|Year : 2011 | Volume
| Issue : 4 | Page : 310-314
Role of plaque in the clearance of salivary sucrose and its influence on salivary ph
A Kumar1, R Hedge2, U Dixit3
1 Department of Pedodontics and Preventive Dentistry, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh, India
2 Department of Pedodontics and Preventive Dentistry, Bharti Vidya Peeth University Dental College, Navi Mumbai, Maharashtra, India
3 Department of Pedodontics and Preventive Dentistry, Dr. D.Y. Patil Dental College, Navi Mumbai, Maharashtra, India
|Date of Web Publication||21-Oct-2011|
Reader, Department of Pedodontics and Preventive Dentistry, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh
| Abstract|| |
Background: The prevalence of dental caries in children, in India, is higher than many of the industrialized countries. The sugar most commonly associated with dental caries is sucrose, as the microorganisms in the dental plaque have the ability to convert this dietary constituent into various organic acids. Aims and Objectives: This study was conducted to study the effect of the presence of plaque on the salivary clearance of sucrose and to study the effect of the presence of plaque on salivary pH, following sucrose clearance. Materials and Methods: Salivary sucrose determination was done by using the anthrone technique. A Digital MHOS pH meter estimated the salivary pH. Results: Presence of plaque increased the salivary sucrose clearance time and decreased the salivary pH at various time intervals. Conclusions: The microbial etiology of dental caries is the dynamic relationship among the dental plaque microbiota, dietary carbohydrates, saliva and pH lowering, and the cariogenic potential of the dental plaque. Caries occur preferentially in the dentition sites characterized by high exposure to carbohydrate and diminished salivary effect.
Keywords: Plaque pH, sucrose clearance, salivary pH
|How to cite this article:|
Kumar A, Hedge R, Dixit U. Role of plaque in the clearance of salivary sucrose and its influence on salivary ph. J Indian Soc Pedod Prev Dent 2011;29:310-4
|How to cite this URL:|
Kumar A, Hedge R, Dixit U. Role of plaque in the clearance of salivary sucrose and its influence on salivary ph. J Indian Soc Pedod Prev Dent [serial online] 2011 [cited 2013 May 25];29:310-4. Available from: http://www.jisppd.com/text.asp?2011/29/4/310/86377
| Introduction|| |
It is well-established that fermentable carbohydrates and microorganisms in the plaque play a significant role in the pathogenesis of dental caries. The sugar most commonly associated with dental caries is sucrose and has been termed as the 'arch criminal of dental caries'. The properties of carbohydrates that make them more cariogenic include the type of sugar, consistency, oral retention, concentration of sugar, and frequency of ingestion.
As the saliva is secreted into the oral cavity it dilutes the sugar present in the food and makes it available to the microorganisms for fermentation and at the same time it reduces the availability of sugars to microorganisms by the virtue of swallowing, which is termed as oral clearance. Oral clearance of sugars has been studied in the past by many researchers. However, the effects of the presence of plaque on the clearance of sucrose from the oral cavity and on the salivary pH have not been extensively studied in children. This study was undertaken with the following objectives:
- To study the effect of the presence of plaque on the salivary clearance of sucrose
- To study the effect of the presence of plaque on salivary pH, following sucrose clearance
| Materials and Methods|| |
A total of 20 children between the ages three and six years were selected for the study.
The selected children and their parents were explained the nature of the study. Informed consent was obtained from the parents to allow their children to participate in the study.
The study design was of a crossover type and included two groups, the Control Group and Plaque Group, as follows:
Control Group (Group I): Children without plaque build-up, where the children were asked to brush with a proper technique twice a day, prior to the study
Plaque Group (Group II): Children with plaque build-up, where children were asked to abstain from brushing their teeth for 48 hours
Children assigned to the Control Group were later assigned to the Plaque Group and vice versa.
All the children were asked to report to the Department of Pediatric and Preventive Dentistry without breakfast in the morning. Upon arrival, all the children from the Control and the Plaque Groups were asked to spit saliva for one minute in a clean plastic container in order to measure the baseline salivary flow rate, sucrose concentration, and salivary pH.
