Preventing Holes in Teeth
– are beliefs justified?
A grade 8-9 science (biology) module
on tooth decay and its prevention
Abstract
This module explores the reasons behind tooth decay and the role of toothpastes.
It explores the value of fluorides in preventing tooth decay and other believes that
have been put forward over the ages to prevent the lost of teeth through decay.
The module considered whether the beliefs are justified.
Sections included
1.
Student activities
2.
Teaching guide
3.
Assessment
4.
Teacher notes
Describes the scenario in more detail and the
tasks the students should perform
Suggests a teaching approach
Gives suggested formative assessment
strategies
Gives background information and activities
using toothpaste
Acknowledgement
This module has been adapted from that developed under the PARSEL project (www.parsel.eu) as part of
an EC FP6 funded project (SAS6-CT-2006-042922-PARSEL) on
Popularity and Relevance of Science Education for scientific Literacy
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Overall Competencies: The students are expected to learn to be able to:
 Development of social values through considering a social and economical
problem with tooth decay.
 Development of scientific skills through designing and performing experiments
with toothpaste.
 Enhancement of personal skills in allowing students to practice co-operative
report-writing as a member of a team and by participating in group
discussions. With the organizing strategies we have suggested, each student
has a personal responsibility to report the findings of his/hers group to a new
arrangement of groups.
 Enhancement in science conceptual learning by studying the background of
tooth decay from chemical and biological aspects and also the concept of
hardness of various substances.
Curriculum content: Tooth Decay
Kind of activity: Library search on causes of tooth decay, Devise tests on the
abrasive action of toothpaste, Group discussion on problems with tooth decay from
a personal and an economical perspective; are beliefs in preventing tooth decay
justified.
Anticipated time: 5 Lessons
This unique teaching-learning material is intended to guide the teacher towards
promoting students’ scientific literacy by recognising learning in 4 domains –
intellectual development, the process and nature of science, personal
development and social development.
Its uniqueness extends to an approach to science lessons which is designed to
follow a 3 stage model. For this the approach is intentionally from society to
science and attempts to specifically meet student learning needs.
This uniqueness is specifically exhibited by:
1.
a motivational, society-related and issue-based title (supported in the
student guide by a motivational, socio-scientific, real life scenario);
2.
forming a bridge from the scenario to the scientific learning to be
undertaken;
3.
student-centred emphasis on scientific problem solving, encompassing the
learning of a range of educational and scientific goals;
4.
utilising the new science by including in socio-scientific decision making to
relate the science acquired to societal needs for responsible citizenship.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Preventing Holes in TeethAre beliefs justified?
Scenario
Everyone knows about the importance of cleaning teeth and the availability of
toothpaste for this purpose. But did you know that toothpaste in the 18 th century was
often dangerous and caused tooth decay by rubbing off the enamel coating on teeth.
Today there are many suggested ways to prevent tooth decay. You may be aware of
drinking water containing fluorides, or softeners. You may be aware also of
toothpastes that include fluoride; or whitener, or antibacterial substances. Are they
really helpful? To find out we need to know more of what causes tooth decay and
how effective are the various treatments.
Your Tasks
Part A
As a group
1.
Find out about the structure of teeth and what tooth-enamel consists of.
2.
Carry out an experiment to determine what type of foods have potential to
damage the enamel.
3.
Write a short report on tooth enamel and your findings. Explain the
mechanisms by which the enamel is damaged. Include in your report what
happens if the enamel is damaged or removed and how it is possible to
protect your teeth?
4.
What are the ingredients in toothpaste? Find out the active substances in
different types of toothpaste and why they are present.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
5.
You probably know that most toothpastes contain fluoride compounds. What is
the effect of fluoride compounds on teeth? Are there potential dangers? What
ingredients of toothpaste have a potential danger to health? Prepare to make
a short 5 minute presentation on this to the class.
Part B
6.
7.
8.
Toothpastes have an abrasive action. The task of your group is to compare
the abrasive effects of different toothpastes. Design an investigation for this
and discuss it with your teacher before starting the experiment.
Record your results in a tabular format. Write a report that contains the
conclusions you have reached.
Discuss ways to prevent holes in teeth and whether the claims of different
ingredients in toothpaste are justified or a danger to health.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Preventing Holes in TeethAre beliefs justified?
Teaching Guide
The aim of this script is to make the students aware of the social impact of not taking
care of their teeth. This creates a link to everyday science and involves them in an
investigation. By planning the experiment the students improve their investigation
skills and their creativity. The lessons conclude by a discussion on how far beliefs
about the ingredients of toothpastes are justified.
This activity relates to:
a) knowledge about teeth and tooth enamel
b) experimentation on foods that can lead to damage to the tooth enamel
c) causes of tooth decay and making decisions on the best way to prevent tooth
decay
d) knowledge about toothpaste, their ingredients and its effects
e) planning and performing experiments concerning the abrasive effect and the
foaming effect of toothpaste
f) discussion on the degree of potential danger of substances present in toothpastes.
Lesson Learning Outcomes
Lesson 1
At the end of the lesson, students are expected to be able to :
1. determine suitable sources of information for the task assigned
2. extract meaningful information on teeth and tooth enamel.
3. prepare written notes which can form the basis for a 5 minute
presentation
Lesson 2
At the end of the lesson, students are expected to be able to:
1.
make a presentation to students in the group
2.
undertake experiments on the effects of foods on tooth enamel
3.
create a report of the findings and its relationship with tooth decay
Lesson 3
At the end of the lesson, students are expected to be able to:
1.
participate in a whole class discussion on tooth decay, its causes and
its prevention.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
2.
plan experiments on comparing the properties of toothpastes related to
tooth care
Lesson 4
At the end of the lesson, students are expected to be able to:
1.
after teacher approval of the experimental plan and appropriate
measures taken with respect to controls and safety, undertake the
experiments
2.
create a written report on the experimental observations, interpretations
and conclusions
Lesson 5
1.
participate in a group discussion on common beliefs about toothpaste
and tooth decay and justify any decision related to whether toothpaste
ingredients constitute any real danger to health.
2.
present the decisions of the group to the whole class
Suggested Teaching Strategy
Preparations beforehand:
Obtain a collection of teeth from human (baby teeth if this is possible) or
animal sources.
Collect different brands of toothpaste. Make sure that you have toothpastes
both with and without fluoride compounds added. (This in itself can be a
starting point for a discussion later on whether to buy toothpaste with or
without fluoride compounds. Also this leads to a possible discussion on how
this is related to the concentration of fluoride ions in your drinking water at
home).
Lesson 1
1.
Present the scenario and after a short discussion, divide the class into 5
groups which are distributed as even as possible. Give each group
responsibility for one of the first five tasks. The tasks are to find out what:
1. does tooth-enamel consist of and what are its properties.
2. kind of food has the potential to damage the tooth enamel. What damage
does it cause?
3. different alternatives are there to protect your teeth?
4. are the ingredients in toothpaste and their purpose? Try to find out which
are the active substances in toothpaste.
5. what is the effect of the use of fluoride compounds on teeth?
