I don't think that's how it spreads though. It's not a specific bacteria. Many species are linked to cavities and gingivitis including Streptococcus, Fusobacterium, Actinomyces, Veillonella, and more. Everyone of us already has these bacteria. The difference isn't so much the specific strains but the specific ecosystem in your mouth
Almost every one of us already has Candida albicans but we don't all get yeast infections. Almost everyone of us already has Cutibacterium acnes but we don't all get pimples. Almost everyone of us already has Streptococcus pyogenes but we don't all constantly have strep throat.
All three of those examples are examples of species that we all normally have and even play beneficial roles for our health (Streptococcus plays important roles in digestion, Cutibacterium can actually improve your skin health and protect your skin moisture barrier, and idk about Candida but I bet it has some benefits too lol). But when the natural ecology is disrupted they can grow out of control. E.g. yeast infections and strep throat are both significantly more common after taking antibiotics which can kill off other beneficial microorganisms that are often necessary to keep those "opportunistically pathogenic" microbes in check
I'm willing to bet it's the same story for bacteria that causes cavities or gingivitis. It's not a specific strain that you should be worried about but a pattern/ecology that you should be worried about. That's much harder to "spread" and has a lot more to do with factors like your daily habits, diet, and even genetics
Almost every one of us already has Candida albicans but we don't all get yeast infections. Almost everyone of us already has Cutibacterium acnes but we don't all get pimples. Almost everyone of us already has Streptococcus pyogenes but we don't all constantly have strep throat.
All three of those examples are examples of species that we all normally have and even play beneficial roles for our health (Streptococcus plays important roles in digestion, Cutibacterium can actually improve your skin health and protect your skin moisture barrier, and idk about Candida but I bet it has some benefits too lol). But when the natural ecology is disrupted they can grow out of control. E.g. yeast infections and strep throat are both significantly more common after taking antibiotics which can kill off other beneficial microorganisms that are often necessary to keep those "opportunistically pathogenic" microbes in check
I'm willing to bet it's the same story for bacteria that causes cavities or gingivitis. It's not a specific strain that you should be worried about but a pattern/ecology that you should be worried about. That's much harder to "spread" and has a lot more to do with factors like your daily habits, diet, and even genetics
tl;dr: I'm with grandma on this