The children were then given 10 ml of sucrose solution (25%) in a cup. They were asked to keep it in their mouth for one minute and then swallow. Unstimulated saliva samples were collected for 60 minutes at different time intervals (0 minute, 2 minutes, 4 minutes, 6 minutes, 8 minutes, 10 minutes, 20 minutes, 30 minutes, and 60 minutes). The saliva samples were analyzed for salivary sucrose concentrations and salivary pH.
Measurement of salivary sucrose and salivary ph
Salivary sucrose determination was done using the anthrone technique (Halhoul and Kleinberg, 1972). 
Salivary pH was estimated by using a digital MHOS pH meter (model PE-133, Elico Pvt. Ltd.).
Statistical analyses were performed to compare the salivary sucrose concentration and salivary pH between the two groups.
| Results|| |
A total of 20 pre-school children, eight boys and 12 girls between the ages of three and six years (mean ± SD: 55.8 ± 7.04 months) were included in this study [Table 1].
Salivary flow-rates at baseline
Mean salivary flow rates for the Control Group and the Plaque Group at the baseline were found to be 0.55 ± 0.12 ml / minute and 0.43 ± 0.10 ml / minute [Table 2]. This difference was found to be statistically significant (P < 0.01)
Salivary sucrose concentration
[Table 3] and [Figure 1] present the comparison of the mean salivary sucrose concentrations for both the groups, at different time intervals.
|Figure 1: Effect of the presence of plaque on the salivary sucrose clearance curve|
Click here to view
|Table 3: Comparison of salivary sucrose concentration in mm / L across the groups at different time intervals|
Click here to view
At baseline, that is, before exposure to sucrose, the mean salivary sucrose concentrations for the Control Group and the Plaque Group were found to be 0.0 mM / L and 0.0 mM / L, respectively, and there was statistically no significant difference between the groups.
Salivary sucrose concentrations at 0 minute, that is, immediately after exposure to the sucrose solution, for the Control Group and the Plaque Group were found to be 202.5 ± 101.5 mM / L and 262.5 ± 111.1 mM / L, respectively, and the difference was found to be statistically significant (P = 0.01).
Like this, salivary sucrose concentrations at all the time intervals, till they reached the baseline level, were higher in the plaque group when compared to the control group and the difference was found to be statistically significant (P = 0.01).
Mean clearance time, that is, time at which the salivary sucrose concentration reaches the baseline level, were found to be 8.2 ± 1.4 minutes for the Control Group and 10.9 ± 4.0 minutes for the Plaque Group [Table 4]. The Mann-Whitney test employed to compare the inter-group differences revealed that sucrose was cleared from the oral cavity significantly faster in the Control Group when compared to the Plaque Group (P < 0.01).
Salivary pH at different time intervals
In all children, in both the groups, the salivary pH reduced gradually to a point and then increased gradually toward the baseline level, which was not reached even 60 minutes after sucrose exposure.
[Table 5] and [Figure 2] present the comparison of the mean salivary pH at different time intervals for both the groups. Salivary pH at the baseline for the Control Group and the Plaque Group were found to be 6.82 ± 0.17 and 6.73 ± 0.21, respectively. This difference was found to be significant (P = 0.006).
|Table 5: Comparison of salivary pH at different time intervals in both the groups|
Click here to view
At '0' minute, that is, immediately after sucrose exposure, the mean salivary pH in the Control Group and the Plaque Group were found to be 6.64 ± 0.20 and 6.48 ± 0.21, respectively. The mean salivary pH in the Plaque Group was significantly lower than that in the Control Group (P = 0.01).
Like this, salivary pH value at all the time intervals, till they reached the baseline level, were lower in the plaque group when compared to the control group and the difference was found to be statistically significant (P = 0.01).
Decrease in salivary pH with time
After exposure to sucrose solution, the salivary pH decreased with time in both the groups. Mean minimum pH for the Control Group was found to be 6.44 ± 0.28 and was significantly higher (P = 0.045) than the mean minimum pH in the Plaque Group (6.26 ± 0.28, [Table 6]).
