I went to get a new Hawley retainer to replace one which is several years old but which I have been continuing to wear most nights. It turns out that the old Hawley  was not fitting properly and had  allowed my teeth to drift slightly out of line. I now have to wear my new Hawley 24/7 for 6 months to get and keep my teeth in the correct position.

So a lesson to all who have had braces to keep a close eye on your teeth even if you think you are following a good retention regime!

My orthodontic treatment provided for 12 months of retainer reviews after the end of my active treatment (one at 6 months and one at 12 months). I think this is quite common. After that it is up to you and your general dental practitioner to keep an eye on whether your teeth are being sufficiently retained.