An adult dwarf caiman, as with any species of croc, will have a very powerful bite. As Adam indicated, if it grabs you and decides to shake, rattle and roll, you could easily part with a finger (well, the finger would part with you, really...)
People always assume that since the dwarf caiman is smaller than the other species, it may not be as strong. Have a good look at an adult P palpebrosus, and you will see that it is perfectly capable of doing the same damage as most crocs of the same size.
The only thing is that these guys may be less inclined to roll than would other species. They do like the shake, though !