Could properly fitted dental branemark implants ever come loose?

Yes: While dental implants have a very successful track record they are not 100% foolproof. The patient's health, immune system and how well they care for their implant all play a role in success. Even if a procedure is succssful 98% of the time, someone will fall into the 2% and experience a failure. Working together doctor and patient can minimize the risk of failure.

Depends: Rarely does this happen. However, so much depends on the restoration placed on them AND the very careful routine monitoring of that and maintenance, both daily and professionally. All implant restorations should be checked for the bite contacts at every cleaning - at least every 4-6 months- and appropriately adjusted. These are not like tooth supported restorations and require special attention.

It is possible: Even with success rates over 94%, any dental implants sometimes become loose and Branemark is not exception. The good news is if your bone is wide enough, and if it is high enough, you can have another implant.