Open contacts adjacent to dental implant restorations?

Open contacts adjacent to restored implants, as early as 3 months post restoration?  How is this possible.

Dr Massoomi open contact

In the most recent edition of the JADA, Dr. Gary Greenstein and his team, examined 5 studies in which the investigators looked the incidence of open contacts after implant restorations are inserted next to a natural tooth.

Results:  An interproximal gap developed 34% to 66% of the time after an implant restoration was inserted next to a natural tooth.  This event occurred as early as 3 months after prosthetic rehabilitation, usually on the mesial aspect of a restoration!

Conclusions.  Normal bite forces cause tooth movement and the implant acts like an ankylosed tooth.

Here is the link for the actual article: