periodontal disease

[Jabberwocky Dragons]

This sounds like a condition that was long in the making. I don't think you had anything to do with it, other than discovering it and taking corrective measures.

x2, 5 months is way too short of time for periodontal disease to spread deep into the bones. There is no way anything you did could have caused this.

I agree with homegrownscales, it would best to go ahead and surgically remove the infection while aggressively treating with antibiotics. Hopefully, the vet may be able to do a relatively less invasive surface debridement rather than removing deep pieces of jawbone. Please keep us updated on the little guy.