Each member of the group should take notes of their findings and be prepared
to make a short, 5 minute presentation to others.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
The teacher gives each individual member of the group a number.
Lesson 2
2.
3.
In new groups, each member reports on the findings of his/her task. Each of
these new groups writes a short report of their collective findings.
The groups also write down the questions that have come up during their
discussions.
Lesson 3
5.
6.
These questions are collected with the reports and form the basis of a
question and answer session with students
Students plan experiments to be carried out in small groups (2-3 students). If
by any chance the students fail to come up with ideas for an experiment you
can give them hints like:
How do you think the abrasive action may be measured?
What do you think is the reason for abrasive action?
How could you measure the foaming properties of toothpaste?
What causes the foaming action of toothpaste?
Can you think of any material which could be used instead of enamel?
If they still cannot come up with something advise them to e.g. count scratches
on a piece of glass under controlled forms.
Lesson 4
7.
When the groups have presented their ideas and the teacher has approved of
their plans for the experimental work, the students may perform their
investigations. Be aware of the importance of the fact that the test should be a
fair one and that the variables are under control.
8.
The students record the results of their investigation in a written report.
Lesson 5
9.
Students discussing in the groups and finding out about the problems with
tooth decay from a personal and an economical perspective; can we believe
toothpastes are good when they contain fluorides, surfactants, foaming
agents, etc?.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Achieving the Educational Competencies
Competency
This is achieved by
1. social and economical
problem with tooth decay
Students discussing in the groups and
finding out about the problems with tooth
decay from a personal and an economical
perspective; how this could be prevented
through better eating habits and better use of
toothpastes.
Students discussing in a group the possible
ways to carry out this kind of investigation
and how to properly control the variables.
This is achieved by the organizing strategies
we have suggested as each student has a
personal responsibility to report the findings
of his/hers group to a new group
constellation
This is achieved by discussing and finding
out from different sources the chemical and
biological explanations for tooth decay and
the effects of toothpaste. In addition,
students will also draw conclusions from their
experimental results.
2. designing and performing
experiments with toothpaste
3. practice cooperative
report-writing as a member
of a team and by
participating in groupdiscussions
4. background of tooth
decay from chemical and
biological aspects and also
the concept of hardness of
chemical compounds.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Preventing Holes in TeethAre beliefs justified?
Assessment
Part A
Assessment by application of Skills
Able to award a social values grade (objective 1)
The teacher listens to the students putting forward their points of view during class
discussion
x
Student unable or unwilling to put forward useful points for the prevention of
tooth decay.
√
Student is able to put forward useful evaluation points and able to reach a
decision on the effects of different toothpastes on tooth decay
√√
Student is able to lead the discussion and put forward important evaluation
points to be considered. The student is able to make an appropriate decision
with justification, unaided.
Able to award a science method grade (objectives 2 and 3)
Teacher observes the students and notes their plan and observations
x
Student not able to contribute to the planning on the abrasiveness of
toothpastes.
√
The student is able to put forward a plan to determine the abrasiveness of
toothpastes and is able to carry out the experiments. The student is able to
make appropriate observations with the aid of the teacher.
√√
The student is able to put forward a good experimental plan and undertake the
experiments, leading to meaningful observations and analysis
Able to award a personal skills grade (objectives 4 and 5)
Teacher observes the students in their groups
x
Student is neither cooperative, leaving the work to others and not joining in the
discussions in a meaningful way
√
Student cooperates as a member of a team and is able to discuss the
procedures to adopt and put forward useful suggestions on the suitability of
different toothpastes
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
√√
Student is able to cooperate and help other students to join in the work of the
group. The student is able to put forward useful suggestions to the group and
encourage others to put forward their ideas.
Able to award a science concept grade (objectives 6 and 7)
Teacher marks the students report
x
Student is unable to explain tooth decay n a meaningful way and to give
meaning to the concept of hardness.
√
Student can explain tooth decay and the meaning of hardness
√√
Student fully understands tooth decay, ways to prevent this and can explain
the importance of the hardness of the tooth enamel using scientific terminology
Part B
Assessment by Lesson
Lesson 1
Dimension
1
Creates written report
based on sources of
information
Lesson 2
Dimension
1
Presentation
2
Cooperates in a
group in writing a
report
Criteria for evaluation
The student:
Finds suitable sources of information
Extracts meaningful information for a
presentation to other students
Mark/grade given (x,√,√√)
Criteria for evaluation
The student:
Presents the information obtained in a
clear and practical manner.
Presents showing an understanding of
the subject.
Uses precise and appropriate scientific
terms and language.
Presents with clarity and confidence
using an audible voice.
Cooperates with others in the group in
compiling the report.
Illustrates leadership skills – guiding the
group by thinking creatively ensuring no
overlap in the report from the
presentations.
Shows tolerance with, and gives
encouragement to, the group members.
Mark/grade given (x,√,√√)
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
3
4
Shows
understanding
Asking questions
Able to explain the causes of tooth
decay and methods for their prevention
Willing to ask questions during the
presentation of others.
Able to recognise where the group did
not have answers to questions
Cooperate with others in making a
written record of the questions for which
the group did not have answers.
Lesson 3
Dimension
1
2
Criteria for evaluation
Mark/grade given (x,√,√√)
The student:
Answers questions
Provides correct written answers to
questions given orally
Provides answers in sufficient detail
especially when called upon to give an
opinion or decision
Writes a plan or report Puts forward an appropriate research/
of an investigation
scientific question and/or knows the
purpose of the
investigation/experiment
Creates an appropriate investigation or
experimental plan to the level of detail
required by the teacher
Puts forward an appropriate
prediction/hypotheses
Develops an appropriate procedure
(including apparatus/chemicals
required and safety procedures
required) and indicates variables to
control
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Lesson 4
Dimension
1
Record experimental
data collected
2
Interpret or calculate
from data collected
and making
conclusions
Criteria for evaluation
Mark/grade given (x,√,√√)
The student:
Makes and Records observations/data
collected appropriately (in terms of
numbers of observations deemed
acceptable/accuracy recorded/errors
given)
Interprets data collected in a justifiable
manner including the use of
appropriate graphs, tables and
symbols
Creates a written report on the
experiments and includes appropriate
conclusions related to the
research/scientific question
Lesson 5
Dimension
1
Criteria for evaluation
The student:
Scientific or socio- Gives a justified socio-scientific
scientific reasoning
decision to an issue or concern,
correctly highlighting the scientific
component
Records the decision of the group and
presents to other groups
Part C
Mark/grade given (x,√,√√)
Assessment by teacher strategy
Assessment Tool based on the Teacher's Marking of Written Material
Criteria for evaluation
Mark/grade given (x,√,√√)
The student:
Writes a plan or report Puts forward an appropriate
of an investigation
investigation/ experiment
Creates an appropriate investigation or
experimental plan to the level of detail
required by the teacher
Puts
forward
an
appropriate
prediction/hypotheses
Dimension
1
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
2
Record experimental
data collected
3
Interpret or calculate
from data collected
and
making
conclusions
4
Answers questions
5
Scientific or socioscientific reasoning
Develops an appropriate procedure
(including
apparatus/chemicals
required and safety procedures
required) and indicates variables to
control
Makes and Records observations/data
collected appropriately (in terms of
numbers of observations deemed
acceptable/accuracy recorded/errors
given)
Interprets data collected in a justifiable
manner
including
the
use
of
appropriate
graphs,
tables
and
symbols
Draws appropriate conclusions related
to the research/scientific question.
