|Year : 2014 | Volume
| Issue : 1 | Page : 26-32
Effect of commonly consumed sugar containing and sugar free fruit drinks on the hydrogen ion modulation of human dental plaque
Nanika Mahajan1, Bhanu Kotwal2, Vinod Sachdev3, Nivedita Rewal4, Rakesh Gupta5, Shefally Goyal6
1 MDS, Registrar, Department of Pedodontics Indira Gandhi Government Dental College, Jammu, India
2 MDS, Senior Lecturer, Institute of Dental Sciences, Jammu, India
3 MDS, Principal and HOD, Department of Pedodontics, ITS Dental College, Ghaziabad, India
4 MDS, Lecturer, Himachal Dental College, Sundernagar, Jammu, India
5 MDS, Professor and HOD, Department of Pedodontics Indira Gandhi Government Dental College, Jammu, India
6 MDS, Himachal Dental College, Sundernagar, Jammu, India
|Date of Web Publication||15-Feb-2014|
Registrar, Department of Pedodontics, Indira Gandhi Government Dental College, Jammu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: With the increased awareness of healthy diet among the population, the intake of fruit juices as health drinks has been increased. This study has been designed to check the potential cariogenicity of fruit drinks frequently consumed by infants and young children. Aim: To compare the acidogenic potential of sugar free fruit juices with fruit juices containing sugar by evaluating the plaque pH changes, following consumption of the above drinks. Design: The study was carried out on 10 children in the age group of 8-15 years. The four fruit juices used were 1) orange juice with added sugar 2) orange juice with no added sugar 3) apple juice with added sugar 4) apple juice with no added sugar. Sucrose rinse of 10% was used as control group. The endogenous pH of the fruit juices and control was assessed using digital pH meter. The plaque pH was assessed at the baseline and after the consumption of the drinks at 5, 10, 20, 30, 40, and 60 minutes time interval using the plaque-harvesting technique. The obtained results were compiled and subjected to statistical analysis using paired t-test. Result: All the fruit juices showed drop in plaque pH. A drop in pH was also observed in the juices despite of no added sugar content. Conclusion: The fruit juices labeled with "no added sugar" or "free from added sugar", contained substantial quantities of sugar and are equally cariogenic as are fruit drinks with added sugar.
Keywords: Cariogenicity, dental caries, fruit drinks, plaque, plaque ph
|How to cite this article:|
Mahajan N, Kotwal B, Sachdev V, Rewal N, Gupta R, Goyal S. Effect of commonly consumed sugar containing and sugar free fruit drinks on the hydrogen ion modulation of human dental plaque. J Indian Soc Pedod Prev Dent 2014;32:26-32
|How to cite this URL:|
Mahajan N, Kotwal B, Sachdev V, Rewal N, Gupta R, Goyal S. Effect of commonly consumed sugar containing and sugar free fruit drinks on the hydrogen ion modulation of human dental plaque. J Indian Soc Pedod Prev Dent [serial online] 2014 [cited 2020 Apr 9];32:26-32. Available from: http://www.jisppd.com/text.asp?2014/32/1/26/127049
| Introduction|| |
The concept of health has prevailed for centuries and dietary habits are apparently changing with modernization. "Healthy diet" is now perceived to be important. Changes in diet have included a substantial increase in the consumption of beverages and fruit drinks. People have become aware of the deleterious effects caused by carbonated beverages on the teeth and they prefer more natural and healthy products such as fruit juices, as they also provide a good source of vitamins. They are popular worldwide with people of all ages and are being aggressively promoted as "health drinks" by manufacturers. 
The potential cariogenicity of fruit drinks frequently consumed by infants and young children has been the subject of much study in the past decade. Fruit juices are thought to cause damage to teeth because of their two properties:
- The low pH and high titrable acidity of some drinks leading to erosion of the enamel surface.
- The levels of fermentable carbohydrate in the drinks which when metabolized by plaque microorganisms generate organic acids leading to drop in the dental plaque pH that can cause demineralization and subsequent dental caries. 
