I have a friend in his mid-20s who still has several of his baby teeth. The permanent teeth have apparently never shown up to push them out of the way. How common is this?
I had my two canids up to when I was 16 or 17 when they were removed. My adult teeth were coming sideways and just stopped and had no plans of ever starting again.
When I was 10 or 11, I had to have ten of my baby teeth removed because they weren’t falling out and the permanent teeth (present, but lazy) weren’t moving on up. This was just one step somewhere in the middle of long and extensive orthodontic effort, however.
I had 2 canine baby teeth til a few years ago (I’m 39). Apparently, the adult teeth were up in the roof of my mouth somewhere and had all but dissolved by the time I could afford to do anything about it. I had them taken out a few years ago 'cause they were a little wobbly and it made me nervous. The bridges look much better. I think it is rather uncommon, though.
I had a baby tooth until I was 38 when it was removed by my dentist.
I have a friend who has NO ADULT TEETH, he kept all his baby teeth until he was about 18 (they looked a little weird though). Then he had to have them extracted and dentures fitted. He’s in the process of having some permanent implants put in, and then bridgework between the implants, as I don’t think they can do his whole mouth.
I’m not sure how rare it it, but I know that every time he goes to the dental hospital he has crowds of dental students and other interested parties asking him questions, so I’m guessing it’s very rare.
I still have one milk tooth on my left lower jaw at the back; no adult molars ever came up on that side (too many came up on the lower right side and the dentist had to pull several of them to make space).
Apparently this is called, “Congenitally missing permanent teeth,” or “hypodontia.”
This site claims to have found the gene that causes this in some people.
This site has a lot of people responding and discussing the issue of missing permenant teeth.
This site claims
This site reports on a study that asks the question, “Has hypodontia increased in Caucasians during the 20th century?”
From my own experience, I was born without 6 permenant teeth. My kanines on my upper arch and my 4 teeth in the center of my bottom arch. The 4 on the bottom were pulled and I now have a bridge there, but the 2 on the top are still there. My dentist is keeping an eye on them because the roots are slowly absorbing away, but they still work fine.
I had it too. When I was 18 or so, my last baby tooth had to be pulled as the adult tooth was dedicatedly making its way out through my gums.
My grandmother kept some of her baby teeth for her entire life (over 80 years). My sister appears to have inherited the trait–I think for the same teeth, too.
So far, only 8 of my adult teeth have grown in. I’m 32. Fixing this problem is extremely expensive (think a few thousand per tooth).
Actually, isn’t about time someone tripped into this thread and shouted “The plural of anecdote is not data! therefore adults do not retain baby teeth!”
? 
Hmmm… I posted a question awhile back about why we lose our baby teeth and not our baby fingers, but the search doesn’t show it. As I recall, one of the Dopers said that he still had his baby teeth, that they hurt and looked wierd.
Thanks for sharing the stories, everyone - I can tell him he’s not alone. If this many people on the Straight Dope have some baby teeth that haven’t fallen out, it can’t be that rare.
And a big thanks to Dragwyr, for all the very helpful links. I’ll be able to pass the info on to my friend.
I retained two cuspids. One is hanging in there at 35, but I lost the other one a couple of years ago. The secondary next to it had undergone endodontics, and the crown that went over it was bonded to the primary. The primary hung on for ten years or so in that condition, but it turned black and started to loosen up, so it had to go. My dentist then put a double crown on to cover the missing primary and the bored-out secondary.
Brave little guy sniff (the primary, not my dentist).
No problem. Hey, us baby-teether’s have to stick together.
I still have two of them. I doubt they’ll ever be removed, since they were straightened out with the rest of my teeth by my orthodontist.