At the National Zoological Park in Washington, D. C., a polar bear suffered a broken tooth, and keepers needed a safe way of treating the problem. The bear was rewarded first for sticking its nose through a slot in the cage door, then for allowing a keeper to lift its lip and touch its teeth. Finally, a veterinarian was able to treat the damaged tooth while the bear waited placidly for its familiar reward. This is an example of .

Explanation:

The process to establish a behaviour that in the present an individual is unable to perform is called shaping. or it can be defined as the procedure involving reinforcing behaviours that is closer to the target/desired  behaviour.

It was first used by B.F Skinner, he if famous for his theories that included changing behaviour through reinforcements.  

The process of shaping is important because an organism may not display the exact target behaviour spontaneously, we can bring it closer to the target behaviour by reinforcing the behaviour that is closer to the desired behaviour.