ive got a crazy mouth with all sortsa issues including missing grown-up teeth. they just never grew in. i had get implants drilled into my jaw to replace them. fun times. i had that done at the same time as i had my wisdom teeth pulled, so happily i was totally knocked out.
however, when they went to remove the babyteeth that they thought would just pop out when tugged on, they took an x-ray and found out that the teeth had fused to my jawbone. they had to rock the teeth back and forth to get them to break off of the bone. the cracking a splitting noise i heard almost made me throw up.