I would like to start of with the exact opposite approach as every pet owner here, how dare you say this is due to irresponsible breeding? Do you know that? It's possible that the breeder you got this animal from ( we don't know who it is I never saw it posted anyway) put lots of money, thought, time, and knowledge into their pairings? That you're off on a whim that it was the breeders fault this happened because a vet who very likely (I might be wrong) knows little about chins ( most don't know much if anything, and do less than 1 chin necropsy a year) said it's because of the breeder?
A DNA could tell the "potency" of certain genes, but does that mean that the breeder purposely bred animals with an issue. Saying that you're going to have that breeder shut down is ridiculous and a great way to get yourself blacklisted from responsible breeders because no one wants to be falsely accused of poor breeding practices. Even if that animal was line bred that doesn't prove anything. The chin could have fallen off of a shelf or out of the cage and that could have also damaged the jaw or caused problems with the jaw. Can you prove that this did not happen? Can you know the chin did not fall out of the cage as a kit? Off of a shelf when you owned it? There is no laws against line breeding so on what grounds are you going to have them shut down on? If you had a pedigree then you would be able to see it right on the pedigree, most reputable breeders give out pedigrees pet people or not.
I agree with what I think Dawn is pointing at, that it's ridiculous to say they saw something in a necropsy that they did not see with xrays or physical exam. Since the results were back 4 days later that is not enough time to have the skull cleaned by beetles unless they had a bunch of very hungry beetles. The chin was eating just enough to sustain barely with 55 to 70 mL daily. You had some great recommendations to see a dental specialist, did you? I personally would love to see the xrays and jaw. You kind of said the xrays don't matter because the chin passed, but yet you want to "prosecute" the breeder? Why not the vets who did not properly diagnose it?
I know this is not a great post to put on someone who recently lost a loved pet, but to me, to read that this is being blamed on the breeder, as a breeder is offensive. Malo is not strictly genetic, and has many environmental factors.
With that said I'm terribly sorry you lost your chin, it's a hard thing to do, but this happens to a lot of people, there is no way to predict what animals will have teeth issues. As Dawn said tons of money has been put into research and trials for it, including hers. You came here looking for help, and you got help from one of the best people who have dealt with teeth issues out of probably the entire chinchilla community at least in the US, if not worldwide. People who have been through what you just went through and more. You're not alone, but threatening one breeder will not solve the issue. If malo could be stopped easily, it would have been done by now. You're money and effort is probably better spent helping other chins or rescues, instead of trying to "take down" one breeder who this doesn't happen again, because in the end, that one breeder is just a drop in the bucket, and really there is no way to prove that it was a genetic issue. If your vet will put that in writing I've love to see it and have his office number.