Numbness after chin implant is not unusual at 3 weeks
Although we prefer for the sensation to be intact, the numbness can be quite normal after chin augmentation especially if combined with neck numbness.
AT about this time, as the nerves recover, you should be experiencing alot of pins and needles sensations. These will be aggravated by tapping over you jaw just below the corners of your mouth.
It would be very unlikely that both nerves were damaged on both sides of your chin.
Discuss your concerns with your surgeon, so that he//she can...