In the Control Group, the mean time interval to reach the minimum pH was evaluated to be 9.1 ± 2.7 minutes. The time required in the Plaque Group to reach the minimum pH was 9.6 ± 1 minutes, which was found to be significantly higher (P < 0.01) than that of the Control Group [Table 7].
|Table 7: Comparison of time required to reach minimum salivary pH across the groups|
Click here to view
| Discussion|| |
Effect of plaque on sucrose retention and clearance
In our study we found that salivary sucrose concentrations at all time intervals, till they reached baseline level, were significantly higher in the Plaque Group than in the Control Group. Also, when the oral clearance time of sucrose was evaluated, it was observed that the clearance was more rapid in the Control Group than in the Plaque Group.
The reason may be that the existing plaque acts as a reservoir, by retaining some of the sucrose solution, which in turn may be released in the saliva at a later stage. This retention may be facilitated by the existence of micro channels running through the plaque, providing movement of fluid within the structure of the plaque (Wood et al.). 
Change in salivary ph with time
In our study we found that after exposure to sucrose, the salivary pH decreased significantly till 9.1 ± 2.7 minutes and 9.6 ± 1.0 minutes in the Control Group and the Plaque Group, respectively, and then it rose slowly. Our findings are concurrent with those of Stephan, 
He suggested that although organisms in he saliva may be producing some acid, the acids arising in the dental plaque or from bacteria colonizing on the tongue and other soft tissues might appear in the saliva, giving rise to a 'Salivary Stephan Curve' similar to the Stephan curve originally discussed by Stephan  in the dental plaque.
Effect of plaque on salivary ph
In our study, the salivary pH at the baseline was found to be significantly higher in the Control Group than in the Plaque Group. Also, the salivary pH values at various time intervals were found to be significantly lower in the Plaque Group when compared to the Control Group. This difference in salivary pH could be attributed to the presence of plaque in the Plaque Group.
It has been reported that the extent of the plaque pH decrease may be attributed the concentration of cariogenic microorganisms in the dental plaque or oral cavity (Kleinberg, Bibby et al.). ,, As children in the Control Group participated in tooth brushing for the removal of dental plaque, lower values of pH in this group are justifiable.
| Conclusions|| |
From our study we conclude that
- The salivary clearance of sucrose from the oral cavity was found to be a two-step process, initial rapid clearance followed by a later slow clearance, in both the groups
- The presence of plaque led to increased salivary sucrose concentrations at all time intervals till they reached the baseline level
- The presence of plaque increased the salivary sucrose clearance time
- The presence of plaque led to decreased salivary pH at various time intervals, including at the baseline
- Minimum salivary pH in the presence of plaque was significantly lower than in the absence of plaque
- Minimum salivary pH was acquired faster in the absence of plaque, which was followed by a slow rise in salivary pH
| References|| |
|1.||Halhoul MN, Kleinberg I. Differential determination of glucose and fructose, and glucose- and fructose- yielding substances with anthrone. Anal Biochem 1972;50:337-43. |
|2.||Wood SR, Kirkham J, Marsh PD, Shore RC, Nattress B, Robinson C. Architecture of intact natural human plaque bioflims studied by confocal laser scanning microscopy. J Dent Res 2000;79:21-7. |
|3.||Stephan RM. Changes in hydrogen ion concentration on tooth surfaces and in carious lesions. J Am Dent Assoc 1940;23:257-66. |
|4.||Stephan RM. Intraoral hydrogen ion concentration on tooth surfaces and in carious lesion. J Am Dent Assoc 1944;23:257-66. |
|5.||Kleinberg I. Effect of varying sediment and glucose concentrations on the pH and acid production in human salivary sediment mixtures. Arch Oral Biol 1967;12:1457-73. |
|6.||Kleinberg I. Biochemistry of dental plaque. In: Staple PH, editor. Advances in Oral Biology. Vol. 4. New York, NY: Academic Press; 1970. p. 43-90. |
|7.||Bibby BG, Mundorff SA, Zero DT, Almekinder KJ. Oral food clearance and the pH of plaque and saliva. J Am Dent Assoc 1986;112:333-7. |
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]