The Buffering Capacities of Various
Drinks: The Potential Influence on
Dental Erosion
Prepared by:
Roba Khalil Naaman
Supervised by:
Dr. Abdelaziz Bamarouf
A Project Report Submitted in Partial Fulfillment
for the Bachelor Degree in Clinical Nutrition
At
Clinical Nutrition Department
Faculty of Applied Medical Sciences
King Abdulaziz University
Jeddah, Saudi Arabia
June, 2008
ABSTRACT
The pH of fruit juices and soft drinks are known to be low
and have been implicated in the increasing incidence of
erosion. The ability to resist ph changes brought about by
salivary buffering may play an important part in the erosion
process. The aim of this study was to measure the initial ph
of
several
widely
available
drinks
(chosen
from
questionnaire) and determine their buffering capacities. As
part of a larger study, the following groups of drinks were
tested: orange juice, soft drinks, energy drinks and plain
mineral water as a control.
The measurement of PH was carried out using a PH
electrode connected to an. One hundred milliliters of each
drink was then titrated with 1M NaOH added in 0.5 ml
increments, until the PH reached 10. Each titration was
repeated several times. The average initial PH was lowest for
Pepsi (2.8) & highest for plain mineral water (7.3). The
buffering capacities were different among those drinks. It
was concluded that the orange juice with their increased
buffering capacities, may induce a prolonged drop in oral
pH.
CHAPTER ONE
INTRODUCTION
CHAPTER ONE
INTRODUCTION
 Eating & Drinking.
 Speaking.
 Smiling.
 Self- esteem.

 Digestion  amylase digests starch
 Lubrication  lubrication of hard substance and make it easy
to swallow
 Dilution  dilute the solid food
 Buffering  is critical for neutralization of acid. (Saliva pH 6.5
– 7.5)
 Defense  saliva has a defensive mechanism against
microorganisms.
Dental erosion is the process whereby tooth enamel and dentin
are destroyed. It does not involve bacteria, but may result from
excessive exposure to acids from foods, beverages, reflux,
regurgitation, or the work environment. Its development seems to be
part of a cumulative process influenced by frequency and time of
acid exposure, oral hygiene practices and individual susceptibility.
There are three types of dental erosion: extrinsic, intrinsic and
idiopathic.
Extrinsic erosion is triggered by foods, beverages, and other external
sources of acid. Intrinsic erosion is related to the regurgitation or
reflux of fluids from the stomach. When the causes are not overt, the
condition is often generalized as idiopathic erosion.
Unlike tooth decay erosion affects the whole surface of the tooth.
Exposure to acid over a long period of time leads to progressive loss
of enamel with the effect that the tooth “shrinks” and crumbles at the
biting edge. Eventually the dentin is exposed leading to pain and
sometimes death of the tooth.
The process is irreversible and requires expensive cosmetic dentistry
to restore function and appearance.
 Physical Changes;
- Change of the color of tooth.
- Change in shape, teeth will begin to appear with broad
rounded concavity, and the gap between teeth will become
larger.
- Cracking, where teeth begin to crack off and have very coarse
feeling.
- Hollows in the teeth and general wearing away of the tooth
surface.
 Non-Physical Changes;
- Sensitivity and Pain when eating hot, cold, sweet food, this is
caused
when the enamel is eroded away exposing the dentin.
Extrinsic Causes
- Dietary acids like fruits and fruit juices that have a very low pH
(high acidity). Carbonated drinks and sports drinks are also very
acidic.
- Medications that are acidic in nature can also cause erosion via
direct contact with the teeth when the medication is chewed or held
in the mouth prior to swallowing such as Vitamin C and
hydrochloric acid supplements.
Intrinsic Causes
- Gastroesophageal reflux: Gastric acids regurgitation into the
esophagus and mouth. These gastric acids have very low pH levels
that can be less than 1, reach the oral cavity and come in contact with
the teeth and cause the erosion.
-Excessive vomiting related to eating disorders such as bulimia,
anorexia nervosa.
-Alcoholism causes erosion, because it is associated with frequent
vomiting.
-Other causes of vomiting that may cause erosion include
gastrointestinal disorders such as peptic ulcers or gastritis,
pregnancy, drug side effects, diabetes or nervous system disorders.
