Introduction: (Initial Observation)
Manufacturers of different brand toothpastes advertise their products with properties such as whitening, preventing plaques, flavor, protecting the the teeth and killing bacteria.
With so many competing claims, it is hard to determine which toothpaste really works.
In this project, you will determine which toothpaste is more effective in removing food color and whitening. First select which brands of toothpaste you wish to experiment with. At least two different brands of toothpaste should be selected for your experiment. For better results, we recommend four or five different brands of toothpastes.
Information Gathering:
For each brand of toothpaste see if there is a company website and find any information the manufacturer provides about that specific toothpaste. Also, search the web for the term “toothpaste ingredients” and other related terms to find useful information about toothpastes.
Following are samples of information that you may find:
Toothpaste cleans your teeth and keeps them healthy. The cleaning is done by detergents and abrasives that rub the plaque away. Abrasives are minerals like silica, limestone, aluminum oxide and various phosphate minerals.
Fluoride is also used to reduce cavities.
Most toothpaste is made from titanium dioxide which comes from minerals called rutile, ilmentile, and anatase. Titanium dioxide is also used to make white paint.
The sparkles in some toothpaste come from mica, a mineral common in many rocks.
The natural color of permanent teeth is largely determined by the dentine, modified by the thickness and translucency of the overlying enamel. Discoloration of teeth can occur because of the deposition of a variety of pigments into or onto the tooth. Such causes of discoloration are usually classified as intrinsic or extrinsic staining respectively; signifying the source of the stain. Clearly, some extrinsic stains can become internalized through enamel defects or cracks or as a result of dentine becoming exposed. Most extrinsic stains appear to be deposited on or in the acquired pellicle. The aetiology of such discoloration is poorly understood but compounds within the diet or from tobacco are considered the most common chromogens.
Source….
Question/ Purpose:
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to measure the stain removal properties of a range of whitening toothpaste products.
You may also express the same purpose in the form of a question like:
Which toothpaste is a better stain remover?
or
How fast do different whitening toothpastes remove the stain?
Question/ Purpose:
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to measure the stain removal properties of a range of whitening toothpaste products.
You may also express the same purpose in the form of a question like:
Which toothpaste is a better stain remover?
or
How fast do different whitening toothpastes remove the stain?
Identify Variables:
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
The independent variable (also known as manipulated variable) is the type or brand of toothpaste.
The dependent variable (also known as responding variable) is the effectiveness of a particular toothpaste in whitening.
OR:
The dependent variable (also known as responding variable) is the time it takes for the stain to be removed.
Constants are:
Exposure time
Concentration
Procedures of testing each toothpaste
Type of food color
Controlled variable is the temperature. (Do all experiments at the same temperature.)
Hypothesis:
You will state which toothpastes have been selected and then the hypothesis will state which of the toothpastes is believed to be more effective in removing stain. Your hypothesis may be based on your own intuition, gathered information, or past experiences with toothpastes.
Experiment Design:
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment: Comparing toothpastes for their whitening effects
Introduction:
A considerable number of toothpastes are available as tooth whitening products. Most appear to contain ingredients that might remove extrinsic stains rather than change natural tooth color. Extrinsic stain removal could be achieved by physical or chemical means. In this experiment we will test the effectiveness of different toothpastes in removing stains. We use glass beads to simulate the mechanical action and pressure of a toothbrush. (You can substitute glass beads with lentils or plastic beads).
Procedure:
Use a few white ceramic bowls or cups with well rounded bottoms for this experiment. Fill up about 1/3rd of all cups with strong tea or food coloring and let them dry. This may take a few days; however you may expedite this by placing the cups in a warm oven. When all cups are dried you can start your experiment as described here:
Use two or three colored cups for each toothpaste that you are testing. Label the cups with the brand of toothpaste that you are going to test in each cup. Also use the same number of colored cups (two or three) as control. Label them “Control”.
In each cup (except control cups) add one gram toothpaste. If you don’t have a scale, just make sure that all cups have the same amounts of tooth paste and that amount is equal to the amount that you usually use for brushing your teeth.
To each cup add one spoon of glass beads (or lentils or small plastic beads) to substitute the effect of a brush.
To each cup add water to the same level as glass beads. Do not add extra water because some beads (lentils or plastic beads) may float.
Place all cups in a flat tray. Place another upside down tray on the top of the cups as cover. Hold both trays and shake them for about one minute. This will ensure all cups get the same amount of agitation.
Remove the top tray. Empty the contents of all cups and rinse the cups by inserting them in a bucket of water.
Compare all cups visually and see which toothpaste removed more stain.
You may visually determine what percent of stain is removed and record your results in a table like this.
| Brand of toothpaste | Rate of stain removing and whitening |
| Brand A | |
| Brand B | |
| Brand C | |
| Control |
You may finally use your results table to draw a bar graph.
***************
Experiment variations:
If you need to use real teeth, you may try getting some real animal teeth from a local butcher. Wash and brush the teeth before starting your experiments. Then boil the teeth in black tea for about 3 hours. In this way you are sure that all teeth are stained the same way and the same amount.
Prepare one cup for each brand of tooth paste that you are testing.
In each cup add one gram toothpaste and 3 colored teeth. If you don’t have a scale, just make sure that all cups have the same amounts of tooth paste and that amount is equal to the amount that you usually use for brushing your teeth.
To each cup add one spoon of beads to substitute the effect of a brush.
Continue the experiment as you did in the main experiment above and then compare the teeth in different cups.
Need something measurable?
You may be required to have a measurable independent variable. In this case you will need to select the question:
How fast do different whitening toothpastes remove the stain?
Your experiment will also change a little. You will need to continue shaking the test cups and observe them (inspect them) every minute. You will measure the number of minutes it takes for each toothpaste to completely remove the stain.
Your results table may then look like this:
| Brand of toothpaste | Time (minutes) taken to remove the stain |
You may finally use your results table to draw a bar graph. Each vertical bar will represent one of the toothpaste brands. The height of bar is the number of minutes it took to remove the stain.
Materials and Equipment:
This is a sample list of materials:
- white ceramic bowls or cups
- Samples of toothpastes
- Tea or food coloring
- Water
- Glass beads (or lentils or plastic beads)
- Two trays
- Watch or clock
Results of Experiment (Observation):
The data can be presented in written form or visually. A bar graph would be an excellent way to display the final results. Each brand tested should have its own bar. The length of the bars should be proportional to the percent of stain removed.
Summary of Results:
All measurements should be recorded in the project book and may be presented in the final project report either as numerical data or shown as a bar graph. For each brand of stain remover tested, the length of the bar should show the percentage of stain removed.
Conclusion:
The conclusion to the report will state the ranking of the various toothpastes and decide if the original hypothesis is supported or not. The conclusions might also state any relationships you have noted between the popularity of a given brand of toothpaste and its effectiveness or its price.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
Possible Errors:
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
References:
Any book or website about toothbrushing can be used as a reference.
