Is your vet experienced with piggies? Dental abscesses can be quite serious, and Bayril generally isn't the best antibiotic for treating abscesses. I sadly lost a guinea pig to a dental abscess a couple of years ago... I don't want to scare you but want to share my experience in case it helps you avoid something similar.
To try to make a long story short- my piggie was having difficulty chewing harder foods and developed a swelling along her jaw. She was taken to a vet who said he had experience with guinea pigs and who had treated my previous exotics (hedgehogs.) He gave her Baytril and lanced and cleaned the abscess under general anasthesia. He told me he checked her teeth and they were fine. I'm guessing by checking them he looked at them, because I never received a bill for an x-ray. She recovered from the anasthesia but did not resume eating, and it was obvious that there was still a deep infection because she continued to ooze really foul, nasty-smelling pus. We had to syringe feed and keep trying to rinse out the really deep wound in her face. After a few days with no improvement, we went back to the vet. He rinsed the wound out again and sent her home still on Baytril. After a couple more days of syringe feeds and oozing pus, her teeth were obviously maloccluded/overgrown and we went back. She was put under again, had her teeth clipped (too short) and the vet told us at that point that the infection was down into her jawbone (osteomyelitis) and the prognosis was bad. He still didn't offer her another antibiotic. A couple days later, she went into what I think was septic shock and died.
Shortly afterwards, my other piggie developed a lump on her back, and I sought out a new vet that only took small animals, even though it was a lot further out of my way. I found out that she doesn't even use Baytril for abscesses because it generally isn't effective against that kind of bacteria. I ended up leaving feeling that my poor piggie had been getting outdated care at the old vet... she may not have pulled through even with a specialist, but I'll always wonder if she would have had a better shot had she been given a different antibiotic and follow-up from a more experienced vet.
So my advice would be to make sure your vet has experience with rodents/guiena pigs and is up to date on what meds are safe and effective against different problems. A lot of vets will tell you that Baytril is the only drug to give for guinea pigs, but this really isn't true anymore. I would also make sure that the vet you see has experience with guinea pig dentals, because if there is an issue with the tooth root there may be an issue with the teeth or the alignment of the teeth, and an inexperienced vet could make the problem worse instead of better.
Sorry for sharing a story with a bad outcome... I know lots of pigs do bounce back from these issues! I would just make sure you have a very experienced vet from the start, because I always wonder if my piggie would have made it had the vet hit her with Zithromax on day one and had identified the malocclusion problem at the first visit.