To overcome these deleterious effects of the fruit drinks, there have been attempts made by industry to produce safe drinks by:
- Altering the citrate content; it has been shown that when small amounts of citrate were added to drinks, the acidogenic response in the plaque is reduced.
- Reducing the amount of fermentable carbohydrates, to the levels so that they would not produce a significant drop in the plaque pH.
- Manufacturing fruit drinks with no added sugar to reduce the cariogenic potential. 
As literature regarding the acidogenic potential and subsequent cariogenicity following consumption of no added sugar in fruit drinks is sparse. The present study has been conducted and designed to study the acidogenic response of commonly consumed fruits drinks containing no added sugar and compare it with fruit drinks containing sugar by using plaque-sampling method.
| Design and Procedure|| |
Sample size: The sample for this study was drawn from children (8-15 years old), visiting the Pedodontic clinics in the Deptt. Of Pedodontics and Preventive Dentistry, Himachal Dental College, Sundernagar.Before conducting this in vitro study, clearance from the institutional ethical committee was obtained.
| Criteria and Clinical Examination|| |
Total of 10 children in the age group of 8-15 years with the missing component due to caries were selected for the study fulfilling the following clinical criteria:
- dft + DFT not more than 3.
- No filling on the labial/buccal & lingual surfaces of teeth.
- No gross malocclusion, especially overcrowding.
- Children with optimum cooperation for the smooth functioning of investigation.
Only those children who had taken the parental consent were selected for the study.
All the test drinks were given to each child in the experiment i.e. sugar containing real apple and orange fruit juices, real active apple and orange carrot fruit juices and also sucrose rinse [Figure 1]
- Before the start of the investigation, each child was given a thorough oral prophylaxis and the child was advised not to brush for 48 hrs.
- The child was then called on the third day at a fixed time, to exclude the variation in plaque metabolism in the experiment.
- The child was advised not to take anything except plain water before coming to the clinic.
- Standardization of pH meters: Before taking any recordings on the pH meters, the instrument was checked and standardized with the standard buffer of pH 4.00 and 7.00
- Plaque collection and pH measurement: Dental plaque samples were collected from different spots on buccal/labial and lingual surface of teeth (within a period of 30-60 sec) and dissolved in the test beakers having 1 ml of double distilled de-ionized water and pH was determined immediately (within 90 sec.) to record resting plaque pH with the help of electrodes of the pH meter.
- Inherent pH of the juices and the sucrose were measured [Table 1].
- Each child was given the test drink to be consumed slowly over a period of 3-5 min. Five minutes after the consumption of drink, the plaque sampling was done in the same manner as described earlier. Similarly, the pH was recorded after 10, 20, 30, 40 and 60 minutes of the post consumption period.
- After each experiment, each of the participating subjects was made to follow the normal oral hygiene regime for five days before the start of next experiment.
- The resting plaque of each child was taken whenever the next experiment was performed.
- Similar sequence of events of procedure was followed for each drink group and sucrose rinse.
Finally, the obtained results were compiled and subjected to statistical analysis.
|Table 1: The different fruit drinks taken, their inherent pH and the approximate amount used|
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| Ethics|| |
The ethics committee of the Himachal Dental College and Hospital, Sundernagar, Himachal Pradesh, India approved the study plan.
| Results|| |
Intragroup comparison of plaque pH modulation of test juices and control was done using paired t-test and the results were found to be statistically significant. On the other hand, inter comparison of plaque pH modulation during post consumption of test juices and control was done using unpaired t-test [Table 2].
|Table 2: Intracomparison of mean plaque pH of various experimental drinks/control at specified time intervals|
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Resting plaque pH for each group did not show much variation, it being 6.39 ± 0.38, 6.51 ± 0.34, 6.37 ± 0.32, 6.42 ± 0.33 and 6.36 ± 0.34 for orange juice with sugar, orange juice with no added sugar, apple juice with added sugar, apple juice with no added sugar sucrose solution, respectively [Figure 2].
|Figure 2: Mean pH values of various test groups (sucrose controlled) at specified time intervals|
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The H + ion modulation of all the four test drinks and control rinse showed an immediate drop in the plaque pH at 5 minutes time interval and a further drop in pH was seen to its lowest point at the end of 10 minutes following the consumption of the drinks, the plaque pH remained below the critical plaque pH for not more than 20 minutes time interval in all other test drinks [Figure 2].
