When the dentist asked if I felt like keeping all my teeth for the rest of my life, I was forced to do the math. The rest of my life? How many years is that? Maybe it’s not actually that many — 30 if I’m lucky, 20 or 25 if I’m like the average American woman my age, which is 60. I don’t like making such calulations, since when I look backward, 20 or 25 years is the blink of an eye ago.

So, yes, I said to him, I’d rather keep all my teeth for the rest of my life if possible, thank you very much.

The question got me thinking about Grandpa and his dentures. Back in the 1960s, when we were growing up, being old automatically meant you had a mouth full of false teeth. In fact, when my brother Avuncular was little he used to ask how long he’d have to wait until he was old enough to have teeth like Grandpa’s — teeth you could take out every night and put in a little water glass by the bathroom sink. Avuncular and I would wake up early when our grandparents were sleeping over, so we could watch Grandpa as he stood at the mirror with a collapsed old-man face and would transform before our eyes: grab the top teeth from the glass, shake them out, put them in, shake out the bottom teeth and put them in, and there he was again, our craggy, stooped, but still-handsome Grandpa.

No one has dentures these days; no one transforms from sunken geezer to pater-familias in an instant anymore. So what my dentist is going to do with these problem teeth at the back of my mouth is put in crowns rather than yank them out. It’s a long, slow process of oral restoration.

Is this the first of a long line of such procedures? Will a doctor soon ask me if I feel like keeping both my hips for the rest of my life, or if I’d like him to insert a fake one to replace the one that’s wearing away? How about one of my organs? My kidneys are likely to putter out, if they’re anything like my father’s were (and I suspect they are), so maybe that will be a question some day, too. Do you want this kidney? Do you want a different one? Do you want to plug yourself up to this dialysis machine and pretend you don’t have kidneys at all, just let the machine do the work for you?

As Ur-Momma (the blog name I’ve given to my mother) says whenever she notices changes in her skin or hair or ability to breathe when walking up the hill near her apartment, a body isn’t designed to last 89 years. No, it’s not, no matter how much care you take feeding and exercising it (care I haven’t been too assiduous about recently). So what happens when that body starts falling apart, by inches — especially when you’re only 60? My two back teeth might be the beginning of a long line of decay — “decay” is actually the word my dentist used in describing the problem that leads me to need a crown — and I suspect that all I’ll be able to do about it, at least for a while, is try to shore things back up as well as I can.

(By the way, the teeth in that photo belonged to George Washington. I saw them in a photo on Twitter posted today by Lindsay Fitzharris, a British medical historian and creator of a web publication called The Chirugeons Apprentice.)