tooth decay

[patty_r66]

We want to use actual human teeth. Where can we get real teeth? Also, we want to measure the depth of a needle penetrating a tooth after it has been soaking in certain liquids. Any ideas?

[agm]

Hi patty_r66,

Welcome to the forum!

Bio is not my speciality, but I'm sure that someone with a more relevant background will come along in the next day or two. However, I have a few initial thoughts to get you started:

--Most science fairs will require you to fill out some additional paperwork if you're using human subjects or human or animal tissues, before any experimentation occurs. For example: http://sciserv.org/isef/students/forms_dates.asp

--Even if you don't have to deal with such forms, you will want to be extra careful with safety equipment and procedures -- a biology expert should be able to give you an idea of what level of protection is necessary.

--Perhaps you could get human teeth from a medical school that uses cadavers in anatomy classes? Or animal teeth from a vet or shelter that puts animals to sleep?

--Due to genetics, nutrition, hygiene, etc, different people's teeth have different degrees of susceptibility to decay, and I would expect this would carry over to their vulnerability to liquids that you might choose to try. In addition, some teeth might already have cavities; when the enamel is missing from an area, it becomes more vulnerable to decay. These considerations would impact the importance of having a large sample size and/or getting lots of teeth from the same person.

--When teeth are removed from the mouth, some parts that are not covered by enamel but are usually covered by gums (so that liquids in the mouth don't contact them) are exposed.

--Have you thought about other ways to measure decay? You could weigh the teeth before and after, accurately measure the force required for a needle to begin penetrating the surface, take photographs and note any visible decay, etc. Some liquids (I think vinegar?) actually make teeth flexible. Maybe you could get access to an x-ray machine through your dentist or doctor? Measuring the depth of penetration might be tricky unless you are able to standardize the force applied.

Good luck, and keep us posted on your ideas,
Amanda

[tdaly]

patty_r66,

agm has provided some great advice. To find out if your science fair requires that you complete some extra paperwork to work with the teeth of humans or other animals, you will want to talk with your teacher or contact the SRC (scientific review committee) of the science fair that you will be attending. Another source of teeth that people have had success with in the past is your dentist. He or she may have teeth that they have pulled. agm's point about the variability of teeth is an important one: every person's teeth are different so the way that they respond to being immersed in the same liquid will differ. You should brainstorm ways to control your tests so that as many factors as you can control are kept the same. Think about, for example, how long you will soak the teeth, the amount of the liquid you will soak them in, where you will push the needle into the tooth, etc. It might be a good idea to measure the decay in multiple ways. You could take before and after photos of the teeth, weigh before and after soaking them, AND do the penetration test. Multiple strands of evidence are more convincing than a single one.

Good luck with the project!

[patty_r66]

THANK YOU FOR YOUR ADVISE. THE LIQUIDS WE ARE SOAKING THE TEETH IN ARE WATER, COLA, BLEACH WATER, AND LEMONADE. DOES THAT SOUND GOOD? IF WE DO BLEACH WATER WHAT SHOULD THE CONCENTRATION BE OF BLEACH TO WATER? WE WERE THINKING ABOUT THE EFFECTS OF TOOTH WHITENING ON TEETH. ALTHOUGH THE PROJECT IS ABOUT WHAT LIQUIDS EFFECT THE TEETH THE MOST. DOES THAT COMPLICATE THINGS OR IS THAT A OK CONCEPT? WE ARE STILL TRYING TO FIGURE OUT HOW TO USE A NEEDLE AND BE ABLE TO MEASURE HOW FAR IT PENETRATES A TOOTH. WE HAVE 4 WISDOM TEETH FROM THE SAME PERSON. THANKS AGAIN, YOUR WEBSITE IS REALLY A GREAT HELP!

[agm]

Hi patty_r66,

I'm glad the forum has been helpful!

One thing to note is that even though tooth whitening is called "bleaching", chlorine bleach (the stuff you might use for cleaning) isn't really what is used. This article (and perhaps some general googling) should help with determining what chemical and concentration you want: http://en.wikipedia.org/wiki/Tooth_whiteners.

It's great that you were able to find teeth. Do they all look pretty similar, or do some have cavities, etc? Have you thought about how long you're going to soak the teeth? For some methods of assessing the results (photos, weighing dried teeth), you could take results multiple times rather than just at the end of the soaking period. Something destructive, like needle penetration, can of course only be done once, but especially if you're concerned about whether it will work out, it's nice to have other measurements to base your conclusions on.

Your experimental design sounds good -- it's definitely important to have water as a control! One thing you might want think about is the mechanisms of tooth decay you're investigating. What is potentially bad about lemonade or cola? There are actually two ingredients that work in different ways. Since both are present in both lemonade and cola, it might be easier to interpret your results if you used two different solutions, each of which contained only one of them. Some background reading:

http://www.associatedcontent.com/articl ... s_and.html
http://www.dental--health.com/sodapop_teethenamel.html
http://www.animated-teeth.com/tooth_dec ... caries.htm
http://www.usc.edu/hsc/healthnow/2008/0 ... our-teeth/

Best wishes, and let us know if you have more questions and how the project turns out!

Amanda

[patty_r66]

Thanks for your really great advise once again!!! Can anyone give me an acceptable way to sanitize the teeth I have? They are actually mine, from some time ago. According to the teacher the project should be overseen be a scientist. The teeth should be cleaned somehow. Any ideas? Thanks much.

[agm]

Hi patty_r66,

Since I'm not qualified to safety advice for biological/human tissue experiments, I'm going to see if I can find another expert to weigh in on that aspect of your experiment. I *expect* that you will end up wanting to wear either latex or nitrile gloves (latex gloves should be available at most pharmacies) and sterilizing the teeth by something like boiling, baking, or soaking in isopropyl alcohol. But again, you should wait for confirmation from either a bio expert here or the supervising scientist that you find.

In the meantime, I suggest asking your family dentist, or any dentist, to supervise your experiment. He or she is likely to be excited that a student is interested in teeth and their health, and it really shouldn't take up too much of his/her time to give you some advice. A dentist can also help you identify a sterilization method that won't contribute to breaking down the teeth and perhaps suggest other or better ways of measuring the effect of the liquids -- if you're lucky, maybe they would even take before/after x-rays for you!

Amanda

[agm]

Hi patty_r66,

Sorry it took me a while to round up more advice for you -- there isn't much to add to what I said before. One thing you might want to think about is that the decay mechanism involving sugar depends on bacteria feeding on the sugar, rather than sugar damaging teeth directly. There might not be a lot of live bacteria left on the teeth since it sounds like they've been sitting around for a few years, but sterilization would kill any that are left. I would not recommend sterilizing some teeth but not others, because anything other than the solution you put them in should be constant for good experimental design. And, anything your dentist consultant says about safety overrides what we've said here.

Best of luck with your experiment. Even if you have no more questions for us, we always like to hear how things turn out!

Amanda

[Milley_09]

Although I am not a patient, but I am an assistant dentist who is working on project related to tooth decay. These days, I am spending hours researching on this topic. I am glad to find informative stuff on this forum. Thanks all for contributing their knowledge here.