Creates a report
Provides correct written answers to
questions given orally or in written
format
Provides answers in sufficient detail
especially when called upon to give an
opinion or decision
Illustrates creative thinking/procedures
in deciding whether beliefs are
justified.
Gives a justified socio-scientific
decision whether the beliefs about
toothpaste ingredients are justified,
correctly highlighting the scientific
components.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
1
2
Student Assessment Tool based on the Teacher's Observations
Dimension
Criteria for evaluation
Mark/grade given (x,√,√√)
The student:
Functioning in the
Contributes to the group discussion
group during
during
the
experimental
phases
experimentation or (planning the investigation/experiment,
discussion
putting forward hypotheses/predictions,
carrying out the experimentation,
analyzing data, drawing conclusions,
making justified decisions).
Cooperates with others in a group and
fully participates in the work of the
group.
Illustrates leadership skills – guiding the
group by thinking creatively and helping
those needing assistance (cognitive or
psychomotor); summarising outcomes.
Shows tolerance with, and gives
encouragement to, the group members.
Performing the
Understands the objectives of the
investigation or
investigation/experimental work and
experiment
knows which tests and measurements to
perform.
Performs the investigation/experiment
according to the instructions/plan
created.
Uses lab tools and the measurement
equipment in a safe and appropriate
manner.
Behaves in a safe manner with respect
to him/herself and to others.
Maintains an orderly and clean work
table.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Student Assessment Tool based on the Teacher's Oral Questioning
Dimension
Criteria for evaluation
Mark/grade given (x,√,√√)
The student:
1
Questions to
individuals in a
Whole Class setting
2
Questions to the
group
3
Questions to
individuals in the
group
Answers questions at an appropriate
cognitive level using appropriate
scientific language
Shows interest and a willingness to
answer
Willing and able to challenge/support
answers by others, as appropriate
Able to explain the work of the group
and the actions undertaken by each
member
Understands and can explain the
science involved using appropriate
language
Willing to support other members in
the group in giving answers when
required
Thinks in a creative manner, exhibits
vision and can make justified decisions
Able to explain the work of the group
and actions taken by each member
Understands the purpose of the work
and
shows
knowledge
and
understanding of the subject using
appropriate scientific language
Can
exhibit
non-verbal
activity
(demonstrate) in response to the
teacher’s questions, as appropriate
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Preventing Holes in TeethAre beliefs justified?
Teacher Notes
Student Worksheet 1
The importance of brushing teeth.
Purpose of experiment
Students
 participate in hands-on activities that lead them to good-health conclusions.

explain how each experiment illustrates the importance of brushing their teeth
every day.
Materials Needed
 hard-boiled eggs
 soft drink, such as cola or root beer
 dried chicken bones
 vinegar
 water and sugar solutions
 water and salt solutions
 fluoride (from a local dentist, or a dental supply store or pharmacy)
Experiment 1
1.
For this simple experiment, fill one container with water and another with a
brown soft drink -- cola or root beer, for example.
2.
Place a hard-boiled egg into each container.
3.
Leave the eggs in the containers overnight.
4.
Pour out the liquid the next day and examine the eggs.
5.
Compare the eggs left in the soda to the egg left in the water.
Experiment 2
1.
Each group of students obtains 2 or more dry chicken bones.
2.
Place one of the bones in a plastic cup; then pour vinegar in the cup to cover
the bone.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
3.
Leave the other bone exposed to the air. Let the bones sit for several days,
and then compare the two bones. What has happened? Why?
Additional Experiments
Lesson Competency
Students learn about the way fluoride strengthens tooth enamel against acid
Materials Needed
 2 boiled eggs
 Large Pickle Jar
 Vinegar
 Plastic Food Storage Bag
 Fluoride Gel
Experiment
1.
Take one egg and put it in a plastic bag containing the fluoride gel. (make sure
the fluoride completely covers the entire egg shell). Leave the other egg as is.
2.
Leave the egg in the fluoride for 24 hours.
3.
Take both eggs and put them in separate jars containing vinegar.
4.
Observe the immediate difference in bubbling or reactivity of the two different
eggs.
5.
Leave overnight
6.
Take both eggs out of the jar and examine.
Example of an Experimental Study on the Effectiveness of Different Ingredients
in Toothpaste on Stained Teeth
Purpose
The purpose of this experiment was to determine which tooth cleaner most effectively
removes stains from teeth.
Hypothesis
The fluoridated toothpaste will be the best cleaner to remove stains from teeth.
Experimental design
The variables controlled in this study were
the sugars (soda pop) and acid
(lemon juice); kind of teeth; kind of cleaner; tooth brush; amount of time brushed.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
The manipulated variable was the substance used to clean the teeth.
The
responding
variable
was
the
whiteness
of
the
teeth.
A colorimeter was used to observe the responding variable (whiteness and
discolouring of the teeth).
Procedure
1.
Make labels for the petri dishes according to the type of stain and cleaner
solution that will be used for that tooth.
2.
Put gloves on to handle teeth.
3.
Pour glycerine out of jar making sure that the teeth remain in the jar.
4.
Place teeth in container of water and boil for ten minutes. Remove the teeth
from the boiling water and dry them thoroughly.
5.
Place each tooth into correct ziplock bag according to label.
6.
Put tooth in colorimeter and record reading. Repeat for each tooth.
7.
Fill six empty petri dishes three-fourths full with only soda pop .
8.
Fill six empty petri dishes three-fourths full with only lemon juice.
9.
Arrange petri dishes in the order in which they appear on the recording chart.
10. Keep them in this order to avoid recording information incorrectly.
11. Soak each tooth in its solution for 2 weeks.
12. At the end of this period of time put on rubber gloves.
14. Remove tooth from petri dish.
15. Put stained tooth in colorimeter.
16. Brush tooth with correct cleaner. 3 min. Clean all surfaces equally.
17. Put tooth in colorimeter and record data.
18. Dispose of teeth and gloves at Tree Top Lab .
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Results
The original purpose of this experiment was to determine which tooth cleaner most
effectively removes stains from teeth.
The results from my experiment indicated that tooth five had the largest amount of
discoloration removed during the brushing process. The reading of the stained
colour was 119.44. The cleaned colour was 63.40. The difference between the
stained and cleaned colour was 56.04.
Conclusion
My hypothesis was that the fluoridated toothpaste would be the best cleaner to
remove stains from teeth.
The results indicate that this hypothesis should be rejected because the greatest
amount of discoloration was removed by the non-fluoridated toothpaste.
Because of the results of this experiment I wonder if the same results would occur
with other kinds of stains, longer staining time, and other cleaning agents.
If I were to conduct this project again I would use cow teeth instead of teeth from
humans, possibly use different stains, and conduct it for a longer period of time.
