Can a chin implant be dislodged if I fall and hit my chin with the ground?

Theoretically a chin implant can be displaced with severe chin trauma/injury. On the other hand, you can also fracture your mandible (chin bone). 

It is highly unlikely to dislodge a chin implant after surgery.  Most patients will form a capsule around an implant which is present about 48 hours after surgery.  After one month, the capsule formed around the implant will prevent the implant from moving easily.  In my patients who are involved in contact activities (boxing, MMA, etc) chin implant displacement resulting from trauma has not been an issue.

It someone with a chin implant were to fall and hit their chin on the ground hard enough, it is possible that the implant could move.  Most small bumps to the area would not cause any movement, but if there is enough force, the implant could shift.  

I have performed many Chin Implant surgeries over the years, some on military, swat and MMA fighters.  If the Chin Implant is placed below the covering of the bone (the periosteum) the implant should be secure at about 1 month after the surgery.  At that time, you'd have to have enough force to move the implant which would break the bone as well.