Buffering capacity of saliva refers to its ability to resist a change
in pH when an acid is added to it. This property is largely due to the
bicarbonate content of the saliva which is in turn dependent on
salivary flow rate. Bicarbonate concentration also regulates salivary
pH. Therefore, there is a relationship between salivary pH, buffering
capacity and flow rate, with pH and buffer capacity increasing as
flow rate increases.
Normally, when an acid enters the mouth, whether from an
intrinsic or extrinsic source, salivary flow rate increases along with
pH and buffer capacity. Within minutes, the acid is neutralized and
cleared from the oral cavity and the pH returns to normal. Patients
with erosion were found to have lower salivary buffer capacity.
Therefore, salivary function is an important factor in the etiology of
erosion. Since many common medications and diseases can lower
salivary flow rate, it is important to assess these salivary
characteristics when evaluating a patient with erosion.
Is the degree to which water can resist a change in pH when
either acid or alkali is added. You may find it defined as "maximum
amount of either strong acid or strong base that can be added before
a significant change in the pH will occur". This definition - instead of
explaining anything - raises a question "what is a significant
change?" - Sometimes even change of 1 unit doesn't matter too much,
sometimes - especially in biological systems - 0.1 unit change is a lot.
Buffer capacity can be also defined as quantity of strong acid or
base that must be added to change the pH of one litter of solution by
one pH unit. Such definition - although have its practical applications
- gives different values of buffer capacity for acid addition and for
base addition (unless buffer is equimolar and its pH=pKa).
This contradicts intuition - for a given buffer solution its resistance
should be identical regardless of whether acid or base is added.
Buffer solution is able to retain almost constant pH when small
amount of acid/base is added. Quantitative measure of this resistance
to pH changes is called buffer capacity.
Moreover, Buffering capacity refers to water's ability to keep
the pH stable, or another way to think of it is a natural resistance to
any change. Think of buffering like there is an imaginary big sponge
in your pond that prevents things from happening too fast. As long as
the sponge is somewhat dry, it can absorb a lot of change. Just the
reverse is true also. If the sponge is saturated then it cannot absorb
anything else.
Above plot shows how the buffer capacity changes for the 0.1M
solution of acetic buffer. As expected buffer exhibits the highest
resistance to acid and base addition for the equimolar solution (when
pH=pKa). From the plot it is also obvious that buffer capacity has
reasonably high values only for pH close to pKa value. The further
from the optimal value, the lower buffer capacity of the solution.
Solution containing only conjugated base (pH 8-10) has buffer
capacity of zero, for the higher pH presence of the strong base starts
to play an important role. In the case of pure acetic acid solution (pH
below 3) pH is already low enough to be resistant to changes due to
the high concentration of H+ cations.
Buffering agent can be either weak acid or weak base that would
comprise a buffer solution. They are usually added to water to form a
buffer solution. They are the substances that are responsible for the
buffering seen in these solutions. These agents are added to
substances that are to be placed into acidic or basic conditions in
order to stabilize the substance. For example, buffered aspirin has a
buffering agent, such as MgO, that will maintain the pH of aspirin as
it passes through the stomach of the patient. Another use of buffering
agent is in antacid tablets, whose primary purpose is to lower the
acidity of the stomach.
Buffering agents are similar to buffer solutions as a result of the
fact that buffering agents are the main components of a buffer
solution. They both regulate the pH of the solution & resist changes
in pH. A buffer solution maintains the pH of the whole system which
is placed into it, whereas a buffering agent is added to an already
acidic or basic solution, which it then modifies & maintains anew pH.
Buffering agents & buffer solutions are almost exactly alike
except for few differences:
1. Solutions maintain pH of a system, preventing large changes in
it, whereas agents modify the pH of what they are placed into.
2. Agents are the active component of buffer solutions.
It is described as the concentration of H ions which is one of the
most important parameters describing solution properties.
Concentrations of H+ can change in a very wide range; it can be 10 M
as well as 10-15 M. Such numbers are inconvenient to use so to
simplify things. Danish biochemist Søren Sørensen developed in 1909
the pH scale and introduced pH definition - minus logarithm base 10
of [H+]:It is much easier to use pH definition and to say "pH of the
solution is 4.1" than to use concentrations - as in "H+ concentration is
0.000079M".
Søren Peder Lauritz Sørensen (January 9, 1868 – February 12, 1939).