Notes on Teeth and Toothpastes
1.
Structure of Teeth
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
2
Tooth enamel
About Tooth Enamel
Tooth enamel is the hardest and most highly mineralized substance of the body.
Together with dentin, cementum, and dental pulp is one of the four major tissues
which make up the tooth.
It is the normally visible dental tissue of a tooth and must be supported by underlying
dentin. Ninety-six percent of enamel consists of mineral, with water and organic
material composing the rest. The normal color of enamel varies from light yellow to
grayish white. At the edges of teeth where there is no dentin underlying the enamel,
the color sometimes has a slightly blue tone.
Since enamel is semi-translucent, the color of dentin and any restorative dental
material underneath the enamel strongly affects the appearance of a tooth. Enamel
varies in thickness over the surface of the tooth and is often thickest at the cusp, up
to 2.5mm, and thinnest at its border, which is seen clinically as the cemento-enamel
junction (CEJ).
Enamel's primary mineral is hydroxyapatite, which is a crystalline calcium phosphate.
The large amount of minerals in enamel accounts not only for its strength but also for
its brittleness. Tooth enamel is the hardest substance in the human body, ranking a 5
on Mohs hardness scale.
The discoloration of teeth over time can result from exposure to substances such as
tobacco, coffee, and tea. This is partly due to material building up in the enamel, but
is also an effect of the underlying dentin becoming sclerotic. As a result, tooth color
gradually darkens with age. Additionally, enamel becomes less permeable to fluids,
less soluble to acid, and contains less water.
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Destruction of teeth
Destruction of enamel by cervical decay from dental caries.
The extent to which tooth decay is likely, known as cariogenicity, depends on factors
such as how long the sugar remains in the mouth. Contrary to common belief, it is not
the amount of sugar ingested but the frequency of sugar ingestion that is the most
important factor in the causation of tooth decay. When the pH in the mouth initially
decreases from the ingestion of sugars, the enamel is demineralized and left
vulnerable for about 30 minutes. Eating a greater quantity of sugar in one sitting does
not increase the time of demineralization. Similarly, eating a lesser quantity of sugar
in one sitting does not decrease the time of demineralization. Thus, eating a great
quantity of sugar at one time in the day is less detrimental than is a very small
quantity ingested in many intervals throughout the day. For example, in terms of oral
health, it is better to eat a single dessert at dinner time than to snack on a bag of
candy throughout the day.
In addition to bacterial invasion, enamel is also susceptible to other destructive
forces. Bruxism, also known as clenching of or grinding on teeth, destroys enamel
very quickly. The wear rate of enamel, called attrition, is 8 micrometers a year from
normal factors. A common misconception is that enamel wears away mostly from
chewing, but actually teeth rarely touch during chewing. Furthermore, normal tooth
contact is compensated physiologically by the periodontal ligaments (pdl) and the
arrangement of dental occlusion. The truly destructive forces are the para-functional
movements, as found in bruxism, which can cause irreversible damage to the
enamel.
Other nonbacterial processes of enamel destruction include abrasion (involving
foreign elements, such as toothbrushes), erosion (involving chemical processes,
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such as lemon juice), and possibly abfraction (involving compressive and tensile
forces).
Dentin
Dentin, less mineralized and less brittle, 3-4 in hardness, compensates for enamel
and is necessary as a support.
Unlike dentin and bone, enamel does not contain collagen. Instead, it has two
unique classes of proteins called amelogenins and enamelins. While the role of
these proteins is not fully understood, it is believed that they aid in the development
of enamel by serving as a framework support, among other functions.
Unlike enamel, the dentin reacts to the progression of dental caries. After tooth
formation, the ameloblasts, which produce enamel, are destroyed once enamel
formation is complete and thus cannot later regenerate enamel after its destruction.
On the other hand, dentin is produced continuously throughout life by odontoblasts,
which reside at the border between the pulp and dentin. Since odontoblasts are
present, a stimulus, such as caries, can trigger a biologic response. These defense
mechanisms include the formation of sclerotic and tertiary dentin.
In dentin from the deepest layer to the enamel, the distinct areas affected by caries
are the translucent zone, the zone of bacterial penetration, and the zone of
destruction. The translucent zone represents the advancing front of the carious
process and is where the initial demineralization begins. The zones of bacterial
penetration and destruction are the locations of invading bacteria and ultimately the
decomposition of dentin.
The faster spread of caries through dentin creates this triangular appearance in
smooth surface caries.
Fluorisis
Many groups of people have spoken out against fluoridated drinking water. One
example used by these advocates is the damage fluoride can do as fluorosis.
Fluorosis is a condition resulting from the overexposure to fluoride, especially
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between the ages of 6 months to 5 years, and appears as mottled enamel.
Consequently, the teeth look unsightly and, indeed, the incidence of dental decay in
those teeth is very small. However, it is important to note that most substances, even
beneficial ones, are detrimental when taken in extreme doses. Where fluoride is
found naturally in high concentrations, filters are often used to decrease the amount
of fluoride in water. For this reason, codes have been developed by dental
professionals to limit the amount of fluoride a person should take.
The acute toxic dose of fluoride is ~5 mg/kg of body weight. Furthermore, whereas
topical fluoride, found in toothpaste and mouthwashes, does not cause fluorosis, its
effects are also less pervasive and not as long-lasting as those of systemic fluoride,
such as when drinking fluorinated water. For instance, all of a tooth's enamel gains
the benefits of fluoride when it is ingested systemically, through fluoridated water or
salt fluoridation (a common alternative in Europe). Only some of the outer surfaces of
enamel can be reached by topical fluoride. Thus, despite fluoridation's detractors,
most dental health care professionals and organizations agree that the inclusion of
fluoride in public water has been one of the most effective methods of decreasing the
prevalence of tooth decay.
Tooth whitening
Tooth whitening or tooth bleaching are procedures that attempt to lighten a tooth's
color in either of two ways: by chemical or mechanical action.
Working chemically, a bleaching agent is used to carry out an oxidation reaction in
the enamel and dentin. The agents most commonly used to intrinsically change the
color of teeth are hydrogen peroxide and carbamide peroxide. A tooth whitening
product with an overall low pH can put enamel at risk for decay or destruction by
demineralization. Consequently, care should be taken and risk evaluated when
choosing a product which is very acidic.
Tooth whiteners in toothpastes work through a mechanical action. They have mild
abrasives which aid in the removal of stains on enamel. Although this can be an
effective method, it does not alter the intrinsic color of teeth.
Micro-abrasion techniques employ both methods. An acid is used first to weaken the
outer 22–27 micrometers of enamel in order to weaken it enough for the subsequent
abrasive force. This allows for removal of superficial stains in the enamel. If the
discoloration is deeper or in the dentin, this method of tooth whitening will not be
successful.
Tooth decay
The second most common of all health disorders is tooth decay. It is second to the
common cold. Tooth decay usually occurs in young children but it can affect any
person. Tooth decay is the leading cause of tooth loss in young people. It has been
shown that eighty four percent of all cavities are located on molars which are in the
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back of the mouth. Molars contain many pits and grooves. It is harder to reach these
areas with a toothbrush. When these grooved areas are not properly cleaned
bacteria settle on the tooth surface and use the food particles left in the mouth to
create acid. It is this acid that creates cavities.
