Did they? Did people in the middle ages brush or clean their teeth? What kind of dentistry did they have? I would guess they probably just pulled teeth that were painful, but did they use any kind of anesthetic during the extraction?
Or did they just let them rot out?
My inquiring tooth wants to know! 
A lot of people wouldnt have lived long enough to suffer tooth problems. Further, their diets were very low on sugars.
This is just funny and tangentially relevant. Hark, a vagrant: 255
I imagine a lot of people picked their teeth - that bit of broccoli or meat sticking between them is irritating to feel with the tongue and any thin object - a splinter, a straw - will help.
Also, FuzzyOgre has a point. I read an article by a dentist who mentioned much tooth decay was rare until sugar became widely available. One of the major new imports when the Dutch first expanded trade in the 1600’s was raw sugar from the Indies - the author said you could see the emergence of gum and tooth problems over the years as sugar became more available, from the highly realistic paintings of the old masters; the chief subject was portraits, and their accurate painting in the mouth area made it easy to diagnose tooth problems.
This says:
From a history of tooth brushes: People realized how important dental health was as early as 3500 B.C. Greeks and Romans used a “brush” that was more of a stick than a brush. . . .
. . . The toothbrush began to take shape in China around 1500 B.C. with advancements on the earlier chewsticks. The chewed end of the stick was made softer and used to brush food from the teeth, while the other end of the stick was filed into a point to use like a toothpick. . . . .
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Colgate has a history here.
There’s evidence of tooth cleaning in Cro-Magnon people. And of course Muhammed demanded all Muslims use toothbrushes.
I’m not sure about Medieval Europe, but I can’t imagine they would have lost this technology. Then again, my impression is that personal hygiene took a huge step backwards during this era, so it wouldn’t surprise me.
As mentioned, tooth brushing goes back to primitive man, with crushed sticks (siwaks or m’swaki), preferably willow, used to rub collected food and tartar off. The Romans used cloth to clean their teeth. It’s likely that many people, if not everyone, cleaned their teeth in the “Dark Ages” (which actually had some surprising engineering and philosophy – don’t believe all the propaganda)
The apothecary shop in Colonial Williamsburg (VA) sells elm toothbrushes…so even in the 18th Century, people knew about tooth decay. The barber shop also made dentures (and he pulled teeth too).
Probably few people had their own teeth after age 40 or so…George Washington used dentures, and found them quite painful. Modern dentistry didn’t begin till the 1860’s-before that, it was extraction via pliers.
If we’re talking about more recent times, a lot of early Appalachian people pulled stems off bushes and chewed down one end, making a splayed, frayed toothbrush. You make a paste out of baking soda and water and rub it across your teeth with your finger, then work it with the brush. Unfortunatly, a lot inherited the weak tooth enamel of their Irish/English forebears and still suffered a lot of cavities.
Thanks, all, for the responses. 
Personal hygiene took a huge step backward later on (under the influence of the church and of some medical theories). People bathed during the dark ages/middle ages. Public baths were commonplace.
I’ve no clue about teeth, though.