Born in Havrebjerg, Denmark, Sørensen was Danish chemist, famous
for the introduction of the concept of pH, a scale for measuring
acidity.
Idea of using letter p to denote concentrations and numbers
that can vary by several orders of magnitude was widely accepted
and is used not only in pH definition, but for example also for
displaying dissociation constants values in tables.
Not only H+ ions are present in every solution. Also OH- ions are
always present, and their concentration can change in the same very
wide range. Thus it is also convenient to use similar definition to
describe [OH-]
6.9
Acidic
&
Lower7.0
Neutral
7.1
&
Alkaline
Higher
A pH reading of 7.0 is called “neutral” or for our purposes “normal.”
A reading of less than 7.0 is called “acidic” and a reading greater
than 7.0 is called “alkaline.” A high pH reading makes it easy for
algae to grow. Try to stay under 7.2 and you will have fewer algae in
your water.
In simpler terms the number arises from a measure of the
activity of hydrogen ions or their equivalent in the solution. The pH
scale is an inverse logarithmic representation of hydrogen proton
(H+) concentration.
Unlike linear scales which have a constant relationship between
the item being measured (H+ concentration in this case) and the value
reported, each individual pH unit is a factor of 10 different than the
next higher or lower unit. For example, a change in pH from 2 to 3
represents a 10-fold decrease in H+ concentration, and a shift from 2
to 4 represents a one-hundred (10 × 10)-fold decrease in H+
concentration. The formula for calculating pH is:
In dimensionless where αH+ denotes the activity of H+ ions, and
is solutions containing other ions, activity and concentration will not
generally be the same. Activity is a measure of the effective
concentration of hydrogen ions, rather than the actual concentration;
it includes the fact that other ions surrounding hydrogen ions will
shield them and affect their ability to participate in chemical
reactions. These other ions change the effective amount of hydrogen
ion concentration in any process that involves H+.
Buffering has both positive and negative consequences. The
erosive potential of beverages is thought to involve several factors
including the low PH and the buffering capacity of the drink. The
ability of a drink to resist PH changes brought about by the salivary
buffering may inevitably result in a prolonged period of oral acidity
and therefore may play an important part in the erosion process.
CHAPTER TWO
MATERIALS &
METHODOLOGY
MATERIALS & METHODOLOGY
MATERIALS
King AbdulAziz University
Faculty of Applied Medical Sciences Lab.
This is the questionnaire were given to the students (clinical
nutrition & physiotherapy) in our collage. The purpose was to know
what the most popular drinks are. Base on these data we choose the
drinks to be studied.
:
1
2
3
4
5
6
7
8
9
1
0
A pH meter is an electronic instrument used to measure the pH
(acidity or alkalinity) of a liquid. A typical pH meter consists of a
special measuring probe (a glass electrode) connected to an electronic
meter that measures and displays the pH reading.
The pH probe measures pH as the activity of hydrogen ions
surrounding a thin-walled glass bulb at its tip. The probe produces a
small voltage
(about 0.06 volt per pH unit) that is measured and
displayed as pH units by the meter.
The meter circuit is fundamentally no more than a voltmeter
that displays measurements in pH units instead of volts. The input
impedance of the meter must be very high because of the high
resistance of the glass electrode probes typically used with pH
meters. The circuit of a simple pH meter usually consists of
operational amplifiers in an inverting configuration, with a total
voltage gain of about -17. The inverting amplifier converts the small
voltage produced by the probe into pH units, which are then offset by
seven volts
to give a reading on the pH scale.
Calibration with at least two, but preferably three, buffer
solution standards is usually performed every time a pH meter is
used, though modern instruments will hold their calibration for
around a month. One of the buffers has a pH of 7.01 (almost neutral
pH) and the second buffer solution is selected to match the pH range
in which the measurements are to be taken: usually pH 10.01 for
basic solutions and pH 4.01 for acidic solutions (It should be noted
that the pH of the calibration solutions is only valid at 25°C). The
gain and offset settings of the meter are adjusted repeatedly as the
probe is alternately placed in the two calibration standards until
accurate readings are obtained in both solutions. The calibration
process correlates the voltage produced by the probe (approximately
0.06 volts per pH unit) with the pH scale. After calibration, the probe
is rinsed in distilled, deionized water to remove any traces of the
buffer solution, blotted with a clean tissue to absorb any remaining
water which could dilute the sample and thus alter the reading, and
then quickly immersed in the sample. Between uses, the probe tip,
which must be kept wet at all times, is typically kept immersed in a
small volume of storage solution, which is an acidic solution of
around pH 3.0. Occasionally (about once a month), the probe should
be cleaned using pH-electrode cleaning solution.