Tooth decay is caused by certain types of acid-producing bacteria which cause
damage in the presence of fermentable carbohydrates such as sucrose, fructose,
and glucose. The resulting acidic levels in the mouth affect teeth because a tooth's
special mineral content causes it to be sensitive to low pH. Specifically, a tooth
(which is primarily mineral in content) is in a constant state of back-and-forth
demineralization and remineralization between the tooth and surrounding saliva.
When the pH at the surface of the tooth drops below 5.5, demineralization proceeds
faster than remineralization (i.e. there is a net loss of mineral structure on the tooth's
surface). This results in the ensuing decay.
Location of caries
Generally, there are two types of caries when separated by location:

caries found in pits and fissures.

caries found on smooth surfaces and
The pits and fissures of teeth provide a location for caries formation.
Pit and fissure caries
Pits and fissures are anatomic landmarks on a tooth where tooth enamel infolds
creating such an appearance. Fissures are formed during the development of
grooves, and have not fully fused (unlike grooves), thus possessing a unique linearlike small depression in enamel's surface structure, which would be a great place for
dental caries to develop and flourish. Fissures are mostly located on the occlusal
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(chewing) surfaces of posterior teeth and lingual surfaces of maxillary anterior teeth.
Pits are small, pinpoint depressions that are found at the ends or cross-sections of
grooves. In particular, buccal pits are found on the facial surface of molars. For all
types of pits and fissures, the deep infolding of enamel makes oral hygiene along
these surfaces difficult, allowing dental caries to be common in these areas.
The occlusal surfaces of teeth represent 12.5% of all tooth surfaces but are the
location of over 50% of all dental caries. Among children, pit and fissure caries
represent 90% of all dental caries. Pit and fissure caries can sometimes be difficult to
detect. As the decay progresses, caries in enamel nearest the surface of the tooth
spreads gradually deeper. Once the caries reaches the dentin at the dentino-enamel
junction, the decay quickly spreads laterally. Within the dentin, the decay follows a
triangle pattern that points to the tooth's pulp. This pattern of decay is typically
described as two triangles (one triangle in enamel, and another in dentin) with their
bases conjoined to each other at the dentino-enamel junction (DEJ). This base-tobase pattern is typical of pit and fissure caries, unlike smooth-surface caries (where
base and apex of the two triangles join).
Smooth-surface caries
There are three types of smooth-surface caries. Proximal caries, also called interproximal caries, form on the smooth surfaces between adjacent teeth. Root caries
form on the root surfaces of teeth. The third type of smooth-surface caries occur on
any other smooth tooth surface.
In this radiograph, the dark spots in the adjacent teeth show proximal caries.
Proximal caries are the most difficult type to detect. Frequently, this type of caries
cannot be detected visually or manually with a dental explorer. Proximal caries form
cervically (toward the roots of a tooth) just under the contact between two teeth. As a
result, radiographs are needed for early discovery of proximal caries.
Root caries, which are sometimes described as a category of smooth-surfaces
caries, are the third most common type of caries and usually occur when the root
surfaces have been exposed due to gingival recession. When the gingiva is healthy,
root caries is unlikely to develop because the root surfaces are not as accessible to
bacterial plaque. The root surface is more vulnerable to the demineralization process
than enamel because cementum begins to demineralize at 6.7 pH, which is higher
than enamel's critical pH. Regardless, it is easier to arrest the progression of root
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caries than enamel caries because roots have a greater reuptake of fluoride than
enamel. Root caries are most likely to be found on facial surfaces, then interproximal
surfaces, then lingual surfaces. Mandibular molars are the most common location to
find root caries, followed by mandibular premolars, maxillary anteriors, maxillary
posteriors, and mandibular anteriors.
Lesions on other smooth surfaces of teeth are also possible. Since these occur in all
smooth surface areas of enamel except for interproximal areas, these types of caries
are easily detected and are associated with high levels of plaque and diets promoting
caries formation.
Signs and symptoms of caries
Until caries progresses, a person may not be aware of it. The earliest sign of a new
carious lesion, referred as incipient decay, is the appearance of a chalky white spot
on the surface of the tooth, indicating an area of demineralization of enamel. As the
lesion continues to demineralize, it can turn brown but will eventually turn into a
cavitation, a "cavity". The process before this point is reversible, but once a cavitation
forms, the lost tooth structure cannot be regenerated. A lesion which appears brown
and shiny suggests dental caries was once present but the demineralization process
has stopped, leaving a stain. A brown spot which is dull in appearance is probably a
sign of active caries.
As the enamel and dentin are destroyed further, the cavitation becomes more
noticeable. The affected areas of the tooth change color and become soft to the
touch. Once the decay passes through enamel, the dentinal tubules, which have
passages to the nerve of the tooth, become exposed and cause the tooth to hurt. The
pain can be worsened by heat, cold, or sweet foods and drinks. Dental caries can
also cause bad breath and foul tastes. In highly progressed cases, infection can
spread from the tooth to the surrounding soft tissues which may become lifethreatening, as in the case with Ludwig's angina.
Causes of caries formation
There are four main criteria required for caries formation: a tooth surface (enamel or
dentin); cariogenic (or potentially caries-causing) bacteria; fermentable carbohydrates
(such as sucrose); and time. The caries process does not have an inevitable
outcome, and different individuals will be susceptible to different degrees depending
on the shape of their teeth, oral hygiene habits, and the buffering capacity of their
saliva. Dental caries can occur on any surface of a tooth that is exposed to the oral
cavity, but not the structures which are retained within the bone.
The minerals in tooth enamel, especially hydroxyapatite, will become soluble when
exposed to acidic environments. Enamel begins to demineralize at a pH of 5.5.
Dentin and cementum are more susceptible to caries than enamel because they
have lower mineral content. Thus, when root surfaces of teeth are exposed from
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gingival recession or periodontal disease, caries can develop more readily. Even in a
healthy oral environment, the tooth is susceptible to dental caries.
The anatomy of teeth may affect the likelihood of caries formation. In cases where
the deep grooves of teeth are more numerous and exaggerated, pit and fissure
caries are more likely to develop. Also, caries are more likely to develop when food is
trapped between teeth.
Bacteria and dental caries
Bacteria which are tiny colonies of living organisms are constantly found in the
human mouth. It is normal for millions of bacteria to be in your mouth. The mouth
contains a wide variety of bacteria, but only a few specific species of bacteria are
believed to cause dental caries: Streptococcus mutans and Lactobacilli among them.
Particularly for root caries, the most closely associated bacteria frequently identified
are Lactobacillus acidophilus, Actinomyces viscosus, Nocardia spp., and
Streptococcus mutans. Mutans streptococci are able to grab any sugar that enters
the mouth. Bacteria in a person's mouth convert sugars (glucose and fructose, and
most commonly sucrose - or table sugar) into acids such as lactic acid through a
glycolytic process called fermentation. This changes the pH in the mouth and forms
acid on the teeth. It is this acid that causes teeth to decay. The lactobacilli are more
able to survive in an acid environment. Bacteria changes all foods into acid. Sugars
and starches are favourites of bacteria. Plaque is formed by bacteria, acid, food
debris, and saliva. Plaque is a sticky substance that sticks to the teeth. Plaque is
easily detected on the grooved chewing surfaces of the back molars, just above the
gum line, and at the edges around fillings. When plaque is not removed from the
teeth it becomes tartar.
