sign of wearout crank teeth?
 

Can someone advise me at what sign to lookfor if a crankteeth is wearout?

it's been riding in mountain and street. 3years in total of 2500km

sorry for my poor english

You should get way, way more than 2500km out of a chain ring.

When the teeth wear, they look sharp and pointy, so that the ends have no roundness.

how many km/miles should a normal crankteeth can handle before it should be replaced? for example: 50% of xc riding and 50% of urban riding(My crank is a 01 ritchey comp from a complete bike).

thank you very much for your advice...

then again, maybe he's cross-chaining.