Rubber bands hooks upper teeth

Hi, a few months ago my orthodontist applied \'hooks\' (that\'s what they called them) on to my upper and lower teeth. Recently, they put a rubber band from the hooks on both sides of my upper teeth towards the back of the upper teeth (hopefully that makes sense) All of my friends have bands, but they\'re not permanently in, yet the ones I have seem to be. I cannot remove them, and food is so easily trapped in i\'m worrying it may lead to the demineralisation of my teeth. What are the permanent rubber bands in my mouth? Is it normal for them to be permanent? Oh, and my dentist gave me fluoride toothpaste and I seem to remember him saying something like \'only use it in the night\', but im not entirely sure if I heard him correctly. What would your advice be on using fluoride toothpaste/mouthwash correctly to ensure I protect my teeth? (is it every time I brush my teeth or only at night?) Thank you! Matt.