I cannot stress enough that there is absolutely no evidence that the lingual frenulum will stretch! That is one authors opinion from about two hundred years ago. it is tantamount to mythology. Why do we keep repeating something that has no basis in reality? As to spontaneous rupture, it can and does occur but we can't count on it. If we could then I and other adults wouldn't still be tongue-tied. And rupture doesn't occur to just the papery thin ones nor are papery thin ones more likely to rupture. i have seen all kinds in adult mouths!!! Alison K. Hazelbaker