Sometimes I wish I’d been a dentist.
When I’m paying my bill, that is! Boy it’s expensive!
Now, I’m always looking for ways to save myself money using my chemical knowledge (which led me to design my own way to make biodiesel, but that’s another story), and now out of necessity I’ve turned my thoughts to dentistry.
This wasn’t planned of course, but the other day I was munching on a pizza with a particularly crusty crust when I felt an almighty CRUNCH as I bit down on it. When I fished the offending item out of my mouth it was a substantial part of one of my teeth.
The tooth in question has an almighty amalgam filling in the middle of it, and so the bits around the edge don’t have a lot of mechanical support, and hence the failure.
So now I had this tooth fragment sitting in my desk as I contemplated my options. The first option of course was the dentist. From previous experience I know what she’d tell me. First it’d need a temporary repair, and then she’d take a mould, and I’d I’d have to come back for a crown.
This of course would involve a couple of thousand dollars (I think – I had one done a few years back). Since this is more than I normally spend on cars that I buy, I figured there had to be other options.
As I thought about it, it occurred to me that there was indeed another option. When we get our teeth repaired these days, amalgams are no longer used. Rather, they have been replaced by UV-curing (epoxy) polymers. They put some white stuff in your mouth, zap it with a UV light for 30 seconds or so, and Bob’s your uncle.
So all I need to do to fix my broken tooth is to find a rapidly curing polymer that can be moulded for long enough for me to hold it in place while it sets. Then it occurred to me that I had just such a product in my garage. I had bought it a while ago because I thought it looked like a useful product, although I didn’t have a use for it at the time:
Here’s how it works.
Have I mentioned that I’m not a dentist? Not sure if I’ve mentioned that yet.
Now, to fix my tooth, I had to prepare the surface correctly, as with any adhesive. This of course was a little tricky, as it was inside my mouth, and moisture was obviously going to be a challenge.
Here’s how I did it:
1. I removed any bacteria (and food) from the surface to be repaired. Anaerobic bacteria are responsible for tooth decay (they produce the lactic acid that dissolves the calcium phosphate from which your teeth are made). This was easily done with a Listerine rinse.
2. I dried the surface to be repaired. For this, I got a cotton bud and soaked it in metho. Then I just rubbed it over the surface liberally.
3. I then repeated with acetone. I was careful with this – if you get it on your tongue the sensation is rather unpleasant.
The area was now (or should have been) dry. An alternative approach would have been a gentle stream of compressed air (if I had a compressor handy), as this is what dentists use.
4. I mixed the epoxy (while holding my mouth open). Took about 30 seconds to get a consistent mix.
5. I pressed it into my tooth, and held it there with firm pressure, attempting to mould it to the approximate contour of my teeth. I poked the unused portion occasionally to get a feel for when it set (about 3 min). Then I just gently removed my fingers from the epoxy and it stayed behind.
When I did this I immediately felt the roughness of the material in my mouth. But it seemed to work, so I was happy, and I figured I’d just let it set fully and then sand it smooth the next day.
But the next day when I woke up it felt smoother. Over the next few days it seemed to smooth out naturally, and a week later it now seems to have conformed to the contours of my teeth naturally.
I haven’t been game to give it any serious bite work, but it’s OK for mushy chewing. And it’s perfectly safe chemically, as the product is certified for use with drinking materials.
And now a disclaimer or two – this technique should certainly not be used to repair a decayed tooth.
Decay is caused by lactic acid, which gradually dissolves the calcium phosphate from which your teeth are made. The lactic acid comes from the breakdown of sugars, caused by anaerobic bacteria, which inhabit plaque. At the microscopic level, therefore, the cavity is a very irregular shape, with little channels and pores in which the bacteria sit, producing the lactic acid. This is why dentists drill before filling – they need to completely remove the decayed area, thus creating a smooth mechanical surface to which the filling can adhere.
If you just plonk an epoxy on top, the bacteria are free to continue their decaying process, and probably at a greater rate, as the lactic acid is not now being washed away.
So I would only use this technique, as I have, for a situation where the failure was purely mechanical, and I was attaching the epoxy to a clean, undecayed surface.
Once again, I am not a dentist, so I’m not recommending this to anyone – I’m just telling you what I did.
Just thought I’d mention that….
One other thing – chemical safety. Is this stuff safe to put in your mouth? As it happens, it is – if you look on the documentation for this stuff it says that it’s safe to use on drinking utensils. The reason is that it’s a thermoset polymer, which means that the polymerisation process is irreversible – it sets into an inert solid that has no chemical toxicity whatever.