They normally do this when they are excited to see you. They want your attention, want a treat or playtime outside of their cage. So it tends to be more of a pet related problem.

You need to stop the rabbit from chewing the wire.
The best way I've found is to get a cage with vertical bars 
instead of the little squares of wire that they hook their teeth on.
If you can't afford a new cage then buy a small piece of closest
(vertical bar type) shelving to line the inside of the cage.
Rabbits normally only chew the front of the cage so the shelving
need only cover that part of the cage. You can replace the cage door with the closet shelving too.

If the bars don't work have a large open topped cardboard box or playpen ready. Put the bunny in it as soon as you arrive. That should be enough of a change to make the bunny happy until you have time to have proper playtime. 

Putting something new in the cage or playpen as soon as you arrive will also be a good distraction. You can use Hay, rotate different toys. The rabbit will want to smell and explore anything new and will forget about the wire chewing. 

Toys are made more exciting when they smell different from the bunnies own environment. When rotating the toys, don't put the unused toys in a box next to the rabbit cage. Put them somewhere that will make them smell different. Like outside, they'll smell like fresh air or leave one on your couch and it will smell like you. I switch the toys among my bunnies and they smell like a different bunny. The rabbits love this and spend hours exploring an old toy.

Proper front teeth will wear down naturally with pellets and hay.
If the teeth don't line-up then they become 
over grown and can even grow through the rabbit's
mouth or the rabbit can starve to death.

If the teeth are already pulled and are growing crooked,
you must clip them down. 
I've used large toenail clippers for want of a better tool.
They worked fine. 
I clipped the teeth down pretty short and was
careful to catch the little pieces of tooth. 
Mostly the bits of tooth  just crumbs into powered and it's not a problem.  It doesn't hurt the rabbit and it feels like trimming glass 
with nail clippers or bits of sand. It's very easy to do. It will have a gritty feeling unlike clipping nails. You can clip quite short. I've had to clip back to almost the base of the tooth. 

If you do clip that short... rabbits have a second set of teeth that grow behind the top front teeth. So when trimming the top teeth and you notice something weird, don't be alarmed.  

The second set of top teeth never grow much past the base of the teeth in front of them. 

There is no "quick" to worry about like clipping the rabbits toenails. You won't cause the rabbit pain or bleeding when clipping the teeth. Just clip short enough so the rabbit can eat.

You'll want to immobilize the rabbit by wrapping him in a towel.
Making sure his feet can't escape and cause trouble buy scratching you to get away.

Lay the rabbit propped up on his back, but elevated so the 
bits of tooth don't go down his throat.

If your rabbit isn't used to being on his back you'll need 
to practice with him when you're not trying to trim his teeth.

It's natural for a rabbit to panic when on it's back and try
to scratch to get away using his back feet.
Most show rabbits are used to being on their back to be examined.
Mine fall asleep or go into a trance. 
With practice your bunny will adjust to this unnatural pose.

The rabbit will want to squirm since it's something new.
You need to make this as calm and enjoyable as possible 
since you'll have to do it every few weeks.

Giving the rabbit Apple branches help them to keep the teeth
short, this can cut back on how often you need to trim his teeth.