On the basis of drop in plaque pH, orange juice with added sugar and the orange juice with no added sugar were found to be highly cariogenic but when both the drinks were compared; orange juice with no added sugar was less cariogenic. This order of cariogenicity was followed by apple juice with no added sugar and lastly, apple juice with added sugar.
Thus, a drop in pH was also observed in the juices despite of no added sugar content.
Area under the plaque pH curve for each test drink and control
In order to have a good idea of the degree and length of time of the acidogenic challenge in the mouth, a simple recording of drop in plaque pH along with the area enclosed by the plaque pH curve below resting pH was calculated. Two softwares namely, MS Excel & autoCAD, were used to calculate the area under the plaque pH curve.
The area under the plaque pH curve were found to be 30.93 ± 0.31, 26.01 ± 0.9, 15.99 ± 0.13, 16.27 ± 0.75 and 14.28 ± 0.35 [Table 3] for orange juice with added sugar, orange juice with no added sugar, apple juice with added sugar, apple juice with no added sugar and sucrose, respectively [Figure 3].
|Table 3: Minimum pH, area under plaque ph curves and api of test drinks as compared to control|
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An acidogenic potential index (API) was calculated, using the area under the curve for 10% sucrose as a baseline, with a score of 1, and the relative API for fruit drinks calculated as a ratio of this score. It can be seen that the API was the highest when orange juice with added sugar (2.16) was consumed followed by orange juice with no added sugar (1.82), apple juice with no added sugar (1.13), apple juice with added sugar (1.11) and sucrose (1) [Table 3].
Experiment conducted to test the validity and reliability of the experiment
In order to calibrate the experiment and to determine its reliability pre and post consumption plaque, H + ion modulations were recorded with 10% sucrose rinse in the same child, 10 times on different days but at the same time. The co-efficient of variation was found to be 0.782, 0.587, 0.8935, 0.716, 0.385, 0.518 and 0.665 among resting plaque pH and post consumption plaque pH at 5, 10, 20, 30, 40 and 60 minutes, respectively.
| Discussion|| |
Dental caries is a biofilm dependent oral disease and the fermentable dietary carbohydrates are the key environmental factors involved in its initiation and development.  Newbrun labeled sucrose as the "arch criminal" of dental caries. , Although the sucrose content of diet and frequency of ingestion have been reported to be of prime importance for the initiation of dental caries, its physical properties such as solubility, rate of clearance, consistency, fat content etc. act as important modulating factors in the causation of dental caries . Also Marthaler described sugars (sucrose and other hexoses) as the "main threat" for dental health.  Koulourides et al., using an intra oral cariogenicity test found that the major food sugars, namely glucose, fructose and maltose, caused a similar amount of enamel demineralization as sucrose but that lactose alone had a lower demineralization potential. 
Over the years, healthy diet is perceived to be important. Changes in diet have included a substantial increase in the consumption of beverages and fruit drinks. People have become aware of the deleterious effects caused by carbonated beverages on the teeth and they prefer more natural and healthy products such as fruit juices, as they also provide a good source of vitamins. They are popular worldwide with people of all ages and are being aggressively promoted as "health drinks" by manufacturers.  These drinks contain added sucrose along with the natural fruit sugars i.e. glucose, fructose. On the other hand, media has focused attention on some drinks in particular which were deemed to be cariogenic on account of their sucrose content. As a result, manufacturers started with newer fruit drinks, sold as no added sugar or containing natural sugars; the natural sugars were glucose and fructose, and it was believed that these drinks were safe for the teeth. 
The present investigation was, therefore, designed to analyze a range of these newer drinks (with no added sugar), currently available in the market, for their acidogenic potential to enable us to plan a low cariogenic diet.