There is acid in the plaque. It is this acid that dissolves the enamel surface of the
tooth and creates holes in the tooth. Most of the bacterial activity occurs within
twenty minutes after eating. This is when the acid is most active. The bacteria
multiply faster and the plaque grows in size and thickness. This makes it harder to
wash the bacteria away with saliva. Bacteria will use the sugars found in candy and
other sweet foods as well as the natural sugars found in fruits and milk. They also
use the carbohydrates found in potato chips, pasta, and bread.
Our teeth are able to repair the damage done to the enamel by the acid in a process
called remineralization. The minerals found in the saliva try to repair the damaged
areas of the tooth surface. But, the rate of destruction of the tooth enamel by acid is
much faster than the natural remineralization that occurs.
If left in contact with the tooth, these acids may cause demineralization, which is the
dissolution of its mineral content. The process is dynamic, however, as
remineralization can also occur if the acid is neutralized; suitable minerals are
available in the mouth from saliva and also from preventative aids such as fluoride
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toothpaste, dental varnish or mouthwash. Caries advance may be arrested at this
stage.
Prevention of caries
Oral hygiene
Personal hygiene care consists of proper brushing and flossing daily. The purpose of
oral hygiene is to minimize any etiologic agents of disease in the mouth. The primary
focus of brushing and flossing is to remove and prevent the formation of plaque.
Plaque consists mostly of bacteria. As the amount of bacterial plaque increases, the
tooth is more vulnerable to dental caries. A toothbrush can be used to remove plaque
on most surfaces of the teeth except for areas between teeth. When used correctly,
dental floss removes plaque from areas which could otherwise develop proximal
caries. Other adjunct hygiene aids include inter-dental brushes, water picks, and
mouthwashes.
Professional hygiene care consists of regular dental examinations and cleanings.
Sometimes, complete plaque removal is difficult, and a dentist or dental hygienist
may be needed. Along with oral hygiene, radiographs may be taken at dental visits to
detect possible dental caries development in high risk areas of the mouth.
Dietary modification
For dental health, the frequency of sugar intake is more important than the amount of
sugar consumed. In the presence of sugar and other carbohydrates, bacteria in the
mouth produce acids which can demineralize enamel, dentin, and cementum. The
more frequently teeth are exposed to this environment, the more likely dental caries
are to occur. Therefore, minimizing snacking is recommended, since snacking
creates a continual supply of nutrition for acid-creating bacteria in the mouth. Also,
chewy and sticky foods (such as dried fruit or candy) tend to adhere to teeth longer,
and consequently are best eaten as part of a meal. Brushing the teeth after meals is
recommended.
It has been found that milk and certain kinds of cheese like cheddar can help counter
tooth decay if eaten soon after the consumption of foods potentially harmful to teeth.
Also, chewing gum containing xylitol (wood sugar) is widely used to protect teeth in
some countries, being especially popular in the Finnish candy industry. Xylitol's effect
on reducing plaque is probably due to bacteria's inability to utilize it like other sugars.
Chewing and stimulation of flavour receptors on the tongue are also known to
increase the production and release of saliva, which contains natural buffers to
prevent the lowering of pH in the mouth to the point where enamel may become
demineralised.
Fluoride therapy is often recommended to protect against dental caries. It has been
demonstrated that water fluoridation and fluoride supplements decrease the
incidence of dental caries. Fluoride helps prevent decay of a tooth by binding to the
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hydroxyapatite crystals in enamel. The incorporated fluoride makes enamel more
resistant to demineralization and, thus, resistant to decay. Topical fluoride is also
recommended to protect the surface of the teeth. This may include a fluoride
toothpaste or mouthwash. Many dentists include application of topical fluoride
solutions as part of routine visits.
Furthermore, recent research shows that low intensity laser radiation of argon ion
lasers may prevent the susceptibility for enamel caries and white spot lesions. Also,
as bacteria are a major factor contributing to poor oral health, there is currently
research to find a vaccine for dental caries. As of 2004, such a vaccine has been
successfully tested on non-human animals, and is in clinical trials for humans of May
2006.
Tooth decay prevention
There are several things that can be done to prevent tooth decay. The timing of your
snacks is critical to preventing cavities. After snacking the acid that is produced is
neutralized by the saliva and is cleared from the mouth. After the acid is removed the
minerals present in saliva crystallize on the enamel and begin to repair the areas that
were damaged by the acid. The longer the interval between meals and snacks
provides more opportunity for the acid to be neutralized and more time for the
damage to be repaired. When frequent snacking takes place there is a constant
attack on the tooth surface by the acid. There is also less time for tooth repair to take
place.
Fluoride has been called a wonder of modern dentistry. It incorporates itself into the
enamel of the tooth and strengthens it and makes it more resistant to attacks by
acid. Fluoride works with the saliva in the mouth to restore, or remineralise the
decayed spot on the tooth. The pH level in the mouth is lower after eating. It is
during this time that fluoride is able to reduce the activity of the mutans streptococci.
Fluoride is found in many tooth cleaners as well as being applied to the teeth by the
dentist at regular visits.
There are many toothpastes that promise better results in cleaning tooth surfaces as
well as helping to control plaque growth and tartar control. The cleaning power of a
toothpaste depends on its ability to remove stains from the surface of the tooth.
Toothpastes contain gentle abrasives to help clean tooth surfaces. Most toothpastes
contain fluoride. Some use stannous fluoride while others use sodium fluoride or
sodium monofluoroshosphate. Tartar control toothpastes contain pyrophosphates to
slow the build-up of tartar above the gumline. The most important factors to reduce
the build-up of plaque on tooth surfaces is regular brushing, twice a day and flossing
to remove debris that is between the teeth.
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Measures of Hardness
There are many different aspects of materials which could be considered as a
measure of hardness. Hardness can mean resistance to scratching, indentation,
bending, breaking, abrasion, cleavage, or fracture. It is easy to confuse durability or
toughness with hardness. A very simple example is to consider a glass ball and a
rubber ball. Glass is harder than rubber, but rubber is more durable. Try bouncing
both on a hard floor, the glass ball will shatter, whereas the rubber ball will bounce.
The aspect of hardness which is measured by Moh's test is the scratchability of a
mineral.
Moh's Hardness Scale
Moh Mineral
10
Diamond
Hardest of all minerals
9
Corundum
It scratches Topaz
8
Topaz
Harder than any common mineral
7
Quartz
Hardest common mineral
It scratches steel and glass easily
6
Feldspar
Steel knife does not scratch it easily
scratches glass
5
Apatite
Steel knife scratches it
4
Fluorspar
Steel knife scratches it easily
3
Calcite
Copper penny scratches it
2
Gypsum
Fingernail scratches it
1
Talc
Fingernail scratches it easily
Tooth enamel rates 5 on the Moh scale.
