The author of this paper, Miklossy, has been beating this particular drum since 1993. Her results have not been replicated. There are at least two citations in the literature, and one peer letter that you can find very easily that repudiate the earlier work completely.
It's intriguing, but a lot more work needs to be done.
Here are two earlier abstracts that trashed her work after the 1993 paper. http://jid.oxfordjournals.org/content/182/3/1006.short and http://journals.lww.com/neuroreport/Abstract/1999/05140/Alzheimer_s_disease_may_not_be_a_spirochetosis.18.aspx
I assure you that after five years of researching this issue, we are quite familiar with this literature, Fred. The research you claim was "trashed" was done 18 years ago and the science has moved on from these papers!
The first you linked to apparently did a search for the DNA of just one specific spirochete, borellea burgdorferi, the spirochete that causes Lyme Disease, in the bodies of AD victims. . . plus the other Borellea members that share that gene sequence that causes Lyme disease. This test is capable of recognizing only the fourteen species of spirochetes that cause Lyme disease, out of more than two hundred so far identified and named species of spirochetes! None of those happen to be oral spirochetes. The borellea family is not really implicated in this set of hypotheses, although I believe some suggested it, along with the one that causes Syphilis, as a candidate back then. It is merely a spirochete, among hundreds, if not thousands, of other species of yet to be identified and classified spirochetes..
The second 1999 paper refers to a study that attempted to find spirochetes by looking with a microscope at the blood of living patients, and a few autopsied brain samples (n=7). I could not read the entire report, but I am aware of the extreme difficulty most microscopy studies have of even SEEING spirochetes because spirochetes are transparent!
We continually run into doctors who buy an inexpensive, standard microscope, thinking they are being economical, who then look and fail to see the spirochetes in the mouths' of their patients. You have to use a Phase Contrast Microscope or you simply won't see them unless you properly prepare the slide by staining! That's a time consuming task. We know of microscopic studies that were reported negative, that when duplicated with PCMicroscopes were found to be positive, with thousands of spirochetes that were literally invisible under the normal light of a regular microscope. Monday, I will look to see if we have a copy of this paper and see what their microscope protocol was. I know that some work was critcized for what I described. I don't know if this was one of those. But, again, the science has moved on since 1999, 12 years ago.