It was an adventure book where the reader could choose various paths for the hero to take (i.e. if you want to do X go to page 20). I remember a sword that needed to be reforged, some dwarves (blatant rip off of LOR). It was perhaps 100 pages and written for children who have not long learned to read I think.
THE SWORD REFORGED! The dwarf king kneels by the fire pit, waiting for you. You hold the hilt forward and the end of the sword that broke from it. You hold it until you can't stand the heat, then thrust the glowing pieces together
That said, Demian's site describes the books in the series as "being about two hundred pages in length", not the 100 you remember.
I remember the Lone Wolf CYOA's from forever ago (ie late 80's/early 90's). Not really for kiddies, but there you go. Wouldn't mind cracking one of those open again... no matter how dated and silly it would be. This probably isn't your answer, but it might be. Most of these were series of books. Lone Wolf had... 60+ I think, and there were others, though I don't care to try to remember them.