Parameters used to study cariogenicity
Earlier H + modulation after the consumption of food was considered the sole test to determine their cariogenicity; but in the recent years, it has been realized that there are some other factors, which also play an important role. These factors include inherent pH of the food consumed and the area under the plaque pH curve. Although, there is no single test to determine the cariogenicity of fruit drinks and food, in the present experiment three parameters that are considered to give a fair insight into their cariogenic potential are:
- plaque pH (comparison between the baseline pH and the post consumption plaque pH at 5, 10, 20, 30, 40 and 60 minutes time intervals)
- the inherent pH of the fruit drinks and
- the plaque pH area under the curve (AUC) below the resting plaque pH.
Plaque pH (comparison between the baseline pH and the post consumption plaque pH at 5, 10, 20, 30, 40 and 60 minutes time intervals)
Stephan in his classic studies in the early 1940s showed that dental plaque exposed to sucrose could rapidly produce acids, causing a rapid drop in pH followed by a gradual recovery toward the baseline plaque pH. , Since that time, a causal association between the production of strong acids from plaque in response to sucrose and caries activity has become well-established. Some plaque bacteria can produce only the pH fall of the Stephan curve, whereas others (arginolytics) can produce both the fall and the rise - the latter through degradation of nitrogenous compounds, the end-products of which can raise plaque pH. , This state of lowered pH persists for up to several hours, depending on the presence of salivary protection factors. The balance between these different metabolic outcomes of bacterial activity dictates the shape of the Stephan pH curve. Thus, an assessment of acid production from carbohydrate by dental plaque bacteria can be used to assess the cariogenicity of dental plaque from a particular site.
The length of the time for which this low pH remains at its minimum is important, because if it reaches the critical pH value, it initiates the dissolution of the enamel. However, a single acidic attack is of minor importance, but if repeated, the ability of the saliva to deal with the acid decreases. Hence, the danger is the frequent use of these fruit juices overtime. With the frequent consumption of acidic, sugar rich drinks, people are at a high risk of acid demineralization, ultimately leading to erosion and caries development. ,
The inherent pH of the fruit drinks
The second parameter determining the cariogenicity of fruit drinks is their inherent pH. The resting plaque pH usually ranges from 6-7. When a low pH drink is consumed, it causes a prolonged immediate drop in this resting plaque pH. It has been found that fruit drinks with low inherent pH show an additive effect, in further lowering the plaque pH below the baseline value. The low pH of the consumed foods or drinks adds to the low pH of the bacterial acids produced by the fermentation.  Thus, the combined acidic environment leads to the faster demineralization of the enamel and subsequently, cariogenicity. Moreover, the drinks with low pH would have higher titratable acidity (a greater amount of alkali is required to bring them from their initial pH to neutrality). These drinks resist change in pH and require greater buffering to reach neutrality.  These findings have been confirmed by Duke et al., in 1988. 
In the present study, the endogenous pH of the all the test drinks was low. This additive effect of the endogenous pH leads to the instantaneous drop of the plaque pH and also the duration for which the plaque pH remained below the resting level was prolonged. The orange juice with added sugar had the lowest endogenous pH (3.15) followed by orange juice with no added sugar (3.45), apple juice with no added sugar (3.92) and lastly, apple juice with added sugar (4.12). It was clear from the data that the test drink with the lowest endogenous pH had the maximum cariogenic potential. Thus, the low pH of drinks proved to be an important factor responsible for the increased cariogenicity of the drinks. The potential cariogenicity of the drinks based on inherent pH co-relates with that of the H + modulation after consumption of fruit drinks.
The plaque pH area under the curve (AUC) below the resting plaque pH
To study the relative duration and extent of pH fall with four test fruits and control (sucrose), the third parameter area under the plaque pH curve was calculated. The longer the low pH prevails, the more is the area under the plaque pH curve below the baseline and subsequently, the more potent is the cariogenic effect. The concept of area between the critical pH and the pH curve is based on two assumptions: First, prolonged pH drop is considered more harmful than a drop of short duration (Kleinberg et al., 1983) because there is more time for calcium and phosphate to be lost from enamel and secondly, the depth of the pH drop in a certain period of time is proportional to the potential dissolution of enamel, so that a pH drop to two units below the critical value is twice as potent as a pH drop to only one unit below during the same length of time.  Thus, the concept behind the calculation of areas assumes that with a critical pH of 5.5 the potency of a pH in plaque of 5.0 for 30 min equals that of pH 4.0 for 10 min. 
