You'll find removable and fixed retainers. Fixed retainers are also called bonded retainers and so are connected for the back of enamel with dental bonding. These are typically chosen typically for younger people who are unlikely to help keep up with their retainer with no it staying mounted into spot. https://simonqmjbt.tinyblogging.com/examine-this-report-on-orthodontic-products-in-uk-76566399