No one should have trouble (pain, parts falling out or off) with their crowns or dental implants. IF they are having this problem, it means the dentist/oral surgeon is not competent. Same thing if your fillings come out. It was not done by a competent dentist.
Implants - Same thing. They should not hurt or come lose if they were properly done. I've had several close friends who had full sets of implants without any pain or problems. (They were in their 70s when they got them and were exchanging the for the dentures they'd had for years and years.
My mother had a bridge anchored to two teeth that had damaged the anchor teeth after many year years.
Her dentist suggested getting a bridge anchored by implants and sent her to a terrific oral surgeon. Painless other than the first day. Once the implants healed, the new bridge was installed via the implants and to this day, she has not had any more problems and it has been over 20 years.
Me - I cracked a molar and had to have it extracted. I was given two choices - bridge or implant. Implant about a third more. I chose the implant, went to the same oral surgeon and 18 years later, no problems at all. The oral surgeon is in the Palm Desert, California area and still practicing.
On the other hand, my aunt went to one in the Seattle, Washington area and had a slew of problems. How competent your dentist and oral surgeon are really truly matters. Truly!!
The problem with dentures and crowns is that they allow the jaw to experience bone loss due to the lack of strong/high bite pressure. The bite pressure is what causes the jaw to remineralize. Implants are better at keeping the bite pressure high which in turn, allows the jaw to remineralize.
Ask around for oral surgeon referrals by people. Look them up on Yelp and Health grades. Google them. Look them up on the state board in the state in which you reside. You can look up professional licenses and see if they have any lawsuits or complaints for free. If you're not sure how to do this, PM me. I'll help you.
Good luck!