Science Buddies: "Ask an Expert"

How can I make a science experiment on teeth whitening which has never been done before?

All it takes is creativity! What do you want to know about teeth whitening that nobody knows yet?

The obvious (and maybe kinda boring) teeth-whitening-related project ideas would be to test different toothpastes or treatments for their whitening efficiency -- so why go with the obvious?
You could examine the effect of teeth whitening treatments on bacterial load or diversity in the mouth, or find out whether any of the treatments dissolve enamel, or alter taste sensitivity; you could measure the effect of white teeth on some aspect of social behavior such as interpersonal trust, or do a theoretical analysis of the value of white teeth as an honest signal of youthful vigor according to evolutionary game theory, or do a cladistic analysis of white enamel in mammals to find out whether white teeth are especially important in species that do more visual communication, or track the change in whiteness of politician's teeth over time for republicans vs democrats in different parts of the country and associate that with local attitudes towards the relationship between beauty and reliability...

I think there are many potential answers to your question. You just need to think about the subject and decide what it is that you want to discover!

Best,

Will

Hi, I really appreciate you answering this question.

However, the main ideas that caputured my interest are:
1) the effect of teeth whitening treatments on bacterial load or diversity in the mouth
2) finding out whether any of the treatments dissolve enamel, or alter taste sensitivity;

But the thing is... when i do ethier one of these experiments.. how am i going to be able to do a performance task on it if i dont have actual teeth to look at. I was planning on using egg shells... any ideas?

Hi there,

You could see whether different tooth whitening agents dissolve egg shells. Because egg shells, like teeth, contain calcium carbonate and proteins, you could do this experiment with them. To do this, you might monitor the weight of the shells before and after application of the tooth whiteners, and over time, to see whether the egg shells dissolve. I would use percentage lost to compare the shells. (Make sure you include a control, to which you only apply water!)

Looking at the effect of tooth whitening agents on bacterial load or diversity in the mouth would also be interesting, but would require you to use human subjects. Let me know if you're interested in working with human volunteers (though you'll need to check that it's okay with your school and/or your science fair), and I will give you more advice on that one.

Best wishes,
Heather

Hi,

I asked my teacher about the effect of tooth whitening agents on bacterial load or diversity in the mouth and he said he’s not too fond of the idea of human or bacteria use, so that’s out of the question... but I think finding any treatments that dissolve enamel would be an okay experiment to do. However, if you have any more unique ideas that are new and never have been done, please feel free to give your opinions...
P.S. When giving ideas, please remember that the whole point of this lab is to basically research about something and then completely come up with something new... and I’m kind of having difficulty on that so i really appreciate everyones responses.

Thanks in advance.

hey,
does anyone know how solubilty of calcium carbonate is dependent on hydrogen peroxide and sodium bicarbonate.

Hi Sehar,

Dissolved molecules are affected by each other if they (1) react with each other or (2) affect the chemical equilibrium.

When calcum carbonate dissolves in water, the reaction looks like this:
CaCO3 + H2O <--> Ca(2+) + CO3(2-) + H2O
Some of the calcium ions and carbonate ions "dissociate" (separate from each other), and float around in the water as ions.

Here is an important equilibrium involving carbonate ions:
CO2 + H2O <--> H2CO3 <--> H(+) + HCO3(-) <--> 2H+ + CO3(2-)

Let's consider sodium bicarbonate first. The chemical formula for sodium bicarbonate is NaHCO3. When you dissolve this in water, it dissociates into sodium ions and bicarbonate ions:
NaHCO3 + H2O <--> Na(+) + HCO3(-) + H2O
Some of the bicarbonate ions can also dissociate: HCO3(-) <--> H(+) + CO3(2-)
This would add carbonate ions to the solution. If you have more carbonate ions in solution, you may cause some of them to pair up with calcium, forming more calcium carbonate. (Sodium is very soluble, so the carbonate ions would pair up with the calcium first.)

Hydrogen peroxide separates into water and oxygen gas:
2 H2O2 --> 2 H2O + O2
Would this affect your calcium carbonate at all? Why or why not?

Hope this helps...

Heather

Hey,
When i conducted my experiment to see whether different tooth whitening agents can dissolve egg shells, these are the results i ended up with:

Starting off, the weight off my egg shells were: Distilled water: 4.43g, Sodium Bicarbonate: 3.11g, Hydrogen Peroxide: 3.91g
End Results of the egg shells were: Distilled water: 4.43g, Sodium Bicarbonate: 3.07g, Hydrogen Peroxide: 3.88g

I was wondering if these results are reasonable?
Also, what may have been the cause for these results?

Note: These results had been taken after three days prior to the experiment being done. The eggshells were weighted after a day to let the egg shells dry.

Hi Sehar,

Your results look great! Congratulations on conducting a successful experiment.

Starting off, the weight off my egg shells were: Distilled water: 4.43g, Sodium Bicarbonate: 3.11g, Hydrogen Peroxide: 3.91g
End Results of the egg shells were: Distilled water: 4.43g, Sodium Bicarbonate: 3.07g, Hydrogen Peroxide: 3.88g

It looks like the distilled water did not affect your egg shells, which is exactly what you would expect. This is a good control group.
Your egg shells lost weight in sodium bicarbonate and in hydrogen peroxide. What you'll want to do is compare the percent weight lost in each group.

Here is how you calculate percent lost:
Percent lost = [ (Original weight - Final weight) / (Original weight) ] x 100

The explanation I gave you before should explain why your eggshells lost weight in sodium bicarbonate:

The chemical formula for sodium bicarbonate is NaHCO3. When you dissolve this in water, it dissociates into sodium ions and bicarbonate ions:
NaHCO3 + H2O <--> Na(+) + HCO3(-) + H2O
Some of the bicarbonate ions can also dissociate: HCO3(-) <--> H(+) + CO3(2-)
This would add carbonate ions to the solution. If you have more carbonate ions in solution, you may cause some of them to pair up with calcium, forming more calcium carbonate. (Sodium is very soluble, so the carbonate ions would pair up with the calcium first.)

Why do you think the shells lost weight in hydrogen peroxide? Start by reading about the properties of hydrogen peroxide (http://en.wikipedia.org/wiki/Hydrogen_peroxide), and consider things like its reactivity in acidic solutions and the formation of free radicals.

Heather

hey thanks for the help !