laboratory studies on the dental effects of soft drinks and other beverages sarah story...
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Laboratory Studies on the Dental Effects of Soft Drinks and Other Beverages
• Sarah Story• Undergraduate in Pre-Dentistry• Biology Department• Tennessee Technological University• Cookeville, TN 38505• Date: April 26, 2006
Introduction: The consumption of soft drinks has increased dramatically over past decades; the
soft drink industry is reported to produce 10 billion 192-ounce cases per year. Over a 50-year period, annual soft drink production appears to have increased five fold, from 100 12-ounce cans per person in 1947 to nearly 600 12-ounce cans per person in 1997. Looking at it another way, the average person in 1947 consumed approximately two cans of soft drinks per week, while the average person in 1997 consumed approximately 12 cans of soft drinks per week, or nearly two cans per day (von Fraunhofer & Rogers 2004).
Dental erosion is a non-carious, pathological loss of tooth surface, distinct from abrasion and attrition, and is defined as the irreversible loss of dental hard tissue by a chemical dissolution by acids other than those produced by bacteria. Over the last two decades, tooth erosion has become a significant clinical problem (Sirimaharaji & others 2002). Nutrition plays a key role in erosion. Any product with a low pH value has the potential to cause structural damage when ingested (Shipley & others 2005). Erosion can occur from frequently consumed soft drinks, fruit juices, and sports/energy drinks.
Introduction continued… The erosive potential of beverages is thought to involve several factors, including low
pH and the buffering capacity of the drink. Soft drinks may contain several different types of acid that contribute to the low pH value. Carbonated beverages will contain carbonic acid formed by carbon dioxide in solution. Even when the carbon dioxide has been released and the drinks become “flat” the pH remains low (acidic). This indicates that soft drinks have inherent acidity due to other acids that are added to stimulate taste and counteract sweetness. These other acids include, for example, phosphoric acid and citric acids present in cola-type drinks (Edwards & others 1999). Fruit juices and fruit-flavored drinks are made from a concentrated source of fruit and consist of organic acids derived from the fruit such as citric acid from oranges, tartaric acid from grapes and malic acid from apples. Added vitamin C (ascorbic acid) may also contribute to the acidity of soft drinks. Typically, soft drinks consumed at meal times are less injurious than those consumed alone and continuous sipping is considered more harmful to dentition than consuming an entire beverage at once. However, it has been reported that certain soft drinks (notably cola beverages) are retained on the dental enamel and are less likely than other beverages to be removed by saliva, resulting in an increased cariogenicity.
Introduction continued… Why does a tooth dissolve in acid? The underlying acidity of beverages is believed to be the primary
factor in the development of dental erosion; this total acid level (known as titratable acid), rather than pH, is thought to be an important factor in erosion because it determines the actual hydrogen ion availability for interaction with the tooth surface. The measurement of a beverage’s total acid content may be a more realistic and more accurate method for predicting erosive potential. Other important factors concerning the erosive quality of beverages include the type of acid and its calcium chelating properties, exposure time, and temperature (Fraunhofer & Rogers 2004). Dental enamel is composed primarily of hydroxyapatite (HA), Ca₁₀(PO₄)₆(OH)₂, but it also contains several impurities such as carbonate and fluoride. Because the proportions of these impurities vary from person to person, and indeed from tooth to tooth, and because the impurities can influence enamel solubility, that solubility is not fixed and varies slightly from person to person (Dawes 2003).
There is no question that erosion causes significant damage to dental enamel, particularly among young people. Although altering drinking habits may prevent erosion by reducing the intake of acidic beverages, such an adjustment cannot always be achieved. However, recent work suggests that modifying beverages (for example, by the addition of citrate ions) alters the acidogenic potential, effectively reducing erosion (Fraunhofer & Rogers 2004).
Objective and Hypothesis
Objective: The objective of my study is to determine which beverage has the most erosive
effect on dental enamel.
Hypothesis: In meeting my objective, I will test my hypothesis that non-cola and energy
drinks will have the most erosive effect on dental enamel.
Null Hypothesis: In meeting my objective, I will test the hypothesis that the erosion on
the enamel will be the same for all beverages tested.
The drinks that were used:
Methods and Materials
The test teeth are sound (caries free) human
molars and premolars that had been extracted for
orthodontic or periodontal reasons. After
sterilization in an autoclave each specimen will be
dried and weighed to 0.01 mg. All studies will be
preformed at room temperature.
The test beverages and test specimens will be
placed in plastic containers with 5 mL of the test
beverage. The specimens will be allowed to soak
in the test beverage for 60 minutes each and then
allowed to dry until for 24 hours and then weighed.
