Crown falling off the implant

I had an NHS implant and crown about 22 years ago after I was hit in the mouth. It became unsightly as my gums have receded and I paid to have the crown replaced with a more pleasing one that wouldn't show and continued under my gum.

The NHS one never moved but this tooth keeps loosening and has fallen out over 5 times this year. My dentist has cemented it back in and is now going to replace the post.

I have had to have some gum excised to reveal the stump which has really upset me and I now don't want to smile. Will a new post help and would using a sonic toothbrush loosen the cement ?