A dental hygienist (those people who do maintenance cleaning at dentist’s offices) told me that saliva quality is key to cavity and periodontal health. The abil

A dental hygienist (those people who do maintenance cleaning at dentist’s offices) told me that saliva quality is key to cavity and periodontal health. The ability of keep all teeth moist prevents plaque/tartar build up. I don’t know how true that is, but this at least provide an alternative hypothesis to the two that you listed.