From what I've read and understand, implants are a flawed concept. It doesn't matter if they are titanium or zirconium, the problem is the micrograp around the implants. The gap is generally big enough to allow to fit 8 bacteria abrest, and of course there is a connection from the oral cavity deep into the bone marrow. There is no way of keeping this sterile. Natural teeth are connected via ligaments and have a fluid that washes out the socket to keep it clean.
If you have a cavitat scan of your mouth and you have implants. You will probably find this.