On Thursday, July 25, 2019 at 12:53:03 AM UTC-5, Jeff Liebermann wrote:

It's difficult for me to resist additional topic drift. It appears
that the GentleWave system is version of what Dr Jacklich did in 1972.

Thanks for that link, Jeff. Interesting stuff! I actually have a Giromatic handpiece, which has a symmetrical (equal back-and-forth) reciprocation action. These days the reciprocation (if employed) is "asymmetric", with greater rotation in the "forward" direction. I've also used the "washed field" technique, though with a handpiece that vibrates at a "sonic" frequency.
The "Gentle Wave" device operates at multiple frequencies ranging from sonic to ultrasonic in a sealed environment under a slight negative pressure. The various solutions that are flowed through the tooth are "de-gassed" to prevent the formation of bubbles which would reduce the efficiency of the process. I don't know to what extent this current technology is derived from earlier devices, but it wouldn't surprise me to find an evolutionary trail. A lot of what we think of as "modern" endodontic technology can be traced back a hundred years or more. See this: https://www.youtube.com/watch?v=8xpOaAPMbxw
Steve