I have just had retainers fitted by a local orthodontist. A few of my teeth have moved over the past few years and the dentist suggested having a mould created and then adjusted the mould so that the mould/teeth were then forced to be perfectly aligned and hopefully this would push the few non-aligned teeth into a straight position. However, when the dentist fitted the retainer, he created slits in the top and bottom so that they were easier to get on. I am slightly concerned, that a) if there is a gap in the retainer, how is it going to move my teeth? and b) I have just paid £400 for technically, a broken retainer.

Please can you advise whether this is normal procedure, (to cut retainers so that they are easier to fit on) and if so, will it actually move my teeth?