The area under the plaque pH curve for the test drinks - orange juice with added sugar, orange juice with no added sugar, apple juice with added sugar, apple juice with no added sugar and sucrose were found to be 30.93 ± 0.31, 26.01 ± 0.9, 15.99 ± 0.13, 16.27 ± 0.75 and 14.28 ± 0.35, respectively. It is evident that the greatest area was found in case of orange juice with added sugar followed by orange juice with no added sugar, apple juice with added sugar, apple juice with no added sugar in order of their cariogenicity.
An Acidogenic Potential Index (API) was calculated, using the AUC for 10% sucrose as a baseline, with a score of 1, and the relative API for fruit drinks calculated as a ratio of this score. Those drinks, which scored above 1.0, had a high cariogenic potential. It can be seen that all the drinks had a API greater than a standard 10% sucrose. API was highest when orange juice with added sugar (2.16) was consumed followed by orange juice with no added sugar (1.82), apple juice with no added sugar (1.13), apple juice with added sugar (1.11) and sucrose (1).
To study the pH fluctuation in the post consumption period following consumption of various fruit drinks and control, the plaque pH was monitored at 5, 10, 20, 30, 40 and 60 minutes interval and compared with the resting pH and control.
The pH fluctuation remained below the critical pH (5.50) until 30 minutes, thereby clearly depicting that acidogenic potential of this drink, after which it started to rise on reaching the resting pH nearly after 60 minutes.
Since data in the present study was obtained with what may be called as young plaque (48 hours), it would be of great interest to know what the response of these fruit drinks would be if still older plaque is used and a more sophisticated method like biotelemetry is used.
However, since this experimental method permitted the measurements of plaque on accessible surfaces of dentition only (buccal, lingual) the results thus obtained cannot be regarded as representative of interdental plaque in which the pH decrease after sugar consumption may be lower than that of labial/lingual plaque. Moreover, the buffering action of saliva is expected to be much less pronounced in interproximal areas as well (Imfeld 1978  ).
In the concluding remark, we would vary on cautiously extrapolating the results of the present study as far as dietary counseling is concerned. Since the acidogenic theory (Miller W,D. 1889  ) of caries etiology is well accepted today, the measurement of the acidogenicity of the commonly used fruit drinks proved beyond doubt that orange juice with added sugar could definitely be categorized as a fruit drink of maximum cariogenic potential and apple juice with added sugar having the least potential. The orange juice with no added sugar and the apple juice with added sugar fall somewhere between the two extremes.
| Conclusion|| |
The present study clearly indicates that the absence or presence of sucrose, as opposed to so called "natural sugars" such as glucose and fructose, makes no difference. The fruit juices labeled with "no added sugar" or "free from added sugar", contained substantial quantities of sugar and are equally cariogenic as are fruit drinks with added sugar. This conclusion is based on analysis of sugar content and acidity of the drinks as well as measurements of plaque pH after consumption of these drinks. It is therefore, important to avoid frequent consumption of these fruit drinks to reduce the risk for dental caries.
| Why this Paper Important for Pediatric Dentistists?|| |
All the fruit juices used in the present study were acidic in nature and reduced plaque pH below critical pH, especially in the caries active group. Hence, it becomes mandatory for us as preventive dentists, to provide appropriate diet counseling, which is tailored for a particular individual to maximize the compliance. At the same time, negative admonitions to stop using these drinks are not likely to be successful. Instead, certain guidance for dental health should follow American Academy of Pediatrics (AAP) guidelines17 to limit the intake of these juices.
Guide lines 
- Ideally serve drinks only at mealtimes.
- Keep drinking times short.
- Use a straw whenever possible.
- Chilled fruit juices should be avoided.
- Fresh fruits can be preferred in places of juices.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]