period of time after a scale and polish calculus would be unlikely to occur in any other areas. PLAQUE COLLECTION AND ANALYSIS.-A sickle-shaped polystyrene instrument was used to collect the plaque from the teeth onto stainless-steel wires which were then immediately placed in a deep-freeze. The plaque samples were homogenized in deionized water at 4 C before analysis and estimation of dry weight. Calcium estimation was done using an atomic absorption spectrophotometera after initial treatment with trichloroacetic acid and lanthanum chloride. Inorganic and total phosphorus estimations were done according to the method of Chen, Toribara, and Warner.6 Dry weight was estimated using an electronic balanceb by drying 1 ml of the plaque homogenate to a constant weight in a previously weighed and tared aluminum cup. Statistical evaluation of any differences observed was done using Student's paired t test.
Results Complete data were available for 40 participants in study 1, 44 in study 2, and 18 in study 3. The loss of participants in studies 1 and 2 was due to a combination of absence of participants, insufficient plaque, and analytical losses. All the participants taking part in study 3 completed the study, but four had incomplete data because of analytical losses. Exposure of a mature plaque to a boiled sweet in study I appeared to have little effect on the mean levels of calcium and phosphorus in the plaque (Fig 1) and none of the differences observed were statistically significant. A similar lack of significant efUnicam SP90, Pye Unicam Ltd., Cambridge, UK. Beckman LM600, Beckman-RIIC Ltd., Croydon, UK. a
b
J Dent Res September-October 1975
ASHLEY
MEAN (S D
TOTAL PHOSPHORUS
CALCIUM
INORGANIC PHOSPHORUS
6.03 5.44 (3.65 351
4.52 4.69
12.74 12.43
(I .38) (2.13)
(3.55) (4.61
14 12
_
I
10
O
6
FIG 1.-Histogram shows mean calcium and phosphorus levels of mature plaque before and after exposure to a sweet (40 participants). Solid bars, before sweets; dotted bars, after sweets.
fect was observed when the effect of solid sucrose was investigated in study 2 (Fig 2). In contrast, investigation of the effect of exposure to a sweet on the mean calcium and phosphorus levels of an overnight starved plaque in study 3 (Fig 3) showed significantly lower levels of calcium (P
The results from three studies on the plaque of children and adults indicated that the response of the plaque to a single five-minute exposure to sugar cubes or boiled sweets (candies) depended on the initial condition of the plaque. Thus, significant decreases in the levels of calcium and phosphorus in plaque were observed in previously starved plaques but not in plaque from participants without previous dietary sugar restriction. There have been several conflicting reports on the effects of a single exposure of sugar on the calcium and phosphorus levels of dental plaque.1'5 As the movement of calcium and phosphate ions from the enamel to the plaque and from the plaque to the oral fluids must be considered essential to the process of caries, the effect of sugar on the calcium and phosphorus levels of plaque is of interest and was investigated in the three studies reported in this article. The first and third of the present three studies assessed the effect on the calcium and phosphorus levels of plaque of exposure to sugar in the form of a boiled sweet (candy) under different experimental conditions. In the second study, the experimental conditions were the same as those of the first, but the exposure to sugar was in the form of solid sucrose. This study was undertaken in case there was any variation due to the differences between boiled sweets and sugar cubes.
Materials and Methods STUDY 1.-The participants were 51 boys 12 to 13 years of age who were taking part in a longitudinal study of the relationship between caries incidence and the levels of calReceived for publication August 20, 1974. Accepted for publication March 4, 1975.
cium and phosphorus in plaque. Boys were chosen because previous experience had shown that in this age group boys tend to be less enthusiastic in their oral hygiene than girls and therefore provide more plaque without any restriction on their normal oral hygiene procedures. Thus, the plaque collected was of unknown age and will be referred to as "mature." All the available plaque was carefully removed from the teeth on one side of the mouth with the exception of the lower anterior teeth. The side chosen was randomized and the lower anterior teeth were excluded because of the greater possibility of contamination of the plaque with calculus in this area. The boys then sucked a boiled sweet for five minutes, and 15 minutes later the plaque was collected from the other side of the mouth. Boiled sweets are approximately two-thirds sucrose and one-third glucose syrup. The glucose syrup used is produced by the partial hydrolysis of maize starch and consists of glucose (15%,), maltose (11%), and higher polymers. The procedure was carried out during the school day and therefore the time since the last meal or other food varied between the boys. STUDY 2.-This study used the same group of boys as study 1 and took place approximately one year later. The experimental procedure was identical to study 1 with the exception that the boiled sweet was replaced by solid sucrose in the form of two cubes of sugar-one being sucked at the commencement of the five-minute period and another halfway through the period. STUDY 3.-The participants were 22 preclinical dental students 19 to 21 years old whose teeth were all thoroughly scaled and polished in the fortnight before the present 1015
Downloaded from jdr.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on April 4, 2015 For personal use only. No other uses without permission.
1016
study. They were given disclosing tablets, a toothbrush, and a nonfluoride dentifrice and were asked to perform their own baseline plaque removal before going to bed on a specified day; they then ceased toothbrushing for two days before plaque collection on the third morning at 8 AM. The students abstained from food and drink that morning. The collection of plaque before and after exposure to a boiled sweet was carried out as in study 1, but only the lingual aspects of the lower anterior teeth were excluded in this study since in such a short period of time after a scale and polish calculus would be unlikely to occur in any other areas. PLAQUE COLLECTION AND ANALYSIS.-A sickle-shaped polystyrene instrument was used to collect the plaque from the teeth onto stainless-steel wires which were then immediately placed in a deep-freeze. The plaque samples were homogenized in deionized water at 4 C before analysis and estimation of dry weight. Calcium estimation was done using an atomic absorption spectrophotometera after initial treatment with trichloroacetic acid and lanthanum chloride. Inorganic and total phosphorus estimations were done according to the method of Chen, Toribara, and Warner.6 Dry weight was estimated using an electronic balanceb by drying 1 ml of the plaque homogenate to a constant weight in a previously weighed and tared aluminum cup. Statistical evaluation of any differences observed was done using Student's paired t test.
Results Complete data were available for 40 participants in study 1, 44 in study 2, and 18 in study 3. The loss of participants in studies 1 and 2 was due to a combination of absence of participants, insufficient plaque, and analytical losses. All the participants taking part in study 3 completed the study, but four had incomplete data because of analytical losses. Exposure of a mature plaque to a boiled sweet in study I appeared to have little effect on the mean levels of calcium and phosphorus in the plaque (Fig 1) and none of the differences observed were statistically significant. A similar lack of significant efUnicam SP90, Pye Unicam Ltd., Cambridge, UK. Beckman LM600, Beckman-RIIC Ltd., Croydon, UK. a
b
J Dent Res September-October 1975
ASHLEY
MEAN (S D
TOTAL PHOSPHORUS
CALCIUM
INORGANIC PHOSPHORUS
6.03 5.44 (3.65 351
4.52 4.69
12.74 12.43
(I .38) (2.13)
(3.55) (4.61
14 12
_
I
10
O
6
FIG 1.-Histogram shows mean calcium and phosphorus levels of mature plaque before and after exposure to a sweet (40 participants). Solid bars, before sweets; dotted bars, after sweets.
fect was observed when the effect of solid sucrose was investigated in study 2 (Fig 2). In contrast, investigation of the effect of exposure to a sweet on the mean calcium and phosphorus levels of an overnight starved plaque in study 3 (Fig 3) showed significantly lower levels of calcium (P