In 1822, Friedrich Moh, a German mineralogist devised a crude but practical method
of comparing hardness or scratch resistance of minerals. It has become universally
known as Moh's scale.
It should more accurately be called a table, because it is not to scale, that is the
numbers allocated to different minerals are not proportional to their actual scratch
resistance, so that the scale is really an ordered list.
Moh took ten well known, easily available minerals, and arranged them in order of
their "scratch hardness". If a specimen to be tested can be scratched by a known
mineral from the list, it is softer than that mineral. If it in turn will scratch another
known mineral, it is harder than that mineral. This gives a very quick and easy field
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test for hardness. As such is it very useful for mineralogists. It is too destructive to be
commonly used in gemmology, but is available, and can be valuable on rough
gemstones.
Toothpaste
Ingredients
A modern toothpaste has much more ingredients than those some years ago. New
toothpaste ingredients have been introduced in order to provide effective protection
against various dental conditions.
The most common active ingredients in toothpastes are :
1.
Fluoride
This is the most popular active ingredient in toothpaste due to its proved ability to
prevent cavities. Fluoride incorporates itself into tooth enamel making your teeth
more resistant to acids produced by plaque bacteria, as well as acids found in fruit
juices, soda (both regular and diet) and certain foods.
Most toothpaste brands use Sodium fluoride (NaF); some brands use Sodium
Monofluorophosphate - SMFP (Na2PO3F). The concentration of fluoride in a
toothpaste for adults is 1000 to 1450 ppm max.
2.
Antimicrobial agents
These fight the bacteria of dental plaque. There are two kinds of antibacterial agents
used as ingredients of toothpastes :
- bactericidal agents as Triclosan that kill bacteria. Triclosan induces damage and
lesions to the cell wall of bacteria resulting in bacteriolysis (death of the cell).
- bacteriostatic agents as Zinc (Zinc chloride or Zinc citrate) that stop the growth of
dental plaque bacteria by inhibiting their metabolism.
The combination of a bacteriostatic with a bactericidal agent as toothpaste
ingredients is the most effective one to fight dental plaque and gum disease.
3.
Surfactants (detergents) and Foaming agents
These help to carry away debris from the mouth and between the teeth. Foam keeps
the toothpaste in our mouths, preventing it from dribbling out as we brush. Common
foaming ingredients in toothpastes are Sodium Lauryl Sulfate (SLS) and ammonium
lauryl sulfate. Unfortunately, SLS and other detergents have been linked to the
promotion of canker sores (mouth ulcers) in susceptible individuals. The presence of
bad-tasting detergents requires the use of strong flavorings to mask the bad taste.
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4.
Anti-tartar agents as Tetrasodium Pyrophosphate (TSPP).
Pyrophosphates are water-softening agents that remove calcium and magnesium
from the saliva, so they can't deposit on teeth creating tartar (calcified plaque).
Pyrophosphate does not remove tartar, it merely helps prevent its formation.
5.
De-sensitising agents to relieve tooth sensitivity.
Strontium chloride works by blocking the tiny crevices (microtubules) that enable cold
and heat sensations to reach the tooth's nerve. Potassium citrate and Potassium
nitrate work in a different way by blocking the mechanism of pain transmission
between nerve cells.
6.
Abrasives
Abrasives give toothpaste its cleaning power. They remove stains and plaque, as
well as polish teeth. Toothpaste should be abrasive enough to remove plaque and
stains, but not abrasive enough to damage tooth enamel. Unfortunately, some
toothpastes are too abrasive, and do damage tooth enamel. This leads to tooth
sensitivity. Damaged tooth enamel also causes yellowing as the thinned enamel
reveals the yellowish dentin layer below. Calcium phosphate (chalk) and alumina
were used as the abrasive base of tooth pastes but they had the disadvantage of
reacting with other chemical ingredients. Today the common abrasives are Silicon
Dioxide (silica) and Titanium Dioxide. Hydrated silica is a transparent abrasive used
not only in white opaque tooth pastes, but in gel toothpastes as well.
Baking Soda (Sodium bicarbonate) is a mild abrasive. It has a mild whitening action
and helps to keep an alkaline environment (not friendly for dental plaque bacteria) in
the mouth.
7.
Teeth Whitening agents
The whitening toothpastes, except of the mechanical whitening action of toothpaste
abrasives, use extra whitening ingredients as the Hydrogen Peroxide or Sodium
carbonate peroxide that breaks down into sodium carbonate (washing soda) and
hydrogen
peroxide.
8.
Flavouring.
Toothpastes come in a variety of flavours, most often being some variation on mint.
These are added to improve the taste of toothpaste. You may have noticed that
toothpastes often have very strong flavouring. This is necessary to cover up the
horrid taste of most detergents, especially SLS.
9.
Humectants
Humectants give toothpaste its texture as well as retain moisture so that your
toothpaste does not dry out. Glycerin, sorbitol, and water are common humectants.
Xylitol is an uncommon, but superior humectant, which also boosts fluoride's cavityfighting power.
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10.
Thickeners
Thickeners also help to create the texture of toothpaste and determine how 'thick'
your toothpaste is. Carrageenan, cellulose gum, and xanthan gum are common
thickening agents.
11.
Preservatives
Preservatives prevent the growth of micro-organisms in toothpaste. This eliminates
the need to refrigerate toothpaste. Common preservatives include sodium benzoate,
methyl paraben, and ethyl paraben.
12.
Sweetener
Sweeteners also improve the taste of toothpaste. Most toothpaste sweeteners are
artificial and contribute very little to cavity formation. Saccharin is a common
toothpaste sweetener.
13.
Colouring Agents
Some toothpastes would look down right disgusting if it were not for colouring agents.
Colouring agents provide toothpaste with pleasing colours. Artificial dyes are used to
make red, green, and blue toothpastes. Titanium dioxide is used to make some
toothpastes white.
14.
Additional ingredients
Enzymes, vitamins, herbs, calcium, mouthwash are often included in the formulas.
Other non active ingredients in toothpaste are water softeners .
Potentially harmful ingredients in toothpaste
Sodium Fluoride: The main ingredient in toothpaste and rat poison
Many people are probably aware that most toothpaste and many mouth rinses
contain fluoride because that's what dentists have recommended for years to prevent
cavities. But did you know that most popular toothpastes contain enough fluoride to
kill a small child within 2 to 4 hours?
In children and youth, minimal ingestion of sodium fluoride causes salivation, nausea,
vomiting, epigastric pain, and diarrhoea. Large doses of the carcinogen may cause
paralysis, muscular weakness and clonic convulsions, followed by respiratory and
cardiac failure.
It’s no wonder that fluoride can cause death in humans! In addition to being one of
the main ingredients in toothpaste as well as rat and cockroach poisons, sodium
fluoride is also a key component in anaesthetic, hypnotic, and psychiatric drugs and
SARIN NERVE GAS!