This process will be preformed over 24 hour
intervals for a 7 day (168 hour) period. The
beverages for each specimen will be replaced daily
with fresh solution after each weighing. Mean
percentage weight losses and weight losses per
unit area will be calculated for each set if enamel
specimens (von Fraunhofer & Rogers 2004).
Actual Experiment Pictures
Results The amounts of enamel dissolution that occurred in the 20 specimens over the 7 day period are
summarized in the table and figure 1. The control, tap water, showed no enamel dissolution. All other
media exhibited a progressive attack on the dental enamel, with a linear or straight line relationship
between the enamel dissolution and exposure time over the test period. Typical dissolution curves are
shown in Figure 1.
The beverage Red Bull showed the greatest affect on the dental enamel followed my Minute Maid
Lemonade. Results from Fruit Punch Gatorade were within .002 grams of Minute Maid Lemonade,
and showed the third greatest enamel dissolution from the tested beverages. The results from Mountain
Dew were within .01-.02 grams of the Red Bull and Minute Maid Lemonade, and resulted in being the
beverage with the least enamel dissolution before the control. The Figures 2 and 3 shows an example of
enamel dissolution in a teenage boy who managed to do decade’s worth of damage to his enamel in just
a few years. Effects such as those in figures 2 and 3 could be expected with continued exposure.
Tables, Figures and Graphs
Fig. 2 and 3. Left- Molar with acid erosion. This teen-ager has the enamel of a 65-year old. Right-Normal molar
Fig. 1. Enamel dissolution in various beverages.
Beverage Container pH Sugar per 12 oz.
7 Day Average Weight
Lost
Mountain Dew Bottle 3.14 46 grams .023 g
Red Bull Can 3.32 27 grams .043 g
Minute Maid Lemonade
Bottle 2.80 40 grams .033 g
Fruit Punch Gatorade
Bottle 2.95 28 grams .035 g
Control(tap water)
Bottle 7.0 0 grams 0 g
Table. Beverages utilized in this study.
Discussion This study exposed caries- free dental enamel to a variety of popular beverages continuously over a
period of 7 days (168 hours). Some criticisms that can be made about this experiment are: the small
sample size of beverages used and the short exposure time (von Fraunhofer & Rogers 2004). The
beverages that were selected were selected because of there potential to have an erosive effect on the
dental enamel based on the results from other researched studies. A larger sample size is usually
preferable when conducting an experiment (von Fraunhofer & Rogers 2004). However, this study was
intended to identify which beverages held the most erosive effect on the enamel.
Regarding the length of the test period, it has to be recognized that realistic testing of enamel
dissolution in soft drinks and other beverages is demanding because it is difficult to determine the
extent of oral exposure for any given individual. Many different factors affect any individual person
which can make them more or less susceptible to enamel dissolution. However, it is possible to make
certain projections through careful experiments. Based on an average daily consumption pf 25 ounces
of soft drink and a residence time in the couth of five seconds, the total exposure time to beverages
would equal 22, 750 seconds (380 minutes or 6.3 hours) per year. However, it is more likely that the
exposure time for a beverage on the dentition is closer to 20 seconds before salivary clearance occurs
which would make the annual exposure time of dental enamel to beverages approximately 90,000
seconds (1,500 minutes or 25 hours).
Discussion Continued…
Despite limitations, certain conclusions can be drawn from this study. First, exposure to
beverages with the presence of simple carbohydrates (sugars found in these beverages)
or artificial sweeteners show noticeable amounts of enamel dissolution. A more
interesting observation was the decreased amount of enamel dissolution in the cola-
based drink when compared to the non-cola drinks. These differences could not be
credited to the beverages pH since there has been no known correlation between pH
and enamel dissolution (Gtenby & others 1989). The pH range for most beverages is
2.0-3.4, which is well below the marked pH for dental caries (5.5). The range suggests
that enhanced enamel dissolution results from effects other than beverage pH, most
likely the additives within non-cola beverages that are added for desired results. As
indicated earlier, acids found in these beverages can alter the effects of dental erosion
because of their ability to lower the pH needed to maintain caries free teeth (Rugg-Gunn
and Nunn 1999). As a result, they can be very aggressive towards dental enamel
(Davani and others 2003).
Conclusions The data reported here indicates that
certain beverages may cause significant
enamel dissolution with repeated exposure.
The non-cola drinks showed the greatest
dissolution of the dental enamel. The data
suggests that enamel aggressively is
determined by beverage composition (such
as additives) rather than beverage pH.
Mountain Dew was found to be the safest
drinks tested followed by Minute Maid
Lemonade, Fruit Punch Gatorade, and lastly
Red Bull. It would seem that reducing
beverage intake and residence time in the
mouth by salivary clearance or rinsing
would be beneficial.
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