How likely is a deep cleaning/root planing to cause root caries?

In January, I had a complete exam with x-ray and there was no mention of
root caries.

In  February, I underwent a full mouth deep cleaning/root planing and there
was no mention of root caries.

On July 17, I had a periodental maintenance treatment.  At this time, the
dental hygienist pointed out that I had significant root caries.  She gave
me Colgate Provident 5000 Plus as treatment.

On July 25, the dentist confirmed the root caries diagnosis and pointed out
several areas where root caries were present, including a crown that must
now be redone.

I am alarmed that the root caries seemed to appear so quickly and in
multiple teeth.  Further, I never had a problem with root caries prior to
the deep cleaning.  I am having extensive (and expensive) crown work done,
which can all apparently be undone in a relatively short time by root
caries.

I'd appreciate any advice or direction on this problem, particularly since
the extensive restorative work I've been undergoing over the past six months
is beginning to appear pointless with the onset of ongoing root caries.

Thanks,

Charles