Fluorides have been used throughout history to alter the behaviour and mood of
human beings. It is a little known fact that fluoride compounds were added to the
drinking water of prisoners to keep them quiet and to hamper non-compliance with
authority, both in Nazi prison camps during World War II and in the Soviet gulags in
Siberia.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
Surprisingly, fluoride has NEVER been approved by the Food and Drug
Administration (FDA) in the USA. Additionally, a 1990 study stated that fluoride has
been shown to NOT reduce cavities and scientists are now linking fluoride to dental
deformity, arthritis, allergic reactions and about 10,000 unnecessary deaths each
year
Are you eating crude oil for breakfast?
There are artificial dyes/colourings often found in familiar toothpaste brands and a
wide variety of other products. Recent studies indicate that FD & C Blue Dyes 1 & 2
can trigger a wide number of behavioural, learning, and health problems. FD&C
colour dyes may also cause potentially severe allergic reactions, asthma attacks,
headaches, nausea, fatigue, nervousness, lack of concentration, and cancer. Using
FD & C Blue Dyes 1 & 2 is just like ingesting crude oil as it too, is synthesized from
petroleum. These dyes were originally made from coal tar oil, which is a black, sticky
tar by-product of steel making and petroleum distillation, and is a source of numerous
complex chemicals. Through repeated human exposure, some of these isolated coal
tar components were classified as active carcinogens, ultimately leading to US
government regulations and restrictions. Nowadays, coal tar dyes are synthetically
engineered rather than extracted from actual coal tar, thereby greatly reducing the
possibility of being contaminated with carcinogenic residuals from the coal itself.
However, the dyes still contain carcinogenic properties. Over several decades of use,
some of these synthetic dyes have come under greater scientific and government
scrutiny due to their carcinogenic and mutagenic activity. Because of this, they are
still referred to in the industry as - coal tar dyes - according to the US FDA.
Even if toothpaste is never swallowed, these dyes can be absorbed within seconds
through the skin on the lips, or through the mucous membrane in the mouth.
According to the Physician's Desk Reference, the mucosal lining inside of the mouth
has an absorption efficiency of over 90 percent. Because of this, these carcinogens
get into your blood, your brain, and your cells in no time at all – especially when you
consider most people use dental care products 2 to 3 times a day.
Sodium Lauryl Sulfate (SLS): The most dangerous ingredient
Perhaps the most dangerous ingredient in personal-care products is Sodium Lauryl
Sulfate (SLS). Because SLS has a foaming property, it is added to toothpastes in
order to generate foam and give the impression that the toothpaste is working.
However, SLS has been found to be quite corrosive and harmful to skin tissue says a
report by the American College of Toxicity.
In the cleaning industry, SLS is used in products such as garage floor cleaners,
engine degreasers and car wash soaps. Elsewhere, SLS is used for clinical testing
as a primary skin irritant. Laboratories use it to irritate skin on test animals and
humans so that they may then test healing agents to see how effective they are on
the irritated skin.
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
The journal of the American College of Toxicology reports that SLS can penetrate
and be retained in the eye, brain, heart, and liver with potentially harmful long-term
effects. Also found in most shampoos including "no tears" baby shampoos, SLS can
keep children's eyes from developing properly, can cause cataracts in adults, can
retard healing, and can impair hair growth.
Triclosan: A pesticide found in many types of toothpaste
Triclosan, a chemical used for its antibacterial properties, is an ingredient found in
many detergents and toothpastes. However, the formulation and structure of this
ingredient are similar to some of the most toxic chemicals on earth. While the
companies that manufacture products containing triclosan claim that it is safe, the
United States Environmental Protection Agency (EPA) has registered it as a
dangerous pesticide. The EPA gives triclosan high scores both as a human health
risk and as an environmental risk.
Triclosan is a chlorophenol, which is a class of chemicals that is suspected of
causing cancer in humans. Externally, phenol can cause a variety of skin irritations,
but since it can temporarily deactivate sensory nerve endings, contact with it may
cause little or no pain. Taken internally, even in small amounts, phenol can lead to
cold sweats, circulatory collapse, convulsions, coma, and death. Additionally,
chlorinated hydrocarbon pesticides can be stored in body fat, sometimes
accumulating to toxic levels. Long term exposure to repeated use of many pesticide
products can damage the liver, kidneys, heart and lungs, suppress the immune
system, and cause hormonal disruption, paralysis, sterility and brain haemorrhages.
Hydrated Silica: A whitener that damages tooth enamel
Hydrated silica, which is primarily used as an abrasive in toothpaste, is made from a
crystallized compound found in quartz, sand, and flint. Tooth enamel re-mineralizes
daily from the supply of ionic calcium and phosphorus in the saliva. Scratching the
surface of the tooth with an abrasive such as hydrated silica harms the enamel and
prevents re-mineralization, much like using sand to clean glass. Severe wear could
eventually occur.
Products containing the ingredients silica and cellulose, in particular, should be
avoided when gum disease, tooth decay, sensitivity and receding gums are present.
While these ingredients can remove tartar and make teeth whiter in appearance, they
also may do harm to dental health by altering the acidic balance of the mouth, gums
and tongue.
Other Problems With Toothpaste
Teeth become sensitive when tooth enamel is worn away, exposing the underlying
permeable tooth layer, known as dentin. Many toothpastes are too abrasive and
actually strip away tooth enamel which never grows back. In fact, the first thing
dentists will do for patients suffering from sensitive teeth is to have them switch to a
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe
less abrasive toothpaste. A toothpaste's abrasiveness is measured by its Relative
Dentin Abrasivity (RDA). The table above shows the RDA of some common
toothpastes.
Toothpaste
Colgate
Mentadent
Crest
Colaget Platinum
Aquafesh Whiteninig
AIM
Close-Up
Relative
Abrasivity
68
103
106
106
113
185
218
Dentin
Whitening Toothpastes
Contrary to what many people think, whitening toothpastes do not increase the
whiteness of the underlying tooth. What they do is remove stains so that the
underlying whiteness of the tooth becomes more apparent.
Think of these toothpastes as "carwashes" for your teeth. In the same way that a
good car washing removes the dirt and grime on your car making it sparkle,
whitening toothpastes remove stains and plaque from your teeth, making your smile
shine.
It is important to note that while effective in removing stains, some brands of
whitening toothpastes can destroy tooth enamel in the process. Due to their harsh
abrasives, these toothpastes, over time, may strip tooth enamel, making teeth appear
yellow and causing teeth to become sensitive to cold or hot foods and liquids,
sweets, baking soda, and highly salted foods.
Bibliography
http://www.encarta.msn.com/find/Concise.asp?z=1&pg=2&ti=028df000
http://www.healthy teeth.org/Cavities.html
http://lveschelabs.dent.umich.edu/
http://www.saveyoursmile.com/healtharticles/cavities.html
http://www.saveyoursmile.com/parents/candy. html
http://www.saveyoursmile.com/parents/kidscavities.html
http://www.toothtalk.com/interest.html
Project funded within the EC FP7 Programme: 5.2.2.1 – SiS-2010-2.2.1
Grant Agreement No.:266589
Supporting and coordinating actions on innovative methods in science education: teacher
training on inquiry based teaching methods on a large scale in Europe