Steven Tyler Performs -- Black Eye, White Teeth

One day after Steven Tyler slipped and broke his face in a Paraguay shower, the rocker hit the stage in Asuncion last night sporting two new teeth ... and a gnarly shiner under his right eye.

Tyler's rep claims the singer was dehydrated from food poisoning when he collapsed in his shower Tuesday morning -- smashing his face and knocking out a couple of teeth.

63-year-old Tyler was treated by a local dental surgeon who replaced the chompers -- and judging by the fact that he performed an entire concert without a hitch ... the surgery couldn't have gone better.