Trimming rabbits teeth is really for experienced people, though no way to get experience other than trying. I used to trim rabbit and rodent teeth with either a sharp scissors, or a cutting tool actually made for trimming teeth, or a nail clippers (like for cat nails). That latter one actually worked best for me, but I still had a rabbit every now and then who's teeth would crack or cut in an irregular and unpredictable way, either splitting down the center or even breaking off at or below the gum line. Though I personally did not see any serious long term repercussions with these bad experiences, split or cracked teeth can lead to serious problems, such as infection, chronic pain, anorexia and even bone loss.
Now that I know better, I no longer cut teeth this way. A dremel or dental drill works far better with little to no risk of cracking or splitting the teeth. However these methods do increase the chances of other problems such as incidentally cutting the lip or tongue, catching the fur or whiskers and causing some pain in that way, or even over-heating the tooth and causing problems with future tooth health. So in the practice I work in, we tend to sedate most rabbits so there is minimal movement and this decreases the risk of other complications I listed above.
But still, by far the best thing to do with overgrowing incisors is to remove them. Pet rabbits do not need them, so might as well take them out. I have not had any problems with the rabbits that I have taken the incisors out of.
While incisor overgrowth tends to be a genetic problem (though rarely due to injury or some sort of infection), molar overgrowth is almost always due to improper diet. So this latter problem, which is more complicated to deal with, is at least avoidable. Fiber fiber fiber fiber... and LONG fiber at that! Rabbits are really designed to eat continuously most of the day while they are not searching for food, hiding from predators or keeping cool... but pet rabbits find not only a lot more time on their hands, they also find less reason to eat all the time... food is higher calorie (eg. pellets etc.) and the lack of exercise allows them to either get overweight, or make them feel less hungry. either way, something bad starts to happen. Eating less, or less fibrous food, allows these molars to overgrow and that leads to a long list of common rabbit problems from sharp molar points, dental abscesses, ocular disease, pain, drooling, poor appetite, gut stasis, hepatic lipidosis, sore hocks, dysbiosis etc... one can pretty much draw a line from improper diet, and often subsequent dental disease, to most other common rabbit diseases. Best to simply feed them properly and avoid all the above problems.
