Better living through dentistry

[j4]

I'm registered with the only dentist within about 25 miles who claimed to take new NHS patients.

They did a checkup and an xray, and a few days after the xray they phoned to tell me that I needed a filling. (Bummer, thought I, I nearly made it to 30 without needing any fillings.)

So I went in for the filling, and when I was on the chair with my mouth propped open they asked if I wanted the NHS filling (mercury filling, lots of drilling under anaesthetic, painful, unsightly grey lump in the tooth, cost = £45) or the private filling (non-mercury, very little drilling, painless, invisible, cost = £70). I opted for the invisible/painless option, which took about 5 seconds of drilling and 2 seconds of holding some kind of instrument against my tooth (I'd been told to close my eyes so I have no idea what).

After that was done, the dentist showed me the xray and said that there was another 'shadow' visible on the xray and I might need another filling. "It's only a very slight shadow, you probably won't even be able to see it," they told me, pointing at a completely blank bit of xray. They were right. They took another xray from a different angle and said they'd phone me back if anything showed up.

Surprise surprise, they reckon I need to pay them another £70. This feels like a phenomenal ripoff; for all I know, they are inventing these 'fillings' out of thin air. They can't provide any evidence except a blank space on an xray where they claim to be able to see something. Now obviously being able to spot things that mere mortals wouldn't spot on a postage-stamp-sized xray is the sort of thing that one might get from 7+ years of training to be a dentist. But they're certainly not inspiring me with confidence.

The 'drilling' is apparently only a tiny bit (no pun intended) on the surface of the tooth, so the 'filling' must only be the merest cat's whisker of the dental equivalent of polyfilla. I've always taken the view that teeth are worth protecting; but, if I was being completely cynical, I would point out that it is hardly rocket science to work out that people of my age a) were probably brought up to take this view of toothcare, b) probably feel slightly guilty about not brushing seven times a day and not using all the available tooth-cleaning technology, so can probably be persuaded that the fault is theirs, and c) have a reasonable amount of disposable cash.

I don't think there's any way I can get a second opinion without paying outrageous amounts of cash to some other private dentist; there simply are no NHS dentists in the area (and of course you still have to pay for checkups even on the NHS). Of course, they know that, too.

But if I just told them I didn't want to have it done, then a) they'd kick me off their books (they'll only take NHS patients in the first place if their teeth are okay) and b) I'd feel as though my teeth were a ticking time bomb in my mouth. Maybe £140 isn't too much to pay for peace of mind. But it still leaves me feeling as though my mouth is full of snake-oil.

Comments

[bellinghman.livejournal.com]

Macro lenses for X-rays would be quite an advance, indeed. I don't think there's anything that actually deflects X-rays, only stuff that blocks them. So X-ray machines use a point source, like a back-to-front pinhole camera.

Straight line optics. You've got to love it.

[fivemack.livejournal.com]

You _can_ reflect X-rays; I was at ESRF yesterday and saw the microfocus beam-line. The X-ray mirror has to be six metres back from the target, is a box two metres long and 50cm square at the ends, has to be kept in an air-conditioned perspex box because it goes out of focus if the temperature changes by one degree, has to be bolted to granite blocks set in the floor, and goes out of focus for fifteen minutes from the vibration from slamming the door to the experiment hutch.

Smaller pixels on the X-ray detector would be a better approach to magnification, but then you'd need a brighter X-ray source, and a longer exposure, and more risk of bad health effects from X-ray exposure.

If only flesh were more transparent, or teeth more reliably opaque.

[rgl.livejournal.com]

And, importantly, for a fixed pixel size on the X-ray detector, magnifying the resulting image will potentially make the job of picking out abnormalities harder rather than easier, due to the increased blockiness (cf the "Lincoln illusion", though at the moment I can't find an online reference to that which isn't slightly misleading).

[bellinghman.livejournal.com]

Aha, interesting. I'm obviously out of date scientifically, even though definitely not practical for dental surgeries!

[hairyears.livejournal.com]

You can refract X-Rays. Or rather, appear to: one of those odd bits of economically-useless research that shouldn't be funded turned up a very peculiar type of lens in horseshoe crabs' eyes. It's an array of tubes - much like fibre-optic cables - acting as beam guides by total internal reflection off their inner surfaces.

The central guide is straight, and they become increasingly curved towards the edge of the 'lens' (picture a longitudinal slice through an onion, or take a column of parallel straws and press it down, so that the outermost straws bow outwards in a barrel shape). The geometry for off-axis incident rays at is quite complex but it can indeed focus an image from a narrow cone of vision.

If this structure can be reproduced at nanometre scales (say, in a distorted crystal) there's a way of focusing X-Rays for high-definition lithography, a topic of interest to Intel and AMD. I know of no attempts to put this discovery to work in medical imaging.

[sparrowsion]

One of the reasons some people are getting excited about metamaterials is that you can make X-ray Fresnel lenses from them. That would take all the fun out of crystallography.

As far as dentistry goes, a short while back my dentist (although not his practice) stopped doing NHS treatment. Rather than switch to one of his junior colleagues, I went private. It's costing me £40 (IIRC) for an annual check-up rather than £15 for an NHS 6-monthly one. If your teeth are in good health, and you're not in an exempt category, I really don't see the advantages to NHS dentistry.

[bellinghman.livejournal.com]

I hadn't considered the possibility of Fresnel lensing - I'd got hung up on traditional lens lenses (i.e. those lenses named because they're shaped like lentils.)

And mirrors. Hmm.

Metamaterials are seriously weird, I'll grant you that.