As with natural teeth, however, implants are prone to everyday wear and tear and occasionally present some difficulties. Rare problems include:
Crookedness. This is rarely a problem but may arise if the implants have been fitted by an inexperienced dentist.
Shifting. Implants are firmly anchored to a post which is attached directly to the jawbone and should not loosen or shift under normal circumstances.
Discolouration. Just as natural teeth can become discoloured by coffee, tea, red wine, smoking and other factors so can implants although they are more resistant to staining. A porcelain implant is less likely to become discoloured.
When properly fitted and cared for dental implants should last you a lifetime, although the actual dental crown will need replacing after a number of years.
Issues with dental crowns can usually be put down to either improper fitting by the dentist (which is unlikely and rare) or failure to take proper care of the teeth.
More detailed information can be found at https://yourdentalhealthresource.com/can-your-dental-implants-become-crooked-or-discolored-over-time/