A buffer solution is one that is resistant to change in pH when
small amounts of strong acid or base are added.
Buffers are important in many areas of chemistry. When the
pH must be controlled during the course of a reaction, the solutions
are often buffered. This is often the case in biochemistry when
enzymes or proteins are being studied. Our blood is buffered to a pH
of 7.4. Variations of a few tenths of a pH unit can cause illness or
death. Acidosis is the condition when pH drops too low. Alkalosis
results when the pH is higher than normal.
Acidity is a measure of a solution’s capacity to react with a
strong base (usually sodium hydroxide, NaOH) to a predetermined
pH value. This measurement is based on the total acidic constituent
of a solution (strong and weak acids, hydolyzing salts, etc.). Acidity is
similar to a buffer in that the higher the acidity, the more
neutralizing agent is needed.
Alkalinity is the measure of a solution’s capacity to react with a
strong acid (usually sulfuric acid H2SO4 ) to a predetermined pH.
The alkalinity of a solution is usually made up of carbonate,
bicarbonate, and hydroxides. Similar to acidity, the higher the
alkalinity is, the more neutralizing agent is needed to counteract it.
METHODOLOGY
The electrode was calibrated at the start of each session
using standard buffers of pH 4.0 & 9.2.
One hundred milliliters of the freshly opened drink,
which was at room temperature, was placed in a beaker &
stirred using a non-heating magnetic stirrer until a stable
reading was obtained. The initial pH of each drink was
measured using a pH electrode. After calibration of the
electrode, several readings were taken of each drink.
One hundred milliliters of each drink was titrated with
1M sodium hydroxide, added in 0.5 ml increments, until pH
reached 10 to assess the total titratable acidity – a measure
of the drinks own buffering capacity. The samples were
again stirred using a non-heating magnetic stirrer until a
stable pH reading was obtained after each addition of
NaOH.
CHAPTER THREE
RESULTS
CHAPTER THREE
RESULTS
other energy drinks
Bison
7up(diet)
b
u
f
f
e
r
i
n
g
7up(reg)
pepsi(diet)
pepsi(reg)
cola(diet)
cola(reg)
other juices
lemon juice
orange juice
milk(powder)
milk(long life)
milk(fresh)
80
60
40
20
0
milk
pepsi
orange
bison
7up
water
7.5
7
6.5
6
5.5
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
pH
The initial pH was lowest for Pepsi and highest for plain mineral
water.
The graphs listed below shows the repeated titration of the
selected drinks. However, the results indicate there were differences
between the buffering capacities of all groups. For instance, the water
changes its pH rapidly from 7.3 to 11.6. On the other hand the
orange juice took the longest period where it reaches the pH of 10. In
addition, there were no difference between the energy drinks & soft
drinks.
Water
14
8
6
4
2
0
2
1
NaOH
Water pH was 7.3. Required 0.5 ml of NaOH to bring the pH up to
10 , by adding 0.5 ml once.
pH
12
10
Milk
12
10
6
pH
8
4
2
0
5
4
3
2
1
NaOH
Milk pH was 6.8. Requiring 6ml of NaOH to bring the pH up to 10,
by adding 0,5ml of NaOH 6 times.
Orange Juice
12
10
6
4
2
0
35 33 31 29 27 25 23 21 19 17 15 13 11 9
7
5
3
1
NaOH
Orange juice pH was 4. Required 17 ml of NaOH to bring the pH up
to 10, by
adding 0.5 ml of NaOH 33 times.
pH
8
Bison
12
10
6
pH
8
4
2
0
17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
NaOH
Bison pH was 2.76. Required 8.5 ml to bring the pH up to 10,by
adding 0.5ml of NaOH 17 times.
Pepsi
12
10
6
4
2
0
18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
NaOH
Pepsi pH was 2.8. Required 8.5 ml of NaOH to bring the pH up to
10,by adding 0.5 ml of NaOH 17 times.
pH
8
7up
12
10
6
pH
8
4
2
0
12
11
10
9
8
7
6
5
4
3
2
1
NaOH
7up pH was 3.7 required 6 ml of NaOH to bring the pH up to 10, by
adding 0.5 ml of NaOH 12 times.
