[logi_cal869]

Modern incidence of gingivitis is estimated to be nearly 50% of adults. This, in an era of dental medicine and oral hygiene.

The elderly would have all been institutionalized a century ago if this had any merit whatsoever. Inflammation has much stronger correlation to disease of the brain than poor oral health.

It’s BS. Your “definitive” is straw man; got bias?

[marktwain]

The elderly would have all been institutionalized a century ago if this had any merit whatsoever. Inflammation has much stronger correlation to disease of the brain than poor oral health.

That does not follow from the analysis at all.

Even today, with many more elderly surviving, 50% of the population does not show Alzheimer's symptoms.

About 10% of people over 65 have Alzheimers, about 1/3 of elderly die with some sort of dementia.

We do not know how many people had gingivitis a century or two ago. Certainly people lost teeth a lot faster. Nor do we have good information on how many had dementia a century or two a go.

Your assumption that:

The elderly would have all been institutionalized a century ago if this had any merit whatsoever.

Is just an assumption.