関連ワード:  how long do fixed retainers last    how long does fixed retainer last    how long do permanent retainers last    how long do bonded retainers last    how long do permanent retainers stay in    how long do permanent bottom retainers last    how long does permanent retainer glue last    how long should permanent retainers stay in    can i stop wearing my retainer after 5 years    how often should permanent retainers be replaced