CHAPTER FOUR
DISCUSSION &
CONCLUSIONS
CHAPTER FOUR
DISCUSSION & CONCLUSION
The results of this study using an in vitro system indicate that
the drinks within any one group behave the same direction due to
their acid content. The repeated titrations were found to be
reproducible for individual drinks.
The buffering capacities of the tested drinks in vitro can therefore be
ranked as follows: orange juice > bison = Pepsi > 7up > milk >
mineral water.
It was also interesting to note that the initial Ph value gave no
indication of the underlying buffering capacity and, therefore, the
erosive potential of the drink. Generally, the pure fruit juices
(orange) had a higher initial PH than the soft drinks (Pepsi & 7up )
but required much more NaOH to rise the PH. This study agree
broadly with those already found in the literature(grobler& van der
Horst, 1982; Grenby et al., 1989) that fruit juices have greater erosive
potential. It was thought important to mention the flavored mineral
water, because it wasn't included in this study, as these drinks
relatively new to the customer and is seen by many as designer
drinks.
Another point of interest was the difference between carbonated and
plain mineral water. The addition of carbon dioxide, forming
carbonic acid in solution, clearly lowers the ph and enhances the
buffering capacity. However, the initial ph of the plain mineral
waters was around that of 7.3 and so the influence of plain mineral
waters on salivary ph and potential dental erosion must be
investigated further.
All these drinks should now be tested in vivo to ascertain if the
increased buffering properties of fruit based drinks have a greater
potential to lower the ph at tooth surface. Many factors will be
involved in the oral cavity, not least the ability of a drink to promote
increased salivary flow due to gustatory stimulation.
In conclusion, it has been found that, in vitro, pure fruit juices
have significantly greater buffering capacity than other soft drinks,
therefore, may have more erosive potential.
For recommendation,
1. Seeing a dentist or an oral surgeon regularly for a routine
checkup promotes healthy teeth.
2. Eating less sweets food and more foods that provide vitamins and
minerals also influences good oral hygiene.
3. Eating food with high sugar content is unhealthy because the
sugar destroys the enamel for about 20 minutes after contact.
4. A way to help prevent the sugars and acids from attacking the
tooth enamel is to rinse the mouth with water after eating sweet
foods.
5. Brushing after these sugar attacks could also be harmful as each
brushstroke also takes away part of the tooth enamel.
6. Another way to help prevent dental erosion is using a straw when
drinking unhealthy beverages. This pushes the liquid to the back
of the mouth so it doesn’t touch the teeth.
7. There is evidence that chewing sugarless gum may decrease the
incidence of caries, better known as decay.
8. The most common way of preventing dental erosion is by
brushing teeth, as removing plaque on a daily basis is vital to
preventing dental erosion. The strength of teeth can be improved
by brushing regularly after every meal and at night.
9. Proper techniques, such as using a soft bristled brush and using a
“pea-sized” amount of toothpaste should be followed. These also
include brushing up on the front part of the bottom teeth and
down on the front part of the top teeth. A back and forth motion
should be used when brushing on the top surfaces of the teeth.
10. Brushing teeth twice a day for two to three minutes at a time is
recommended. Flossing before brushing will also aid in better
dental care.
11. Many cavities start in the contact area between teeth, so flossing
is a very important aspect to erosion prevention.
12. On a larger scale, communities are trying to prevent dental
erosion among its youth through school programs that offer
dental sealants. The sealants are offered to children who
wouldn’t normally receive these benefits from a dentist because
of the expense.
REFERENCES
Example of a Scientific Article:
Edwards M., Creanor S.L., Foye R.H. & Gilmour W.H. Buffering
Capacities of Soft Drinks: The Potential Influence on Dental Erosion.
Journal of Oral Rehabilitation (1999):923-927
Example of a Web Site Address:
<http://www.wikipedia.org>
<http://www.dentalhealth.org.uk>
<http://www.mypyramid.gov>
<http://www.fao.org>
<http://www.dentalinsurance.co.uk>
http://www.dentalhealth.org.uk
http://www.fdiworldental.org
http://services.juniata.edu
www.mwpca.orghttp://
http://www.thejcdp.com