This article appears in New Scientist:
newscientist.com/article/21...
Apparently the culprit is Porphyromonas gingivalis, the key bacteria in chronic gum disease. The mechanism is described in the article.
I think there are two aspects of interest to afibbers:
1. Afibbers have increased risk of dementia including Alzheimers
2. Gingivitis is also associated with a 50% increased risk of AF
So it would seem like a really good idea for afibbers to get rid of any gum disease. It's a double whammy, reducing the risk of both AF and Alzheimers.