When I was 5, German measles had me running a 105° fever for 4 days. I recovered, but the illness caused damage that wasn't apparent until several years later, when my permanent teeth came in. All had a deep groove across the face of the tooth and none of them had any enamel. By the time the condition was discovered and corrected, they were permanently discolored, and much weaker than normal, healthy teeth. As a result, I now have 32 crowns...every tooth. Over the years, I've occasionally chipped or broken one, or just worn them out (I sometimes grind my teeth in my sleep), and have had to have some of them replaced, but other than that, I've never had any problem with them, and I've never had a root canal. I have, now and then, had an ill-fitting temp that needed some minor adjustment, and on 2 occasions, I've had the crown to come off...both times while I was in Brazil, and both times I superglued it back on and it was fine until I could get back and have them recemented.