Science Experiment With Teeth

So You Want to Do the Tooth Enamel Erosion Experiment

I ran this one for my kid's 8th-grade science fair. What follows is how it actually went, not the sanitized version you see in lab manuals. The core idea is simple enough — you're demonstrating what happens when tooth enamel meets acid over time. Your independent variable is the liquid. Your dependent variable is enamel degradation, which you measure by weight loss, visual changes, or a combination of both. The control is a tooth sitting in distilled water. You need intact teeth. Not the whole tooth with root and pulp still attached — those won't give clean results because the dentin underneath behaves differently than enamel. You want extracted premolars if you can source them ethically. My go-to was actually buying extracted wisdom teeth from a dental supplier online. They come in packets. Each one ran about $3 to $5. Used ones from oral surgery clinics sometimes offer these for educational discounts if you ask. Don't skip the paperwork, though. Some suppliers require you to be a school or institution.

Setup and Procedure

Here's the actual method that worked without falling apart: Label four jars clearly. Distilled water, white vinegar, cola, and orange juice. Those last three are your test liquids. Fill each jar so a tooth is fully submerged. If the tooth floats, weigh it down with a small glass marble or stainless steel nut. I tried paper clips and they corroded in the vinegar within two days, contaminating the results. Weigh each tooth on a digital scale that reads to 0.01 grams before you start. Record the number. Put them in their jars. Wait five to seven days. Check daily just to make sure nothing's floating away or drying out. Weigh them again at the end. The enamel mass loss is your data point.

The cola one surprised me. Vinegar caused noticeably more enamel degradation by weight than the cola did, even though everyone expects soda to destroy teeth faster. That's because vinegar is acetic acid at a much lower pH than most colas. The phosphoric acid in soda is milder than people assume. This is probably the most counter-intuitive finding for anyone doing this for the first time. The orange juice was borderline — citric acid eats at enamel but not aggressively in a one-week window. Distilled water showed essentially zero change.

A Problem I Ran Into and How I Fixed It

My second batch of teeth — the ones I'd bought from a different supplier — had micro-fractures that weren't visible to the naked eye. The enamel flaked off in the vinegar jar during the first 48 hours, and the weight data was garbage because I couldn't tell if the mass loss was actual acid erosion or just physical damage from pre-existing cracks. I caught it when the weight dropped by nearly 15 percent in two days, which is way outside normal range for enamel dissolution. The workaround was straightforward. I examined every tooth under a $20 magnifying lamp before submerging any of them. Anything with visible surface irregularities or cloudiness got discarded. That cut my usable sample from twelve teeth down to eight, but the data held together. You save yourself a week of wasted effort by doing this step. It's easy to skip when you're eager to start the timer.

Measurement Approaches and Where They Get Messy

Weight loss is the most quantitative method, but it has a blind spot. Enamel dissolution isn't uniform. The surface can demineralize and then partially reprecipitate minerals from the solution, which masks the true erosion rate. If you want to account for this, you should measure surface texture changes too. A basic profilometer costs around $150 used on eBay, but honestly, for a school project the weight measurements plus clear photos are sufficient. Just don't claim your results represent total enamel loss if your methodology only tracks mass difference. If you go the visual route, take photographs under the same lighting conditions before and after. Use a coin for scale. Light reflection off wet enamel is misleading — dry the teeth gently with a paper towel and let them air for thirty seconds before photographing. Wet teeth look more eroded than they actually are because the refractive index changes and the surface scatters light differently.

What This Experiment Doesn't Tell You

The biggest limitation is time scale. Five to seven days in vinegar is not equivalent to years of soda consumption in a human mouth. Saliva buffers acids. Your teeth aren't sitting in a jar of vinegar for a week in real life. The experiment demonstrates that acids dissolve enamel, which is the point, but the kinetics are artificially accelerated. Don't frame your conclusions as if they represent real-world dental exposure timelines. They don't. Vinegar is roughly pH 2.5. Most sodas are around pH 2.5 to 3.5. Human stomach acid is pH 1.5 to 3.5. The comparison only works if you're careful about what you're actually claiming. Another thing beginners miss: temperature matters. I left one set of jars on a windowsill where afternoon sun warmed the liquids to about 28 degrees Celsius. The erosion rate in those jars was measurably faster than the ones kept at room temperature. If you run replicates, keep them all in the same environment. Don't put one on the desk and one near the radiator and wonder why your data has variance you can't explain.

Disposal and Ethics

Don't flush the teeth. Put them in a sealed bag and throw them in the regular trash. The liquids can go down the drain with plenty of water, but if you're doing this with a class of twenty students all pouring vinegar down one sink, the plumbing might not appreciate it. Dilute with water first. Using human teeth is legal for educational purposes in most places, but some districts have policies about biological specimens. Check with your teacher or school administrator if you're in an organized class setting. The ethics question is mostly about sourcing — buying extracted teeth from legitimate suppliers is fine. Don't try to collect teeth from friends or family as a project. That gets weird fast and unnecessary.

Quick Reference

Extracted premolars or molars from a dental supplier — roughly $3 to $5 each
Digital scale reading to 0.01g — any basic kitchen or jewelry scale works
Four glass jars with lids — wide mouth is easier for retrieval
White vinegar, cola, orange juice, distilled water
Glass marbles or stainless steel weights to keep teeth submerged
Magnifying lamp for pre-experiment inspection
Camera with consistent lighting for documentation
Labels and permanent marker
Paper towels for drying
Timeline: 5 to 7 days, with daily checks taking about 5 minutes each That's it. The whole thing costs under $30 in materials and takes a week. The data is readable and the procedure is repeatable. Just inspect your specimens before you start and keep your conditions consistent. Most bad results come from sloppy setup, not bad science.