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Sitting in the dentist's chair is one of the last refuges of single-tasking.
You can't check your phone every couple of seconds or engage in light-hearted banter. No.
About the only thing for it is to lie, as if on a back-to-front zero gravity mattress, and think.
It's good to be somewhere that freeform thinking is the only option.
Sort of like a meditation space, if you can ignore the loom and prod of the white-clad figures.
Except if you start thinking about things like the time you wrote that essay entitled ''Do as I say, not as I do'' when you were 10 about the hypocrisy of adults.
And how you have become one of those adults, at least when it comes to all things dental.
You know that you have to brush at a 45-degree angle for two minutes.
You know floss is your friend.
Of course you do, because you tell your kids that.
And you know the dentist is your friend too, and you will probably get a sticker (oh no, wait, that's just the kids, isn't it?) if you open really wide and don't bite the nice dentist's finger.
So why do your teeth ache so much in anticipation?
You realise the low grade on the essay had nothing to do with your writing ability and everything to do with the subject matter.
To distract yourself, you think of other uses for toothbrushes.
This proves much more painful than what is going on in your mouth.
You think of kitesurfers who take still-packaged toothbrushes on tropical jaunts as part of their emergency kit, for cleaning coral wounds.
You imagine how all those new-fangled variegated brushes would mash up the cuts.
You try not to think about those frat pranks where they film their antics and then show the toothbrush user a week later.
Way to get an education, kids. Or about toothbrushes and bulimia.
Or jailbreaks with stealthily filed toothbrush weapons.
You concentrate instead on useful cleaning ideas. Bike chains. Dimpled copper pots. Cheese graters. Toilet-seat hinges.
As long as it doesn't make it back into your frat-mate's bathroom afterwards.
When you get back into the world of the internet, with actually squeakingly clean teeth that you really should love more and treat better, you congratulate yourself that you only bit the hygienist once and that she was really very nice about it. Considering.
You resolve to brush your teeth better, for longer.
You remember that you used to make the kids watch a YouTube clip to inspire them to brush properly, and while looking it up you get distracted (on the internet? When does that ever happen?) by facts and stories.
You marvel that a man called William Addis invented the modern toothbrush while in prison, in the 1770s. He'd been rioting.
And so would you, probably, if you had to brush your teeth with coal and a rag.
His prototype was made from a sucked-clean dinner bone, into which he drilled some holes and tied and glued some cow bristle he got from a guard.
You read that his company stayed in family hands until 1996 and now makes over 70 million toothbrushes a year. Not bad.
You wish your own ancestors had thought of cow-composite cleaning devices.
You are grateful for synthetic fibres because you learn that badger hair used to be used in toothbrushes and that, frankly, doesn't sound OK.
Getting further away from any hope of brushing, you are sort of shocked to find out that 4.8 billion people own a mobile phone and only 4.2 billion own a toothbrush.
You hypothesise that either millions of us must be into couples-toothbrush-sharing or else there's something very messed-up going on here.
You are not surprised to learn that there is now an App-driven toothbrush available, at a three-figure sum, so you can get feedback on your brushing and compete with others in your family to have the cleanest teeth.
You fleetingly consider said app as a good investment compared with regular and prolonged dental intervention.
But then where would you find the time and the fun to sit and ''Aaaaah'' and think?