Lots of useful threads on this topic already. I have a simple question for those of you who had whose children have twin blocks. To correct an overbite (4mm) my daughter’s (14) newly fitted blocks cause her bottom jaw to stick out 4mm beyond her top teeth. This is causing significant facial alteration/disfigurement and excessive pain. Can’t even get to sleep. Most images and websites show blocks either levelling top and bottom teeth or reducing to a 2mm overbite. I haven’t seen a single one that creates a 4mm underbite. I am going to query this with the orthodontist but wanted to know how far forward other people’s bottom teeth were pushed with the blocks? Does anyone also end up with a massive underbite?